7.5 Bilious vomiting
Causes
The possible causes of bilious vomiting are as shown in Table 7.5.1 and are discussed below:
Intestinal atresia
As the lesion is congenital, the child will present in the neonatal period, although increasingly, some of these infants are diagnosed on antenatal ultrasound scans.1 Proximal lesions, such as duodenal or jejunal atresia, will usually present in the first 24 hours of life whereas more distal lesions, such as ileal or colonic atresias, can present later. Duodenal atresia may be associated with Down’s syndrome and cardiac anomalies in up to 30% of cases.2
Anorectal anomalies
Typically the anus is imperforate and the rectum communicates with the urinary tract or perineum via a fistula. It may occur as part of the VACTERL association of anomalies (vertebral, anorectal, cardiac, tracheo-oesophageal, renal and limb).3 The diagnosis should normally be made as part of the routine assessment of a neonate following delivery, but is occasionally missed, leading to a complete or partial distal obstruction and late onset bilious vomiting. Infrequently, the anomaly may present outside the neonatal period once the child commences solids.
Meconium ileus
This condition occurs in about 10–20% of neonates with cystic fibrosis (CF), although uncommonly it may occur in the absence of CF.4 There may be a family history of CF. The condition results from the occlusion of the bowel lumen by abnormally viscous enteric secretions in the small bowel and may be complicated by an atresia.
Hirschsprung’s disease
In this condition the enteric nervous system is abnormal, leading to a distal physiological obstruction. The condition is more common in males by a ratio of 4:1.5 In 75% of cases, so called ‘classical’ Hirschsprung’s disease (HD), a variable extent of the rectum and sigmoid colon is involved, leading to a distal colonic obstruction.6 In the remaining 25% of cases, bowel proximal to the sigmoid colon will also be aganglionic. About 10% of children with HD will also have Down’s syndrome.7 The cardinal feature of HD is the failure to first pass meconium within 24 hours of birth in a term infant, with the later development of bilious vomiting in the first few days of life.