Intraoperative Measuring of Small Bowel Length Compared to Measuring by Magnetic Resonance Imaging (MRI) in Morbid Obese Patients

Background: An important step during a gastric bypass operation for the treatment of morbid obesity is the measuring of the small bowel length in order to define the lengths of the alimentary, biliopancreatic and common channel. The measuring itself is technically simple but has always an error due to the variable state of contraction of the small bowel. In distal gastric bypass a common channel length of 100 to 150 cm is chosen which induces an iatrogenic short bowel syndrome. At several reoperations we found a length increase of the common channel of up to 80% compared to the measured length at the initial operation. Former studies seem to indicate that an adaptation of small bowel length may occur in animals with short bowel syndrome or after intestinal bypass surgery. Longterm results of gastric bypass surgery often show weight regain after 3 to 5 years which could be due to the afore mentioned compensatory mechanism. Newer MRI protocols allow for non-invasive measurement of the small bowel length. Comparing the preoperative and later on several postoperative measurements by MRI with the initial intraoperative length measuring should allow to validate the new MRI protocol and in the same time quantify the eventual small bowel length increase. Objective: In-vivo verification of small bowel length measurements made by MRI, quantification of a possible increase of the common channel length in the long run after distal gastric bypass. Methods: The preoperative small bowel length measurement by MRI is compared to the length measured intraoperatively. MRIs before discharge postoperatively as well as after 6 and 12 months are used to detect an eventual increase of the common channel length.