134: Surgical Diseases of the Newborn: Alimentary Tract Obstruction

Type C tracheoesophageal (TE) fistula is the most common type of esophageal atresia (85%). The esophagus ends blindly ∼10–12 cm from the nares, and the distal esophagus communicates with the posterior trachea (distal tracheoesophageal fistula [TEF]). Type A “pure” esophageal atresia implies esophageal atresia without TEF (10% of cases). It has a similar presentation without the distal gastrointestinal air.

Because of the esophageal obstruction, the infant is unable to handle secretions, with subsequent “excess salivation” and aspiration of pharyngeal contents. Communication between the tracheobronchial tree and the distal fistula allows the crying newborn to greatly distend the stomach with air. This impairment of diaphragmatic excursion can promote basilar atelectasis and respiratory distress. Additionally, the distal TEF permits reflux of gastric secretions directly into the tracheobronchial tree, causing chemical pneumonitis or pneumonia.

Pregnancy can be complicated by polyhydramnios. Typically, the newborn is unable to manage oral secretions and requires frequent suctioning. Attempted feedings result in prompt regurgitation, coughing, choking, and cyanosis.

A nasogastric tube cannot be passed beyond 10–12 cm from the nares. Chest radiograph shows the tube ending in the region of the thoracic inlet. The upper pouch can be better visualized by insufflating 20–30 mL of air into the tube as the radiograph is being taken. Air in the gastrointestinal tract confirms presence of a distal fistula. The radiograph should also be examined for skeletal anomalies, pulmonary infiltrates, cardiac size and shape, and abdominal bowel gas patterns. Appropriate evaluation for VATER/VACTERL association is necessary

1. Preoperative treatment should focus on protecting the lungs by evacuating the proximal esophageal pouch with an indwelling Replogle tube or frequent suctioning. Placing the baby in an upright (45-degree) position lessens the likelihood of reflux of gastric contents up the distal esophagus into the trachea. Broad-spectrum antibiotics should be administered. An echocardiogram should be obtained to assess for cardiac and aortic arch anomalies.

2. Surgical therapy. The steps and timing of surgical therapy must be individualized to the baby's anatomy. Some surgeons perform preliminary gastrostomy to decompress the stomach and provide additional protection against reflux. Single-stage TEF ligation and esophageal anastomosis via thoracotomy or thoracoscopy is the preferred intervention if allowed by the neonate's clinical status.

3. Type A esophageal atresia is associated with a higher incidence of a long gap between the proximal and distal esophageal segments. Delayed surgical correction allows growth of the segments and permits primary anastomosis. Enteral nutrition is provided via gastrostomy.

Obstruction of the lumen of the duodenum may be complete, partial, pre- or postampullary, and caused by either intrinsic or extrinsic problems.

1. Duodenal atresia is a complete obstruction of the lumen, and duodenal stenosis is a partial obstruction. Frequently, it is associated with trisomy 21 (33%).

2. Annular pancreas is a congenital anomaly of pancreatic development in which pancreatic tissue encircles the descending duodenum. This results in either complete or partial duodenal obstruction.

3. Malrotation refers to various abnormalities of intestinal rotation and fixation that can cause complete or partial duodenal obstruction. Abnormal peritoneal attachments (Ladd bands) may extrinsically compress the duodenum. Volvulus occurs when the entire midgut twists on its vascular pedicle, the superior mesenteric artery. This results in duodenal obstruction, midgut ischemia, and eventual necrosis

1. General. Neonates with duodenal obstruction typically present with bilious vomiting. Abdominal distention is not common. Polyhydramnios may be evident on prenatal examination.

2. Duodenal atresia. Down syndrome, esophageal atresia, and imperforate anus are associated with duodenal atresia. The emesis is nonbilious when the obstruction is proximal to the ampulla of Vater.

3. Midgut volvulus. Presents with bilious vomiting and evidence of intestinal ischemia (lethargy, acidosis, bloody stools, etc.). This occurs most frequently in the first few weeks of life. Previously, the baby may have been well or had only minor feeding difficulties. This is a true surgical emergency.

The exact cause of the obstruction may not be fully elucidated before laparotomy.

1. Abdominal radiographic study. The “double bubble” is the pathognomonic finding of complete duodenal obstruction. Only 2 abdominal lucencies are seen: 1 in the stomach and 1 in the first portion of duodenum. The remainder of the gastrointestinal (GI) tract is gasless.

2. Radiologic contrast studies

   1. Partial obstruction probably requires an upper GI (UGI) series to identify the site of difficulty.

   2. Malrotation is best evaluated by UGI study to identify the ligament of Treitz. Occasionally, contrast enema may be useful to document the position of the cecum. Malrotation with volvulus is an emergency, and imaging studies should not delay surgical intervention in a baby who is critically ill

1. Duodenal atresia or annular pancreas. In cases of atresia or annular pancreas, gastric decompression controls vomiting and allows for “elective” surgical correction.

2. Malrotation. Malrotation mandates immediate surgical intervention when identified because the viability of the intestine from the duodenum to the transverse colon may be at risk from midgut volvulus.

3. Unknown proximal obstruction. In cases in which the source of the obstruction is unclear, appropriate resuscitation and early surgical exploration are warranted to prove that the obstruction is not due to a lesion causing intestinal ischemia.

A proximal intestinal obstruction is an obstruction of the jejunum.

Jejunal obstruction typically results from segmental atresia of the bowel, usually as the result of an in utero vascular accident.

Infants with jejunal obstruction usually have bilious vomiting associated with minimal abdominal distention because only a few loops of intestine are involved in the obstructive process.

A plain abdominal radiograph reveals a few dilated small bowel loops with no distal gas. It may be difficult to distinguish between jejunal atresia and midgut volvulus by plain films alone. Small amounts of distal gas may indicate that a volvulus has occurred.

Surgical correction is required. The dilated proximal bowel is usually resected or tapered. Outcome is determined by the remaining bowel length and other comorbidities.

The term distal intestinal obstruction denotes partial or complete obstruction of the distal portion of the GI tract. It may be either small bowel (ileum) or colon. It may be a physical obstruction (meconium disease or atresia) or a functional obstruction (small left colon syndrome or Hirschsprung disease). Differential diagnosis includes the following:

1. Jejunal/Ileal atresia may be single or multiple. Usually, this is a complete obstruction.

2. Meconium ileus

   1. Uncomplicated (simple) obstruction of the terminal ileum occurs by pellets of inspissated meconium. Meconium ileus is associated with cystic fibrosis (CF).

   2. Complicated meconium ileus implies compromise of bowel viability, either prenatally or postnatally, due to perforation, volvulus, or atresia.

3. Colonic atresia.

4. Meconium plug syndrome.

5. Hypoplastic left colon syndrome is frequently found in babies of diabetic mothers.

6. Hirschsprung disease (congenital aganglionic megacolon).

Neonates with obstructing lesions in the distal intestine have similar signs and symptoms. They typically have distended abdomens, failure to pass meconium, and bilious emesis

1. Abdominal radiographs. These show multiple dilated loops of intestine. The site of obstruction (distal small bowel vs colon) cannot be determined on plain films.

2. Contrast radiologic studies. The preferred diagnostic test is contrast enema. It may identify colonic atresia, outline microcolon (signifying complete distal small bowel obstruction), or suggest a transition zone (indicating Hirschsprung disease). The procedure can identify and treat meconium plug and hypoplastic left colon syndromes. If the test is normal, ileal atresia, meconium ileus, and Hirschsprung disease are possibilities.

3. Cystic fibrosis (CF) evaluation. Newborn screening for immunoreactive trypsinogen (IRT) (done on all infants) is done as part of the newborn screening to rule out CF. If the level is high, further testing is done (blood tested to determine whether CF gene mutations are present or a repeat IRT is done), followed by sweat chloride.

4. Mucosal rectal biopsy for histologic detection of ganglion cells. This is the appropriate test for Hirschsprung disease. Laparotomy is sometimes necessary to determine the exact nature of the problem in infants with normal results of barium enema.

See also Chapter 67.

1. Nonoperative management. In cases of meconium plug and hypoplastic left colon, this is accomplished with stimulation and is “curative” by either water contrast enema(s) or rectal stimulation.

   1. Passage of time and colonic stimulation by digital examination and rectal enemas promote return of effective peristalsis.

   2. Infants who achieve apparently normal bowel function should be evaluated for Hirschsprung disease by rectal mucosa biopsy. A small percentage of patients with meconium plug syndrome are proven to have colonic aganglionosis.

   3. Uncomplicated meconium ileus can often be treated by nonoperative means. Repeated enemas with Hypaque or acetylcysteine (Mucomyst) may loosen the inspissated meconium in the terminal ileum and relieve the obstruction.

2. Surgical therapy. Urgent surgical intervention is required for atresias, complicated meconium ileus, and whenever the diagnosis cannot be made by other means. Hirschsprung disease is always treated surgically. There are 3 accepted types of surgical intervention for Hirschsprung disease. Laparoscopic, open, and transanal procedures have been described:

   1. Staged repair with colostomy creation using ganglionic bowel in the neonatal period.

   2. One-stage pull-through procedure while the infant is in the neonatal intensive care unit.

   3. Delayed 1-stage repair when the infant has doubled his or her birthweight. Therapeutic irrigations/enemas are used to keep the distal colon decompressed.

See also Chapter 67.

An imperforate anus is the lack of an anal opening of proper location and size. There are 2 types: high and low.

1. High imperforate anus. The rectum ends above the puborectalis sling, the main muscle responsible for maintaining fecal continence. There is never an associated fistula to the perineum. In males, there may be a fistula to the urinary tract. High imperforate anus is much more common in males.

2. Low imperforate anus. The rectum has traversed the puborectalis sling in the correct position. Variants include anal stenosis, imperforate anus with perineal fistula, and imperforate anus without fistula.

Diagnosis is made by perineal inspection and calibration of any opening that drains meconium (eg, fifth digit probe, rectal thermometer, or soft feeding tube). All patients with imperforate anus should have radiographic studies of the lumbosacral spine and urinary tract because there is a high incidence of dysmorphism in these areas. Spinal ultrasound and magnetic resonance imaging are used to evaluate for tethered cord.

Neonatal surgical intervention consists of colostomy for high anomalies and perineal anoplasty or fistula dilation for low lesions. If the level is not known, colostomy creation is preferred to blind exploration of the perineum. If a colostomy is done, the distal limb can be studied with contrast enemas to ascertain the level at which the rectum ends and to determine whether a fistula exists.

See also Chapter 113.

In most centers, necrotizing enterocolitis (NEC) is the most common indication for abdominal operation in neonates. It is caused by a combination of mucosal injury, relative hypoxia, and infection of the intestinal wall.

Radiographic diagnosis of “true” NEC requires the presence of pneumatosis intestinalis and/or portal venous air. Abdominal distention, bloody bowel movements, and feeding intolerance in a neonate who previously tolerated enteral feeds are all signs of NEC. Definitive diagnosis requires radiographic evidence or a pathologic specimen from the affected bowel

1. Nonoperative management. Includes intestinal decompression with a Replogle-style nasogastric or orogastric tube, aggressive fluid resuscitation, broad-spectrum antibiotics (include anaerobic coverage), and inotropic support as necessary. Serial abdominal examinations, labs, and abdominal radiographs should be obtained. Early surgical consultation is encouraged.

2. Surgical therapy. Abdominal exploration is usually reserved for infants with full-thickness necrosis of the intestine. Pneumoperitoneum indicates intestinal perforation and is best identified with a left lateral decubitus radiograph. Relative indications for surgery include abdominal wall erythema and a fixed abdominal mass. Delayed stricture formation complicates 15–25% of NEC cases and presents with signs of a bowel obstruction.