Bariatric surgery risks include everything from mild side effects such as discomfort after eating to serious complications and even death. Patients must be aware of these potential risks so they can give informed consent prior to the procedure. Here is a broad overview of the various complications that may accompany weight-loss surgery (WLS).

Bariatric Surgery Complications

Gastric bypass and duodenal switch carry the same risks as other major operations including excessive bleeding or complications from anesthesia. Some of the most life-threatening complications are associated with the recovery period immediately after surgery. Pulmonary embolism and wound infection are the two most common causes of fatalities after weight-loss surgery. Rare but serious complications include:

  • Stroke
  • Heart attack
  • Incision line reopening
  • Vein inflammation
  • Kidney failure
  • Internal bleeding

Somewhat more common significant bariatric surgery complications include:

  • Leakage along the staple line
  • Irregular heart beat
  • Pneumonia
  • Blood loss requiring transfusion

Beyond these surgical risks, there are a wide variety of complications that can occur as a result of changes to the gastrointestinal system.

  • Anastomic ulcers (at the opening where the stomach meets the intestine)
  • Restriction or blockage of the opening leading from the stomach to the intestines
  • Adhesions or blockage elsewhere in the intestines
  • Leakage between the surgically created pouch and the rest of the stomach
  • Incision hernia
  • Internal hernia or twisted bowels
  • Vitamin and mineral deficiencies (such as low iron and B12 levels)

Long-Term Bariatric Surgery Risks

Because gastric bypass and duodenal switch make permanent changes to the stomach and intestines, they are associated with many side effects over the long term. Some may lessen over time while others are liable to remain for a lifetime.

  • Nutrient deficiencies
  • Osteoporosis
  • Gallstones
  • Gall bladder infection
  • Kidney stones
  • Inflammation of the stomach lining (gastritis)
  • Reactive hypoglycemia (severe low blood sugar)

Female WLS patients who are of childbearing age should avoid pregnancy until their weight has stabilized and any complications have been identified and controlled.

Normal Side Effects of Gastric Bypass

There are some side effects of gastric bypass surgery that simply come with the territory. They can be associated with nutrient deficiencies or the physical restriction of the stomach. Strict adherence to post-WLS lifestyle recommendations may reduce the severity and frequency of these bariatric surgery complications.

  • Dumping (lightheadedness, stomach cramps, diarrhea, pounding heart, sweating and other unpleasant symptoms that occur from eating too much sugar or fat at one time after gastric bypass)
  • Nausea and vomiting
  • Belching and flatulence
  • Food blockage (food getting stuck in the digestive tract – occurs due to eating too quickly or not chewing food thoroughly)
  • Dehydration due to inability to drink large amounts of fluid at one sitting
  • Rapid intoxication from even small amounts of alcohol
  • Fatigue, body aches, chills
  • Depression and other mood changes
  • Dry skin and hair loss
  • Irregular menstrual cycle
  • Intolerance of many foods (especially dairy)
  • Weight regain

Loose, sagging skin after weight loss is a significant problem for patients who were previously morbidly obese. They may need extensive plastic surgery to remove excess skin. These cosmetic procedures are not covered by insurance and must be paid for out of pocket.

Bariatric Surgery Risks for Banding

Gastric banding is a less invasive procedure since it does not involve cutting or removing any portion of the gastrointestinal system. However, it is associated with other side effects including problems with the band and its components. These issues may require surgical revision or removal of the band depending on the severity of the complication.

  • Band erosion (band growing into the stomach)
  • Band intolerance (adverse reaction to the foreign object in the body)
  • Band and/or port leakage (filler leaking out, making the band ineffective)
  • Band slippage (band moving out of position)
  • Band and/or port infection
  • Port inversion or dislocation

There are also many complications that can occur in the digestive system from the esophagus all the way down through the colon. These include:

  • Bowel perforation during surgery
  • Dilation of the esophagus
  • GERD (acid reflux)
  • Trouble swallowing
  • Blockage caused by a lump of food getting trapped
  • Gall stones
  • Hiatal hernia (stomach protruding up through the diaphragm into the lower part of the esophagus)
  • Pouch dilation (enlargement or stretching of the stomach pouch, defeating the purpose of the gastric band)
  • Dehydration
  • Ulcers
  • Inflammation of the intestines
  • Weight regain

Constipation, nausea, vomiting, gas, upset stomach and adverse reactions to certain foods are all very common side effects of gastric banding.

Studies About Bariatric Surgery Risks

The American Society for Metabolic and Bariatric Surgery released a consensus statement in 2004. The organization suggests that 30-day death rates from gastric bypass are about .5 percent and just .1 percent for gastric banding (assuming a skilled surgeon is performing the operation). The serious complication rate is estimated at about 5 percent for both procedures.

One of the largest studies conducted by David Flum from the University of Washington in 2003 reviewed data from 62,000 patients. Dr. Flum found that about one in 50 patients undergoing gastric bypass died within 30 days of the surgery. More recent findings from the same researcher show a substantial drop to between three and eight deaths per 1,000 patients within a month of bariatric surgery. However, this new data combines the much less invasive gastric banding surgery with gastric bypass.

Gastric banding has a low 30-day mortality rate. However, it is associated with a different set of issues. For example, according to a 2005 study, only 55 to 60 percent of patients who undergo banding lose the desired amount of weight. About 10 percent experience serious long-term complications. A 2006 study found a major reoperation rate of 20 percent for gastric banding patients. The procedure is still fairly new, so much more research will need to be done into mortality and complication rates.

Numbers from other studies on bariatric surgery show a wide range of results. A multi-center study published in 2011 found a 30-day mortality rate of just .3 percent among 6,100 patients. A study of 16,000 Medicare patients found a 2 percent mortality rate at 30 days and 4.6 percent at one year. A study that followed 60,000 Roux-en-Y gastric bypass surgery patients found that hospitalization rates were almost 20 percent within a year of surgery (compared to less than 8 percent before the surgery). Most of the hospitalizations were directly related to complications from the WLS. Ventral hernia repair and revision surgery for the gastric bypass were the most common reasons for hospitalization. By year three, the hospitalization rate was still 14.9 percent.

Understanding Bariatric Surgery Numbers

This procedure is associated with what many doctors and patients feel to be an unacceptable mortality rate. Traditional gastric bypass does carry a risk of death that is higher than for common surgeries such as gall bladder removal. Laparoscopic gastric bypass carries a somewhat lower risk while gastric banding rarely results in death within 30 days of the surgery. Patients undergoing bariatric surgery often have other health complications that may increase their overall risk compared to candidates for other common surgeries.

The variation in how these studies were conducted makes it difficult to put a specific number on the risks for bariatric surgery. The risks may turn out to be substantially higher or lower as more information is collected and as surgical techniques are further refined. However, it is clear that a number of factors increase the risk substantially:

  • Extreme obesity
  • Age over 65
  • Comorbidities (diseases such as diabetes that can increase surgical and postoperative risks)
  • Invasive surgical technique (open vs. laparoscopic or banding procedures)
  • Inexperienced surgeon

Patients should understand that bariatric surgery entails ongoing medical care. This may include hospitalization to treat complications and/or undergo revision surgery.