This procedure combines reducing the ingested volume (see gastroplasty) and a decreased absorbtion at the level of the small intestine.
Relating to the size of the stomach left is the restrictive aspect of the procedure more pronounced.
The bypass of the small intestine will decrease the reabsorption of nutrients and fat, making a higher production of fatty faeces. The more important the bypass, the more will there be faeces up to a diarroea.
This procedure is usually performed by laparoscopy.
A small gastric pouch is created by stapling. A portion of the small intestine is sutured on this pouch. By this way, about 1 meter of small intestine is bypassed and doesn't receive anymore food ("biliary" loop *).
This procedure is essentially restrictive because of the small volume of nutrients entering into the stomach ( the gastric pouch has about 40cc of capacity, just like in the gastroplasty procedure).
The malabsorptive effect is less important but depends on the length of the "alimentary " loop (**) (between 1 and 1.5 meter).
This operation is usually performed by laparoscopy approach but is technically more difficult to perform than a gastroplasty. Operative time is around 2 hours.
Post-operative complications are rare but more severe (fistula, absess) and are managed medically or surgically (drainage by laparoscopy).
The main secondary effect is the "Dumping Syndrome": the rapid income of sweet nutrients in the small intestine can produce nausea, transpiration, abdominal pain and diarrhea appearing a few minutes after this kind of meal. The elimination of sweet meals avoids these symptoms.
It is also important to know that, by performing such a procedure, the rest of the stomach and the biliary tract are no more reachable for further endoscopic investigation.
The mean weight loss is equivalent to an excess weight loss of 70 to 100% after 12 to 16 months and shoud be maintained between 60 et 80% after 5 years.