Micronutrient deficiencies are common and can occur at any time
While many clinicians recognize that vitamin deficiencies can occur after weight loss surgeries which bypass the duodenum, such as the RYGB or the BPD/DS, it is important to note that vitamin and mineral deficiencies occur commonly even in patients with intact intestinal absorption such as those who underwent sleeve gastrectomy (SG) and even despite regained weight due to greater volumes of food (and micronutrient) intake over time.
The most common vitamin deficiencies include iron, vitamin B12, thiamine (vitamin B1), and vitamin D, but deficiencies in other vitamins and minerals may found as well. Anemia, bone fractures, heart failure, and encephalopathy can all be related to postoperative vitamin deficiencies. Most bariatric surgery patients should have micronutrient levels monitored on a yearly basis and should be taking at least a multivitamin with minerals (including zinc, copper, selenium and iron), a form of vitamin B12, and vitamin D with calcium supplementation. Additional supplements may be appropriate depending on the type of surgery the patient had or whether a deficiency is found.
The differential diagnosis for abdominal pain after bariatric surgery is unique
While the usual suspects such as diverticulitis or gastritis should be considered in postbariatric surgery patients just as in others, a few specific complications can arise after weight loss surgery.
Marginal ulcerations (ulcers at the surgical anastomotic sites) have been reported in up to a third of patients complaining of abdominal pain or dysphagia after RYGB, with tobacco, alcohol, or NSAID use conferring even greater risk.7 Early upper endoscopy may be warranted in symptomatic patients.
Small bowel obstruction (SBO) may occur due to surgical adhesions as in other patients, but catastrophic internal hernias with associated volvulus can occur due to specific anatomical defects that are created by the RYGB and BPD/DS procedures. CT imaging is insensitive and can miss up to 30% of these cases,8 and nasogastric tubes placed blindly for decompression of an SBO can lead to perforation of the end of the alimentary limb at the gastric pouch outlet, so post-RYGB or BPD/DS patients presenting with signs of small bowel obstruction should have an early surgical consult for expeditious surgical management rather than a trial of conservative medical management.9
Cholelithiasis is a very common postoperative complication, occurring in about 25% of SG patients and 32% of RYGB patients in the first year following surgery. The risk of gallstone formation can be significantly reduced with the postoperative use of ursodeoxycholic acid.10
Onset of abdominal cramping, nausea and diarrhea (sometimes accompanied by vasomotor symptoms) within 15-60 minutes of eating may be due to early dumping syndrome. Rapid delivery of food from the gastric pouch into the small intestine causes the release of gut peptides and an osmotic fluid shift into the intestinal lumen that can trigger these symptoms even in patients with a preserved pyloric sphincter, such as those who underwent SG. Simply eliminating sugars and simple carbohydrates from the diet usually resolves the problem, and eliminating lactose can often be helpful as well.