Principles of Surgery, Companion Handbook - page 39

Chapter 37 Pediatric Surgery

Principles of Surgery Companion Handbook

CHAPTER
37
PEDIATRIC SURGERY

General Considerations
Lesions of the Neck
 Cystic Hygroma (Lymphangioma)
 Thyroglossal Duct Remnants
 Branchial Cleft Anomalies
 Torticollis
Respiratory System
 Congenital Diaphragmatic Hernia (Bochdalek)
 Congenital Lobar Emphysema
 Congenital Adenomatoid Malformation
 Pulmonary Sequestration
 Bronchogenic Cysts
 Bronchiectasis
 Foreign Bodies
Esophagus
 Tracheoesophageal Fistula and Esophageal Atresia
 Esophageal Atresia (Associated Abnormalities)
 Corrosive Injury of the Esophagus
 Esophageal Substitution
 Gastroesophageal Reflux (GER)
Gastrointestinal Tract
 Pyloric Stenosis
 Intestinal Obstruction in the Newborn
 Appendicitis
Duplications, Meckel's Diverticulum, and Mesenteric Cysts
 Duplications
 Meckel's Diverticulum
 Mesenteric Cysts
Hirschsprung's Disease
Imperforate Anus
Biliary Atresia
 Choledochal Duct Cyst
Deformities of the Abdominal Wall
 Embryology
 Umbilical Hernia
 Patent Urachus
 Patent Omphalomesenteric Duct
 Omphalocele
 Gastroschisis
 Exstrophy of the Cloaca (Vesicointestinal Fissure)
 Congenital Deficiency of the Abdominal Musculature (Eagle-Barrett Syndrome, Prune-Belly Syndrome)
 Inguinal Hernia
Genitalia
 Cryptorchidism
 Vaginal Anomalies
 Ambiguous Genitalia (Intersex Syndromes)
 Ovarian Cysts and Tumors
Neoplastic Disease
 Wilms' Tumor
 Neuroblastoma
 Rhabdomyosarcoma
 Teratoma
 Liver Tumors
Trauma

GENERAL CONSIDERATIONS

Fluid and Electrolyte Balance Initial intravenous fluids in a newborn should consist of 10% dextrose and water with a volume of 65–100 mL/kg/day. After the first 10 days of life, maintenance fluid is 100 mL/kg/day, and the solution should consist of 5% dextrose and quarter-normal saline. Daily potassium needs are met by 2 mEq/kg potassium chloride. Additional fluid losses are replaced with an equal volume of fluid containing electrolytes equivalent to those lost. Maintenance fluid requirement for children weighing more than 10 kg consists of 50 mL/kg for the next 10 kg and 25 mL/kg thereafter. Hyperosmotic fluids may cause intracranial hemorrhage in the neonate and should be used with extreme caution.

Acid-Base Equilibrium Arterial blood gases permit monitoring of the alveolar ventilation and acid-base equilibrium. Acute metabolic acidosis implies inadequate tissue perfusion, and its etiology must be investigated. A rising PCO2 usually indicates the need for assisted ventilation, and a falling PaO2 may indicate compromised ventilation-perfusion secondary to parenchymal disease or a right-to-left shunt. In addition, the respiratory or metabolic nature of the imbalance is determined. Correction is made by adjusting ventilation and the possible infusion of sodium bicarbonate.

Blood Volume and Blood Replacement The estimated blood volume of the newborn is 85 mL/kg of body weight. However, the premature infant has a relatively larger blood volume than does the full-term infant. The transfusion requirement of packed red blood cells is 10 mL/kg. The use of fresh frozen plasma (20 mL/kg) and platelet transfusions (1 unit/5 kg) should be considered when transfusion exceeds 30 mL/kg.

Hyperalimentation and Nutrition Parenteral hyperalimentation will meet caloric needs for growth and recovery from illness if the alimentary tract cannot. Protein, carbohydrate, and fat, plus minerals and vitamins, may be administered by either a central or a peripheral intravenous route. The latter carries less risk. (The former is used when peripheral access no longer exists or the infusate is highly concentrated.) Prolonged hyperalimentation may lead to intrahepatic cholestasis. Jaundice and cirrhosis may develop, which can be irreversible and lead to death of the infant. Enteral nutrition continues to be the preferred route.

Venous Access Most infants requiring short-term intravenous medications and nutrition can be managed by peripheral intravenous catheter placement. For long-term access, Silastic central venous catheters are used. Catheters may be inserted by cutdown (external jugular vein, facial vein, or proximal saphenous vein) or percutaneously (subclavian or internal jugular veins). Chest x-ray confirms central location. Catheter-related sepsis occurs in about 10 percent of patients.

Thermoregulation Cold stresses the infant because of impaired thermogenesis and causes increased glucose and oxygen requirements to meet metabolic needs. The use of overhead radiant warmers regulated by servo controls and the appropriate wrapping of infants during transport and surgery will help protect the infant.

Pain Control It is now generally accepted that all children, including neonates, experience pain after surgery. Proper doses of intravenous narcotics should not cause respiratory depression. Different methods of pain control have been shown to be effective in infants and children, and these include patient-controlled analgesia (PCA), epidural catheters, and caudal blocks. Regional blocks such as those given for hernia repairs appear to be effective.

LESIONS OF THE NECK

Cystic Hygroma (Lymphangioma)

Etiology and Pathology The lesion results from sequestration or obstruction of lymphatic vessels most frequently in the posterior triangle of the neck, axilla, groin, and mediastinum. Adjacent tissues may show lymphatic infiltration and also nests of vascular tissue. Lesions at the thoracic inlet may cause airway obstruction. Sudden enlargement due to infection caused by streptococcal or staphylococcal organisms also may cause airway obstruction. These may be detected by prenatal ultrasound and are associated with abnormal karyotypes and hydrops fetalis.

Treatment Total excision is the treatment of choice. Radical excision is avoided in this benign lesion. Needle aspiration is worthless because of lack of communication between the cysts. Injection by sclerosing agents has not proved effective.

Thyroglossal Duct Remnants

Pathology and Clinical Manifestations The thyroglossal duct descends from the foramen cecum in conjunction with the development of the hyoid bone. Remnants from the duct will develop into a cyst, which may become apparent at about age 2–4 years. The cyst is located in the midline, over or inferior to the hyoid bone, and moves with swallowing. Occasionally the cyst may become infected, but this usually clears with penicillin therapy. The differential diagnosis includes lymphadenopathy, a dermoid cyst, or rarely, ectopic thyroid.

Treatment Infection should be controlled first with drainage and antibiotics. Total excision involves removal of the cyst, the central portion of the hyoid bone, and the tract to the foramen cecum (the Sistrunk procedure).

Branchial Cleft Anomalies

Branchial cleft sinuses and cysts represent remnants from embryologic structures. The most common are from the second branchial cleft. Complete sinuses extend from a fistulous opening in the skin anterior to the sternocleidomastoid muscle and pass superiorly through the bifurcation of the carotid artery to enter into the pharynx anterior and inferior to the tonsillar fossa. Other remnants may contain cartilage. Sinuses drain a mucoid material and occasionally may become infected. Total excision is necessary to prevent recurrence.

Torticollis

Fibrosis of the sternocleidomastoid muscle shortens the muscle, rotating the head to the contralateral side. About 20 percent require surgical transection of the muscle, but most resolve spontaneously or respond to physical therapy.

RESPIRATORY SYSTEM

Congenital Diaphragmatic Hernia (Bochdalek)

Pathology The pleuroperitoneal canal in the posterolateral portion of the hemidiaphragm is the last portion to close during embryonic development. The bowel returning from the umbilical cord to the abdominal cavity herniates into the chest when the canal fails to close. This usually involves the left side of the chest. The result is failure of development of the lung on the ipsilateral side by the encroaching intestine and on the contralateral side by the mediastinal shift. The abdomen is scaphoid, and the heart tones are shifted away from the side of herniation. A chest radiograph reveals gas-filled loops of bowel in the chest. An antenatal ultrasound will demonstrate the lesion. Symptoms at birth are respiratory distress and cyanosis. The underlying pathophysiology is increased pulmonary vascular resistance and pulmonary artery hypertension, which can lead to a persistent fetal circulation with a right-to-left shunt.

Treatment Surgical closure via the abdomen is accomplished after the infant is stabilized by endotracheal intubation and ventilation. Sodium bicarbonate may be given intravenously once the PCO2 is reduced to further correct a metabolic acidosis. At operation, the posterior rim of the diaphragm must be dissected from overlying peritoneum, and a two-layer closure is achieved. Rarely, insufficient diaphragm exists, and a synthetic patch is necessary for closure. The need for a patch or the inability to achieve a PaO2 greater than 100 mmHg and a PCO2 less than 40 mmHg after correction is a bad prognosis. Pulmonary vasodilators have little therapeutic effect. The use of high-frequency ventilation and extracorporeal membrane oxygenation (ECMO) has resulted in increased survival of these severely compromised infants. These may be used preoperatively and occasionally continued intraoperatively.

Congenital Lobar Emphysema

The right middle and upper lobes and the left upper lobe are the most frequently involved. Sudden expansion of the involved lobe can lead to respiratory distress and cyanosis because of compression of the remaining lung. Emergent surgical excision of the involved lobe may be needed to relieve the distress. Lobar emphy-sema developing more slowly may resolve gradually, and judicious observation is warranted. Cardiac anomalies may coexist. It is caused by intrinsic bronchial obstruction from poor cartilage development.

Congenital Adenomatoid Malformation

This is frequently confused with a diaphragmatic hernia because of the cystic proliferation of the terminal airways, most frequently located in the left lower lobe. This results in an expanding lesion that by chest radiography may have a similar appearance to a congenital diaphragmatic hernia. Treatment is an urgent resection done through a thoracotomy on the affected side and is curative.

Pulmonary Sequestration

This lesion consists of a mass of nonfunctioning lung tissue usually in or adjacent to the left lower lobe. There is no bronchial communication to the respiratory tree, and the arterial supply is usually systemic, frequently coming from the aorta below the diaphragm. The condition is revealed as a shadow on the chest radiograph. Air may be seen in the intralobar variety if there is communication with adjacent lung alveoli. The latter may present clinically with cough, hemoptysis, and recurrent pulmonary infections. These are classified as extralobular or intralobular depending on their location.

Bronchogenic Cysts

These can present at any age and occur anywhere along the respiratory tract. Treatment is resection and may be needed emergently if airway compression occurs. Histologically, the cysts are hamartomatous lesions, usually a single cyst lined with respiratory epithelium with cartilage and smooth muscle.

Bronchiectasis

Bronchiectasis is an abnormal dilatation of the bronchi and bronchioles associated with chronic infection. This is usually associated with an underlying congenital pulmonary anomaly, cystic fibrosis, a foreign body, or immunodeficiency. Symptoms include chronic cough, purulent secretions, recurrent pulmonary infections, and hemoptysis. The diagnosis is made by computed tomography (CT). Treatment is medical, with antibiotic therapy and postural drainage. Lobectomy is indicated for localized disease not responding to medical management.

Foreign Bodies

Airway These are found most frequently in the airways of toddlers. Peanuts or small parts of toys may be aspirated, and the child presents with cough and unilateral wheezing. A radiograph of the chest will show atelectasis of the involved lobe and the foreign body if it is radiopaque. Occasionally, a clinical diagnosis of asthma eventually will be found to be caused by an unrecognized foreign body in the airway. Bronchoscopy and extraction of the body are the treatment.

Esophagus Swallowed coins are the most common foreign body to lodge in the esophagus. The most frequent locations for foreign bodies to become trapped are the cricopharyngeus, the aortic arch, and the gastroesophageal junction. Symptoms vary from an inability to swallow saliva to respiratory distress because of tracheal compression. Treatment is esophagoscopy and removal of the foreign body. Occasionally, foreign bodies are advanced to the stomach, where one would expect them to pass through the rest of the gastrointestinal tract without difficulty.

ESOPHAGUS

Tracheoesophageal Fistula and Esophageal Atresia

Clinical Manifestations Between 85 and 90 percent of these lesions are made of a blind upper pouch with a tracheal communication to the lower esophagus (Fig. 37-1). An isolated trache-oesophageal fistula occurs in 2–4 percent of such children. There are frequently associated congenital anomalies that affect the outcome. Imperforate anus and/or congenital cardiac disease occurs in 10–12 percent of these infants. Excess salivation and attempted feedings result in choking and cyanosis. The diagnosis is made by the inability to pass a Replogle tube into the stomach. Instillation of air will prove the diagnosis on a chest x-ray. A radiograph of the infant will reveal air in the intestinal tract if a fistula coexists.



FIGURE 37-1 Five major varieties of esopageal atresia and tracheoesophageal fistula. A. Esophageal atresia without associated fistula. B. Esophageal atresia with tracheoesophageal fistula between proximal segment of esophagus and trachea. C. Esophageal atresia with tracheoesophageal fistula between distal esophagus and trachea. D. Esophageal atresia with fistula between both proximal and distal ends of esophagus and trachea. E. Tracheoesophageal fistula without esophageal atresia (H-type fistula).



Treatment Sump suction via the Replogle tube is applied to the upper pouch, and broad-spectrum antibiotics are begun.

Primary Surgical Correction The operation is performed via a posterolateral thoracotomy using a retropleural approach. The fistula is ligated and transected at the trachea. The esophagus is repaired using a single-layer anastomosis.

Delayed or Staged Repair For infants that are extremely premature or have serious coexisting anomalies, a gastrostomy is placed and repair delayed. Once the infant has been stabilized, pulmonary infection cleared, and other anomalies assessed, total correction should be performed. If the gap is too great to anastomose the two ends, additional length in the upper pouch may be achieved by a circular myotomy. A colon interposition can bridge a gap too long to permit a primary anastomosis. This is performed as a delayed procedure when the child is larger and has greater reserve.

Postoperative Complications Anastomotic leaks are not infrequent, and most heal spontaneously. Between 10 and 20 percent develop strictures that usually present as choking and gagging. A contrast esophagogram is confirmatory, and simple dilatation is corrective. Gastroesophageal reflux is common. Most children respond favorably to medical management, but about a third require an antireflux procedure.

Esophageal Atresia (Associated Abnormalities)

There are several associated abnormalities known to occur with esophageal atresia. These have come to be known as the VATER syndrome. This is to remind one that the V stands for vertebral abnormalities and also the fact the most common cardiac abnormality is the ventricular septal defect (VSD). The A stands for the atresias, especially imperforate anus or duodenal atresias. The TE stands for tracheal and esophageal abnormalities. This should serve to remind one that if one is faced with a child with an imperforate anus, the child should be checked for esophageal and tracheal abnormalities. The R stands for abnormalities of the renal system and also to remind one that there can be abnormalities of the radial aspect of the forearms.

ISOLATED ESOPHAGEAL ATRESIA

This is diagnosed by a plain film demonstrating a nasogastric tube coiled in the blind upper pouch and no air in the intestinal tract. A cervical esophagostomy may be performed, and a feeding gastrostomy will permit feeding the infant. When the child is older, the defect is bridged by a colon interposition or a reversed gastric tube.

ISOLATED (H-TYPE) TRACHEOESOPHAGEAL FISTULA

The symptoms may be delayed and confusing. There is usually choking on feeding, especially with liquids. Gaseous abdominal distention develops, and frequently there is a history of repeated aspiration pneumonia. The diagnosis is made by a careful contrast study via the esophagus or, more safely, by bronchoesophagoscopy. Surgical division of the fistula, usually through the neck, is curative.

LARYNGOTRACHEOESOPHAGEAL CLEFT

This rare anomaly is frequently present in association with esophageal atresia. It is another type of an abnormal separation of the trachea from the esophagus. In this situation, there is an open cleft from the larynx to the vocal cords and occasionally extending down to the carina. Surgical correction, while certainly possible, frequently requires a tracheostomy, gastrostomy, and extensive surgical intervention.

Corrosive Injury of the Esophagus

This type of injury is caused by ingestion of strong alkaline or acid substances. All children suspected of swallowing a corrosive agent should have esophagoscopy within 24 h of the injury. The scope is passed only to the first evidence of injury; further insertion may lead to perforation of the injured esophagus. If the injury is circumferential, a string is passed for future guidance during dilatations, and a gastrostomy is performed. Steroids are generally not used. Antibiotics are administered for 3 weeks. Dilatation is started after 3 weeks and continued as needed until any stricture has resolved.

Esophageal Substitution

There are two indications for this procedure: unrelenting stricture of the esophagus and a large defect in esophageal atresia. The connection is achieved with either colon based on the middle colic vessels or a reversed gastric tube fashioned from the greater curvature of the stomach or a free jejunal graft. The conduits are usually placed in the native esophageal bed but can be brought up behind the lung root in the left chest or substernally.

Gastroesophageal Reflux (GER)

GER occurs to some degree in all children. However, it is pathologic when children manifest failure to thrive, esophagitis, esophageal stricture, or repeated aspiration pneumonias.

Clinical Manifestations These children usually have a history of repeated vomiting. There may be symptoms of asthma. Esophagitis can lead to chronic blood loss and anemia. A barium swallow will reveal the anatomy of the esophagus but may not reveal reflux. A pH probe placed in the distal esophagus should reveal the reflux. Esophagoscopy and biopsy may reveal esophagitis.

Treatment Most children respond to medical therapy, propping, and thickened feedings. Drugs such as ranitidine (an H2 blocker) or cisapride (a prokinetic agent) may relieve the reflux. If medical therapy fails and the reflux is life-threatening or causing esophagitis and stricture, surgical correction is indicated. The most frequently used procedures are the complete (Nissen) or partial (Thal) fundic wrap around the distal esophagus.

GASTROINTESTINAL TRACT

Pyloric Stenosis

Clinical Manifestations Vomiting, progressing to explosive (projectile), begins after the first 2–3 weeks of life. The vomitus is nonbilious. Most infants are males, and the disease is hereditary, although penetrance is low. A metabolic alkalosis develops with depressed serum chloride and potassium levels and an elevated sodium bicarbonate level. Most tumors are palpable in the right upper quadrant and may be demonstrated by ultrasonography or a contrast study.

Treatment Metabolic alkalosis is corrected by intravenous 5% dextrose and half-normal saline with 30 mEq/L of potassium chloride at two times maintenance until the urine specific gravity is less than 1.010, the chloride level is greater than 95 mEq/L, and the bicarbonate is less than 30 mEq/L. A Fredet-Ramstedt pyloromyotomy is then performed. Before operation, a nasogastric tube is passed to empty the stomach and prevent vomiting during induction of anesthesia. Small, frequent feedings of an electrolyte solution are begun 4 h after operation; the volume is gradually increased to maintenance, and then formula is given. Discharge is usually 24–36 h postoperatively.

Intestinal Obstruction in the Newborn

Bilious vomiting in the newborn means intestinal obstruction until another cause is proved. An abdominal radiograph will help determine the level of obstruction. If there is a proximal incomplete obstruction, an upper gastrointestinal series is required to diagnose malrotation with possible midgut volvulus. A barium enema is useful to look for malrotation, a microcolon signifying ileal obstruction, colonic atresia, Hirschsprung's disease, meconium ileus, meconium plug, or small left colon syndrome.

DUODENAL MALFORMATIONS

Obstruction may be complete, as in atresia, or partial, as in annular pancreas, stenosis, or bands associated with malrotation. The abdominal radiograph classically shows the “double bubble” of air in a distended stomach and duodenum. Intrinsic obstructions are managed by a side-to-side duodenoduodenotomy. If obstruction is secondary to volvulus from a malrotation, timely surgery is needed to prevent infarction of the midgut secondary to occlusion of the superior mesenteric vessels. Duodenal webs usually contain the common bile duct and must be approached with extreme caution. One-third of all such infants have Down syndrome (trisomy 21).

INTESTINAL ATRESIA

This condition is believed to be due to an antenatal vascular accident or volvulus. There may be simple atresias or loss of considerable amounts of intestine with a deep cleft in the mesentery and resulting short-gut syndrome. Multiple atresias exist in about 10 percent of such patients. A radiograph usually will determine the level of atresia, and a barium enema will detail the rotation of the colon and its caliber. The disparity in caliber of the two atretic ends can be managed by an end-to-oblique anastomosis using a single layer of nonabsorbable sutures. A complementary gastrostomy aids greatly in the management of these children, who may have a prolonged period before enteric function is restored. About 10 percent will have cystic fibrosis. All should have a sweat test. The “apple peel” or “Christmas tree” deformity is a type of jejunal atresia resulting from occlusion of the superior mesenteric artery distal to the middle colic artery. The small bowel distal to the occlusion is short and spirals about a longitudinal vessel supplied by the middle colic and marginal vasculature of the colon.

MALROTATION AND MIDGUT VOLVULUS

During the sixth week of fetal development, the midgut herniates into the umbilical cord and begins its return to the abdominal cavity in the tenth week. During its return, the midgut undergoes a 270-degree counterclockwise rotation around the superior mesenteric artery. This results in the ligament of Treitz being in the left upper quadrant and the cecum in the right lower quadrant. If this does not occur, peritoneal attachment between the ascending colon and right abdominal wall are elongated and create Ladd bands that are able to obstruct the second portion of the duodenum. The resulting stalklike mesentery containing the superior mesenteric artery results in the potential for a volvulus of the intestine around the superior mesenteric vessels that can result in a midgut strangulation. If this occurs, rapid third-space fluid loss occurs in the midgut. Bilious vomiting, abdominal distention, and resulting abdominal tenderness are pertinent manifestations. Urgent laparotomy is required, with a counterclockwise derotation of the volvulus and division of the peritoneal bands. A Ladd's procedure that results in the duodenojejunal junction being in the right abdominal gutter and the entire colon being on the left side will, it is hoped, create enough adhesions to avoid a recurrence. An incidental appendectomy is also done routinely. If this operation is done emergently, massive resection of ischemic small bowel may be avoided.

MECONIUM ILEUS

Infants born with this condition almost always have cystic fibrosis. Inspissated meconium caused by a lack of pancreatic enzymes and viscid mucus obstructs the distal ileum. The infant presents with late bilious vomiting, palpable loops of bowel with maleable meconium, a low small bowel obstruction on the radiograph, and a microcolon on contrast enema. Antenatal perforation of the intestine will be revealed by calcific densities noted on the abdominal radiograph. Uncomplicated obstruction can be relieved by a detergent in Gastrografin enema with fluoroscopic control. The hyperosmolality of the solution must be diluted to prevent diarrhea and dehydration. Complicated conditions are managed surgically by the creation of temporary ileostomies and irrigation of the obstructed bowel with acetyl cysteine (Mucomyst).

NECROTIZING ENTEROCOLITIS (NEC)

This condition almost exclusively affects the stressed premature infant. There is a breakdown of the mucosal barrier, and endogenous bacteria invade the bowel wall. This causes vomiting, abdominal distention, and bloody stools. Sepsis, metabolic acidosis, and third spacing soon follow. There is a left shift in the white blood cell count, and the platelet count falls. The diagnosis is made by palpation of tender loops of bowel on abdominal examination and demonstration of pneumatosis intestinalis on an abdominal radiograph. Gas also may be noted in the hepatic portal veins.

The disease may be corrected in most infants by medical therapy: decompression of the intestinal tract by a nasogastric tube, giving adequate amounts of intravenous fluids (both electrolyte and colloid) to restore circulating volume, and the administration of broad-spectrum antibiotics to treat the sepsis. Frequent observation and abdominal radiographic examination are needed to document improvement or progression of the disease, which then requires surgical management. Free air on the abdominal radiograph is a specific indication for surgery. Necrotic bowel is excised and enterostomies fashioned. The latter are closed after the child recovers. Thought may be given to primary anastomosis of the small bowel to prevent the large caustic fluid losses that occur with small bowel fistulas. Postoperative parenteral hyperalimentation is needed to provide adequate calories for healing and continued growth of the infant. Occasionally, intestinal strictures may develop with signs of obstruction in infants recovering on medical management. This condition requires surgical correction.

INTUSSUSCEPTION

This is a common cause of intestinal obstruction in the infant. The usual age range is 3 months to 3 years. The lead point may be a hypertrophied Peyer's patch in the terminal ileum, which then intussuscepts into the cecum and ascending colon. If intussusception occurs in the child over age 5 years, a different cause must be suspected that may include malignant disease. Such lead points include polyps, Meckel's diverticulum, and non-Hodgkin's lymphoma.

Clinical Manifestations The onset is sudden and consists of severe, crampy abdominal pain lasting a minute. There is usually marked pallor, suggesting shock. A period of ease follows, only to have the brief episode of pain recur. Vomiting usually follows, and during a period of relaxation, a soft elongated mass can be felt in the right upper quadrant. The absence of bowel in the right lower quadrant (Dance's sign) may be noted. A bloody mucoid stool may be passed (“currant jelly” stool), and a guaiac test of the smear from a rectal glove is usually positive. A barium enema will reveal the “coiled-spring” appearance of the intussuscepted bowel.

Treatment Air enema is the preferred method of diagnosis and treatment. Air pressure should not exceed 120 mmHg. If successful, air will reflux into the small bowel. The child is hydrated with intravenous fluids and observed for 4–6 h. If all symptoms are relieved, oral fluids are begun and the child is discharged. If reduction is not achieved, it must be accomplished by celiotomy. The intussusceptum is gently milked out of the intussuscipiens by distal pressure until reduction is complete. An incidental appendectomy is usually performed. If the serosa of the intussuscipiens begins to split during reduction, resection of the intussuscepted bowel is carried out with primary anastomosis. The recurrence rate is about 3 percent for both hydrostatic and operative reduction.

Appendicitis

The incidence of perforation rises as the age of the patient decreases (25 percent of adolescents, 80 percent children less than 5 years of age). Vomiting, right lower quadrant pain and tenderness, and leukocytosis are common findings. Plain abdominal films, sonography, and abdominal CT scans with enteric contrast material may aid in the diagnosis. Definitive management is appendectomy.

DUPLICATIONS, MECKEL'S DIVERTICULUM, AND MESENTERIC CYSTS

Duplications

These may occur anywhere in the intestinal tract but are usually in the ileum. They are usually cystic masses but also may be long tubular structures. They lie in the leaves of the mesentery and share a common wall with the adjacent bowel. They usually present as a palpable, movable mass or as an acute abdomen if torsion and infarction occur. If the duplication communicates with the intestinal tract and contains gastric mucosa, gastrointestinal bleeding may be the presenting sign. Diagnosis is made by sonography or a technetium pertechnetate scan. The lesion should be excised with the adjacent bowel if it is short. Longer lesions may be treated with multiple enterotomies in the duplication with mucosal stripping or the creation of a distal connecting anastomosis if no ectopic gastric mucosa exists.

Meckel's Diverticulum

This is a persistent portion of the omphalomesenteric duct and occurs in about 2 percent of the population 2–3 ft from the ileocecal valve on the antemesenteric border of the ileum. It is usually asymptomatic but may present as appendicitis, intestinal obstruction, or most commonly, intestinal hemorrhage. The latter occurs if there is aberrant gastric mucosa within the diverticulum. The stools are maroon, and the hematocrit drops appreciably. Diagnosis may be made by technetium scan. The treatment is surgical excision.

Mesenteric Cysts

These also lie in the leaves of the mesentery but, unlike duplication cysts, contain no mucosa or muscular wall. They are believed to result from obstructed lymphatic channels. They present as a palpable, movable mass and may cause intestinal obstruction. The diagnosis is suspected by sonography. Excision is the treatment, and adjacent bowel may need to be resected. If the lesion is large, marsupialization to the peritoneal cavity is indicated.

HIRSCHSPRUNG'S DISEASE

This usually is a disease of male infants and consists of the absence of ganglion cells with hypertrophied nerve fibers in the rectum and sigmoid colon. Longer segments may be involved, and in the long-segment disease, the sex incidence is equal. There is an increased incidence in children with Down syndrome. The aganglionic segment is spastic and causes obstruction. This presents as distal obstruction in the newborn with abdominal distention and vomiting. Occasionally, it may present with diarrhea and toxicity from an enterocolitis that carries a serious mortality rate when fully developed. Chronic constipation with poor nutrition may occur in the older child.

Diagnosis A barium enema usually shows a megacolon in the innervated bowel, and the distal aganglionic colon has a more normal caliber. This may not be apparent during the first 2–3 weeks of life. Definitive diagnosis is made by a biopsy of the distal rectum to search for the presence or absence of ganglion cells. This can be a suction biopsy of the mucosa and submucosa or a full-thickness biopsy of the rectal wall as a surgical procedure.

Treatment Initially, a colostomy is performed through ganglionated bowel (Fig. 37-2). A pull-through procedure is accomplished when the child weighs 10 kg. If the child is older and has a megacolon, pull-through is delayed until the bowel has returned to normal caliber. The colostomy may be closed at the time of the pull-through or as a third stage depending on the surgeon's judgment. The various procedures used are a Swenson, Duhamel, and Soave endorectal pull-through.



FIGURE 37-2 The three basic operations for surgical correction of Hirschsprung's disease. A. The Duhamel procedure leaves the rectum in place and brings ganglionic bowel into the retrorectal space. The common wall, indicated by lines, is crushed to eliminate the septum. B. Classic Swenson operation (1948) is a resection with end-to-end anastomosis performed by exteriorizing bowel ends through the anus. C. The Soave operation is performed by endorectal dissection and removal of mucosa from the aganglionic distal segment and bringing the ganglionic bowel down to the anus within the seromuscular tunnel.



IMPERFORATE ANUS

This congenital anomaly occurs equally in both sexes in up to 1 in 5000 births. It results from the failure of normal development of the urorectal septum, which divides the cloaca and separates the urinary from the hindgut systems. The lesion is considered “high” when the rectal pouch ends above the levator ani muscles and “low” when it ends below. High lesions usually have fistulas to the vagina in the female and to the prostatic urethra in the male. Low lesions usually have fistulas to the perineum or male urethra. There are frequently associated anomalies involving other systems, which is known as the VATER syndrome.

Diagnosis The diagnosis is determined by physical examination. The level is determined either by a fistulogram or by a perineal injection of contrast material into the blind pouch under fluoroscopic control. A cystourethrogram should be performed to look for an associated fistula or ureteral reflux. “Inverted” radiographs are not reliable.

Treatment Initially, a sigmoid colostomy is performed if the lesion is high. If the lesion is low, a perineal proctoplasty may be attempted in the newborn. High lesions are best managed by a posterior sagittal anoproctoplasty, as described by Pena, using a muscle stimulator to identify the anal sphincters, vertical fibers, and the levator ani muscles. The rectum is detached from the fistula without sacrificing any of its distal length and placed precisely through the above muscle complex. The colostomy is closed several months later following complete healing of the pull-through. The caliber of the cutaneous anastomosis is maintained during the healing phase with the daily insertion of Hegar dilators.

BILIARY ATRESIA

Neonatal jaundice is usually physiologic. It becomes abnormal if it persists beyond 2 weeks, especially if the direct fraction of bilirubin is elevated. Biliary atresia affects both the extrahepatic biliary tree and the liver.

Etiology and Pathology The cause is unknown, but an infectious etiology is suspected. Atresia or hypoplasia may involve all or part of the extrahepatic biliary ducts and also the intrahepatic ducts.

Clinical Manifestations Jaundice is present from birth but may not be marked until after the first several weeks. The urine becomes dark and stools acholic. The abdomen may gradually become distended by the enlarging liver or ascites. Eventually, the spleen enlarges also.

Diagnosis The serum bilirubin level gradually rises, and the direct fraction is at least half the total. After a month of observation, a nuclear scan using technetium-99m IDA (DISIDA) is performed after pretreatment with phenobarbital. If there is no excretion of the radionuclide into the intestinal tract, atresia is virtually ensured. A sample of duodenal contents may be assayed for the presence of bile. An ultrasound may reveal a choledochal duct cyst. The intrahepatic ducts are never dilated in biliary atresia. Screening tests for infectious and metabolic causes should be negative. Percutaneous needle biopsy of the liver will establish the diagnosis with a high degree of certainty.

Differential Diagnosis The differential diagnosis includes physiologic jaundice, total parenteral nutrition–induced jaundice, hemolytic disease, sepsis, neonatal hepatitis (a probable variant of biliary atresia), alpha-trypsin deficiency, the inspissated bile syndrome, biliary hypoplasia, infection with different viruses, or metabolic defects.

Treatment Surgical exploration should be performed, and if possible, a cholecystogram should be obtained. If no ductal system is found, a dissection of the porta hepatis is carried out to see if any proximal duct is present. If there is none, the porta hepatis is excised between the right and left hepatic arteries, and a portoenterostomy, Roux-en-Y, is performed. If a duct is present, it is anastomosed to a Roux-en-Y loop of jejunum. If the operation is performed prior to the third month of life and the diameter of the bile ducts in the resected porta hepatis is greater than 100 mm, there is an excellent chance for prolonged bile excretion into the intestinal tract. Inflammation of the liver may continue, with the development of fibrosis and portal hypertension. If portoenterostomy fails, liver transplantation becomes an option.

Choledochal Duct Cyst

There are a variety of such cysts according to Alonso-Lej. The most common type is the fusiform dilatation of the common bile duct with the cystic duct opening into it. The female-male ratio is 4:1. The classic symptom triad consists of pain, a palpable mass, and jaundice.

Diagnosis This is accomplished by ultrasound or CT. Occasionally, endoscopic retrograde cholangiopancreatography (ERCP) will be required.

Treatment Surgical excision and anastomosis of the proximal duct to a defunctionalized Roux-en-Y loop of jejunum is the treatment of choice. If the cyst lining is not resected, there is a risk of malignant degeneration.

DEFORMITIES OF THE ABDOMINAL WALL

Embryology

Four separate embryologic folds contribute to the formation of the abdominal wall: cephalic, caudal, and right and left lateral folds. These coalesce at the umbilical ring surrounding the two arteries and left umbilical vein. The developing gut herniates into the umbilical cord during the fourth through the eighth weeks of gestation and returns to the enlarging abdominal cavity from the ninth to the tenth week. Failure of the cephalic fold to close results in sternal defects and the pentalogy of Cantrell. Caudal fold abnormalities include extrophy of the bladder or the cloaca. Lateral fold defects result in omphalocele. Gastroschisis results from an antenatal herniation of the gut to the right of the cord.

Umbilical Hernia

These hernias result from failure of closure of the umbilical ring. They frequently are small, less than 1 cm, and will close spontaneously. Larger ones may not close and sometimes are so disfiguring that early closure is justified. Supraumbilical hernias produce a protrusion of the umbilical skin, but the defect is adjacent and superior to the umbilicus. The pigmented portion of the skin points inferiorly. These defects do not close spontaneously, and early repair is justified. Repair of an umbilical hernia is done through a skinfold incision around the navel; the navel may be excised. Incarceration is extremely rare.

Patent Urachus

During development of the abdominal cavity, the bladder communicates to the umbilical cord through the urachus. If this tract persists, urine will be observed emanating from the navel. Incomplete closure may result in a urachal cyst, demonstrated by sonography. These are rare abnormalities and are treated by surgical excision.

Patent Omphalomesenteric Duct

During fetal life, this duct connects the ileum to the yolk sac via the umbilical cord. Normally, the duct involutes, but a portion may persist as a Meckel's diverticulum seen in about 2 percent of the population. If the entire duct persists, ileal contents will spill from the umbilicus. The diagnosis is made by stool observed at the umbilicus or intubation of the duct and instillation of contrast material. A radiograph will reveal the material flowing into the terminal ileum. Complete excision is the definitive treatment.

Omphalocele

These present at birth as herniation of abdominal contents into the umbilical cord. They may be small and contain only a small amount of intestine or large and contain liver in addition to intestine. There may be rupture of the cord and herniation of the contents into the amniotic cavity. Associated anomalies are noted in about two-thirds of these children. Primary closure of the abdominal wall is the surgical goal. If the mass of the contents is small, closure is easy. In large omphaloceles, the intestine and liver have lost the “right of domain,” and primary closure is frequently not possible. If other life-threatening anomalies are present, escharification of the cord may be accomplished using silvadene, pigskin, or povidone-iodine solution. This will allow epithelialization over the defect. If the child's condition will permit closure, this can be accomplished as a staged repair. A pouch of prosthetic material is sutured to the medial borders of the recti and covers the herniated viscera. The size of the pouch is decreased by taking multiple tucks within 7 days. This returns the contents to the enlarging abdominal cavity. Once reduction is complete, the pouch is removed and a primary repair accomplished. Severe associated anomalies account for the 20–30 percent mortality in this malformation.

Gastroschisis

This condition was once thought to represent a ruptured omphalocele but now is believed to represent rupture of the umbilical cord at the site of the resorbed right umbilical vein. The intestine herniates through a small defect to the right of the umbilical cord. The fallopian tube also may herniate. Intestinal atresia is the only associated abnormality and occurs infrequently. The intestine may appear normal but more frequently is covered by a thickened peel. Often primary closure is possible by manually stretching the abdominal wall. This will require intubation and mechanical ventilation for several days following surgery to allow the abdominal cavity to stretch and relieve the subdiaphragmatic pressure. If pressures are too great, staged closure with a prosthetic pouch is accomplished as in giant omphalocele. There may be considerable delay in return of intestinal function, and central venous hyperalimentation should be initiated early.

Exstrophy of the Cloaca (Vesicointestinal Fissure)

This is a severe congenital malformation involving the inferior abdominal wall. Included are omphalocele, exstrophy of the bladder, separation of the symphysis pubis, foreshortened colon, imperforate anus, prolapse of the distal ileum through the bifid bladder, and epispadias in the male. Many of these children do not survive. The operation involves a proximal colostomy, closure of the omphalocele, and preferably closure of the bladder or creation of a bowel loop with transplanted ureters.

Congenital Deficiency of the Abdominal Musculature (Eagle-Barrett Syndrome, Prune-Belly Syndrome)

This is a rare syndrome affecting males almost exclusively. There is usually minimal muscular development in the abdominal wall. In addition, there are undescended testes and hydroureters and a megacysticus. Treatment involves antibiotics to prevent or treat urinary tract infections. An operation involves reductive abdominoplasty. Orchidopexy is performed at 6–12 months of age. Urinary diversion should be avoided unless obstruction occurs.

Inguinal Hernia

Indirect inguinal hernias result from failure of closure of the processus vaginalis, which usually occurs by 2–3 months of age. Incarceration is particularly likely in young infants, and surgical correction is recommended early after diagnosis. Gentle maneuver reduction by manual compression usually is successful. If this maneuver is unsuccessful, immediate surgery is necessary to prevent necrosis of intestine or the gonad. A hydrocele of the cord may mimic an incarcerated hernia, but there is no pain and no vomiting because intestinal obstruction does not exist. Hydroceles of the tunica vaginalis may herald an associated hernia and in children over age 2 usually does. In infant females, an ovary may incarcerate in the hernia sac. These usually are associated with sliding hernias, and at surgery, the sac must be opened in all such patients to prevent ligating the fallopian tube.

Treatment involves a high ligation of the sac. No repair of the floor of the inguinal canal is indicated unless the internal ring is so stretched that the transversalis fascia is incompetent. If the hernia is a slider, the sac is ligated distal to the sliding component. A purse-string suture is placed at the base of the sac, and following excision of the sac, the stump is inverted and the purse-string tied.

There is controversy over repairing the opposite, asymptomatic side. Many advocate repair if the child is under 1 year of age or if the presenting hernia is on the left side.

GENITALIA

Cryptorchidism

The testes develop from the urogenital ridge and by the seventh month of gestation lie in the pelvis. They then begin their descent along with the developing processus vaginalis into the scrotum. The undescended testis may lie in the abdominal cavity or the inguinal canal. An ectopic testis that has passed through the external ring may lie in the superficial inguinal pouch, the thigh, or the perineum. There is increased risk of malignancy in the gonads of the patient with an undescended testis, probably due to the character of the testes themselves rather than to their position. Histology of the undescended testis reveals decreasing spermatogonia after 2 years of age. Therefore, orchidopexy is recommended before that age. The rationale for orchidopexy is to protect spermatogenesis, place the testis in a less vulnerable position, make early detection of malignancy possible, and most important, make the child feel the equal of his peers.

Vaginal Anomalies

Anomalies range from imperforate hymen to vaginal agenesis. Diagnosis is made by physical examination. Vaginal obstruction leads to hydrocolpos and may present as a large abdominal mass. Ultrasound may help delineate the anatomy. Surgical reconstruction depends on the extent of pathology.

Ambiguous Genitalia (Intersex Syndromes)

Normal sexual differentation of the gonad occurs in the sixth fetal week and depends on a gene located on the Y chromosome. Wolffian (male) and müllerian (female) ducts exist in the embryo until sexual differentation. The fetal testis secretes testosterone and müllerian-inhibiting substance. Testosterone stimulates maturation of wolffian duct structures into epididymis, vas deferens, and seminal vesicles. Müllerian-inhibiting substance produces regression of the female structures. In the absence of the fetal testis, the müllerian system proceeds to full maturation. Any disruption of the orderly steps of sex differentiation may present as an intersex problem. These may be classified as a true hermaphrodite, a male pseudohermaphrodite, a female pseudohermaphrodite, or mixed gonadal dysgenesis. Most of these patients present with ambiguous external genitalia.

The true hermaphrodite is the rarest and usually has an XX karyotype. They usually have an ovary and a testis or an ovotestis. The male pseudohermaphrodite has bilateral testes, but there is a persistence of müllerian duct structures due to a defect in androsynthesis or müllerian-inhibiting substance. Female pseudohermaphrodites usually have a defect in adrenal cortisol synthesis, resulting in adrenal hyperplasia and increased adrenocorticotropic hormone (ACTH) production. The latter stimulates the production of adrenal androgens and masculinization of the developing female infant. Mixed gonadal dysgenesis may result in malignant degeneration of the gonad. Determination of the sex of rearing must be made early. This involves studies of urinary and serum biochemical factors, physical and radiologic examinations, chromosomal studies, and occasionally, celiotomy and study of the gonads with biopsy.

The appearance of the external genital abnormalities may be surgically modified by reducing and recessing an enlarged clitoris, repairing and elongating the penile hypospadias, vaginoplasty, or insertion of testicular prostheses.

It is important to remember that the external appearance of the genitalia is a major influence on the determination of the assigned gender. Infants with two X chromosomes should be assigned the female gender. Infants with an X and Y chromosome should be raised as males only if a sufficient phallus exists to be functional as a male. In addition, abnormal development of the vagina may cause a variety of abnormalities. These range from an imperforate hymen to vaginal agenesis. Physical examination is usually sufficient for diagnosis, although ultrasound occasionally is necessary. Surgical repair depends on the defect. Imperforate hymen requires a simple incision of the hymen, whereas vaginal agenesis requires a complex reconstruction either from skin flaps or using intestine to create a neovagina.

Ovarian Cysts and Tumors

Infrequently females develop ovarian cysts and tumors that may be either neoplastic or nonneoplastic. Nonneoplastic cysts are usually simple, follicular, inclusion, paraovarian, or corpus luteum. Additionally, they may be solid, such as those seen in endometriosis, or inflammatory lesions. Neoplastic lesions are classified on the primordial cell layers, those being mesenchymal, germinal, and germ cell. Most commonly, children complain of abdominal pain, with obstruction of the urinary tract or intestine being common, along with endocrine imbalances. On physical examination, a mass is not uncommon, although ascites and abdominal distention are not common. With increasing frequency, ultrasound in the prenatal period has become diagnostic, with surgical excision being recommended for lesions greater than 5 cm in diameter. This is especially true of complex lesions, although resolution of simple cysts is not unusual. Laparoscopic or percutaneous drainage has been reported.

NEOPLASTIC DISEASE

Cancer is the second leading cause of death after trauma in children 1–14 years of age. Improved survival over the past two decades is due to several factors: better diagnostic imaging, new chemotherapeutic drugs, collaboration between surgeons, chemotherapists, and radiation therapists, and multi-institutional studies that evaluate new treatments and protocols.

Wilms' Tumor

Wilms' tumor is an embryonal neoplasm of the kidney that usually presents as an asymptomatic mass in the flank and upper abdomen. The peak age of incidence is 1–3 years. Associated conditions include familial aniridia, Beckwith-Wiedemann syndrome, urinary tract defects, hemihypertrophy, and chromosomal deletion, suggesting genetic influences. Bilateral involvement occurs in 5–10 percent of series.

Genes specific for the Wilms' tumor have been discovered that actually may be responsible for the development of this tumor. These include suppressor genes that have been cloned (WT1 and WT2), along with mutations and deletions.

Evaluation consists of CT scans to study the tumor-containing kidney, the status of the contralateral kidney, and the rest of the abdominal viscera. CT scan of the chest will reveal any pulmonary metastases, the most likely site of the metastic disease. Ultrasound examination of the abdomen will reveal any tumor extension into the renal vein or vena cava. The role of magnetic resonance imaging (MRI) is yet to be defined.

Treatment Surgical excision is performed through a wide transabdominal incision. The entire kidney and tumor are removed, along with the attached ureter. Invasion of the tumor into adjacent viscera is treated by excision of the involved tissue in continuity with the tumor. Paraaortic nodes are sampled for staging, biopsies of any suspicious areas are taken, and the opposite kidney is evaluated for tumor. Chemotherapy is given to all children; the mainstays are actinomycin-D and vincristine. Doxorubicin (Adriamycin) is added for children with more advanced disease, as is radiation therapy.

If the tumor is of “favorable” histology and all the tumor is removed at surgery, cure rate approaches 97 percent. A small percentage of tumors are of “unfavorable” histology, and their cure rates are diminished. Preoperative chemotherapy reduces massive tumors, making resection safer and possible. One must follow patients for development of second malignancies.

Neuroblastoma

Following central nervous system tumors and lymphomas, neuroblastoma is the next most common solid neoplasm in children. Therapy has not been nearly so successful as in Wilms' tumor. Neuroblastomas arise from neural crest cells and are seen most frequently in the adrenal medulla. Less frequently noted sites include the posterior mediastinum, neck, and pelvis. Over 90 percent of children present before age 9 years, and 60 percent are younger than age 5. Two-thirds will present with asymptomatic abdominal masses, and the majority will have metastases at diagnosis. The most frequently noted site of metastasis is bone. Prognosis is age-related. About 85 percent of children under 1 year of age will be cured even with metastatic disease to skin, liver, or bone marrow. Only 15 percent of children over age 2 are cured.

Evaluation consists of CT scans of the involved body cavity plus bone marrow examination and bone scans. Catecholamines and their metabolites will be elevated in serum and urine. Serum ferritin and neuron specific emolase levels correlate with poor prognosis. Tumor DNA and N-myc are also prognostic indicators.

Treatment Total surgical excision in children over 1 year of age is the only hope of cure. This may include laminectomy, especially in posterior mediastinal tumors, where extension may occur through the vertebral foramina. The tumor may be radiosensitive and responsive to chemotherapy, but these adjunctive treatments have not altered the dismal prognosis associated with metastatic disease in patients over age 2. Bone marrow transplantation offers a promising outcome.

Rhabdomyosarcoma

This is an embryonic tumor arising from a variety of mesenchymal tissues. Common sites of origin are the head and neck, extremities, and the genitourinary tract. Diagnosis is made by incisional or excisional biopsy. Sites of metastasis include the lung, regional lymph nodes, liver, brain, and bone marrow. Extent of disease is determined by MRI, CT scans, and bone marrow biopsy.

Wide local excision, sparing mutilating surgery, is accompanied by radiation therapy and chemotherapy. Commonly used drugs include actinomycin-D, vincristine, and cyclophosphamide.

Prognosis is affected by site of origin and the pathologic type. Embryonal pathology is more favorable than alveolar histology. A 60 percent 5-year survival can be anticipated. The best prognosis is with total surgical excision.

Teratoma

These tumors are composed of all three embryonic germ layers. They are usually benign but can harbor malignant elements. Sites are varied, with the most frequently noted site being the sacrococcygeal area (40 percent). Other sites include the anterior mediastinum, ovary, retroperitoneum, testis, and neck. Therapy involves total surgical excision. Newer chemotherapeutic agents including cis-platinum have improved the outlook in higher-staged malignant disease. Radiation is used without proven effect on survival.

Liver Tumors

More than two-thirds of all liver tumors in children are malignant. Hepatoblastoma is the most common malignant tumor of the liver; 65 percent of these are diagnosed before age 4 years. Hepatocellular carcinoma is the next most common lesion, with a peak incidence between ages 10 and 15. Most present with an upper abdominal mass. There may be weight loss, fever, and anorexia. Alpha-fetoprotein levels are elevated in 90 percent of children with hepatoblastoma and serve as a good marker for follow-up evaluation. Double-contrast CT scan of the abdomen and chest and celiac axis angiography are required for adequate evaluation of the tumor.

Preoperative chemotherapy to debulk massive tumors along with complete surgical extirpation results in cure of most hepatoblastomas. Half these tumors are completely resectable, and 80 percent are curable with adjunct chemotherapy. Children with hepatocellular carcinoma have a more dismal prognosis because fewer are completely resectable. Their survival is only 15 percent.

TRAUMA

Injuries account for 46 percent of all pediatric deaths, more than cancer, congenital anomalies, pneumonia, heart disease, homicide, and meningitis combined. Motor vehicle crashes account for 20 percent, drowning 8 percent, burns 5 percent, and firearms 1 percent of all trauma deaths. The establishment of major trauma centers skilled in the management of child trauma has improved survival statistics. Most fatal cases have associated head trauma, and the management of these injuries affects survival rates. By virtue of their soft, pliable skeletons, growing bodies, and immature emotional development, children constitute special trauma patients whose injuries and management differ markedly from those in the adult.

For a more detailed discussion, see Guzzetta PC, Anderson KD, Altman P, Newman KD, and Schnitzer JJ: Pediatric Surgery, chap. 37 in Principles of Surgery, 7th ed.

Books@Ovid
Copyright © 1998 McGraw-Hill
Seymour I. Schwartz
Principles of Surgery Companion Handbook