Surgery
Kathryn Q. Bernabe
Brad W. Warner
The constellation of pediatric surgical disease is enormous. Of the myriad of congenital and acquired problems that require the expertise of a pediatric surgeon, the most common are discussed in this chapter, with a focus on diagnosis and surgical management.
Congenital Disorders
ABDOMINAL WALL DEFECTS
Definition and Anatomy
Abdominal wall defects allow herniation of abdominal contents through the abdominal wall.
In omphalocele, the defect is at the umbilical ring. The defect has a thin membranous sac covering over the herniated abdominal contents. Rupture of the sac can occur, thus exposing the intra-abdominal organs.
In gastroschisis, the defect is to the right of the umbilicus/umbilical cord. The herniated contents are not covered by a sac.
Epidemiology
The incidence of omphalocele is 1 in 4,000 births.
The incidence of gastroschisis is 1 in 6,000-10,000 births.
There is no gender predominance.
Anomalies associated with the two defects differ.
Omphalocele is associated with Beckwith-Wiedemann syndrome; pentalogy of Cantrell; cloacal exstrophy; trisomies 13, 18, and 21; Turner syndrome; and Klinefelter syndrome.
Gastroschisis is typically not associated with any chromosomal anomalies, but intestinal atresia, foreshortened intestine, and bowel with poor motility may be present.
Etiology
Omphalocele is thought to occur because of a failure of the intestines to return to the abdomen during gestation.
Gastroschisis is thought to be a defect at the site of involution of the second umbilical vein.
History and Physical Examination
Abdominal wall defects are associated with elevated maternal α-fetoprotein levels and can be diagnosed by prenatal ultrasound at 14 weeks’ gestation.
In omphalocele, the small and large bowel, the stomach, and sometimes the liver may be visible through the membranous sac.
In gastroschisis, the exposed bowel is thickened and may be covered in a fibrin peel. The entire midgut is generally herniated, but other organs, including the stomach or pelvic organs, may also herniate.
Imaging
Prenatal. Imaging involves thorough ultrasonographic examination to look for other anomalies. This initial imaging may further dictate the need for fetal echocardiography and amniocentesis for karyotyping. Cesarean section and early premature delivery are not indicated unless necessary for other obstetric reasons.
Postnatal. In combination with a detailed physical examination, imaging is directed at identifying other congenital anomalies. Commonly, abdominal ultrasound, cardiac echocardiogram, and other radiographic techniques are used.
Treatment
Postnatal
Nasogastric decompression at birth is mandatory.
Any trauma to the omphalocele membrane should be avoided. Herniated bowel in gastroschisis should be treated similarly. Typically, to protect the abdomen immediately after delivery, the lower half of the neonate’s body can be gently placed in a clear plastic bowel bag to maintain moisture and heat during transportation to a neonatal intensive care unit (NICU). Avoid placing saline-soaked gauze over the bowel as it can lead to significantly decreasing the neonate’s body temperature. Wrapping the bowel with gauze should also be avoided since it prevents the ability to assess bowel perfusion and may create a tourniquet effect.
A heat lamp may be necessary to maintain normothermia.
Fluid losses can be significant, and fluid status should be monitored closely.
Antibiotics are indicated in gastroschisis, and in the case of omphalocele membrane rupture.
Surgery
Primary closure can be performed in infants with small defects when the volume of herniated contents is small.
Staged closure, using a silo that is placed at the bedside, is used for gastroschisis defects when the abdominal cavity at birth is too small to accommodate the herniated contents.
Postoperative care in the NICU may include mechanical ventilation and monitoring for abdominal compartment syndrome. Intestinal ileus is expected after closure especially for gastroschisis, and total parenteral nutrition (TPN) may be necessary.
Results and Complications
Outcome is largely dependent on gestational age at birth and the presence of other congenital and genetic anomalies.
Long-term complications include gastroesophageal reflux and adhesion-related bowel obstruction.
Short gut syndrome and need for long-term parenteral nutrition may be a significant problem in children with gastroschisis.
CONGENITAL DIAPHRAGMATIC HERNIA
Definition and Anatomy
A congenital diaphragmatic hernia (CDH) is a defect in the diaphragm allowing herniation of abdominal contents into the thorax.
Most cases (80%) are left sided. Rare cases are bilateral.
Epidemiology
Incidence is ˜1 in 2,000-5,000 births.
The condition is associated with pulmonary hypoplasia and pulmonary hypertension.
Etiology
The cause is a defect in diaphragmatic development.
A genetic cause is not currently known. There is emerging evidence that Vitamin A may play an important role in diaphragm development.
History
Maternal history of polyhydramnios exists in 80% of cases.
CDH can be diagnosed on prenatal ultrasound. Prenatal chromosomal analysis should be performed.
Physical Examination
Tachypnea, grunting, cyanosis, and decreased breath sounds occur on the affected side.
A scaphoid abdomen with an asymmetric and distended chest may be seen.
Hypotension may be present as a result of mediastinal compression and obstruction of venous return to the heart.
Laboratory Studies and Imaging
Tests include blood gas analysis as well as preductal and postductal oximetry.
A chest radiograph showing bowel in the chest and a paucity of bowel gas in the abdomen confirms the diagnosis.
Cardiac anomalies can occur in up to 25% of infants with CDH; a cardiac echocardiogram is warranted. Major cardiac anomalies are associated with significantly lower survival rates.
Differential Diagnosis
Congenital diaphragmatic eventration is a possibility.
Congenital cystic pulmonary airway malformations.
Treatment
Nitric oxide may be necessary for pulmonary vasodilatation.
Extracorporeal Membrane Oxygenation
Extracorporeal membrane oxygenation (ECMO) may be useful when there is inadequate oxygen delivery in the face of adequate volume resuscitation, circulating hemoglobin, pharmacologic support, and ventilation.
Infants should generally be >34 weeks’ gestation, weigh >2,000 g, have no major intracranial hemorrhage, have been on a mechanical ventilator for <14 days, and have no lethal congenital anomalies.
Surgery
Surgical closure is not an emergency; rather, it should be performed when the infant is physiologically stable and the pulmonary vascular tone has been maximally optimized.
Preoperative treatment includes:
Nasogastric tube, intravenous fluid, intubation, and mechanical ventilation
Ventilation by mask or “bagging” is contraindicated to avoid distension of the bowel.
Blood gas analysis, as well as preductal and postductal oximetry, should be monitored serially.
Results and Complications
Mortality rates 20%-52% (infants with CDH who require ECMO)
To date, no factors that reliably predict outcome have been identified.
Gastroesophageal reflux occurs in 45%-85% of patients.
ESOPHAGEAL ATRESIA AND TRACHEOESOPHAGEAL FISTULA
Definition and Anatomy
Esophageal atresia (EA) is a discontinuity in the esophagus. There may be an associated fistulous connection between the esophagus and the trachea, which is known as a tracheoesophageal fistula (TEF).
Classification is based on the location of the TEF, if present. Eighty-five percent of patients have the type where there is a blind-ending upper pouch with a fistula between the trachea and distal esophagus.
Other types include a fistulous connection between the proximal portion of the esophagus with or without an atresia.
Epidemiology and Etiology
Incidence is ˜1 in 4,000 live births with a slight male predominance.
About 50% have an associated congenital anomaly (e.g., VACTERL, trisomies 18 and 21, CHARGE syndrome).
Abnormal separation of the esophagus and trachea occurs during the 4th week of gestation.
History
Maternal polyhydramnios is characteristic.
Diagnosis can be made by prenatal ultrasound.
Physical Examination
A newborn with EA has excessive drooling and episodes of cyanosis or respiratory distress. It is impossible to pass a feeding tube into the infant’s stomach.
A newborn with an isolated TEF swallows normally and does not drool, but may choke and cough while eating.
A newborn with a distal fistula or an isolated fistula may have a distended abdomen due to the inspired air communicating through the fistula.
Laboratory Studies and Imaging
Tests include complete blood count (CBC), electrolyte panel, and type and screen.
Chest and abdominal radiographs after placement of a catheter into the infant’s mouth show catheter location in the esophagus.
Coiling of the catheter tip in the proximal esophagus suggest an atresia while air in the stomach suggests a distal or isolated fistula.
Patients with a proximal fistula or no fistula at all do not have air in the abdomen.
Echocardiogram determines the location of the aortic arch, which is important in operative planning.
Given the frequent association with other VACTERL (Vertebral, Anorectal, Cardiac, Tracheo-Esophageal, Renal, Limb) anomalies, a careful physical examination, along with chest radiography, sonography of the spine and kidneys, and an echocardiogram are also required.
Treatment: Surgery
Preoperative treatment includes:
The neonate is placed in an upright position and a nasoesophageal or oro-esophageal tube is inserted to suction saliva and prevent aspiration. The infant should not be fed orally.
Mechanical ventilation is needed if the infant is in respiratory distress or has pneumonia. Bag-mask ventilation is contraindicated if a distal fistula is present because it causes worsening and clinically significant abdominal distension.
The goal of surgery is to separate the esophagus from the trachea and restore esophageal continuity.
Complications
Dysphagia is a common postoperative symptom.
Gastroesophageal reflux (40%) and recurrent respiratory tract infections from silent aspiration may require fundoplication.
Late complications include anastomotic stricture, tracheomalacia, and food impaction.
MALROTATION
Definition and Anatomy
Abnormal positioning of the midgut results in a narrow mesenteric base, conferring a risk of life-threatening midgut volvulus, bowel obstruction, and mesenteric vessel occlusion, which is a surgical emergency.
Instead of the usual left-of-spine position, the ligament of Treitz lies to the right of the midline; there is a narrow mesenteric base and Ladd bands overlying the duodenum.
Epidemiology and Etiology
Seventy-five percent of infants present when <1 month of age, and 90% are symptomatic within the 1st year.
Malrotation can also present in childhood and adulthood.
The incidence at autopsy is 0.5%-1%.
Associated anomalies occur in about 50% of patients and include CDH, abdominal wall defects, tracheoesophageal anomalies, intestinal webs and atresias, anorectal malformations, orthopedic and cardiac anomalies, situs inversus, and asplenia and polysplenia.
Abnormal rotation and fixation of the small bowel occurs during gestation.
History
The most common symptoms are bilious vomiting, colicky abdominal pain, and distension.
If midgut volvulus is present, this is an emergent situation. These patients may be lethargic, irritable, and in shock.
Children who are not diagnosed in infancy may present with chronic abdominal pain, vomiting, diarrhea, and failure to thrive.
Occasionally, malrotation is an incidental finding on a radiographic workup for another problem.
Physical Examination
Abdominal distension, dehydration, and possibly signs of shock are found.
Abdominal tenderness and blood on rectal examination are suggestive of bowel ischemia.
Laboratory Studies and Imaging
Tests include CBC, electrolyte panel, and type and screen.
Upper gastrointestinal (GI) contrast study is diagnostic.
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