Congenital anomalies of GI tract

Esophageal Atresia - Tube Troubles

• Developmental failure of the tracheoesophageal septum to fuse, leading to an incomplete esophagus.
• Most common variant (~85%) is proximal esophageal atresia with a distal tracheoesophageal fistula (TEF).
• Presents with polyhydramnios in utero. Neonates show excessive drooling, choking, and cyanosis during feeding.
• Diagnosis confirmed by inability to pass a nasogastric tube into the stomach.

⭐ 📌 Associated with VACTERL syndrome: Vertebral defects, Anal atresia, Cardiac defects, Tracheo-Esophageal fistula, Renal anomalies, and Limb abnormalities.

Gastric & Duodenal Defects - Exit Blocks

• Pyloric Stenosis: Most common gastric outlet obstruction in infants. Presents at 2-8 weeks.

  • Clinical: Projectile non-bilious vomiting, palpable epigastric "olive" mass, visible peristalsis.
  • Labs: Hypokalemic, hypochloremic metabolic alkalosis due to vomiting HCl.
  • Dx: Abdominal ultrasound.

• Duodenal Atresia: Congenital failure of duodenum to recanalize.

  • Clinical: Bilious vomiting within hours of birth.
  • X-ray: "Double bubble" sign (air in stomach and proximal duodenum).

• Annular Pancreas: Ventral pancreatic bud abnormally encircles the 2nd part of the duodenum, causing obstruction.

⭐ "Double bubble, double trouble": The "double bubble" sign of duodenal atresia is frequently associated with Down syndrome.

Midgut Malrotation - Twisted Guts

• Pathophysiology: Failure of the midgut to complete its normal 270° counter-clockwise rotation during fetal development.
• Anatomy: Cecum remains in the RUQ, fixed by fibrous Ladd's bands, which can compress the duodenum.
• Presentation: Bilious vomiting in a neonate is the hallmark sign.
• Complication: Midgut volvulus - intestine twists around the superior mesenteric artery (SMA), leading to ischemia and necrosis.
• Diagnosis: Upper GI series shows abnormal position of the ligament of Treitz.

⭐ Bilious emesis in the first few days of life is a surgical emergency until proven otherwise, often indicating malrotation.

Abdominal Wall Defects - Innies vs. Outies

• Omphalocele ("Innie")

  • Midline herniation of abdominal contents (liver, bowel) into the base of the umbilical cord.
  • Sealed by a membranous sac (peritoneum + amnion).
  • Caused by failed fusion of lateral embryonic folds.

• Gastroschisis ("Outie")

  • Paraumbilical (typically right) full-thickness wall defect.
  • Uncovered bowel herniation; exposed to amniotic fluid, causing inflammation.
  • Due to vascular insult (omphalomesenteric artery occlusion).

⭐ Omphalocele has a high rate of associated anomalies: Trisomies 13, 18, 21, cardiac defects, and Beckwith-Wiedemann syndrome.

Hindgut & Remnants - Final Hurdles

• Hirschsprung Disease
  • Cause: Failed migration of neural crest cells to the distal colon → aganglionic segment (Auerbach & Meissner plexuses absent).
  • Presentation: Failure to pass meconium within 48 hours, bilious vomiting, abdominal distension.
  • Diagnosis: Rectal suction biopsy is the gold standard, revealing no ganglion cells.
• Imperforate Anus
  • Cause: Incomplete separation of the cloaca or failed breakdown of the anal membrane.
  • Presentation: No anal opening; meconium may pass via a fistula to the urethra, perineum, or vagina.
  • Associated with VACTERL syndrome.

⭐ Hirschsprung disease is strongly associated with Down syndrome (Trisomy 21).

High‑Yield Points - ⚡ Biggest Takeaways

• Tracheoesophageal fistula classically presents with polyhydramnios, followed by choking and cyanosis with the first feed.
• Duodenal atresia is defined by the "double-bubble" sign on X-ray and its strong association with Down syndrome.
• Pyloric stenosis causes non-bilious projectile vomiting and a palpable "olive-like" mass at 2-6 weeks of age.
• Meckel's diverticulum (Rule of 2s) is the most common anomaly, often causing painless rectal bleeding.
• Hirschsprung disease is an aganglionic megacolon causing failure to pass meconium in a newborn.