Investigations

• abdominal X-ray ^c looking for 
  • extent of colitis (extent of faecal residue, evidence of mucosal ulceration and alteration of haustral pattern) ^c
  • small bowel distension: presence of ≥ 3 loops of gas-filled small bowel ^c

Why?

Ulcerative colitis: small bowel distension and pancolitis increases the risk that medical therapy will fail

Outcome c	Risk Factor	PEER	OR (95% CI)	NNH (95% CI)
colectomy	small bowel distension not independent	30%	3.56 (1.33 to 9.47)	3 (2 to 16)
colectomy	pancolitis not independent	30%	6.38 (2.12 to 19.18)	2 (2 to 6)
toxic megacolon	increased small-bowel gas on supine plain abdominal film (> 74 cm²) not independent	39%	2.58 (1.89 to 3.53)	2 (1 to 3)