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The patient may have a fistulous tract, which opens:

In girls, posterior to the vagina within the vestibule

In boys, to the posterior urethra

In boys, meconium in the urine should be sought. This condition occurs only when a fistula is present between the rectal pouch and the urinary tract.

Problems in patients with fistulas

They may develop symptomatic urinary tract infections.

They may also develop a hyperchloremic acidosis caused by reabsorption of chloride by the colonic mucosa.

This acidosis is characterized by lethargy, tachypnea, and elevation of the serum chloride and the blood urea nitrogen (BUN).

Although the condition may resolve in time, treatment with bicarbonate may be required; and, if the condition is severe or cannot be corrected, the rectal pouch–urinary tract fistula may need to be divided before the definitive procedure is undertaken.

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Radiographs. If no external fistula is identified, the surgeon must determine whether the rectum has traversed the puborectalis sling. Using a cross-table lateral radiograph of the pelvis, the surgeon can identify the extent of the rectum by visualizing the end of the infracolonic air.

A line drawn from the posterior portion of the symphysis pubis to the tip of the coccyx (the pubococcygeal line) aids when differentiating the infralevator type from the supralevator type.

Air visible in the bladder suggests a posterior urethral fistula, which implies a supralevator type.

If the distance from the tip of the colonic air column to the anal dimple is greater than 2 cm, the lesion is the supralevator type. An ultrasound examination may prove more accurate in defining the distance.

D Operative management

Infralevator type. If an external fistula is identified, several alternatives are available for the initial management.

If the fistula can be dilated, it may function satisfactorily until the patient is older, at which time the opening can be relocated to the correct site (the Pott's anal transfer).

If the mucosa is close to the opening, the fistula may be enlarged by a procedure known as a Denis

Browne cutback.

These procedures are performed more commonly in girls, because the infralevator type of imperforate anus occurs more often in girls.

Supralevator type. The treatment for the supralevator type of imperforate anus is, first, the formation of a colostomy, followed by the formation of a neorectum and anus.

The sagittal posterior anoplasty (Peña procedure) has been used for reconstruction of all levels of imperforate anus. The goal is to bring the rectum down to the perineum within the sphincter complex to try and maximize continence.

E

Postoperative management depends on the type of imperforate anus. Basically, the goal of treatment in these patients is to have a socially accepted, continent child. These children require patience during toilet training; they are usually trained between 3 and 5 years of age.

Infralevator types of anus require constant dilatations until the stool obtains bulk.

Supralevator types of anus require colostomy care until the definitive procedure can be performed. With the formation of a new anus, the patient may require dilatations to prevent strictures.

F Prognosis

The mortality rate among patients with an imperforate anus is directly related to the associated anomalies.

Functional morbidity is directly related to:

Inappropriate management

Associated neurologic dysfunction due either to spina bifida or to sacral agenesis with poorly developed neuromuscular control in the lower pelvis

The development and use of either irrigating stomas or cecostomy buttons for prograde enemas have shown a simple solution for a poor outcome (constipation or soilage).

VIII Hirschsprung's Disease

A Overview

Hirschsprung's disease is caused by the congenital absence of parasympathetic ganglia cells in the wall of the gastrointestinal tract.

As a result, the affected portions of the bowel are unable to relax and allow effective peristalsis to occur.

Hirschsprung's disease always involves the rectum and extends proximally with no skip areas. Any other part of the gastrointestinal tract, or even the entire tract, may also be involved.

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Male predominance is 4:1, except when the entire colon is involved. In that situation, the frequency ratio is reversed, with females predominating.

Approximately 30% of patients with Hirschsprung's disease have a relative afflicted with the disease.

B Clinical presentation

Hirschsprung's disease may go undiagnosed for years after birth. It should be suspected in any patient with a chronic unexplained illness and an abnormal bowel pattern dating back to early infancy.

Newborns with Hirschsprung's disease present with a history of nonpassage of meconium.

Meconium is usually passed within 24 hours after birth in term infants and within 48 hours in

premature infants.

Distention and bilious vomiting are common.

Physical examination in the newborn reveals a distended abdomen.

Occasionally, loops of stool -filled bowel may be palpated.

A rectal examination shows the ampulla or rectal vault to be empty and the sphincter tone to be increased. Classically, when the examining finger is removed, an explosion of watery stool occurs.

Infants and older children have a history of obstipation and constipation as well as failure to thrive.

Bouts of diarrhea, vomiting, and abdominal distention may herald the development of enterocolitis.

Enterocolitis is sometimes associated with Hirschsprung's disease. If left untreated, it has a high mortality rate (up to 50%).

C

The diagnosis is confirmed by radiographic and tissue studies.

Abdominal radiographs reveal air–fluid levels and a distended bowel. Often, no air is seen in the rectum.

Barium enema shows spasm and a narrowed lumen in the affected bowel.

A transition zone is often present, showing a dilated proximal gut and a narrowed distal gut.

This zone represents the most distal area in which ganglia cells are present.

In most patients, this zone is in the rectosigmoid segment of the colon.

The ratio of the diameter of the sigmoid colon to the diameter of the rectum on contrast enema is greater than 1 in patients with Hirschsprung's disease.

In patients with total colonic Hirschsprung's disease or with a longer segment involving the small bowel, the findings may not be as clear, and the transition zone may not be identified. The sigmoid– rectum ratio is not helpful.

A follow-up radiograph is obtained in 24 hours when the barium enema is inconclusive in a newborn with suspected Hirschsprung's disease. The appearance of residual barium in the bowel is very suggestive of Hirschsprung's disease.

Tissue confirmation

Biopsy specimens are examined for the presence of Auerbach's plexus in the muscular layer. The specimen can be obtained by either of two procedures.

Seromuscular biopsy of the bowel wall at laparotomy

Full -thickness transrectal biopsy, which requires general anesthesia

Suction biopsy technique is currently used as the first step.

With this procedure, the biopsy specimen is examined for Meissner's plexus in the submucosal layer.

The procedure can be performed at the bedside, with little risk to the patient.

Although the procedure is simple, it produces small specimens and requires an experienced pathologist for a correct interpretation.

Staining for acetylcholinesterase (which is increased in Hirschsprung's disease) may aid in the histologic diagnosis.

D Preoperative management

Once the diagnosis has been made, the patient is prepared for surgery. P.568

If enterocolitis is present preoperatively, the patient requires parenteral antibiotics and gastric decompression. In addition, rectal decompression and irrigations with saline or an antibiotic solution are performed.

The classic surgical approach is to perform a colostomy in an area of intestine that has ganglia cells.

Once the gastrointestinal tract is patent, the child can be fed orally.

E Operative management

There are a variety of different operative approaches for Hirshsprung's disease. Many surgeons will do a primary pullthrough at the time of diagnosis if the patient is stable. If not, a colostomy will need to be performed to relieve the obstruction and allow enteral feedings.

Goals of surgery. Although different operative procedures are available for the definitive repair, all have two goals in common:

Removal of most or all of the involved intestine

Re -establishment of a functional, continent gastrointestinal tract by bringing well-inervated intestine to the anus.

Procedures. The four most commonly performed are the Swenson, Duhamel, and Soave procedures, and the recently described transanal approach. These procedures can be performed in a tradional open fashion or laparoscopically assisted.

Swenson's procedure is the standard operation, but it is difficult to perform and is not used today by most pediatric surgeons.

The involved colon is excised to within 1 cm of the anal mucocutaneous margin.

The bowel is then sutured to the cuff of distal anorectal segment, thus establishing gastrointestinal continuity.

Duhamel procedure

The involved colon is excised to the level of the peritoneal reflection within the abdomen.

The proximal normal bowel is tunneled between the sacrum and the rectum and is then

anastomosed end -to -side to the low anorectum.

Soave procedure

In this operation, the involved colon is also excised to the level of the peritoneal reflection.

The mucosa is removed in the remaining rectum.

The proximal normal bowel is pulled through the stripped anorectal segment and is sutured to the anorectal junction.

Transanal approach

In this operation, the rectal mucosa is dissected from the rectal wall transanally up to the peritoneal reflection.

The abdomen is entered transanally through the rectal wall.

The proximal normal bowel is pulled through the stripped anorectal segment is and sutured to the anorectal junction.

Sequelae. Enterocolitis may occur after these operations because the internal sphcinter is still abonormally innervated. Because the mortality rate is high if untreated, early diagnosis and treatment are critical.

F

The prognosis for infants properly treated for Hirschsprung's disease is good.

Anal dilatation may be necessary intermittently if constipation occurs secondary to the retained aganglionic internal anal sphincter.

Problems of incontinence and fecal soiling occur occasionally.

Postoperative constipation may reflect a group of patients with poor gastrointestinal motility as a spectrum of the disease. These patients have responded to prokinetic agents. Recent studies have raised the question of poor neurotransmission as a problem with Hirschsprung's disease. However, if constipation persists, biopsy at the surgical anastomosis should be considered to document ganglion cells at this site.

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IX Disorders of Infancy

A Pyloric stenosis

In this condition, hypertrophy of the muscular layer of the pylorus causes gastric outlet obstruction. The classic symptom is nonbilious projectile vomiting.

The etiology of the condition is unknown. However, certain consistent elements imply a hereditary, genetic basis.

It is a male -predominant disease; the male:female ratio is 4:1.

The offspring of a female with pyloric stenosis have a 10 -fold greater chance of developing pyloric stenosis, whereas offspring of a male with pyloric stenosis have a four-fold greater chance of developing pyloric stenosis.

The condition is more common in whites than in blacks.

Clinical presentation. Pyloric stenosis occurs early in life, usually between the age of 2 weeks and 2 months.

The history is one of nonvomiting at birth, a gradual onset of vomiting, and final progression to nonbilious projectile vomiting.

Vomiting may lead to dehydration.

A hypochloremic, hypokalemic metabolic alkalosis may be present; this condition varies with the degree of dehydration.

Jaundice is present in 10% of the infants. It is thought to be caused by a deficiency of glucuronyl transferase and resolves after surgical treatment of the pyloric stenosis.

With the improvement of survival of premature infants with various other anomalies, a group of older (2–4 months of age) infants is developing pyloric stenosis. It is unclear whether this situation represents a delay in diagnosis because of parenteral feeding or a true older presentation. However, the diagnosis should be considered in this subgroup if feeding problems develop or persist.

Diagnosis

The physical examination can often provide the diagnosis.

Palpation of a midepigastric mass in the right upper quadrant of an infant with projectile vomiting is the sine qua non of pyloric stenosis. However, finding the mass may require experience, persistence, and patience.

Complete evacuation of the stomach by a nasogastric tube may aid in finding the mass.

Ultrasonography, however, has become the most common method of diagnosis due to the case of the study and “the lost art of physical exam.” Although the examination does not require a cooperative patient, it does rely on the experience of the person performing the study. The criteria for diagnosis are documented.

The length of the pylorus is measured; if greater than 15 mm, pyloric stenosis is suspected.

The width of the muscular wall is measured; if greater than 4 mm, pyloric stenosis is suspected.

Upper gastrointestinal series may be helpful in the diagnosis. The findings include:

Gastric retention of 3–4 hours

Elongation and narrowing of the antrum

A “string” sign or “railroad track” sign (one or two thin barium tracts, respectively, through the pylorus)

A mass effect on the antrum

Nonprogression of a peristaltic wave through the pylorus to the duodenum

Preoperative management

Correction of the alkalosis and volume deficits is necessary.

The conditions are corrected by fluid replacement and potassium supplementation.

Adequate hydration is determined by voiding patterns (the normal infant voids 4 to 5 times a day).

Alkalosis correction is measured by the serum bicarbonate, which should be less than 28 mEq/dL, or serum chloride, which should be greater than 92 mEq/dL before surgery is considered.

Nasogastric decompression may also be instituted to protect against aspiration and to aid in the quicker return of gastric motility in the postoperative period.

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Operative management. The surgical procedure is pyloromyotomy. This procedure involves an incision of the serosa over the pylorus and division of the hypertrophic muscle of the antrum but not the duodenum. The stomach is not entered.

Postoperative management

The patient may be started on feedings of glucose and water or an electrolyte infant formula (e.g., Pedialyte) 4–6 hours after surgery.

Vomiting occurs in 50%–80% of patients because of gastric atony or acute gastritis.

This vomiting is usually self-limited and has been decreased with preoperative gastric decompression.

Occasionally, the patient will benefit from gastric lavage with half -strength bicarbonate solution.

Feedings are advanced on a prescribed schedule, and full feedings are usually reached by 24 hours after surgery. The patient may be discharged at this point.

Complications

Duodenal perforation is the major complication.

Its danger is not so much its occurrence as the problem of its being overlooked at the time of surgery.

The perforation is handled by a simple repair, nasogastric decompression for 24–48 hours, and antibiotics.

If it is recognized and handled appropriately, the major difficulty is an extended hospital stay.

If the perforation is missed, the morbidity is severe, and the incidence of mortality is significant.

Apnea may also occur in the early postoperative period.

The patient should, therefore, have an apnea monitor in place for the first 24 hours postoperatively.

Postoperative apnea is associated with a serum carbon dioxide level greater than 28 mL/dL.

An incomplete pyloromyotomy may cause recurrent symptoms. This operation can be evaluated best with ultrasonography. Pyloric measurements decrease to normal 2–4 weeks after a complete pyloromyotomy.

Prognosis. Once adequately treated, pyloric stenosis does recur, and long-term studies indicate no sequelae such as ulcer disease, food intolerance, or hiatal hernia. In addition, no problems with growth and development occur.

B

Biliary atresia is a disease that affects the development of the biliary duct system both intra - and extrahepatically. It occurs once in every 25,000 births.

The etiology of the disease is unknown. Many possible causes have been implicated but not confirmed, including viral infections, hereditary factors, neonatal hepatitis, and malformation of the extrahepatic ductal system. Biliary atresia appears to develop after birth. Although isolated fetal cases have been described in Japan, no cases have been reported in the United States.

Types. Classically, biliary atresia is divided into correctable and uncorrectable types. However, the current belief is that biliary atresia represents a progressive spectrum of disease and that these divisions have little bearing on the eventual outcome.

Correctable biliary atresia occurs in 20% of the cases.

A normal common bile duct becomes atretic at some distal point.

It is called “correctable” because the duct can be anastomosed to a jejunal conduit.

Uncorrectable biliary atresia. No macroscopic biliary system is present in the portal triad. Until the Kasai operation, no procedure had been successful in establishing bile drainage of the liver.

Clinical presentation. Clinically, the child presents from 4 weeks to 4 months of age as a healthy but jaundiced infant with few other complaints. Some patients have associated light stools.

Laboratory studies show conjugated hyperbilirubinemia.

Liver function studies may or may not be abnormal, depending on the degree of liver damage from cholestasis.

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Diagnosis. The most important rule of thumb is that persistent jaundice beyond the first month of life must be evaluated. This condition may not affect the outcome in patients with medical causes of conjugated hyperbilirubinemia (for whom no effective therapy may exist). However, the prognosis of surgery for biliary atresia is related to the age at diagnosis.

The workup is designed to differentiate true anatomic obstruction of the biliary tree from other causes of hyperbilirubinemia.

TORCH (toxoplasmosis, o thers, rubella, cytomegalovirus, and h erpes simplex virus) titers are checked for possible infection.

Serum electrophoretic patterns are examined for α 1 -antitrypsin deficiency.

Ultrasonography is performed to identify the gallbladder and the fibrotic bile duct at the portohepatis. If the gallbladder is not seen or the fibrotic ducts are not located, an exploratory laparotomy should be strongly considered instead of further tests.

Nuclear scans using technetium 99m (99m Tc) -labeled iminodiacetic acid derivatives look for biliary excretion into the gastrointestinal tract. The accuracy of these tests may be enhanced with the administration of phenobarbital sodium (PBS). PBS stimulates liver enzymes and improves the excretion of bile in patients without biliary atresia.

Percutaneous liver biopsy is very helpful in experienced hands. If it shows bile duct proliferation in the face of hepatocellular necrosis, biliary atresia should be suspected.

If biliary atresia cannot be ruled out by these methods, the child should undergo a diagnostic laparotomy.

If an intraoperative cholangiography demonstrates a normal patent biliary system, a wedge biopsy of the liver is taken and the surgical procedure is ended.

If patency cannot be demonstrated, the porta hepatis is explored in an effort to find the atretic duct.

If an extrahepatic duct can be found, a Roux -en -Y loop of jejunum is anastomosed to it. This is the so-called correctable biliary atresia.

If the common duct cannot be found, the dissection is then carried to the hilus of the porta hepatis and a Kasai procedure (hepatoportal enterostomy) is performed. This involves anastomosing a loop of jejunum to the liver hilus, incorporating the area where the common bile duct should be.

Prognosis

Two factors influence the outcome of the Kasai operation:

At surgery, the patient is less than 10 weeks old.

The best results are obtained in patients 8–12 weeks old.

To date, there have been no long-term survivors among patients who had repairs done when they were more than 20 weeks old. This is caused by the irreversible liver damage that results from cholestasis.

The microscopic stage of the biliary tree is examined from the hilar dissection specimen.

Patients with ductules greater than 120 µm in diameter have a good prognosis.

Patients with ductules smaller than 70 µm have a very poor prognosis.

A “gray zone” occurs when the ductules are between 70 and 120 µm. Although bile