Category: Bowel Resection
Gastrointestinal (GI) Bleed following weight loss surgery is rare but does require knowledge of the particular bariatric surgical procedure the patients has and how to proceed with diagnostics to fully evaluate the situation. Acute or chronic gastrointestinal bleeding can cause anemia in patients. However, Anemia may also be caused by nutritional deficiencies (iron, vitamin , minerals), Kidney disease, bone marrow disease and others. The work-up for anemia following weight loss surgery follows a routine protocol. If there is an evidence of bleeding from intestine (bloody emesis, bloody bowel movement, “tar” like black bowel movements) then the diagnostic work up would include an upper and lower endoscopy.
Upper endoscopy Esophagogastroduodenoscopy (EGD): evaluates the esophagus, stomach and a limited area of the duodenum past pyloric valve.
Lower endoscopy Colonoscopy or coloscopy: evaluates the rectus and the entire colon.
Between these two tests, there is still a considerable amount of the small bowel that is not accessible or visualized with endoscopic procedures. For the small bowel, examination Capsule endoscopy is an option in an intact GI tract. Patients who have had Gastric bypass RNY or the Duodenal Switch, the large segments of the small bowel can not be visualized or examined with capsule endoscopy.
Patients who have had Duodenal Switch, Gastric Bypass and SADI – S would need a tagged red cell scan or CT angiography if GI bleed is suspected in areas of the small intestine that are inaccessible by endoscopic procedures.
We are all aware of the arterial and venous systems. Arteries take the oxygenated blood from the heart to the organs and the veins take the blood back to the lungs to unload the carbon dioxide and reload oxygen to be taken back to the organs. In addition to the arterial and venous vascular systems, we also have the lymphatic channels that flow into the lymphatic system.
The Lymphatic channels and system may be new to some, however, it is the third vascular network that is much less defined. The Lymphatic system collects fluids that has left the artierial/venous vascular system along their travel outlined above and take it back to the venous system. The lymphatic vessels transport this fluid to the lymph nodes throughout the body where the nodes filter the fluid of bacteria and harmful substances. Eventually, the fluid makes it way back to the venous system via the Superior Vena Cava. Additionally, Lymphatics collect the lipids within the GI tract and transport them to the venous system for metabolism. Most of the time these serosal lymphatic vessels are very small and hard to notice on the bowel.
Example of Lymphatic channels
The following image is in a patient who had small bowel obstruction. The obstruction had resulted in vascular congestion at the base of the mesentery. The congestion had effected the low pressure system of the veins and the lymphatics disproportionately more that the arterial system. The white-milky tubular structures are the lymphatic channels filled with lipids.
There are three layers to the small intestinal lymphatic system, in the villi, submucosal and serosal layers and has the unique ability to transport absorbed intra-lumenal nutrients. There is a need for further research in the areas of health, obesity and disease in regards to the lymphatic system.
Duodenal switch (DS) operation results in the highest success rate of all weight loss surgical procedures. Patients, over time, will experience some weight gain many years after DS procedure. There are a number of suspected mechanisms that may be responsible for the weight gain:
1-Ageing may slow the metabolism and the activity down.
2-Over time patients may not be as adherent to healthy dietary and lifestyle changes as they may have been immediately after surgery.
3- Hypertrophy of the alimentary and common channels over time increases in surface area f allowing greater caloric absorption leading to increased weight gain.
It has been demonstrated in bowel resection studies, as well as rat studies, that the nutrient stimulated regions of small intestine increase villus height and total weight, crypt depth and proliferation as well as wall thickness, as an adaptation to compensate for the loss of absorptive capacity in the resected bowel. This observation may be applied to DS procedure as seen in histological slides from a patient who had to have an operation done requiring bowel resection. The segment of the bowel resected included the junction of the biliopancreatic, common and alimentary limbs.
The histologic slides are the same size of tissue, photograph and magnifications.
It is significant that the Muscular and the mucosa of the alimentary limb over time have hypertrophied (thickened) and this represents more surface area, increased blood flow to and from the mucosa and the resultant incased absorption be partly responsible for weight gain.
Layers of the GI Tract (excluding esophagus and rectum)
Mucosa – The inner most layer of the GI tract, which lines the lumen and comes into direct contact with digested food and the secretions. The mucosa itself is Composed of 3 layers:
1-Epithelium (the inner most layer) which is responsible for most of the digestive, absorptive and secretory processes of the GI tract.
2-The lamina propria; a layer of connective tissue.
3-The muscular mucosae, which is a thin layer of smooth muscle that aids in the passing of material through the GI tract.
Muscularis – Muscular layer of the GI tract consisting of an inner circular layer and an outer longitudinal layer. The circular layer prevents back flow of digestive contents whereas the longitudinal layer shortens the GI tract and is responsible for peristalsis.
Serosa – “Seran Wrap” type covering the outside of the GI track (excluding the esophagus and the rectum). It is composed of Smooth muscle membrane formed by two layers of epithelial cells which secrete serous fluid (lubricants).
E, Wallace LE, de Heuvel E, Chelikani PK, Zheng H, et al. (2010) The influence of nutrients, biliary-pancreatic secretions, and systemic trophic hormones on intestinal adaptation in a Roux-en-Y bypass model. J Pediatr Surg 45: 987–995