Large Bowel Obstruction

Question 1

What are the common causes of large bowel obstruction in a neonate?

Answer 1

Common causes include Hirschsprung’s Disease, neonatal small left colon syndrome, meconium plug syndrome, and meconium ileus.

Question 2

How can large bowel obstruction be differentiated from distal (ileal/colonic) atresia?

Answer 2

Large bowel obstruction can be differentiated from distal atresia using a contrast enema.

Question 3

How can an anorectal malformation be identified in neonates?

Answer 3

An anorectal malformation can be identified through perineal inspection.

Question 4

What is Hirschsprung’s disease (HD)?

Answer 4

Hirschsprung’s disease is a congenital functional bowel obstruction caused by a lack of ganglion cells in the Meissner, Auerbach, and submucosal myenteric parasympathetic nerve plexuses of the distal bowel, leading to dilatation and hypertrophy of the proximal normal bowel.

Question 5

How common is Hirschsprung’s disease (HD)?

Answer 5

Hirschsprung’s disease occurs in all ethnic groups with an incidence of approximately 1 in 5,000 live births.

Question 6

What percentage of patients with Hirschsprung’s disease have a family history?

Answer 6

About 4% of patients with Hirschsprung’s disease have a family history, with a higher risk of long-segment disease in these cases.

Question 7

What causes Hirschsprung’s disease at the cellular level?

Answer 7

Hirschsprung’s disease occurs when the normal migration of neuroblasts in the bowel wall is disturbed, resulting in a part of the colon lacking normal ganglion cells. This leads to a loss of coordinated peristalsis and causes functional obstruction.

Question 8

How does Hirschsprung’s disease present macroscopically?

Answer 8

Macroscopically, there is a narrow aganglionic segment from the anal verge, a transitional zone, and then a dilated proximal portion with a thickened bowel wall due to hypertrophy of the muscle. This dilatation develops over time and is usually absent in patients with total colonic aganglionosis.

Question 9

What is the classical histological picture of Hirschsprung’s disease?

Answer 9

The classical histological picture of Hirschsprung’s disease is the absence of ganglion cells in the intramuscular Auerbach (myenteric) plexus and the submucosal Meissner plexus. Additionally, proliferation of peripheral nerves may be observed in the affected bowel.

Question 10

How can Hirschsprung’s disease be identified histologically?

Answer 10

Acetylcholinesterase staining techniques show thickened parasympathetic nerves in the affected zone, along with neurofibrils in the lamina propria and muscularis mucosa.

Question 11

How far does the abnormality in Hirschsprung’s disease extend?

Answer 11

The abnormality in Hirschsprung’s disease always includes the internal anal sphincter and extends proximally for varying distances.

Question 12

What is the most common anatomical distribution of Hirschsprung’s disease?

Answer 12

In 70% of cases, the abnormal segment is in the rectosigmoid area, with a male to female ratio of 4:1.

Question 13

In what percentage of Hirschsprung’s disease cases is a long segment of colon affected?

Answer 13

In 20% of cases, a long segment of colon is affected.

Question 14

How often does total colonic involvement occur in Hirschsprung’s disease?

Answer 14

In approximately 10% of cases, the entire colon may be affected, with a male to female ratio of 1:1.

Question 15

What are the signs and symptoms of Hirschsprung’s disease in neonates?

Answer 15

In neonates, Hirschsprung’s disease presents with signs of bowel obstruction, such as abdominal distension, vomiting, and failure to pass meconium.

Question 16

What is Hirschsprung’s enterocolitis and how does it present?

Answer 16

Hirschsprung’s enterocolitis presents with features of severe sepsis, abdominal distension, a tender, erythematous abdomen, and bloody stools. X-ray features may resemble necrotizing enterocolitis in severe cases.

Question 17

What are the key treatments for Hirschsprung’s enterocolitis?

Answer 17

Treatment includes urgent bowel decompression (nasogastric tube and rectal washouts or stoma), broad-spectrum antibiotics, and intravenous fluid resuscitation to prevent mortality, which is about 50% in Hirschsprung’s disease.

Question 18

When do about 50% of patients with Hirschsprung’s disease present, and what are their symptoms?

Answer 18

About 50% of patients with Hirschsprung’s disease present after the neonatal period with chronic constipation, abdominal (gaseous) distension, failure to thrive, and an empty rectum with explosive evacuation of loose stool upon rectal examination.

Question 19

What other conditions might present similarly to Hirschsprung’s disease in older children?

Answer 19

In older children, conditions like chronic constipation, anal/rectal stricture, pelvic tumor mass-effect, or idiopathic chronic intestinal pseudo-obstruction may present similarly to Hirschsprung’s disease.

Question 20

What are some common comorbidities associated with Hirschsprung’s disease?

Answer 20

Comorbidities in Hirschsprung’s disease include trisomy 21 (Down syndrome) in about 2-4% of cases, other rare neurological disorders in around 5% (including ophthalmological disorders), and secondary genitourinary obstruction that may lead to vesico-ureteric reflux and hydronephrosis.

Question 21

What does an abdominal X-ray (AXR) show in Hirschsprung’s disease?

Answer 21

An abdominal X-ray (AXR) typically shows dilated loops of bowel in Hirschsprung’s disease.

Question 22

What does a contrast enema reveal in Hirschsprung’s disease?

Answer 22

A contrast enema shows an inverted recto-sigmoid ratio with a funnel-shaped transition zone. A saw-tooth appearance of mucosal fasciculations may be seen in the rectum, especially if enterocolitis is present.

Question 23

What does follow-up X-ray show in Hirschsprung’s disease?

Answer 23

Follow-up X-ray in Hirschsprung’s disease may show a delay in passing contrast through the bowel.

Question 24

What is the gold standard diagnostic test for Hirschsprung’s disease?

Answer 24

The gold standard diagnostic test for Hirschsprung’s disease is a fresh rectal suction biopsy, which reveals the absence of ganglion cells and nerve fiber hypertrophy in the lamina propria and muscularis mucosa on special histochemical stains (e.g., Meier-Ruge cholinesterase or Calretinin).

Question 25

What role does manometry play in the diagnosis of Hirschsprung’s disease?

Answer 25

Manometry is used in older patients with suspected Hirschsprung’s disease. In normal individuals, distension of the rectum results in reflex relaxation of the internal sphincter (rectosphincteric reflex), which is absent in patients with Hirschsprung’s disease.

Question 26

What is the initial management approach for Hirschsprung’s disease?

Answer 26

Initial management includes neonatal resuscitation, bowel decompression, and regular rectal examinations and washouts. Warm saline enemas or saline rectal washouts are typically used 1-3 times daily (10-30ml/kg) to maintain decompression.

Question 27

When is a primary pull-through performed in Hirschsprung’s disease management?

Answer 27

A primary pull-through is performed if the bowel is decompressed and of suitable calibre.

Question 28

When is a divided colostomy performed in Hirschsprung’s disease?

Answer 28

A divided (“double barrelled”) colostomy or ileostomy is performed in the normal bowel above the transition zone if rectal washouts are not successful in decompressing the bowel or in cases of delayed presentation with a grossly dilated bowel.

Question 29

When is definitive surgery carried out in Hirschsprung’s disease?

Answer 29

Definitive surgery (pull-through) is performed 6 months later, once the proximal dilated bowel has returned to a more normal calibre after decompression.

Question 30

What determines the approach for definitive surgery in Hirschsprung’s disease?

Answer 30

The approach for definitive surgery depends on the length of the aganglionic segment and whether a stoma has been fashioned. Patients with a short segment and no stoma can undergo a perineal pull-through procedure, while those with a stoma or longer segments require a laparotomy.

Question 31

Describe the procedure for a perineal pull-through in Hirschsprung’s disease.

Answer 31

In a perineal pull-through, the aganglionic bowel is resected through the anus, starting 1cm above the dentate line. The normal bowel is then pulled through the rectum and anastomosed just above the anal sphincter. This can be aided by laparoscopic dissection (laparoscopic-assisted endo-rectal pull-through).

Question 32

When is a laparotomy used in Hirschsprung’s disease surgery?

Answer 32

A laparotomy is performed if there is a stoma or a longer involved segment. The stoma is mobilized, and the aganglionic segment is resected via a combined perineal and abdominal approach.

Question 33

What are the two common types of surgery for a long segment of Hirschsprung’s disease after a laparotomy?

Answer 33

For longer segments, a Soave or Swenson type operation is performed, where the ganglionated bowel is anastomosed to the anal canal above the dentate line.

Question 34

What is the surgical approach for total colonic aganglionosis in Hirschsprung’s disease?

Answer 34

In total colonic aganglionosis, a Duhamel pull-through (retro-rectal side-to-side anastomosis of ganglionated bowel to retained aganglionic rectum, creating a rectal pouch) or an ileo-anal anastomosis may be done when the child is older.

Question 35

Why is it important to avoid damage to the sphincter or dentate line during Hirschsprung’s disease surgery?

Answer 35

Damage to the sphincter or dentate line should be avoided during surgery to prevent functional problems with bowel control and to preserve normal anal sphincter function.

Question 36

What is the long-term outcome for most Hirschsprung’s disease patients?

Answer 36

The long-term outcome for most Hirschsprung’s disease patients is good, with 93% achieving a positive result. However, some patients experience ongoing problems, including Hirschsprung’s enterocolitis, constipation, and other complications.

Question 37

What complications might indicate an anastomotic stricture in Hirschsprung’s disease?

Answer 37

Obstructive symptoms like a distended abdomen, repeated enterocolitis, and constipation may indicate an anastomotic stricture, which may require dilations, or a transition zone pull-through, necessitating redo surgery.

Question 38

What is the treatment for ongoing constipation in Hirschsprung’s disease patients?

Answer 38

Most Hirschsprung’s disease patients require Senna preparations for ongoing constipation due to the aganglionic sphincter. Functional bowel management, including laxatives and sometimes rectal enemas, may also be needed.

Question 39

What are the functional problems that can arise post-surgery in Hirschsprung’s disease patients?

Answer 39

Post-surgery, patients may experience functional problems such as soiling at night or overflow incontinence due to chronic constipation and fecal impaction, which require bowel management with laxatives and sometimes rectal enemas.

Question 40

What is the prognosis for patients with small bowel aganglionosis in Hirschsprung’s disease?

Answer 40

Small bowel aganglionosis has a poor prognosis if less than 40cm of normal small bowel remains. In such cases, parenteral nutrition through a central venous line and bowel-lengthening techniques may help enable long-term survival.

Question 41

What is neonatal small left colon syndrome (NSLCS)?

Answer 41

NSLCS is a congenital distal bowel obstruction caused by abnormal or immature motility of the left colon, often associated with maternal diabetes and maternal drug exposure (e.g., anti-epileptics, opiates, magnesium sulfate).

Question 42

What percentage of babies with mothers who have gestational diabetes are symptomatic for neonatal small left colon syndrome?

Answer 42

Around 5% of babies with mothers who have gestational diabetes will be symptomatic for neonatal small left colon syndrome.

Question 43

What is the definitive treatment for neonatal small left colon syndrome (NSLCS)?

Answer 43

The definitive treatment for NSLCS is bowel washouts, which may be stopped after a few days to weeks once the baby is stooling normally.

Question 44

What additional support may be required during the treatment of neonatal small left colon syndrome?

Answer 44

During treatment, parenteral nutritional support and frequent small-volume feeds may be required to maintain adequate growth and development.

Question 45

What is meconium ileus (MI) and what causes it?

Answer 45

Meconium ileus is a congenital distal bowel obstruction caused by mechanical obstruction of the terminal ileum lumen by abnormally thick meconium. It is due to abnormal secretion of pancreatic enzymes and other gastrointestinal secretions, typically in cystic fibrosis.

Question 46

What genetic disorder is associated with meconium ileus, and what is its prevalence in different populations?

Answer 46

Meconium ileus is associated with cystic fibrosis, an autosomal recessive disorder caused by mutations in the transmembrane chloride transporter gene. Cystic fibrosis has an incidence of 1:2000 births in Caucasians, 1:12,000 in the Coloured population, and 1:20,000 in the Black population.

Question 47

What percentage of patients with cystic fibrosis have meconium ileus?

Answer 47

About 20% of patients with cystic fibrosis have meconium ileus.

Question 48

What diagnostic tests are indicated for meconium ileus?

Answer 48

Genetic testing and sweat tests are indicated for diagnosing cystic fibrosis, which is associated with meconium ileus.

Question 49

How is inspissated meconium managed in meconium ileus?

Answer 49

Inspissated meconium can be washed out through a T-tube surgically inserted into the terminal ileum. In some cases, an ileostomy may be done, with special types allowing irrigation of the distal bowel without completely disrupting the passage of stools.

Question 50

What role does N-acetyl cysteine play in the management of meconium ileus?

Answer 50

N-acetyl cysteine is given orally or via nasogastric tube to dissolve sulphide bonds in the inspissated meconium, facilitating loosening of the meconium and relieving the obstruction.

Question 51

What is the long-term management for meconium ileus

Answer 51

Long-term management of meconium ileus involves the use of oral pancreatic enzymes to address the underlying cystic fibrosis and aid digestion.

Question 52

What is meconium plug syndrome (MPS)?

Answer 52

Meconium plug syndrome (MPS) is a congenital distal bowel obstruction caused by a plug of meconium in the colon. It can result from various disorders, including Hirschsprung’s disease, dysmotility of prematurity, impaired gastrointestinal motility due to maternal drugs (e.g. opioids), congenital hypothyroidism, and meconium disease like cystic fibrosis.

Question 53

What does the meconium plug typically look like in meconium plug syndrome (MPS)?

Answer 53

The meconium plug in MPS typically has a white tip

Question 54

What is the definitive treatment for meconium plug syndrome (MPS)?

Answer 54

The definitive treatment for MPS involves bowel decompression through an initial contrast enema (which is both diagnostic and therapeutic) and subsequent warm saline enemas or saline rectal washouts. Adequate decompression is necessary to relieve the obstruction. Gastrograffin or N-acetyl cysteine washouts may also be required.

Question 55

What additional tests are recommended for patients with meconium plug syndrome (MPS)?

Answer 55

Additional tests recommended for patients with MPS include blood tests to check for hypothyroidism and abnormalities in calcium and phosphate levels, as well as a sweat test for cystic fibrosis, based on the clinical picture.

Question 56

What are the antenatal features of neonatal bowel obstruction, particularly in meconium ileus?

Answer 56

In neonatal bowel obstruction, polyhydramnios may be seen in approximately 10% of patients with meconium ileus. Antenatal ultrasound may reveal dilated bowel loops, and in meconium ileus, dense meconium may be visualized. In complicated meconium peritonitis, an intra-abdominal cyst with calcifications may be seen.

Question 57

What are common postnatal signs of gastrointestinal issues in newborns?

Answer 57

• Vomiting • Abdominal distension

Question 58

What might indicate Hirschsprung’s disease in a newborn?

Answer 58

• Abdominal tenderness and redness, suggesting Hirschsprung’s enterocolitis • Enterocolitis may develop and lead to a toxic megacolon

Question 59

What can be palpated in a newborn with meconium ileus?

Answer 59

Palpable, indentable abdominal masses due to inspissated meconium

Question 60

What is the normal timeline for passing meconium in newborns?

Answer 60

90% of normal newborns pass meconium within 24 hours

Question 61

How does meconium ileus differ in terms of meconium passage?

Answer 61

Babies with meconium ileus may pass only small amounts of meconium

Question 62

What test can confirm a normal patent anus in a newborn?

Answer 62

A gently passed lubricated nasogastric tube can confirm a normal patent anus

Question 63

What are the consequences of ongoing vomiting in newborns with gastrointestinal issues?

Answer 63

Ongoing vomiting leads to dehydration and progressive metabolic acidosis

Question 64

What are potential complications of Hirschsprung’s disease in the postnatal period?

Answer 64

Septicaemia with pyrexia, tachycardia, and septic shock • Hirschsprung’s enterocolitis (toxic megacolon) occurs in ~16%, especially in the 2nd-4th weeks postnatally

Question 65

What can cause metabolic and biochemical derangements in newborns with gastrointestinal issues?

Answer 65

Bacterial translocation from a grossly distended bowel • Meconium peritonitis

Question 66

What is the role of abdominal x-ray in investigating gastrointestinal issues in newborns?

Answer 66

• An abdominal x-ray can show signs of distal bowel obstruction and complications, such as: • Bowel perforation (pneumoperitoneum) • Calcification from antenatal perforation with sterile meconium peritonitis

Question 67

What is the purpose of a contrast enema in cases of distal bowel obstruction?

Answer 67

A contrast enema helps differentiate mechanical causes of luminal obstruction, such as atresia, from causes of functional bowel obstruction and luminal obstruction (e.g., Hirschsprung’s disease, neonatal small left colon syndrome, meconium obstruction)

Question 68

How can a contrast enema be therapeutic?

Answer 68

• In cases of functional bowel obstruction (e.g., Hirschsprung’s disease, NSLCS) and meconium obstruction, the hygroscopic water-soluble contrast medium can: • Draw water into the bowel lumen • Help flush out meconium plugs • Decompress the bowel

Question 69

What are some complications of obstructive gastrointestinal conditions in newborns

Answer 69

• Pneumoperitoneum • Hirschsprung’s disease complications • Complicated meconium ileus • Meconium peritonitis • Septicaemia due to enterocolitis

Question 70

What can happen in Hirschsprung’s disease if there is delayed presentation?

Answer 70

• Gross dilation of the proximal normal bowel may occur, which could be complicated by Hirschsprung’s enterocolitis • Perforation of the proximal normal bowel, often in the caecum

Question 71

How does complicated meconium ileus relate to cystic fibrosis

Answer 71

About 50% of cases of meconium ileus are associated with cystic fibrosis

Question 72

What are the features of meconium peritonitis in a newborn?

Answer 72

• Caused by antenatal perforation with sterile peritonitis • Leads to ascites and focal calcification due to subsequent inflammatory reactions • If the perforation does not seal off, a central gas bubble or a large air-fluid level may be seen on x-ray from communication with a “meconium pseudocyst” • Antenatal volvulus of meconium-filled bowel may lead to atresia

Question 73

How can septicaemia occur in obstructive gastrointestinal conditions?

Answer 73

Septicaemia can develop due to enterocolitis, especially in conditions like Hirschsprung’s disease