AGA technical review on short bowel syndrome and intestinal transplantation.

The normal human small intestine length is generally considered to be between 3 and 8 meters, depending upon whether radiologic, surgical, or autopsy measurements are made.1–5 Short bowel syndrome (SBS) occurs when there is 200 cm of bowel remaining. This is an approximate length as most methods of residual intestine measurement (such as radiologic contrast studies, pathology of the resected specimen, and perioperative measurement of unweighted intestine) are not especially accurate. Because absorption is related to the amount of residual intestine, it is more important to document the amount of remaining, viable intestine. Those patients at greatest nutritional risk generally have a duodenostomy or a jejunoileal anastomosis with 35 cm of residual small intestine, jejunocolic or ileocoloic anastomosis with 60 cm of residual small intestine, or an end jejunostomy with 115 cm of residual small intestine.6–8 It has been suggested that intestinal failure is better defined in terms of fecal energy loss rather than residual bowel length.9 Given the observations that fecal energy loss does not always correlate well with residual bowel length,9 and the significant individual variability in jejunal absorption efficiency,10 it is reasonable to consider a more standardized approach to defining intestinal failure and “functional” SBS from a clinical standpoint. However, fecal energy loss is a function of both energy intake and energy absorption. Patients who are unable to increase their oral intake sufficiently or are unable to absorb sufficient energy despite significantly increased intake, are defined as patients with intestinal failure and require parenteral nutrition support. A standardized diet may be useful for clinically defining functional SBS, although there is insufficient data with regard to what the composition of such a diet optimally should be.