Abdominal Wall Defects Flashcards
What are some common congenital abnormalities that occur in the abdominal wall?
Common abdominal wall defects include Exomphalos and Gastroschisis, which differ significantly in clinical presentation.
How are abdominal wall defects classified?
Abdominal wall defects can be classified into the following types:
- Periumbilical: Exomphalos, Gastroschisis.
- Lower midline: Bladder Exstrophy, Cloacal Exstrophy.
- Upper midline: Sternal defects, Cardiac ectopy.
- Generalized: Diastasis of the rectus sheath, Prune Belly syndrome.
What defects fall under periumbilical classification?
Exomphalos and Gastroschisis.
What defects fall under lower midline classification?
Bladder Exstrophy and Cloacal Exstrophy.
What defects are classified under upper midline?
Sternal defects and Cardiac ectopy.
What are some generalized abdominal wall defects?
Diastasis of the rectus sheath and Prune Belly syndrome.
What is Gastroschisis?
Gastroschisis is the congenital extrusion of bowel through an anterior abdominal wall defect in the umbilical area.
How is Gastroschisis typically diagnosed?
It is usually diagnosed on prenatal ultrasound.
What is a common delivery outcome for babies with Gastroschisis?
Babies with Gastroschisis may be born prematurely.
Do babies with Gastroschisis always require a cesarean section?
No, they do not inevitably require delivery by cesarean section, but some centers may perform a preterm, pre-labor C-section.
Does Gastroschisis have a sac?
No, Gastroschisis never has a sac.
Where does the umbilical cord arise in Gastroschisis?
The umbilical cord arises from the normal place to the left of the defect.
What does the evisceration in Gastroschisis typically contain?
The evisceration usually contains intestine, which may be oedematous and thickened.
Is Gastroschisis associated with major congenital anomalies?
It is rarely associated with major congenital anomalies.
What other condition may Gastroschisis be associated with?
Gastroschisis may be associated with intestinal atresia.
How does the prognosis of Gastroschisis compare to Omphalocele?
Infants with Gastroschisis have a better prognosis than those with Omphalocele.
What is the mortality rate for babies with Gastroschisis?
The mortality rate is approximately 10%.
What is the proposed embryological cause of Gastroschisis?
It is thought to be caused by a vascular incident, such as occlusion of the right omphalomesenteric artery, disruption of the umbilical ring, and herniation of the bowel.
How does the vascular theory explain intestinal atresia in Gastroschisis?
The vascular theory also explains the occurrence of intestinal atresia, which is thought to have the same aetiology in some babies with Gastroschisis.
What are some other theories regarding the cause of Gastroschisis?
Other theories include a ruptured umbilical cord hernia or a congenital weakening of the right side of the cord.
What is the incidence of Gastroschisis?
The incidence is approximately 1 in 5,000 live births.
What maternal factors are associated with an increased risk of Gastroschisis?
- Low maternal age.
- Low socio-economic status.
- Use of aspirin, ibuprofen, or pseudoephedrine in the first trimester.
- Alcohol and cigarette use.
What fetal factor is associated with Gastroschisis?
Being small for gestational age is an associated factor.
Is Gastroschisis commonly associated with major congenital anomalies?
No, Gastroschisis is rarely associated with major congenital anomalies.
What is a common associated condition with Gastroschisis?
Gastroschisis may be associated with bowel atresia in about 15% of cases.
Why might bowel atresia be missed in the initial presentation of Gastroschisis?
Bowel atresia may be missed initially because the bowel is often covered in a thick inflammatory exudate in many cases.
How is antenatal diagnosis of Gastroschisis typically made?
Antenatal ultrasound diagnosis facilitates planned delivery in a tertiary hospital.
Who should be present during the delivery of a baby with Gastroschisis?
A paediatric surgeon should be present if the birth is planned.
What is the focus of immediate post-birth management for Gastroschisis?
Immediate post-birth management focuses on maintaining normal physiology and protecting the bowel from injury.
Why is fluid loss high in infants with Gastroschisis?
Fluid loss is high because exudate from the involved bowel is not reabsorbed by the peritoneal cavity.
Why is temperature loss significant in infants with Gastroschisis?
Temperature loss is great because the exposed intestines release heat to the environment.
What complications can arise from the defect in Gastroschisis?
The defect could be small and constrict the blood supply to the bowel.
What fluids should be given to an infant with Gastroschisis?
Insert an IV line and give maintenance fluids, adding 10% extra fluid to compensate for evaporative fluid losses from exposed viscera. If presentation is delayed, resuscitation boluses may be required.
How should urine output be managed in Gastroschisis?
Monitor urine output closely.
What should be done regarding feeding in a baby with Gastroschisis?
Insert a nasogastric tube (NGT) and keep the baby nil by mouth (NPO).
How can the exposed bowel be protected after birth?
Place the bowel in a preformed ‘Silo’ if available or cover it with plastic (not gauze) to protect the bowel and help keep the baby warm.
What should be done before transferring the baby with Gastroschisis?
Give antibiotics prior to transfer.
What should be done if the bowel appears ischaemic?
If the bowel is ischaemic, it could be due to twisted mesentery or too small a defect. Untwist the bowel or extend the defect towards the patient’s right if needed. Enlargement of the defect may relieve ischaemia.
How should the defect be enlarged in cases of ischaemia?
Inject local anaesthetic, lift the sheath away from the bowel with a mosquito clip, then cut approximately 1 cm left laterally.
What is the next step in managing a baby with Gastroschisis after stabilisation?
Arrange urgent transfer to a neonatal unit with paediatric surgical expertise. Delaying transfer for more than 24 hours is associated with almost 100% mortality in third-world settings.
When is silo reduction required in Gastroschisis?
Silo reduction is often required if there is significant abdomino-visceral disproportion to prevent abdominal compartment syndrome.
How is the bowel managed during silo reduction?
The bowel is placed within a preformed silo, and each day, the bowel is manually reduced into the abdominal cavity.
What happens once all the bowel contents are inside the abdomen during silo reduction?
Once all contents are in the abdomen, the defect is taped closed with the remnants of the umbilical cord over the defect, and the dressing is kept in place for a week.
What occurs to the abdominal wall after silo reduction?
The umbilical ring contracts, and the abdominal wall closes.
What is a potential complication of silo reduction?
Silo reduction can result in an umbilical hernia in about 20% of cases.
What is an alternative to silo reduction for closing the defect?
Once the silo contents are reduced, surgical closure of the muscles and skin can be performed as an alternative.
When is direct reduction and surgical closure possible in Gastroschisis?
Direct reduction and surgical closure are possible in cases with minimal bowel extrusion.
What can be used if a preformed silo is not available?
A preformed silo can be fashioned from a PTFE sheet or an IVI bag and sewn to the rectus sheath, managed as above.
What happens if too much pressure is applied during bowel reduction?
Applying too much pressure during bowel reduction can lead to abdominal compartment syndrome, causing decreased cardiac output, caval compression, respiratory compromise, renal failure, bowel ischaemia, and lower extremity underperfusion.
How can abdominal compartment syndrome be avoided during bowel reduction?
Gradually returning the bowel to a small abdominal cavity with delayed secondary closure of the defect (5-10 days) helps prevent abdominal compartment syndrome, though it increases the risk of wound infection.
What is done if a concomitant atresia is present in Gastroschisis?
If the bowel is in good condition, primary repair can be performed.
If the bowel has serositis, is oedematous, or matted, a staged approach is used. The atresia is reduced, the abdomen is closed, and the atresia is repaired later via laparotomy.
How long does it typically take for babies with Gastroschisis to reach full feeds?
The average time to full feeds is 28 days due to post-operative gut dysfunction related to exposure and serositis.
How is nutritional support managed in the post-operative period?
Parenteral nutrition (PN) is required for 2 to 3 weeks until the ileus is resolved.
What determines the outcome for babies with Gastroschisis?
The state of the bowel and residual bowel length determine the outcome.
What is the survival rate for babies with Gastroschisis in the absence of atresia or bowel ischaemia?
Survival is greater than 90% in the absence of atresia or bowel ischaemia.
What are the common causes of mortality in Gastroschisis?
Mortality is usually due to central venous line infections or necrotizing enterocolitis (intestinal infection).
What long-term complications can arise from parenteral nutrition in these infants?
Long-term parenteral nutrition can cause liver dysfunction, but this resolves once PN is stopped.
What are common long-term issues for babies with Gastroschisis?
Bowel obstruction secondary to adhesions or undiagnosed atresias is fairly common.
Short bowel syndrome is a problem in babies with necrotic or congenitally short bowel.
What is Exomphalos (Omphalocele)?
Exomphalos (Omphalocele) is a congenital herniation of some intra-abdominal contents through an opening in the umbilical ring.
Where is the defect located in Exomphalos?
The defect is located in the midline of the abdominal wall.
What covers the defect in Exomphalos?
The defect is covered by a membrane, from which the umbilical cord arises.
What can be seen through the membrane in Exomphalos?
Multiple eviscerated organs can be seen through the membrane.
Does an Omphalocele have a sac?
Yes, an Omphalocele always has a sac.
What are the characteristics of the sac in Omphalocele?
The sac may be intact or ruptured and has three layers: peritoneum, Wharton’s jelly, and amnion.
Where does the umbilical cord arise in Omphalocele?
The umbilical cord arises from the apex of the sac.
What organs can be found in the sac of an Omphalocele?
The sac contains intestinal loops, liver, spleen, and bladder.
What factors affect the prognosis of Omphalocele?
The prognosis depends on the associated anomalies.
What is the classification of Exomphalos?
Exomphalos minor: < 5cm diameter sheath defect.
Exomphalos major: > 5cm sheath defect or contents include liver.
What is the embryological cause of Exomphalos?
Exomphalos results from incomplete closure of the abdominal wall in the 11th-12th week of development.
What causes the defect in Exomphalos?
The defect is caused by the failure of migration and fusion of cephalic, caudal, and lateral embryonic folds of the abdominal wall, leading to herniation of the bowel through the defect.
What covers the hernia contents in Exomphalos?
The hernia contents are covered with a transparent membrane made of amnion and peritoneum.
What is the incidence of exomphalos?
The incidence of exomphalos is about 1-3 per 10,000 births.
What percentage of babies with exomphalos have karyotype abnormalities, and which trisomies are commonly involved?
About 30% of babies with exomphalos have karyotype abnormalities, commonly including trisomy 13, 18, and 21. Smaller defects have a higher incidence of chromosomal abnormality.
What proportion of babies with exomphalos have other associated malformations, and which organ system is most commonly affected?
At least half of the babies with exomphalos have other associated malformations, with cardiac anomalies being the most common.
What gastrointestinal abnormality is present in 100% of babies with exomphalos?
All babies with exomphalos (100%) have associated malrotation.
What is the triad of features in Beckwith-Wiedemann Syndrome, and why is diagnosis important?
The triad of Beckwith-Wiedemann Syndrome (BWS) includes Exomphalos, Macroglossia, and Hypoglycaemia. Diagnosis is important because severe hypoglycaemia in the neonatal period can cause hypoglycaemic brain damage if untreated. Additionally, there is an increased risk of solid-organ tumors, such as nephroblastoma and hepatoblastoma, requiring long-term screening.
What are the components of the Pentalogy of Cantrell?
The Pentalogy of Cantrell consists of epigastric exomphalos, an anterior diaphragmatic defect, a sternal cleft, pericardial defects, and cardiac defects.
What genitourinary anomaly is associated with exomphalos?
Bladder exstrophy is another condition associated with exomphalos.
Why is antenatal ultrasound detection important in exomphalos?
Antenatal ultrasound detection facilitates planned delivery in a tertiary unit and allows consideration of amniocentesis to evaluate for associated chromosomal anomalies.
How does the fluid resuscitation requirement in exomphalos compare to gastroschisis?
Exomphalos generally requires less fluid resuscitation than gastroschisis.
How should the exomphalos sac be protected after birth?
Cover the sac with plastic dressings to prevent injury.
How should the umbilical clamp be managed to protect the exomphalos sac?
Replace the umbilical clamp with a soft silk tie to prevent the hard clamp from tearing the sac.
What are the initial stabilization steps for a baby with exomphalos?
- Nil by mouth and administer IV fluids (10% dextrose-containing maintenance fluids).
- Keep the baby warm.
- Administer antibiotics.
- Monitor blood glucose levels.
- Give Vitamin K.
Why is it important to check blood glucose levels in babies with exomphalos?
Blood glucose monitoring is important due to the risk of hypoglycaemia, especially in Beckwith-Wiedemann Syndrome. Some babies may require 12-15% dextrose-containing maintenance fluids, preferably via a central line, or maintain a backup IV line at all times.
What should be done if there is a delay in surgery for exomphalos?
If surgery is delayed, discuss feeding with a pediatric surgeon.
What should be done before transferring a baby with exomphalos to a surgical unit?
Conduct a physical examination and perform investigations to exclude congenital abnormalities, including:
1. Chest X-ray (CXR).
2. Echocardiogram (ECHO).
3. Ultrasound of kidneys, ureters, and bladder (KUB).
What factors determine the method of closure in exomphalos?
The method of closure depends on the general condition of the child, the size of the defect, the size of the baby, the sac contents, and the presence of complications.
Is there an urgency to repair the exomphalos if the sac is intact?
No, as long as the sac is intact, there is no urgency to repair the defect.
What is the primary aim of exomphalos closure?
The aim is to reduce the contents into the abdomen and close the defect.
What is primary surgical closure, and when is it preferred?
Primary surgical closure is the preferred method when feasible, involving the reduction of abdominal contents without vessel kinking or increased abdominal pressure, excision of the sac, and layered abdominal wall repair. It is typically used for small defects.
When is non-operative management indicated in exomphalos?
Non-operative management is reserved for very large defects, severe associated cardiac anomalies, or complicated exomphalos in patients not suitable for surgery.
What substances are used to treat the sac in non-operative management?
Apply 1% mercurochrome (or 1% Betadine in 70% alcohol) once-off, or use a dry silver-based dressing.
How does the healing process occur with non-operative management?
The sac is allowed to dry out, forming granulation tissue that gradually epithelializes from the skin edges. Large defects may take 3-4 months to become fully covered.
How are large ventral hernias managed after non-operative treatment of exomphalos?
The large ventral hernia is closed after a few months to years, sometimes requiring a staged procedure with prosthetic material or tissue flaps to augment the abdominal wall.
When is delayed secondary closure used in exomphalos management?
It is used in cases with a ruptured sac and a very large defect.
How is delayed secondary closure performed?
A plastic or silastic “silo” is secured to the abdominal sheath to cover the bowel. The bowel is gradually reduced into the abdominal cavity twice daily, allowing secondary closure of the sheath 3-10 days later.
What factors influence the outcome of exomphalos?
Outcomes depend on the size of the initial defect and the presence of associated physical and chromosomal abnormalities.
What is the mortality rate for exomphalos, and what are the most common causes of death?
The mortality rate is 40%, mostly due to associated cardiac conditions and sepsis.
How long do babies with exomphalos typically stay in the hospital, and why?
They stay for a minimum of 2 to 3 weeks for parenteral nutrition, which carries its own risk of complications.
What is a common complication of non-operative management of exomphalos?
Rupture of the sac, which requires intervention to cover exposed organs and is associated with a poor outcome.
Where does the umbilical cord arise in Exomphalos
The umbilical cord arises from the apex of the sac and the
umbilical vein and artery runs in the wall of the membranous sac.
