Chronic intestinal obstruction

The symptoms of chronic intestinal obstruction may arise from two sources — the cause and the subsequent obstruction.

The causes of obstruction may be organic:

intramural — faecal impaction;

mural — colorectal cancer, diverticulitis, strictures (Crohn’s disease, ischaemia), anastomotic stenosis;

extramural — adhesion (small bowel only), metastatic deposits, endometriosis; or

functional — Hirschsprung’s disease, idiopathic megacolon, pseudo-obstruction.

The symptoms of chronic obstruction differ in their predominance, timing and degree from acute obstruction. Constipation appears first. It is initially relative and then absolute, associated with distension. In the presence of large bowel disease, the point of greatest distension is in the caecum and this is heralded by the onset of pain. Vomiting is a late feature and therefore dehydration is exceptional. Examination is unremarkable, save for confirmation of distension and the onset of peritonism in late cases. Rectal examination may confirm the presence of faecal impaction or a tumour.

Investigation

Plain abdominal radiography may confirm the presence of large bowel obstruction. All such cases should be confirmed by a subsequent single contrast water-soluble enema study to rule out functional disease. Organic disease requires a laparotomy, whilst functional disease requires colonoscopic decompression and conservative management.

In the presence of organic obstruction, after resuscitation surgical management depends on the underlying cause and the relevant chapters in this book should be consulted.

Hirschsprung’s disease

This is due to failure of complete migration of the ganglion cells of the large bowel to the anus. This results in an aganglionic segment producing physiological obstruction. Eighty per cent present in the neonatal period with acute large bowel obstruction, whilst 20 per cent present with failure to thrive or severe constipation.

Barium enema reveals a characteristic narrow segment, whilst a full-thickness rectal strip biopsy will show absence of ganglion cells. The rectoanal inhibitory reflex is absent on physiological testing.

Treatment consists of an initial loop colostomy followed by a definitive pull-through procedure.