Congenital Abdominal Wall Defects and Umbilical Hernias Flashcards

Question

What timing/mode of delivery is optimal for gastroschisis and omphalocele?

Answer 1

Vaginal delivery has been shown to be both safe and beneficial to the mother and baby. Cesarean should be reserved for specific obstetric or fetal indications. Term or close to term delivery is recommended for both.

Answer 2

The intestines need to be covered with a ‘bowel bag’, and intravenous fluid resuscitation should be started. Babies should be positioned laterally to reduce mesen- teric kinking. The defect should be enlarged at the fascial level if it is too tight.

Answer 3

Care should be taken to prevent damage to the sac, and cover with a moist gauze. Intravenous fluid resuscitation should be started at the same time that a cardiac evaluation is performed and examination for other syndromes and defects is carried out [3].

Answer 4

Regardless of which approach is used, maintaining adequate bowel perfusion by avoiding kinking of the mesenteric vessels and high intra-abdominal pressures is key to maintaining bowel viability. Overall, outcomes are equivalent for simple gastroschisis that is closed primarily versus being placed in a silo. Definitive closure can be obtained in a variety of ways, ranging from sutured closure of the skin and fascia, to sutureless closure using the umbilical stalk as a patch to close the skin defect and allowing the defect to close spontaneously.

Answer 5

If the fascial defect appears to be causing bowel compromise the fascia can opened. The facial opening is generally extended to the patient’s right (opposite the umbilical cord) to avoid injury to the umbilical vein medially. The skin does not need to be opened in most cases.

Answer 6

Closing or vanishing gastroschisis refers to when the fascial defect decreases in size or closes completely prior to birth. This can result in bowel compromise with an atresia and potential for short bowel syndrome [2].

Answer 7

Complex gastroschisis is defined as those patients with intestinal complications including atresia, ischemia, or perforation at birth. Development of NEC was con- sidered to be complex, however that is not present at birth and has been excluded [1, 2].

Answer 8

The amniotic sac can rupture prenatally in patients with omphalocele. While the basic principles of the bowel requiring coverage to prevent dehydration and infection still apply, recognition of this is critical as it affects the workup that the patient requires and the comorbidities that will affect the patient’s course. In general, these patients will not have adequate abdominal domain to be able to place a spring-loaded silo and will require a silo or mesh to be sewn to the fascia and skin for placement. These are difficult conditions to manage [3].

Answer 9

Following abdominal closure, patients should be closely monitored for signs of abdominal compartment syndrome, including respiratory compromise, hypotension, and impaired renal function. Nutritional support with parenteral nutrition will be required until bowel function returns.

Answer 10

Impaired bowel motility and ability to absorb nutrients both lead to feeding difficulties in neonates with gastroschisis. This bowel dysfunction is thought to be related to the inflammatory peel that occurs as a result of contact of the bowel with amniotic fluid, as well as to decreased numbers of interstitial cells of Cajal seen on pathologic analysis. Use of prokinetic agents has not been shown to improve time to goal feeds. It takes 2–4 weeks in cases of simple GS for the dysmotility to resolve [2].

Answer 11

A variety of options exist that are used based on the size of defect and the ability of the patient to undergo surgical interventions. Primary repair can be performed in some patients with small defects (with those <1.5 cm commonly called hernias of the cord) when the patient has adequate abdominal domain and the associated anomalies do not preclude surgical intervention. Other methods include staged closure, in which the amniotic sac is inverted to serially reduce the abdominal content until the abdomen can be closed primarily or with mesh. Delayed closure involves excising the amniotic sac and sewing a mesh to the abdominal wall fascia or skin that can be used for reduction prior to closure. Scarification involves the use of topical agents to promote formation of an eschar over the amniotic sac that will gradually epithelialize over time. If closure of the abdomen does not involve closure of fascia, the resulting ventral hernia is generally closed primarily or in stages when the child is several years old [1, 3].

Answer 12

Overall outcomes for patients with gastroschisis are largely based on whether it is a simple or complex defect. Those with complex GS have longer length of stay and are far more likely to develop intestinal failure and liver disease. Gastroschisis remains the leading cause of intestinal failure requiring intestinal transplant. It is also associated with cryptorchidism, which is generally addressed at one year of age. Malrotation is part of the defect, but rarely leads to volvulus. Intestinal obstruction may occur and present with bilious emesis and should be promptly assessed [1, 2]. For patients with omphalocele, outcomes are likely related to several factors, most notably associated cardiac and neurologic anomalies. Additionally, pulmonary hypoplasia is common in omphalocele patients with large defects and can lead to long term respiratory failure requiring tracheostomy. Several risk stratification categories have been created, but none is commonly used [1, 3].

Answer 13

Neurodevelopmental outcomes among patients with gastroschisis have not been well studied and are largely unknown to date. Patients with omphalocele overall have decreased motor and language score for age, with 35% having severe neu- rodevelopmental delay, which may reflect the multiple congenital issues. Simple gastroschisis patients are not considered to have any long-term neurodevelopmental issues [1–3].

Answer 14

``` Sternal cleft Ectopia cordis Cardiac structural defects Epigastric omphalocoele Morgagni hernia ```

Answer 15

B. Lateral umbilical ligament is the remnant of the omphalomesenteric vein.

Answer 16

E. Gastric contents

Answer 17

D. Silver sulfadiazine

Answer 18

B. Short mesentery.

Answer 19

A. Develops because of involution of right umbilical vein, which may leave a weak area.

Answer 20

Gastroschisis occurs in 1 in 4000 live births. An increased incidence in mothers younger than 21 years of age has been widely documented, although the reasons leading to the rising numbers are unclear. There has been a significant worldwide increase in the incidence of gastroschisis in all maternal age groups over the past two decades. Preterm delivery is more frequent in infants with gastroschisis, with an incidence of 28% compared with only 6% in babies without an abdominal wall defect.

Answer 21

Week 4 AOG: The abdominal wall forms during the fourth week of gestation when differential growth of the embryo causes infolding in the craniocaudal and mediolateral directions. Week 6 AOG: During the sixth week, rapid intestinal and liver growth leads to herniation of the midgut into the umbilical cord. Elongation and rotation of the midgut occurs over the ensuing 4 weeks. Week 10: By week 10, the midgut returns to the abdominal cavity, where the first, second, and third portions of the duodenum and the ascending and descending colon assume their fixed, retroperitoneal positions. At the most basic level, an abdominal wall defect involves an interruption of these embryologic processes and results in abnormal development. One theory suggests that gastroschisis results from failure of the mesoderm to form in the anterior abdominal wall. Currently, the ventral body folds theory, which suggests failure of migration of the lateral folds (more frequent on the right side), is most widely accepted. This implies that a gastroschisis develops early in gestation and before an omphalocele might develop. [H&A] — The exact etiology of gastroschisis is not well understood. Possible explanations include rupture of the physiologic umbilical hernia, perforation of the abdominal wall to the right of the umbilicus due to weakness following resorption of the right umbilical vein, or failure of migration of the lateral abdominal folds, more frequently on the right. The anomaly is therefore best considered to result from an in utero accident or single event, a concept supported by the rare association with chromosomal syndromes or extraintestinal congenital anomalies. [Sherif]

Answer 22

There are a variety of potential agents that have been implicated in the development of gastroschisis; however, no specific causal relationship has been established. A number of possible causative factors, including tobacco, certain environmental exposures (nitrosamines), cyclooxygenase inhibitor use (aspirin and ibuprofen), and decongestants (pseudoephedrine and phenylpropanolamine), have been suggested as etiologic agents. The well-known association of lower maternal age and low socioeconomic status with a higher incidence of gastroschisis has been linked with violence against women during gestation as a potential factor. Other factors such as change in paternity for gestations also have been suggested.

Answer 23

Most pregnancies complicated by gastroschisis are diagnosed sonographically by 20 weeks’ gestation. Routine ultrasonography (US) often suggests the abnormality that is confirmed on a higher level US. Often US is performed because of an abnormal maternal serum α-fetoprotein (AFP) level, which is universally elevated in the presence of gastroschisis. Detection of bowel loops freely floating in the amniotic fluid and a defect in the abdominal wall to the right of a normal umbilical cord are diagnostic of gastroschisis. Intrauterine growth restriction (IUGR) has been noted in a large number of these fetuses. Some fetuses with gastroschisis are not diagnosed prenatally and are discovered at the time of delivery, which can result in challenges with neonatal management. These neonates must be transferred to a center with the ability to care for gastroschisis. Fortunately the incidence of previously unknown gastroschisis at delivery is becoming rare with improved prenatal care. Data regarding outcomes of gastroschisis with inborn versus outborn babies does not suggest a worse outcome for either group.

Answer 24

The ideal prenatal test would be able to accurately differentiate gastroschisis fetuses at risk for complications such as intestinal loss or closing defects. Despite extensive use of US in fetal gastroschisis and the identification of multiple potential predictors of an adverse outcome (such as complex gastroschisis), there is no consensus on their use in selecting fetuses for early delivery. Factors that maternal-fetal medicine experts consider important for gastroschisis are intra-abdominal bowel dilation, bowel wall thickening, gastric dilation, IUGR, polyhydramnios, liver herniation, urinary bladder herniation, and changes in bowel dilation over the gestation. Two systematic reviews/meta-analyses looked at the accumulated studies on prenatal indicators and risk factors in gastroschisis, noting the same predictors listed earlier. Both reviews concluded that although in some cases a combination of two or more indicators may be used to identify fetuses at risk for complications, there was no reliable factor, and much discrepancy existed between centers and experts regarding the exact definition of normal and abnormal. Gastroschisis is associated with a variable degree of inflammatory thickening of the visceral bowel walls, which results in the characteristic appearance of “matted” intestinal loops. The reason for this inflammatory “peel” is unclear, but the presence of elevated levels of cytokines (interleukin-6 [IL-6], IL-8, tumor necrosis factor [TNF]-α) in the amniotic fluid, in addition to the effects of fetal urine, is thought to cause the abnormal collagen deposition. One report noted a significant decrease in interstitial cells of Cajal (ICCs) in gastroschisis bowel in neonates compared with controls, further implicating the role of the proinflammatory state in utero. Studies in animal models have shown that the duration of amniotic fluid exposure is correlated with the degree of the inflammatory peel and intestinal dysmotility. Efforts to reduce this exposure by either amniotic fluid exchange or intrauterine furosemide treatment, which induces fetal diuresis, have shown to be beneficial in animals. These animal studies spurred early human trials with amniotic fluid exchange in Paris and Italy, but these trials have proven inconclusive and are not being performed in humans at this time. The optimal mode and timing of delivery for a fetus with gastroschisis has been debated for many years. Proponents of routine cesarean delivery (C-section) argue that the process of vaginal birth results in injury or increased risks for infection and sepsis. However, the literature suggests that both vaginal delivery and C-section are safe. A metaanalysis failed to demonstrate a difference in outcomes for infants delivered either vaginally or by C-section. Therefore, the delivery method should be at the discretion of the obstetrician and the mother, with C-section reserved for obstetric indications or fetal distress. Preterm delivery of the fetus with gastroschisis has been advocated to limit exposure of the bowel to the amniotic fluid. Damage to the pacemaker cells and nerve plexi may contribute to the profound dysmotility and malabsorption seen in these infants. Early delivery may theoretically mitigate these effects, but the data are increasingly against preterm delivery. Although a number of singlecenter retrospective studies have suggested that elective preterm delivery before 37 weeks’ gestation is beneficial and have reported an earlier time to attaining full enteral feeds and a decreased length of stay, these investigators also utilized a care pathway that may have been responsible for the improved outcomes. Currently available evidence does not support the practice of elective preterm delivery for gastroschisis.

Answer 25

Neonates with gastroschisis have significant evaporative water losses from the open abdominal cavity and exposed bowel. Appropriate intravenous access should be obtained and fluid resuscitation initiated after birth. Nasogastric (NG) decompression is important to prevent further gastric and intestinal distention. Routine endotracheal intubation is not necessary. The bowel should be wrapped in warm saline-soaked gauze and placed in a central position on the abdominal wall. The neonate should be positioned on the right side to prevent kinking of the mesentery with resultant bowel ischemia. Viscera are covered by a plastic wrap or the infant is placed partially in a plastic bag (“bowel bag”) to reduce evaporative losses and improve temperature homeostasis. Although gastroschisis most often is an isolated anomaly, thorough examination of the neonate is important. Concomitant bowel atresia is the most common associated anomaly in patients with gastroschisis, with rates ranging from 7–28% in several series. A review of the literature noted rare occurrences of associated anomalies in the cardiac, pulmonary, nervous, musculoskeletal, and genitourinary systems, as well as chromosomal abnormalities in babies with gastroschisis. Additional evidence suggests that excess fluid resuscitation is detrimental and results in edema, an increase in time to closure, and an increased risk of abdominal compartment syndrome.

Answer 26

Over the course of the last two decades, realization that there was a subset of gastroschisis neonates that were at higher risk for morbidity and mortality has led to the development of risk stratification. This risk was based on the presence or absence of any intestinal complication (atresia, ischemia, perforation, or development of necrotizing enterocolitis [NEC]) and could be classified as complex or simple gastroschisis. Patients with complex defects have a higher mortality rate, require multiple operative interventions, and have a prolonged hospitalization, increased rates of sepsis, and higher rates of prolonged cholestasis and need for intestinal transplantation due to intestinal failure. This definition and an improved understanding have allowed better parental counseling, hospital planning, and transfers to centers with advanced capabilities to care for complex patients. In addition, this classification allows for an improved ability to compare treatments—for example, simple versus complex defects—and remove the variability associated with the complex patients.

Answer 27

The primary goal is to expeditiously return the viscera to the abdominal cavity while minimizing the risk of damage due to intestinal injury or increased intra-abdominal pressure. The two main treatment options are primary repair and delayed closure with use of a temporary silo and serial reduction. In all cases, inspection of the bowel for obstructing bands, perforation, or atresia should be undertaken. Bands crossing the bowel loops should be lysed before silo placement or primary abdominal closure to avoid potential subsequent intestinal obstruction. The choice of which course to undertake is dependent on the presentation of the bowel, as well as surgeon and institution preferences, and is both variable and controversial.

Answer 28

Attempted primary closure is usually performed in the operating room under general anesthesia, but some surgeons have advocated primary closure at the bedside without anesthesia. Some surgeons prefer to close the skin only and leave the fascia separated. Others have described the use of the umbilicus as an allograft. A prospective randomized study comparing sutureless closure to sutured repair noted that the time to full feeds and length of stay was significantly longer in the sutureless group, despite no additional complications. Youssef et al. performed a systematic review and meta-analysis of flap versus fascial closure, and found that flap repair was associated with equivalent or superior outcomes to fascial closure. Prosthetic options for fascial closure include nonabsorbable mesh or bioprosthetic materials such as porcine small intestinal submucosal mesh. In the past, most surgeons have excised the umbilicus during closure; however, preservation of the umbilicus has been shown to lead to an excellent cosmetic result. Therefore, most surgeons will now try to save it.

Answer 29

Intra-abdominal pressure measured by either the bladder or stomach pressure has been used to guide the surgeon during reduction. Pressures higher than 10–15 mmHg are often associated with decreased renal and intestinal perfusion, and a silo or patch may be needed, whereas above 20 mmHg they correlate with organ dysfunction and complications. Similarly, an increase in central venous pressure greater than 4 mmHg has been correlated with the need for silo placement or patch closure. Splanchnic perfusion pressure, the difference between mean arterial pressure and intra-abdominal pressure, also has been used to guide the reduction. A splanchnic perfusion pressure less than 44 mmHg implies a decrease in intestinal blood flow.

Answer 30

In the mid-1990s, a prefabricated silo was developed with a circular spring that is positioned under the fascial opening, without the need for sutures or general anesthesia. This has made it possible to insert the silo in the delivery room or at the bedside. After placement, the bowel is reduced daily into the abdominal cavity as the silo is shortened by sequential ligation. It is important to continuously assess the bowel viability while in the silo to ensure the bowel is receiving adequate blood flow. When the contents are entirely reduced, fascial and skin closure are performed. This process usually takes between 1 and 14 days, with the majority within 5 and 6 days, depending on the condition of the bowel and the neonate. Definitive closure in the operating room is similar to that for primary closure with the choices for sutureless versus skin versus fascial closure; again, prospective trials and systematic reviews would suggest that sutureless repair is associated with a longer hospital stay. Residual ventral hernia rates are reported to be 60–84% in the sutureless repair technique, the majority of which close spontaneously. Closure of the skin in a transverse direction may create a “keyhole” appearance with a horizontal scar to the right of the umbilicus. Some surgeons advocate a vertical closure to allow for a central umbilicus. A purse-string type skin closure around the umbilicus can be performed to create a scar around the umbilical stump for improved cosmesis. The routine use of a preformed silo has increasingly come into favor, with the theory being that avoidance of high intra-abdominal pressure will avoid ischemic injury to the viscera and allow earlier extubation. However, it is still possible that the bowel can become ischemic in the silo and close observation and serial examinations are important to assess for the bowel’s viability. Current evidence suggests that there is no significant difference in outcome with either approach (silo vs immediate closure) for patients with simple gastroschisis.

Answer 31

Up to 10% of neonates with gastroschisis have an associated atresia, most commonly jejunal or ileal. In a database review of 4344 infants with gastroschisis, a 5% incidence of small bowel atresia and a 2% incidence of large bowel atresia were noted. In addition to making the defect a complex one, an atresia requires significant alteration in the management scenarios. Data from a multicenter study found that in the complex group, the atresia patients had significantly worse outcomes. Management of the atresia depends on the state of the intestine. Most surgeons will not perform a bowel anastomosis in the setting of an extensive inflammatory peel as there will be concern for the integrity of the sutures. An analysis of the CAPSNet data specifically looking at early versus late operations for intestinal atresia associated with gastroschisis (defined as before or after 21 days of life) found there was no significant difference in outcomes and potential for early feeding if the operation was performed sooner. However, an anastomosis was not always performed at operation. At times, depending on the extent of the inflammatory exudate on the intestine, it is not possible to make the diagnosis of an atresia at closure. In those cases, the atresia is usually diagnosed a few weeks later when there is no return of bowel function and a contrast study is obtained. In these cases, an operation is usually deferred for 3–4 weeks to allow some resolution of the inflammation. If it is detected at the time of birth or final closure, an ostomy can be created to allow earlier resumption of feeding while waiting for the intestines to normalize. Some surgeons have chosen to create an early stoma, particularly in the case of a distal atresia, to allow for enteral feeding while awaiting repair. There is no consensus about the optimal management for these complicated problems. [H&A] — Atresia associated with gastroschisis can present in one of three patterns. The first is confirmed atresia at birth after examination of the bowel during attempted primary closure or silo reduction. The second is suspected atresia that cannot be immediately confirmed due to severe bowel matting. The third is atresia or stenosis diagnosed several weeks after birth due to lack of progression of bowel function. Gastroschisis-associated atresia is a challenge as the bowel matting and inability to confirm distal patency often preclude a primary intestinal anastomosis on the first day of life. The choices are to reduce the bowel with the atresia in place or divert the obstruction for later anastomosis. The former option is quite safe, as perforation of an intestinal atresia during the first few weeks of life is highly unlikely given the poor motility of gastroschisis bowel and the ability to decompress the obstruction medically with a nasogastric tube. The surgical dictum has been to wait 6 weeks and allow the bowel quality to improve before addressing the obstruction. The evidence for this practice is weak. A much shorter wait of 2–3 weeks allows for enough improvement to dissect the bowel, perform an anastomosis, and initiate enteral feeds earlier. Patients with suspected atresia at first inspection of the bowel, and all patients who have shown a lack of onset of bowel function by the end of the fourth week of life, should be investigated by a small bowel fall-through study. A high suspicion of mechanical obstruction on this study should prompt a laparotomy, bowel resection, and primary anastomosis unless another contraindication exists. In fact, intestinal strictures associated with gastroschisis can present after hospital discharge. [Sherif]

Answer 32

An intestinal atresia should be differentiated from “vanishing bowel” in infants with gastroschisis. A “closing gastroschisis” is when the defect size decreases prior to delivery. As the hole gets smaller, the blood supply to the viscera progressively diminishes and can result in an atresia. In extreme cases, the intestine outside the abdominal cavity completely disappears and results in congenital short bowel syndrome. There is no prenatal US finding that can reliably distinguish this condition. However, intra-abdominal bowel distention or dilation can occur, which can help in deciding to deliver early in some patients. Although this is a rare finding, it usually results in short bowel syndrome. [H&A] — A particularly devastating form of complex gastroschisis, closing gastroschisis, is increasingly being reported. This is essentially a strangulated gastroschisis due to in utero closure of the defect. The anomaly also presents with a wide spectrum of findings, but typically results in bowel atresia proximally and distally with severe ischemia or necrosis of the eviscerated bowel. Short bowel syndrome is common. Closing gastroschisis may be suspected if intra-abdominal bowel dilatation is seen on ultrasound, in combination with a stable, dilating, or possibly shrinking extra-abdominal bowel mass. This may be an indication for early delivery, affording an opportunity to salvage the bowel from an impending catastrophe. Ultrasound findings showing progressive intra-abdominal and extra-abdominal dilatation, raises the suspicion of closing gastroschisis. [Sherif]

Answer 33

In cases in which primary closure has been performed, care must be directed to ensure there are no effects from increased abdominal pressure. These effects may range from perturbations in ventilation, renal function, and gastrointestinal ischemia. If an abdominal compartment syndrome is suspected, prompt laparotomy and silo placement should be performed. Gastroschisis is associated with abnormal intestinal motility and nutrient absorption, both of which gradually improve in most patients. Introduction of enteral feeding is often delayed for weeks while awaiting return of bowel function. The exact cause of the prolonged dysmotility is poorly understood but may be linked to the diminished number of ICCs in the intestine and the degree of peel. During this waiting period, nasogastric decompression and parenteral nutrition are required. When bowel activity begins, enteral feeds can be started and slowly advanced. Because progression to full enteral feeding can take weeks, central venous access is important. Early oral stimulation is recommended to prevent loss of the sucking reflex. Prokinetic medication may be helpful in the postoperative period but lacks evidence. Postoperative NEC has been found in full-term infants with gastroschisis in higher than expected frequencies (up to 18.5%). Significant bowel loss from NEC can predispose to short bowel syndrome and its associated hepatic and infectious complications. On the other hand, another group found that the clinical course of babies with gastroschisis who developed NEC often followed an uncomplicated course. There are reports suggesting that infants with gastroschisis who were fed breast milk had a lower incidence of NEC than those who were fed formula.

Answer 34

Long-term outcomes for infants born with gastroschisis are generally excellent. However, the presence of complex disease is the most important prognostic determinant for a poor outcome. A recent population-based cohort study from the United Kingdom with 301 patients noted that babies with complex gastroschisis took a median of 21 days longer to reach full enteral feedings, had longer total parenteral nutrition (TPN) use, and had almost 2 months longer length of hospitalization. In addition, they were twice as likely to develop intestinal failure and six times more likely to develop liver disease. Gastroschisis is also the most common reason for intestinal transplantation due to intestinal failure. Two studies have looked at the potential effect of hospital volume on gastroschisis outcomes. A CAPSNet report divided hospital into low- and high-volume centers based on their mean number of cases. They found tremendous practice variability in terms of management. However, the volume or practice variability did not seem to change outcomes. A second study using the California birth-linked database noted that high-volume hospitals had lower mortality when compared with low-volume facilities. At this point, it is unclear if there is any volume outcome relationship for gastroschisis, especially simple defects. Another study compared the outcomes of simple gastroschisis between Canada and the United States and noted significantly less mortality in Canada. Most gastroschisis patients have an intestinal rotational anomaly. This is typically not repaired at the time of closure and does not have the same incidence of midgut volvulus as other causes of malrotation. One study compared the incidence of volvulus between omphalocele and gastroschisis, and noted a higher incidence of volvulus developing after repair in children born with an omphalocele (4.4% vs 1.0%). The authors indicate that a Ladd procedure should be considered at the time of repair in infants born with an omphalocele. All parents of babies born with an abdominal wall defect should be cautioned regarding bilious emesis and instructed to take urgent action if that occurs. Cryptorchidism is associated with gastroschisis in 15–30% of cases. Several retrospective analyses have shown that placement of the herniated testis into the abdominal cavity will result in normal testicular descent into the scrotum in most cases. Most centers recommend allowing a year for spontaneous descent and then performing an orchiopexy if needed. The orchiopexy can be performed laparoscopically at that time. Cosmetic appearance of the abdomen is important for many children. If the umbilicus is sacrificed during the repair of the gastroschisis defect, up to 60% of children report psychosocial stress from not having an umbilicus. Long-term problems such as neurodevelopmental delay, learning issues, and overall health-related quality of life have not been well studied for gastroschisis. A number of investigators are looking at these outcomes at school age and beyond. Although the number of patients is low, the data suggest that gastroschisis survivors have long-term issues with verbal intelligence and poor performance with attention deficits. One study pointed out that the ones that fared the worst had complex gastroschisis or were preterm, which carries a higher risk for neurodevelopmental delays. Further evaluation and assessment of these children is critical to understand their long-term issues and be able to design interventions to help them achieve their full potential.

Answer 35

The incidence of omphalocele seen at 14–18 weeks is as high as 1 in 1100, but the incidence at birth drops to 1 in 4000–6000. As opposed to gastroschisis, the incidence and prevalence of omphalocele has remained stable in the United States. Thus, there is a considerable “hidden” mortality for a fetus with an omphalocele resulting from spontaneous loss of the fetus or termination. One review noted that requests for termination of pregnancy in omphalocele cases were as high as 83%.

Answer 36

The current understanding of the etiology for an omphalocele suggests that this defect is not from a failure in body wall closure or migration. Rather, because the umbilical cord is attached to the sac, it is thought that an omphalocele develops due to a failure of the viscera to return to the abdominal cavity. Defects in the FGF, HOX, and SHH pathways are implicated in the development of omphalocele using an animal model. Other intra-abdominal viscera including liver, bladder, stomach, ovary, and testis also can be found in the omphalocele sac. The sac consists of the covering layers of the umbilical cord and includes amnion, Wharton jelly, and peritoneum. The location of the defect is in the mid-abdominal or central region but may occur in the epigastric or hypogastric regions as well.

Answer 37

As opposed to a gastroschisis, an omphalocele has a relatively high incidence of associated defects. These can range from chromosomal abnormalities—trisomies 13, 18, 21, and 45 X—to syndromes and nonsyndromic organ system anomalies (e.g., Beckwith–Weideman, pentalogy of Cantrell). The severity and number of these associated issues determine the outcomes in omphaloceles.

Answer 38

Elevation of maternal serum AFP is also present in many pregnancies complicated by omphalocele, although not as common as in gastroschisis. The diagnosis of omphalocele can be made by two-dimensional US at the time of the normal 18-week US evaluation for dates. Early first-trimester detection is possible if three-dimensional US is utilized. US evaluation is very useful for the detection of associated anomalies in these infants. This is important as an isolated omphalocele has a survival rate of over 90%, but those with other defects (such as cardiac) are much less likely to survive. Prenatal US and karyotyping are able to identify only 60–70% of the associated defects that are found postnatally. Prenatal screening in an infant with an omphalocele requires a detailed evaluation of the cardiac (14–47% incidence of anomalies) and central nervous (3–33% anomalies) system as severe defects may lead to a discussion about termination of the pregnancy. There has been attention focused on developing a reliable sonographic predictor of postnatal morbidity and survival. Unfortunately, the prenatal finding of a “giant” omphalocele has not been accurate in predicting postnatal outcomes. Investigators have studied ratios between the greatest omphalocele diameter compared with abdominal circumference (O/AC, or omphalocele ratio), the femur length (O/FL), and the head circumference (O/HC), and have attempted to correlate these ratios with postnatal morbidity and mortality. Of these variables, the most useful may be the O/HC or the O/AC. Prospective studies are needed to assess the usefulness of this information.

Answer 39

The route of delivery of infants with an omphalocele should be dictated by obstetric considerations as C-section has not been shown to be advantageous. Pregnancies are usually allowed to come to term, and spontaneous labor with vaginal delivery is preferred. There is no advantage of carrying an omphalocele fetus post term. Therefore, induction is performed in mothers in whom spontaneous labor has not occurred. However, many neonates with giant omphaloceles continue to be delivered by C-section in the United States because of the fear of liver injury.

Answer 40

After delivery, a thorough search for associated anomalies is important. All neonates should undergo an echocardiographic evaluation. Renal abnormalities should be assessed by abdominal US. Neonatal hypoglycemia can be associated with Beckwith–Weideman syndrome. Blood samples for genetic evaluation should be obtained as well. In preparing infants with omphalocele for transport, risks arising from associated anomalies should be specifically addressed. Infants with an omphalocele do not have as significant fluid and temperature losses as those with gastroschisis, but these losses are still higher than those with an intact abdominal wall. The sac itself can be covered with saline-soaked gauze and an impervious dressing to minimize these losses. An NG tube should be inserted and placed to suction.

Answer 41

Risk assessment in omphalocele is not as clear cut as in gastroschisis, in which there is a relatively straightforward division into simple and complex types. There are several ways to do risk adjustment for omphaloceles. One is based on the presence or absence of associated anomalies. Isolated is one category in which there are no other abnormalities or they are relatively minor. Such a determination is important as isolated defects have a better prognosis. Omphaloceles may also be classified based on where they are in relation to the abdomen—hypogastric, central, and epigastric. Cloacal exstrophy is associated with a hypogastric defect, whereas epigastric ones tend to have a higher incidence of cardiac anomalies and are associated with pentalogy of Cantrell. Finally, there is also a size-based classification that separates omphaloceles into hernias of the cord, small, medium, large, and giant defects. There are data that suggest increasing size has a direct correlation with worse outcome, but the exact definition of these sizes is lacking, which makes it challenging to compare in the literature.

Answer 42

There are a large variety of repairs described, as a one-sizefits-all option does not exist. In a recent survey, authors of reports from 1967–2009 discussing closure of giant omphaloceles were asked to see if they were still using the same approach or whether they had modified their techniques. Interestingly, 42% of the authors no longer use the approach they favored in the original article. They concluded that there is currently no completely accepted technique to treat giant omphaloceles and two methods are used the most: staged closure and delayed closure. Bauman et al. reported a systematic review of the literature for repair of a giant omphalocele, with the data favoring initial nonoperative scarification. The definition of a giant defect is variable as some surgeons use size alone, others consider the presence or absence of liver herniation, others use an estimate of the amount of intestinal contents, and still others have used a combination of the amount of liver and intestine in the sac as well as size. This lack of an accepted definition is part of the reason for an inability to arrive at a consensus for management. [H&A] — First, is the omphalocele small or large? A defect resulting in only bowel herniation is usually small and can be closed primarily without tension or increased intra-abdominal pressure. This is the case even if the entire bowel mass is herniated. If the omphalocele is large and contains solid organs, this should prompt the second question: Are there significant cardiorespiratory comorbidities that are resulting in oxygen dependence, respiratory insufficiency, or hemodynamic instability? If the answer to this question is affirmative, the baby is best served by omitting any surgical procedure and applying local treatment to produce an eschar of the sac. The most common agent used currently is silver sulfadiazine which is applied to the sac once or twice daily. A controlled ventral hernia results and can be closed in one or more procedures later in life after the cardiorespiratory morbidities have been addressed. A component separation technique may be required in these patients to avoid mesh placement, but the overwhelming majority can be closed primarily. If the baby does not appear to have any significant cardiorespiratory comorbidity after 24–48 hours of observation, the goal should be to obtain complete fascial closure during the first few weeks of life in a primary or staged manner. Primary closure should be attempted and has proved successful in many cases of large defects containing all or most of the liver, such as seen in the index case. The surgeon can get an impression of abdominal domain by examining the abdomen. In some patients, the abdomen will appear “empty” despite a large omphalocele. In giant omphaloceles, the rectus muscles are always far apart. Transverse closure may be easier. Interrupted figure of eight or Smead-Jones sutures placed along the defect and then tied sequentially is my preferred technique. If the contents cannot be reduced due to lack of abdominal domain, or if the closure results in increased mean airway pressure over 25cm H2O or hemodynamic compromise, the surgeon can either use a biologic mesh to close the abdomen or convert to a staged closure by installing a spring-loaded or sutured silo, with or without an abdominal expander. In selected patients, the redundant omphalocele sac can be used as a silo. Vacuum-assisted closure (VAC) has also proved useful in these difficult cases. [Sherif]

Answer 43

Treatment options in infants with omphalocele depend on the size of the defect, the baby’s gestational age, and the presence of associated anomalies. Defects that are less than 1.5 cm in diameter are referred to as a hernia of the cord and are repaired shortly after birth if there are no major associated anomalies. The defects that are larger but still easy to close as they have minimal associated loss of abdominal domain also can be closed in the neonatal period. Primary closure consists of excision of the sac and closure of the fascia and skin over the abdominal contents. It is not unusual for an omphalomesenteric duct remnant to be associated with a small omphalocele. When dealing with a larger or medium-sized omphalocele, care must be taken when excising the portion of the sac covering the liver, because the hepatic veins may be located just under the epithelium/sac interface in the midline and can be injured. The inner portion of the sac is often adherent to the liver, and significant hemorrhage can result from tears in the Glisson capsule. Therefore, it is usually best to leave that part of the sac on the liver and not try to remove it. The inferior portion of the sac covering the bladder can be quite thin, and excision of the sac in this area may lead to bladder injury. The intra-abdominal pressure can become elevated during reduction and repair, leading to abdominal compartment syndrome. Therefore, in larger defects, some surgeons will measure bladder pressure and have mesh available if primary closure is not feasible. There are reports of primary closure of a giant omphalocele shortly after birth with good outcomes. In a report from London, 12 of 24 babies with a large defect had an immediate repair without any mortality. Compared with other similar infants, these patients had a shorter ventilator requirement and time to full feeding. However, this trial was not prospective, and there was significant selection bias with using immediate repair for the full-term and normal birth weight neonates.

Answer 44

In many cases, the loss of domain in the peritoneal cavity prevents primary closure without an undue increase in intra-abdominal pressure. Multiple methods have been proposed to obtain primary abdominal wall closure in these babies. Staged closure in the neonatal period involves the use of different techniques. These can be classified into methods that utilize the amnionic sac with serial inversion, and those in which the sac is excised and replaced with mesh and then closed over time. Amnion inversion allows gradual reduction of the sac followed by sac excision and primary or mesh closure. This technique has mostly fallen out of favor with only a few series reporting its use. Methods involving primary repair with mesh require removal of the amnionic sac, with the mesh used to bridge the fascial gap followed by skin closure. Repeated procedures to excise central portions of the mesh may eventually allow native fascial closure, or the mesh may be left in situ with skin over it. Some authors have advocated the use of biologic mesh that allows vascular and tissue ingrowth. Vacuum-assisted closure of these defects has been described as has a novel external skin closure system. There are many different techniques because no one method is uniformly applicable or successful.

Answer 45

Historically, children with large omphaloceles were managed using skin flaps that were mobilized to cover the exposed viscera, leaving a large ventral hernia that could, hopefully, be closed later. In 1967, Schuster first described the use of a Silastic silo to allow staged reduction for children with an omphalocele. With this method, the omphalocele sac is excised and the Silastic sheeting is sewn to the rectus fascia. Alternatively, the silo can be sutured to the full thickness of the abdominal wall. In our experience, the use of the preformed spring-loaded silos is usually unsuccessful in babies with omphalocele as the large size of the defect and lack of abdominal domain allows the silo to become easily displaced and it can be difficult to perform any reductions. Serial reductions for the silo that is sewn to the fascia are performed on a once- to twice-daily schedule until definitive closure can be obtained. If the fascial edges cannot be approximated in a reasonable time, prosthetic or mesh closure can be utilized.

Answer 46

Nonoperative techniques have in common the use of an agent that allows an eschar to develop over the intact amnion sac. This eschar epithelializes over time, leaving a ventral hernia that will likely require repair later in life. This approach is employed when the surgeon considers the defect too large to allow for a safe primary repair, or if the neonate has significant cardiac or respiratory issues. This is not a new concept, having evolved from the time of Dr. Robert Gross, who described using skin flaps in 1948. The primary concern in a baby with a large omphalocele is that an attempt at initial repair will result in potential life-threatening abdominal compartment syndrome or the inability to provide skin coverage. Initial reports described mercurochrome, alcohol, and silver nitrate as the eschar-producing agents that were very effective but were associated with toxicity (Fig. 48.13). Subsequently there have been reports of a number of substances, including silver sulfadiazine, povidone-iodine solution, silver-impregnated dressings, neomycin, and polymixin/bacitracin ointments. A randomized study from Africa compared povidone-iodine and Acacia nilotica, a naturally occurring plant substance, for scarification, and noted that there was a trend to earlier oral feeding and discharge with Acacia. Manuka honey use has been described in a report from Africa. The eschar and epithelialization may take 4–10 weeks. There are also reports that combine the use of an agent listed here with compression dressing, which helps in sequentially reducing the contents into the abdomen and facilitates subsequent closure. Rarely, operative closure may not be needed as the defect contracts and gradually closes, similar to an umbilical hernia. However, most patients will eventually require closure of a ventral hernia between 1 and 5 years of age. The ventral hernia repair is performed using a variety of techniques: primary fascial closure, autologous repair with component separation, or mesh repair.142,161–163 Although all may be successful, the number of patients in each report is small and failures are rarely reported. In some cases, innovative techniques have been utilized to recreate the abdominal domain, including the use of tissue expanders (Fig. 48.15). 164–166 While the initial reports of the staged Gross operation had significant mortality and morbidity, current results are much better. A systematic review of the literature that compared the use of staged surgical closure versus nonoperative scarification therapy in giant omphaloceles noted that survival and morbidity were better in the nonoperative managed patients.142

Answer 47

In cases in which the amnionic sac ruptures in utero, the prenatal imaging may be difficult to distinguish from gastroschisis. A large ruptured omphalocele is one of the most challenging pediatric surgical conditions to manage. At birth, there is the urgent need to cover the exposed viscera like a gastroschisis. However, the abdominal wall configuration and the defect itself are usually not amenable for placing a spring-loaded silo. In addition, as opposed to gastroschisis, there is a much more substantial loss of intra-abdominal domain that makes gradual reduction of the viscera very difficult. The goal is to cover the exposed abdominal viscera, which can be challenging. One small series had good outcomes in terms of survival, but there was a high incidence of intestinal fistulas, sepsis, and pulmonary hypoplasia. In most cases, a silo will have to be fashioned by suturing to the abdominal wall and skin together. Despite the creation of a silo, the reduction is usually still not possible, and some surgeons have advocated the use of biologic mesh to create a bed for skin to grow over and be grafted. At that point, the delayed closure of the ventral hernia may be contemplated. Respiratory issues such as pulmonary hypoplasia may complicate the management.

Answer 48

After any type of neonatal repair, most patients will require mechanical ventilation for several days. Feeding may commence when bowel activity resumes. Antibiotics are administered postoperatively for only 24–48 hours unless there are concerns for a wound infection. If a ventral hernia develops, repair may be deferred for 1 year or later to allow stabilization and a natural increase in abdominal domain. The method used for closure (primary vs staged with delayed primary closure or mesh) has not been shown to affect length of hospitalization, likely because the patient numbers are very small and because patient selection plays a role. The time to enteral feeding may be shorter with primary closure, though this probably reflects a smaller and therefore more favorable defect. In a review of treatment of omphaloceles at one institution, the authors reported a 12% incidence of complications of increased intra-abdominal pressure after closure, including acute hepatic congestion requiring reoperation, renal failure requiring dialysis, and bowel infarction. In this retrospective review, wound complications, including skin and fascial dehiscence, occurred in up to 25% of patients undergoing primary closure. In one study looking at escharification, feedings were not withheld with a time to initiate feeds reported at 14 days, versus 23.5 days in the babies who underwent operative correction. Discharge is possible whenever the family is able to care for the patient adequately. Pulmonary hypoplasia and hypertension are associated with omphalocele, especially the large or giant varieties. Although the etiology of this complication is unclear, it may be related to disrupted thoracic development due to the abdominal wall defect, which leads to pulmonary hypoplasia. Although pulmonary hypoplasia has traditionally been thought to be the primary driver of respiratory insufficiency, a two-center review of echocardiograms obtained beyond the transitional physiology period found pulmonary hypertension in over 50% of the patients. This can become a complicated management issue postoperatively even when nonoperative management is chosen, and the infant may need long-term ventilator support, nitric oxide, and/or a tracheostomy.

Answer 49

Long-term outcomes for omphalocele patients are also closely dependent on the associated anomalies and conditions. Several long-term medical problems can develop in patients with large omphaloceles. These include gastroesophageal reflux disease (GERD), pulmonary insufficiency, recurrent lung infections or asthma, and feeding difficulty with failure to thrive. In one study of 23 patients with omphalocele, 43% were found to have GERD by esophageal biopsy or pH monitoring. The larger the defect size, the higher the incidence of GERD as well as delay in attainment of full feeds. Patients younger than 2 years had an increased rate of reflux compared with those older than 2 years of age. In this study, only 1 child required a fundoplication, suggesting that reflux improves as the child ages. Feeding difficulties can occur in up to 60% of infants with a giant omphalocele, and many require a gastrostomy. These difficulties seem to resolve by childhood, with height and weight measurements approaching their peer group. The respiratory insufficiency associated with giant omphaloceles may be secondary to abnormal thoracic development, with a narrow thorax and small lung area leading to pulmonary hypoplasia. Also, it may be associated with poor intrauterine diaphragmatic motion and altered chest wall development. Prolonged respiratory difficulties can occur in up to 20% of infants with giant omphaloceles, leading to increased time of mechanical ventilation and the need for supplemental oxygen during the neonatal period. Some neonates may require a tracheostomy. Interestingly, in a study looking at the longterm cardiopulmonary consequences of large abdominal wall defects, lung volumes and oxygen consumption were found to be normal, indicating that patients who survive childhood generally have good lung development. Neurodevelopmental outcomes in patients with congenital defects has come under increasing scrutiny as the survival rates have improved. Not surprisingly, the outcomes with omphaloceles are closely related to the associated anomalies and their severity. One study noted that patients with giant defects had mild to profound neurodevelopmental delays and a majority of survivors were affected to some degree. The authors noted that, overall, the mean language and motor scores were below average, while 35% had severe neurodevelopmental delays. Thus, while improved surgical and neonatal intensive care has resulted in substantial survival advantages, there needs to be a focus on long term neurologic outcomes for these patients.

Answer 50

After birth, closure of the umbilical ring is the result of complex interactions with the lateral body wall folding in a medial direction, fusion of the rectus abdominis muscles into the linea alba, and umbilical orifice contraction that is aided by elastic fibers from the obliterated umbilical arteries. Fibrous proliferation of the surrounding lateral connective tissue plates and mechanical stress from rectus muscle tension also may help with natural closure. Failure of these closure processes results in an umbilical hernia. The hernia sac is peritoneum and is usually very adherent to the dermis of the umbilical skin. The diameter of the actual fascial defect can range from several millimeters to 5 cm or more. The extent of skin protrusion is not always indicative of the size of the fascia defect. Frequently, small defects can result in alarmingly large proboscis-like protrusions. Thus, it is important to palpate the actual fascial defect by reducing the hernia to assess whether operative or nonoperative treatment is appropriate.

Answer 51

The incidence of umbilical hernia in the general population varies with age, race, gestational age, and coexisting disorders. In the United States, umbilical hernias are present in 15–25% of newborns or approximately 800,000 children annually. Historical studies suggest a higher incidence of umbilical hernia in the African-American population, with an incidence from birth to 1 year of age ranging from 25–58%, whereas Caucasian children in the same age group have an incidence of 2–20%. Premature and low birth weight infants have a higher incidence than full-term infants. Infants with other conditions, such as BeckwithWiedemann syndrome, Hurler syndrome, various trisomy conditions (trisomies 13, 18, and 21), and congenital hypothyroidism, also have an increased incidence, as do children requiring peritoneal dialysis.

Answer 52

For many years, it has been known that umbilical hernias will close spontaneously. It is very safe to observe the hernia until ages 4–5 years to allow closure to occur. Pressure dressings and other devices to keep the hernia reduced are not suggested and do not enhance the closure process. Instead they may result in skin irritation and breakdown. A number of studies have demonstrated spontaneous resolution rates of >90% of hernias by 1 year of age. One study found that 50% of hernias still present at age 4–5 years will close by age 11 years. Another study suggests that hernias with fascial defects greater than 1.5 cm are unlikely to close by age 6 years, whereas other series conclude that even large defects may spontaneously resolve without an operation. The primary danger associated with observation is the possibility of incarceration or strangulation. Studies have shown these complications to be quite rare, with an incidence less than 1%. Patients with small fascial defects (0.5–1.5 cm in diameter) appear more prone to incarceration. Operative closure of an umbilical hernia is generally straightforward and usually can be completed as an outpatient procedure. A small transverse infraumbilical incision is made, usually placed in the redundant skin, which is inverted at the conclusion of the procedure, thereby hiding the incision. The hernia sac is identified and dissected free from the dermis underlying the umbilical cicatrix. The authors’ preference is excision of the sac to the fascial edges, although other surgeons prefer a more limited excision of the sac or inversion of the sac through the fascial opening. Interrupted sutures with 0 or 2-0 nonabsorbable or longlasting absorbable sutures are placed and tied, closing the fascial defect in a transverse direction. Using 3-0 absorbable suture, the dermis of the umbilicus is tacked in two places to the fascial closure. Inversion of the umbilical skin may be impaired in the setting of a fascial remnant of the umbilical stalk or a thickened dermis. To improve skin inversion, radial partial-thickness incisions on the undersurface of the umbilicus in the fascia and dermis can be performed. The skin incision is closed with an absorbable subcuticular suture, and a dressing is applied. Many surgeons use a pressure dressing to help prevent the development of a hematoma and keep the umbilical skin inverted, but it is not clear if this type of dressing is necessary. Methods used commonly in the adult, such as prosthetic placement, are almost never needed in the child. Excision of the redundant skin is usually not needed because the umbilicus tends to return to a normal appearance after the hernia is repaired. This can take up to 12 months to occur, and the family should be reassured appropriately. If the umbilicus fails to return to an acceptable appearance after 1–2 years, there are a number of techniques described to restore it to a more normal configuration. Complications of umbilical hernia repair are infrequent and include seroma or hematoma formation. These are usually self-limited and resolve spontaneously. Wound infections generally can be managed with local care and antibiotics, whereas a recurrent hernia, occurring in less than 1%, requires reoperation.

Answer 53

Hernias of the abdominal wall through the midline linea alba, also termed epigastric hernias, are common, with an incidence up to 5%. Half of these patients are symptomatic on presentation. These hernias present as either a small painless mass, which becomes painful with activity, or a small painful incarcerated mass. Typical contents are preperitoneal fat, with a location between the umbilicus and xiphoid process. These hernias can be multiple and can be found along with an umbilical hernia. An epigastric hernia should not be confused with diastasis recti, which is generalized weakness in the linea alba from umbilicus to xiphoid, and almost always resolves by 10 years of age. Epigastric hernias do not resolve and should be repaired. A small midline incision over the hernia is generally used, with suture repair of the defect after the contents (preperitoneal fat) are reduced or excised. The site of the hernia always should be marked before general anesthesia is induced because the defect may be difficult to find after muscle relaxation. Recurrence is not common.

Answer 54

Spigelian hernias are quite rare in children and can be difficult to detect and diagnose. The actual defect occurs at the intersection of the linea semicircularis, linea semilunaris, and the lateral border of the rectus abdominis muscle. It usually involves absence or attenuation of the transversus abdominis and internal oblique muscles. These hernias occur more frequently in girls and occur equally on both sides of the abdomen. The hernia defects range in size from 1–3 cm. Pain in the area with a feeling of fullness or an actual mass are the most common symptoms. They are occasionally associated with skeletal abnormalities, and also may be associated with ipsilateral cryptorchidism. Ultrasonography may aid in the diagnosis. In select cases, computed tomography may be needed. Repair consists of a transverse incision over the defect with excision of the hernia sac and closure of the defect. Frequently, the sac is found below the external oblique muscle and may require mesh if the defect is large. A tension-free closure is important to prevent recurrence in this area that has a high level of muscle tension.

Answer 55

Lumbar hernias typically present by 2 years of age as a visible bulge in the area bordered by the 12th rib, sacrospinalis muscle, and internal oblique muscle. Occasionally, they extend inferiorly to the iliac crest. These hernias tend to develop at the site of penetration of the intercostal nerves and vessels, or of the ilioinguinal, iliohypogastric, and lumbar nerves. The bulge is usually due to herniated preperitoneal fat. Physical findings include a soft mass that is easily reducible. Although frequently asymptomatic, repair is advisable because the defect never resolves spontaneously and incarceration is possible. Repair sometimes requires prosthetic reinforcement of the fascia or muscle closure because the tissue available for repair is usually thin and weak. Using absorbable biosynthetic mesh that will not cause scoliosis later is preferred in the growing child. Recurrence is not uncommon, but several operations may be needed. Bilateral lumbar hernias can be corrected with either staged or simultaneous closures, depending on the surgeon’s and family’s preferences.

Answer 56

Answer: 4 - Bladder Explanations: • The pelvic portion of the umbilical artery remains patent and becomes the superior vesical artery. The superior vesical artery supplies the superior portion of the bladder. • The remainder of the umbilical vessel is converted into the medial umbilical ligament, which extends from the pelvis to the umbilicus. • The umbilical artery originates from the internal iliac artery and travels within the umbilical cord to the placenta in utero. • The distal part of the superior vesical artery converts to the medial umbilical ligament, which courses superiorly along the abdominal wall to the umbilicus. StatPearls

Answer 57

E All statements A, B and C are true. Syed/MCq

Answer 58

E 80 percent Syed/MCQ

Answer 59

C Umbilical hernia was classified as small if fascial defect is less than 0.5 cm, medium if fascial defect is 0.5–1.5 cm, and large if fascial defect is greater than 1.5 cm. Syed/MCQ

Answer 60

Beckwith–Wiedemann Syndrome (BWS) occurs in 20%–25% of patients with omphalocele. This association is particularly important, since BWS may cause early neonatal hypoglycemia and CNS damage. All patients with omphalocele should therefore undergo close blood-sugar monitoring for 48–72 hours after birth. In addition, the syndrome confers a significant risk of development of embryonal tumors during childhood, and close monitoring with ultrasound should be instituted starting at birth. Molecular and cytogenetic testing can identify a number of epigenetic and genomic alterations of chromosome 11p15 in individuals with BWS. These tests are now available to screen for BWS in a fetus and confirm the diagnosis in a child. Sherif

Answer 61

D The abdominal wall forms during the fourth week of gestation from differential growth of the embryo causing infolding in the craniocaudal and mediolateral directions. The lateral abdominal folds of the embryo meet in the anterior midline and surround the yolk sac, eventually constricting the yolk sac into a yolk stalk that becomes the site of the umbilical cord. During the sixth week of gestation, rapid growth of the intestine causes herniation of the midgut into the umbilical cord. By week 10, the midgut returns to the abdomen and undergoes rotation and fixation. Exomphalos or omphalocele represents a failure of the body folds to complete their journey. most exomphali are lateral-fold defects and are always at the umbilicus. The rectus muscles often insert far apart on the costal margins. The insult occurs early in embryogenesis, hence they are frequently associated with other anomalies. The exact aetiology of Gastroschisis is not clear. It is thought to be caused by a failure of the umbilical coelom to develop. The elongating intestine then has no space in which to expand and ruptures out of the body wall just to the right of the umbilicus, which is unsupported as a result of resorption of the right umbilical vein. umbilical cord hernia is a simple failure of the midgut to return to the peritoneal cavity at 10–12 weeks. SPSE 1

Answer 62

C Gastroschisis occurs in four in 10 000 live births, and is often diagnosed by antenatal ultrasonography by 20 weeks’ gestation. There is an increased incidence in younger mothers, and pre-term delivery is more frequent in infants with gastroschisis. most cases of gastroschisis are isolated defects and associated anomalies are uncommon (10%), the most common being intestinal atresia, which is seen in around 10% of cases of gastroschisis. This is in contrast to exomphalos where associated anomalies are more common (50%), most commonly being cardiac and chromosomal abnormalities. The defect in gastroschisis is usually around 4 cm and to the right of the umbilical cord, without any sac. SPSE 1

Answer 63

E The incidence of exomphalos is lower than gastroschisis, around one in 5000 live births, and the defect is covered with a sac. more than half the cases of exomphalos have associated anomalies such as cardiac and chromosomal anomalies. most common chromosomal anomalies are trisomies 13 and 18, and it is also associated with Down’s syndrome. The risk of chromosomal abnormalities is higher with central defect, and those containing only bowel, compared with neonates with epigastric exomphalos or those containing liver and bowel. Pulmonary hypoplasia is also common and may result in early respiratory distress. An unusual form of exomphalos is cephalic fold defect or pentalogy of Cantrell (exomphalos, anterior diaphragmatic hernia, sternal cleft, ectopia cordis and intracardiac defect such as a ventricular septal defect or a diverticulum of the left ventricle.) SPSE 1

Answer 64

A umbilical cord hernia is an uncommon defect that is small and occurs at the umbilicus; it is covered with a sac and is often confused with an exomphalos. The differences are that it contains only midgut, never liver, and the abdominal wall above the defect is normal, with the rectus muscles meeting in the midline at the xiphoid. These patients have malrotation, as the midgut fails to return to the abdominal cavity to complete rotation and fixation. SPSE 1

Answer 65

B Most cases of gastroschisis are born by spontaneous vaginal delivery. Induction of labour at term is usually preferred to reduce the risk of late third-trimester fetal loss. After birth, patients are initially managed with nasogastric tube, and fluid resuscitation to compensate for serous fluid loss from the exposed bowel and defect. Exposed bowel is wrapped with cling film, before definitive treatment is planned. Various treatment options include silo placement in the neonatal unit or operating theatre, serial reductions and delayed abdominal wall closure, primary reduction with operative closure, and primary or delayed reduction with umbilical cord closure. Intestinal hypomotility is usually seen in cases of gastroschisis, hence central venous access should be established early for parenteral nutrition (usually takes 30 days before full enteral feeding is established). If an atresia is encountered at the time of abdominal wall closure, if the bowel is not too matted, resection and primary anastomosis can be done. If condition of the bowel makes primary anastomosis inadvisable, the bowel can be reduced with the atresia intact and repair can be undertaken 4–6 weeks after initial abdominal wall closure. Some surgeons have elected to create a stoma, particularly in cases of distal atresia. SPSE 1

Answer 66

D Cases of exomphalos can be born by either normal vaginal delivery or caesarean section, and neither mode of delivery has been found to be superior. However, with a large exomphalos, many prefer delivery by caesarean section because of fear of liver injury. After delivery a thorough search for associated anomalies should be undertaken. Treatment options in infants with omphalocele depend on the size of the defect, gestational age and presence of associated anomalies. In infants with small defects, the loss of abdominal domain may not be excessive and primary closure may be appropriate. In many cases, the defect is large and the loss of domain in the peritoneal cavity prevents primary closure without an undue increase in intra-abdominal pressure. In such cases, various methods such as muscle flaps, prosthetic patch repair and tissue expanders can be used to obtain primary fascial closure of the abdominal wall. In those cases, where primary closure is not possible, a staged silo repair can be done. Escharotic therapy with silver sulfadiazine or other non-toxic antibacterial dressing, which results in gradual epithelialisation of the exomphalos sac, is another form of delayed closure that can be used in neonates who cannot tolerate an operation because of prematurity, pulmonary hypoplasia, congenital heart disease or other anomalies. In the cephalic fold defect (pentalogy of Cantrell), the sternal cleft and pericardial defect need no special treatment. The exomphalos defect can be managed with primary skin closure, and the intracardiac defect can be treated later. A non-tension repair of the central tendon of the diaphragm can be done using a Gore-Tex patch and the fascia of the abdominal wall can be closed once cardiorespiratory stability has been achieved. SPSE 1

Answer 67

E The long-term outcome for patients with gastroschisis is excellent, with an overall survival of more than 90%. The presence of intestinal atresia, which is found in 10% of cases, is the most important prognostic determinant for a poor outcome. mortality is mainly related to intestinal failure, associated liver disease, and factors associated with small-bowel and/or liver transplantation. Necrotising enterocolitis has been encountered in full-term infants with gastroschisis in higher-than-expected frequencies (up to 18.5%). Cryptorchidism is associated with gastroschisis with an incidence of 15%–30%, and gastro-oesophageal reflux in 16% of cases. most cases of cryptorchidism, even after replacement of herniated testes into the abdominal cavity, will result in normal testicular descent. most long-term survivors of gastroschisis will lead normal lives. SPSE 1

Answer 68

E Survival rates for exomphalos range from 70% to 95%, with most of the mortality being related to the associated cardiac and chromosomal anomalies. most infants with smaller defects recover well without any long-term issues. A number of long-term medical problems occur in patients with larger defects, such as gastro-oesophageal reflux, pulmonary insufficiency, recurrent lung infections or asthma and feeding difficulty with failure to thrive. A high incidence of gastro-oesophageal reflux of around 43% can be seen in cases of exomphalos, most of which improves with age. The respiratory insufficiency associated with larger defects may be secondary to abnormal thoracic development with a narrow thorax and small lung area leading to pulmonary hypoplasia. SPSE 1