Closure of Mesenteric Defect Can Lead to a Decrease in Internal Hernias After Roux-en-Y Gastric Bypass

• Internal hernias are one of the most serious complications that can occur after gastric bypass surgery, happening when part of the intestine slips through small openings created during the procedure, which can cause severe pain and require emergency surgery.
• Dr. de la Cruz-Muñoz led a study showing that closing these openings during the original gastric bypass surgery significantly reduces the chance of developing an internal hernia afterward.
• This finding has had a lasting impact on how bariatric surgeons perform gastric bypass worldwide, with routine closure now considered a standard safety practice by most bariatric surgeons.
• The study was published in Surgery for Obesity and Related Diseases (SOARD), the official journal of the American Society for Metabolic and Bariatric Surgery, with Dr. de la Cruz-Muñoz as lead author.
• For patients considering gastric bypass, this research demonstrates that Dr. de la Cruz-Muñoz has specifically studied and published on ways to make the procedure safer.

Why This Study Was Needed

During Roux-en-Y gastric bypass, the small intestine is rerouted, and this creates openings in the mesentery, the tissue that carries blood vessels to the bowel. The two most important are at the jejunojejunal anastomosis (where the intestinal limbs are joined) and Petersen’s space (behind the Roux limb). After surgery, as patients lose fat inside the abdomen, these openings enlarge and loops of bowel can slip through them. This internal hernia can cause intermittent pain or a sudden small bowel obstruction that may become life-threatening. In the 2000s surgeons disagreed about whether closing these spaces was worth the extra time, and published data were conflicting.

How the Study Was Done

This study reviewed 2,079 laparoscopic gastric bypass operations performed by Dr. de la Cruz-Muñoz from 2001 to 2009. In September 2003 he changed his technique and began routinely closing the jejunojejunal mesenteric defect with a running permanent suture. Patients operated on before that change (group 1) were compared with those operated on afterward (group 2).

What the Study Found

• 37 patients developed a symptomatic internal hernia over the study period: 36 in group 1 and only 1 in group 2 (P < .001).
• In group 1, 35 hernias (10%) occurred at the jejunojejunal mesenteric defect and 6 (1.7%) at Petersen’s space.
• In group 2, there were no hernias at the closed mesenteric defect (0%) and a single hernia at Petersen’s space (0.1%).
• Hernias appeared a median of 20 months after surgery, often during the period of rapid weight loss.
• Presentation varied: some patients arrived acutely with severe pain or obstruction, while others had months of vague, intermittent pain after meals.

What This Means for Patients

If you are having gastric bypass, ask your surgeon whether the mesenteric defects are closed. Closure is now considered standard practice, and a Swedish multicenter randomized trial (Lancet, 2016) later confirmed that closing both defects significantly reduces internal hernias and reoperations for small bowel obstruction.

If you already had a bypass, especially years ago, know the symptoms: crampy pain in the upper or left abdomen, often after eating, that comes and goes, or severe pain with nausea and vomiting. Imaging can be normal between episodes. Persistent abdominal pain after bariatric surgery after bypass deserves evaluation by a bariatric surgeon, and severe pain is an emergency. Read more in our article on chronic abdominal pain after bariatric surgery, our complete guide to gastric bypass and our guide to warning signs after surgery. When a hernia is found, laparoscopic internal hernia repair after bypass is usually curative.

Clinical Pearls

• Closing the jejunojejunal mesenteric defect reduced internal hernias at that site from 10% to 0% in one surgeon’s series.
• Internal hernias typically appear one to three years after surgery, during rapid weight loss.
• Chronic, intermittent postprandial pain may be the only symptom; normal imaging does not rule it out.
• Petersen’s space should also be closed; randomized data now support closing both defects.

Strengths and Limitations

The study is large and comes from a single surgeon, which keeps technique consistent apart from the one change being tested. It is retrospective and compares two time periods, so increasing experience may also have contributed, and patients who sought care elsewhere for a hernia could have been missed. Follow-up for the later group was shorter.

Expert Commentary

I changed my technique in 2003 after seeing internal hernias in patients who had otherwise done very well. Once I began closing the mesenteric defect, hernias at that site disappeared. That was the reason we wrote this paper.

Closing these spaces is now standard practice in gastric bypass. I still evaluate patients from other programs who have intermittent pain years after a bypass, and an internal hernia is one of the first things I look for.

— Dr. Nestor de la Cruz-Muñoz