Pediatric GI, GU & Surgery

The vomiting infant: bile is the branch point

Localize by color. Nonbilious vomiting localizes the obstruction above the ampulla of Vater, as in pyloric stenosis. Bilious (green) vomiting signals obstruction below it: malrotation with volvulus, intestinal atresia, or Hirschsprung disease.

Bilious vomiting in a neonate is malrotation with midgut volvulus until proven otherwise. It is a surgical emergency because the twisted mesentery strangles the midgut, so evaluate immediately rather than observing.

Pyloric stenosis. Repeated loss of gastric HCl produces a hypochloremic, hypokalemic metabolic alkalosis, often with paradoxical aciduria as the volume-depleted kidney trades H⁺ for sodium. Pyloromyotomy is not an emergency: the alkalosis must be corrected before anesthesia. Early-infancy macrolide (erythromycin) exposure raises the risk.

Malrotation. An upper GI series shows a corkscrew duodenum and a ligament of Treitz displaced to the right of midline. The Ladd procedure untwists the bowel, divides obstructing bands, and places the bowel in nonrotation. Duodenal atresia is the other classic neonatal cause of bilious vomiting, with a double-bubble sign and an association with Down syndrome.

Intussusception, Hirschsprung, and NEC

Intussusception. Ileocolic telescoping is the usual form; episodes of inconsolable crying alternate with lethargy, and currant-jelly (blood and mucus) stool is a late sign of mucosal ischemia. Lymphoid hyperplasia after a viral illness is the usual lead point in infants, while a Meckel diverticulum or polyp is more likely in older children. Air or contrast enema is both diagnostic and therapeutic; peritonitis, perforation, or failed reduction means surgery.

Hirschsprung disease. Failed neural-crest migration leaves the distal colon aganglionic, always starting at the rectum and extending proximally, so the segment cannot relax. A rectal exam that produces an explosive gush of stool (squirt sign) is a classic clue, and a contrast enema may show a narrow distal segment below a dilated colon. Rectal suction biopsy showing absent ganglion cells is the gold standard; treatment is surgical resection with pull-through. Watch for enterocolitis, the major cause of death.

Necrotizing enterocolitis. The x-ray hallmark is pneumatosis intestinalis (air in the bowel wall), with portal venous gas in severe disease and free air when the bowel perforates. Breast milk feeding lowers the risk.

Biliary atresia and conjugated jaundice

Never normal. Direct (conjugated) hyperbilirubinemia in an infant is always pathologic and mandates urgent evaluation, most importantly to catch biliary atresia early. Fractionate the bilirubin in any infant still jaundiced beyond 2 weeks; acholic stools are the tell.

Biliary atresia obliterates the extrahepatic bile ducts, causing jaundice persisting past 2 weeks, conjugated hyperbilirubinemia, acholic (pale) stools, dark urine, and hepatomegaly. Ultrasound may show an absent or small gallbladder, a HIDA scan shows no excretion into the gut, and an intraoperative cholangiogram confirms it. The Kasai portoenterostomy works best before 8 weeks of age; many children still need a liver transplant, and biliary atresia is the leading indication for pediatric liver transplantation.

Genitourinary anomalies

Vesicoureteral reflux. Retrograde flow of urine from bladder to ureters presents with recurrent febrile UTIs, often after prenatal hydronephrosis. A voiding cystourethrogram (VCUG) demonstrates and grades reflux I through V, while a DMSA scan detects renal scarring. Untreated reflux with infection causes scarring, hypertension, and chronic kidney disease. Low grades often resolve with growth; management ranges from prophylactic antibiotics to ureteral reimplantation or endoscopic injection.

Hypospadias. The urethral meatus opens on the ventral penis, often with chordee (ventral curvature). Do not circumcise, because the foreskin is needed for the repair, typically done at 6–12 months. It may coexist with cryptorchidism.

Hypospadias plus an undescended testis, or bilateral nonpalpable testes, should prompt evaluation for a disorder of sex development, including a virilized 46,XX infant with congenital adrenal hyperplasia.

Cryptorchidism. An undescended testis usually descends by 6 months; if not, orchiopexy is performed by 6–12 months. Cryptorchidism raises the risk of infertility and testicular cancer (seminoma). The cancer risk persists after orchiopexy, but placing the testis in the scrotum allows self-examination and monitoring. A retractile testis that can be brought fully into the scrotum is a normal variant.

Abdominal masses: Wilms tumor vs neuroblastoma

Avoid vigorous palpation of a suspected Wilms tumor: rupturing the capsule spreads tumor and upstages the disease.