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With resection for intestinal gangrene, short-bowel syndrome may develop.

Omphalocele. The outcome for an omphalocele is related to the size and location of the defect and to the presence of associated anomalies. The overall mortality rate ranges from 20%–60%.

IV Esophageal Atresia and Tracheoesophageal Malformations

Esophageal atresia and tracheoesophageal malformations occur once in every 3,000 live births. They encompass a spectrum of lesions that can vary greatly in their time of presentation and in their treatment. A high incidence of associated maldevelopments in other organ systems may complicate the treatment of these patients.

A Types of lesions

(Fig. 29 -2)

Esophageal atresia (proximal pouch) with a distal tracheoesophageal fistula is the most common type; it occurs in 86% of patients.

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FIGURE 29-2 Esophageal atresia. A: Esophageal atresia with distal tracheoesophageal fistula. B: Proximal and distal blind pouches without fistula. C: H fistula. D: Esophageal atresia with proximal tracheoesophageal fistula. (Adapted from

Altman RP, et al. Pediatric surgery. In Guzetta PC, Anderson KD, Altman RP et al. eds. Principles of Surgery, 7th ed. New York: McGraw-Hill; 1989:1724.

)

Pure esophageal atresia (proximal and distal blind pouches) without a fistula occurs in 7% of patients.

Tracheoesophageal fistula without atresia (the H fistula) occurs in 5% of patients.

A proximal and a distal tracheoesophageal fistula are combined with a proximal atresia (the least common type) in 2% of patients.

B Associated anomalies

In approximately 40% of these patients, other malformations are present in one or more organ systems.

An endocardial cushion defect affects the heart, which is the most common single involved organ.

The VACTERL complex, a well-recognized anomaly complex, involves vertebral, anal defects, cardiac anomalies, tracheoesophageal fistula, renal and l imb dysplasia.

The complex may be fully or partially demonstrated; that is, one or any combination of lesions may occur.

If it seems to be partial, the complete complex must be ruled out.

C

The diagnosis of esophageal atresia and tracheoesophageal fistula is usually made soon after birth, when the affected infant exhibits some form of respiratory distress.

Physical examination

Aspiration of material from the upper pouch causes some symptoms.

The infant may appear to be salivating excessively and may drool continuously.

The aspiration may also cause coughing spasms, intermittent choking, or cyanosis that develops when the infant is feeding.

Continuous aspiration of gastric secretions occurs if a fistula is present. This aspiration is more severe and more harmful than that from the upper pouch.

Tachypnea and signs of pneumonia may develop.

A scaphoid abdomen due to the unused gastrointestinal tract accompanies pure atresia.

Attempts to pass a tube through the nose into the stomach will fail, because the tube will stop in the blind pouch of the esophagus, thus confirming the suspicion of esophageal atresia.

Radiographs of both the chest and the abdomen are important in order to make a diagnosis and to prepare for treatment.

The chest film will show the blind upper pouch and also the failure of passage by the gastric tube.

A gasfree abdomen is characteristic of pure atresia.

Hyperventilation, atelectasis, or pneumonia must be evaluated so that the proper surgical approach (i.e., immediate vs. delayed repair) can be chosen.

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Identification of the aortic arch is also necessary for proper surgical management. The use of echocardiography may also assist in determining not only the aortic anatomy but also any associated congenital heart anomalies (see IV B ).

The length of the esophageal defect can be measured on a lateral film.

D Preoperative management

Several steps should be taken once the diagnosis is made.

Decompression of the proximal pouch by means of a sump tube with constant suction (Replogle tube) is required.

An upright position is maintained, using a chalasia chair.

Gastrostomy is performed if delayed repair is chosen.

This procedure prevents further gastric aspiration.

It also provides a route for preoperative feedings if surgery is delayed for an extended period.

Stretching the proximal pouch daily in a pure atresia shortens the distance between the esophageal ends in preparation for eventual repair.

E Operative management

Primary repair at the time of presentation can be undertaken if the defect measures less than 2 cm and no signs of pneumonitis are present. Delayed repair may be needed if the defect is greater than 2 cm or extends the length of 2½ vertebral bodies. At the time of surgery, the approach is the same for either immediate or delayed repair.

Broad -spectrum antibiotic therapy is begun.

If not previously undertaken, a gastrostomy may be performed, although this measure is controversial.

An extrapleural dissection through the hemithorax opposite the aortic arch is currently favored to prevent empyema from occurring as the result of an anastomotic leak.

The tracheoesophageal fistula is repaired.

A primary esophagostomy is performed.

The distal esophagus must be carefully dissected because the blood supply is tenuous.

An adequate length of esophagus is necessary to create a tensionfree anastomosis and is obtained by dissecting the proximal pouch. The use of myotomies may aid in gaining length for closure.

A drain is placed in the extrapleural space.

F

Postoperative management is directed at potential pulmonary and esophageal problems.

The infant is extubated as soon as possible to protect the tracheal repair.

Vigorous pulmonary toilet is necessary to clear up any previous pneumonia and to prevent the need for reintubation.

Reintubation may disrupt the esophageal repair, the tracheal repair, or both.

A degree of tracheal malacia compromises pulmonary function.

Chest percussion is mandatory to prevent early postoperative problems.

The infant is kept upright, because esophageal function will not yet be adequate for swallowing oral secretions.

Esophagotracheal suction is done carefully and with a specifically defined length of tubing. Disruptions of the esophagus can occur during placement of a suction catheter through the anastomotic line.

The esophagus is evaluated after 7 days by means of a swallow study.

If no leak is present, oral feedings are started; if feedings are tolerated, the extrapleural drain is removed.

Normal in utero development. The midgut develops extra-abdominally. It then migrates intraperitoneally, where it undergoes a 270 -degree rotation. The results are as follows:

The cecum ends up in the right lower quadrant.

FIGURE 29-3 Malrotation and volvulus of the midgut.

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The right colon becomes fixed in the right paracolic gutter.

The duodenum becomes fixed in the retroperitoneal location, with the superior mesenteric artery passing over the duodenum.

Displacements caused by malrotation

The cecum is not in the right lower quadrant, and the duodenum does not pass posteriorly to the superior mesenteric artery.

Instead of the base of the small bowel being fixed from the ligament of Treitz to the cecum in the right lower quadrant, the whole midgut is anchored on the superior mesenteric artery.

Various stages of fixation of the cecum can be seen, but it is usually fixed to the right upper quadrant with the fibrinous bands (Ladd's bands) that extend across the second portion of the duodenum.

Sequelae to malrotation. Two serious problems may accompany this lesion, which must, therefore, be handled expeditiously.

Intestinal obstruction can result from adhesive bands across the second portion of the duodenum

fixing to the right upper quadrant.

A midgut volvulus, which is more serious than intestinal obstruction, can also occur.

This volvulus develops when the intestine twists on its vascular pedicle (the superior mesenteric artery) and causes ischemia as well as obstruction of the entire midgut.

The result can be catastrophic, and gangrene of the entire small bowel can occur.

Symptomatic malrotation is now being recognized in the older child. This is manifested by an atypical type of abdominal pain or vomiting caused by a partial or intermittent duodenal obstruction. Volvulus is rare in this group, but cases have been reported.

B Clinical presentation

Bilious vomiting is the usual presenting symptom.

Passage of a bloody stool is a late occurrence and implies ischemia, with necrosis of the bowel mucosa, bowel wall, or both.

The infant may appear normal, with hemodynamic stability, or may be dehydrated and in shock.

C

Early diagnosis of malrotation is crucial to prevent the development of a volvulus with resultant intestinal gangrene. Therefore, when malrotation in an infant is suspected and cannot be ruled out, all efforts are made to confirm the diagnosis rapidly.

Radiographs are very useful when making the diagnosis.

The plain film may demonstrate the “double -bubble” sign, which is produced by intestinal gas confined to the stomach and duodenum, with small amounts of gas in the residual, unused gastrointestinal tract. In a newborn with bilious vomiting, this sign is an indication for surgery.

The upper gastrointestinal series may demonstrate an abnormally located ligament of Treitz, the presence of the duodenum to the left of midline, a duodenal obstruction, or a “beaked” end in the barium column at the point of the intestinal twist.

Prompt surgical exploration is imperative if the diagnosis of malrotation is suspected but cannot be ruled out, because most infants with obstructive malrotation have a volvulus.

D Operative management

Surgical procedures for malrotation vary with the presence or absence of volvulus and the status of the intestine.

Simple malrotation is treated by the Ladd procedure.

This procedure consists of releasing the adhesive bands and mobilizing the duodenum. The goal is to broaden the mesentery of the intestine as much as possible and to separate the duodenum and ascending colon.

The cecum is placed in the left upper quadrant and the duodenum in the right lateral abdomen so that both organs will be in positions that should prevent intestinal obstruction or ischemia.

An appendectomy is performed, and the remaining abdominal contents are examined for other anomalies, such as a duodenal web.

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Malrotation with volvulus requires several preliminary steps.

The first step is a counterclockwise detorsion of the midgut volvulus.

The bowel is then examined for viability and for areas of necrosis.

If small areas of gangrene are present, resection is performed, followed by the Ladd procedure.

If large amounts of the midgut appear necrotic, long lengths of bowel are not resected. Instead, the bowel is untwisted, and the abdomen is closed and then re-explored 24 hours later. This second look allows marginally viable tissue to recover, with the hope of minimizing the amount of bowel to be resected.

E Prognosis

The recurrence of a midgut volvulus after surgical exploration and a Ladd procedure occurs in as many as 10% of cases, usually in the immediate postoperative period.

The long-term sequelae are minimal after repair of simple malrotation. However, when extensive intestinal resection is required, the result depends strongly on the amount of intestine remaining. Extreme resections result in severe malabsorption and even in death.

VI Intestinal Atresia

A

Duodenal atresia and stenosis occur because the second portion of the duodenum fails to recanalize in the early embryonic stages. The lesion may be complex, partial, or in the form of a web (which is identified by an upper gastrointestinal study).

Associated anomalies

Trisomy 21 occurs in 30% of infants with duodenal malformations.

Cardiac lesions and various elements of the VACTERL complex are present in many infants.

An annular pancreas may be present, with the pancreas forming a ring around the duodenum. This anomaly is now thought to result from the malformation, rather than being a cause of duodenal stenosis.

The diagnosis is usually made from two simple findings.

Bilious vomiting that occurs soon after birth in a nondistended infant suggests a high obstruction.

Abdominal radiographs show the classic double -bubble sign, which involves air in the stomach and a proximally dilated duodenum.

This sign suggests duodenal obstruction but can also be seen with malrotation.

Although duodenal atresia or stenosis in itself is not life threatening, malrotation is life threatening (see V ).

If delay in treatment is being considered in the patient with a double -bubble radiograph, a barium contrast study is necessary to rule out malrotation.

This study may be a barium enema to localize the cecum or an upper gastrointestinal study to see the duodenal sweep.

Preoperative management

Gastric decompression and fluid resuscitation are performed as needed.

Broad -spectrum antibiotic therapy is begun.

Because these lesions have a high association with other more critical anomalies, stabilization and evaluation of these lesions can be done before surgery. However, this combination can be done only if malrotation is ruled out as the cause of duodenal obstruction.

Operative management has as its goal the re-establishment of a patent gastrointestinal tract.

The site of obstruction is identified.

Usually a duodenoduodenostomy can be performed. If this cannot be done, a duodenojejunostomy is a good alternative. Gastrojejunostomy is contraindicated.

If a web is present, the duodenum is opened at the site of obstruction, the web is excised, and the duodenum is closed. Care must be taken to identify the ampulla of Vater, because it is also located on the mesenteric side of the web.

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If an annular pancreas is present, care is taken not to damage this structure.

In no circumstance is the pancreas divided.

The annular pancreas is not the obstructing lesion (as is the duodenal stenosis), and the mortality rate is extremely high among patients whose annular pancreas is divided.

The annular pancreas can usually be bypassed by a duodenoduodenostomy.

Because 15% of the patients have other gastrointestinal atresias, a thorough search is undertaken to ensure the patency of the entire gastrointestinal tract.

A nasogastric tube is used for gastrointestinal decompression.

Postoperative management is simple but requires patience.

Gastrointestinal decompression is important to protect the suture line and to prevent possible aspiration.

The return of gastrointestinal function is slow, not only because of gastric and duodenal dysfunction but also because the distal intestine is small owing to disuse.

Nutritional support by hyperalimentation is usually needed.

Prognosis. Long-term results of surgery are good. Mortality in these patients is related to prematurity of the infant and to associated anomalies.

B

Jejunal, ileal, and colonic atresias are caused by in utero vascular accidents that result in ischemia of a segment of bowel, with consequent stenosis or atresia. The ileum is most commonly affected; the jejunum and colon are affected less often. The severity of the lesion is related to the size of the vascular arcade that was affected in utero.

Associated anomalies. Because they are not embryonic maldevelopments, associated anomalies are much less common than with duodenal atresia. However, approximately 10% of patients have cystic fibrosis. DNA studies to identify the cystic fibrosis gene are now available and can be used if a sweat test is inadequate or unavailable. Patients with these atresias should have a sweat chloride test by 2 months of age to rule out cystic fibrosis.

Clinical presentation. The diagnosis is suspected when an infant develops bilious vomiting after 24 hours of life.

The degree of abdominal distention varies with the level of the obstruction.

The passage of meconium does not rule out an atresia, because the gastrointestinal tract was intact before the vascular accident.

All patients with small bowel or colonic atresia should have an early evaluation for cystic fibrosis.

Diagnosis

Abdominal radiographs show various degrees of obstruction, depending on the level of the atresia or stenosis.

The picture can be confused with meconium ileus.

In atresia, air–fluid levels are present; whereas a meconium ileus shows only distended bowel, without fluid levels, and a soap -bubble appearance.

Contrast studies are helpful in both diagnosis and management.

A contrast enema will reveal colonic lesions and perhaps low ileal lesions.

Hirschsprung's disease, meconium ileus, and other congenital disorders may also be ruled out, making diagnosis of the atresia more certain.

Preoperative management includes gastrointestinal decompression and fluid replacement. Begin broadspectrum antibiotic therapy.

Operative management. Surgery is performed to re-establish intestinal continuity.

The current procedure of choice is an end -to -end intestinal anastomosis.

This procedure may be difficult to accomplish because of the marked size disparity of the bowel—the proximal bowel is dilated, and the distal, unused bowel is small.

Because of the variations in size, tapering of the proximal bowel may aid in the repair.

The distended bowel has been found to have varying degrees of impaired motility. Therefore, gastrointestinal function may be extremely slow to return.

A nasogastric tube is placed to allow decompression, prevent aspiration, and protect the suture line.

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A thorough abdominal examination for multiple atresias is performed. Their overall occurrence rate is 6%, but the frequency is high with ileal atresia and very low with colonic atresia.

In a patient with both an atresia and meconium ileus , the distal intestine may contain inspissated small bowel secretions. In this situation, the site of inspissation should be irrigated with a 4% acetylcysteine (Mucomyst) solution to relieve any potential obstruction before the atresia is repaired.

Postoperative management involves decompression and patience.

Hyperalimentation may be needed until the gastrointestinal tract begins to function.

Malabsorption, if present, may prolong the recovery time.

Prognosis. Because associated anomalies are few, survival is a function of the prematurity of the infant. Current results show a survival rate of almost 100%.

C

“Apple -peel” atresia, a severe form of small bowel atresia, is known by this name because of its appearance.

This atresia occurs during a large vascular accident to one or more of the mesenteric arcades in utero.

Stenting procedures have been developed to preserve gastrointestinal length in patients with both apple - peel and multiple atresias.

In these patients, return of gastrointestinal function is very prolonged, and malabsorption is common.

VII Imperforate Anus (Fig. 29-4)

Abnormal termination of the anorectum has a clinical spectrum that ranges from a fistulous opening in the perineal area or a colourethral fistula to a completely blind ending of the rectum. The incidence of these malformations ranges from 1 in 1,500 to 1 in 5,000 births. The male:female ratio is 2:1.

A Types

Although many classifications have been proposed for an imperforate anus, the simplest division is on the basis of sex and the relationship to the levator ani.

Infralevator (low) type. The rectum passes through the puborectalis sling. This type is more common in girls.

Supralevator (high) type. The rectum does not pass through the puborectalis sling. This type is more common in boys.

B

Associated anomalies are common in patients with an imperforate anus, and this congenital defect is associated with the VACTERL syndrome.

The genitourinary tract is the most commonly involved organ system.

Malformations include renal agenesis, renal dysplasia, hypospadias, epispadias, bladder exstrophy, vaginal atresia, and cloacal exstrophy.

These findings have been reported in up to 40% of patients with imperforate anus.