Oesophageal atresia

 • Occurs in 1 in 3500 live births.

 • results from faulty division of the foregut into the tracheal and oesophageal channels during the first month of embryonic life.

• In the majority of cases, there is a communication between the distal oesophagus and the trachea known as a tracheo- oesophageal fistula.

 • Neonates present with coughing and choking during feeding due to aspiration.

 • At least half of affected babies have other congenital abnormalities, and cardiac defects account for the majority of deaths in infants with oesophageal atresia.

 Duodenal atresia

 • Less common than oesophageal atresia.

 • Associated with Down’s syndrome in 30% of cases.

 • Caused by failure of epithelial apoptosis and incomplete canalization of the duodenal lumen by 8 weeks of gestation.

 • the obstruction is usually distal to the ampulla of Vater.

 • Prenatal ultrasound shows dilation of the proximal duodenum and stomach with polyhydramnios.

 Exomphalos

 • An anterior abdominal wall defect at the umbilicus that causes abdominal contents to protrude through the umbilicus.

 • the protrusion is covered by a delicate transparent sac composed of the amniotic membrane and peritoneum.

 • Arises due to failure of the midgut to return to the abdomen from the umbilical coelom during embryogenesis.

 Gastroschisis

 • An anterior abdominal wall defect which lies to the side of the umbilicus through which loops of bowel protrude.

 • Unlike exomphalos, there is no protective covering sac.

 Malrotation

 • Malpositioning of the intestine and mesentery due to failure of rotation of the developing gut as it returns from the umbilical coelom to the abdomen during development.

 • A malrotated bowel is likely to have a narrow mesenteric base, predisposing to volvulus around the superior mesenteric artery.

 • Compromised arterial blood supply leads to ischaemic necrosis of the entire midgut, extending from the duodenum to the transverse colon.

 • Necrosis causes bleeding into the bowel and a high risk of perforation.

 • Without prompt surgical intervention, the condition can be fatal.

Meckel’s diverticulum

• A remnant of the vitellointestinal duct, the structure that connects the primitive gut to the yolk sac.

• typically said to be ‘2 in (5 cm) long, 2 ft (60 cm) from the ileo- caecal valve in 2% of the population’.

 • the mucosa of the diverticulum may contain areas of gastric or pancreatic tissue (heterotopia).

 • Most children with a Meckel’s diverticulum are asymptomatic.

 • the most common symptom is painless rectal bleeding due to ulceration in a diverticulum containing acid- secreting gastric mucosa.

 • Small bowel obstruction may also occur, related to intussusception or incarceration.

Imperforate anus

 • Umbrella term for any atretic condition of the rectum or anus.

• Lesions range in severity from a stenosed anal canal to anorectal agenesis.

• Surgically, they are considered as either high or low anomalies, depending on the level of termination of the bowel with respect to the pelvic floor.

 • Low defects are easier to correct and postoperative function is good.

• higher defects are more difficult to correct as they are more likely to be associated with fistulae between the rectum and the genitourinary tract, as well as a deficient pelvic floor.

Hirschsprung’s disease

• Not strictly a malformation, but a congenital gastrointestinal (GI) condition in which there is absence of ganglion cells from a variable length of the intestinal wall.

• results from failure of neuroblasts to migrate from the oesophagus to the anal canal during weeks 5– 12 of gestation.

 • Absence of ganglion cells causes spasm in the aganglionic segment.

 • Presents with intestinal obstruction and failure to pass meconium 24 h after birth.

• rectal suction biopsy is the gold standard for the diagnosis of hirschsprung’s disease. the key feature is the absence of ganglion cells in the submucosa and abnormally thick nerve fibres in the mucosal layer. the diagnosis is made at the time of surgery by frozen section with histochemical staining for acetylcholinesterase.