Neonatal bowel obstruction is the most common neonatal abdominal surgical emergency ¹. It is generally divided into high and low obstruction according to the level of the transition point, since imaging appearances, underlying pathology, treatment, and prognosis differ.

It is divided into:

• high bowel obstruction - proximal to the ileum

• low bowel obstruction - involving the ileum or colon

Epidemiology

It is estimated to occur in about 0.05% of all live births ².

Clinical presentation

The clinical presentation is not specific and depends on the location of the obstruction. But usually, neonates will present with:

• abdominal distension and tenderness

• bilious vomiting

• constipation

• feed intolerance

• bile-stained vomit/aspirates

• respiratory distress with acidosis

• sepsis, blood-stained stools, or diarrhoea in case of necrotising enterocolitis

• failure to pass meconium in the first days

Pathology

Aetiology

High obstruction

• oesophageal atresia

• gastric atresia

• duodenal atresia

• duodenal stenosis

• duodenal Web

• annular pancreas

• jejunal atresia

• jejunal stenosis

• midgut volvulus

• ileal atresia or stenosis

Low obstruction

Small bowel obstruction

• ileal atresia or stenosis

• necrotising enterocolitis

• Hirschsprung disease

• meconium ileus

Large bowel obstruction

• meconium ileus

• meconium plug syndrome

• necrotising enterocolitis

• colonic atresia or stenosis

• Hirschsprung disease

• anal atresia and anorectal malformations

Radiographic features

Plain radiograph

Abdominal radiographs are the first imaging modality in neonatal acute abdomens. The features vary widely depending on the level of the obstruction, and generally demonstrate:

• dilated bowel loops: bowel diameter greater than the interpedicular width of L1 ³

• number of dilated loops

  • high obstruction <3 dilated loops

  • low obstruction >3 dilated loops

• absence of rectal gas: can be confirmed only if the radiograph is performed >24 hours after birth

• air-fluid levels: due to ineffective peristalsis

• small bowel or colon involvement

  • if there is no gas in the rectum, AP abdominal radiographs are unreliable to differentiate the colon from small bowel, since haustra are hard to identify in neonates ⁴

  • to differentiate small and large bowel in neonates, a colon enema may be performed

• intramural bowel gas: suggestive of necrotising enterocolitis

  • granular faeces should not be seen in the neonatal bowel (exclusive milk diet); if seen, it is indicative of pneumatosis intestinalis

• neonatal pneumoperitoneum

• portal venous gas

• double bubble sign

• triple bubble sign

Fluoroscopy

Contrast enema is usually performed, to locate the level of obstruction. The features depend on the cause of the obstruction.

Ultrasound

Ultrasound is the second line imaging modality for assessing acute abdomens in neonates. It may show:

• dilated bowel loop

• ineffective peristalsis

• prominence of the valvulae conniventes

​Findings suggestive of bowel ischaemia:

• extraluminal free fluid

• loss of peristalsis

• bowel wall thickening with effacement of mural architecture

• intramural bowel gas

Treatment and prognosis

The treatment depends on the aetiology of the obstruction.