How much bowel is enough?

The normal length of the small bowel is variable and depends on how it is measured. The root of the mesentrey streatchs from the ligament of Treitz to the ileo-caecal junction and is only about 40 cm. The bowel attached to the mesentry measures about 3 m in the abdomen and 7-8 m when taken out.

The surface area of the intestine is maximised by the circular folds of the mucosal surface (Vavlulae Conniventes), the villi (1 mm long) and the micro-villi (0.1 long). Due to these features the surface area of the gut is about 30 $m^2$.

We need about 1 cm of small bowel per Kg body weight in continuity with a moderate length of colon to avert the short bowel syndrome. This bowel must be normal and not be badly diseased or the mucosa will not function normally. A greater length of small bowel is needed if there is no residual colon in continuity. In addition the adaptive capacity of the ileum appears to be greater than the adaptive capacity of the jejeunum so preservation of the ileum is a good prognostic factor.

$$1 cm / Kg body weight = \mathbf{Sufficient length of small bowel}$$