Risks and Benefits of Bariatric Surgery

The decision to undergo surgery for weight loss is a serious one. Before making this decision, you must understand both the risks and benefits of any weight-loss surgical procedure.

The risks of obesity surgery are not insignificant and must be weighed against the benefits as you lose weight and become free from obesity and its related problems. It is important for you to understand that the risks of surgery are low and that the majority of patients have no complications.

Less than 2 percent of patients suffer complications as a result of surgery. Risks include wound infections, hernias, and leaks from any of the staple lines, bleeding, ulcers, breathing problems, strictures at the connection between to stomach pouch and small intestine and blood clots.

After bariatric surgery, you must remain under medical surveillance for the rest of your life.


Any surgery has a risk of bleeding. Although typically there is little bleeding, sometimes a blood vessel may begin to bleed several hours after the surgery is finished. This can result in hemorrhage, either internally, or at the skin level. Bleeding usually stops by then, but occasionally another operation may be necessary to find and stop the bleeding.

Part of the surgery is performed near the spleen. The spleen contributes to the immune system and fights certain bacteria. It is a fragile organ that can bleed easily if injured. Bleeding can usually be successfully stopped in an injured spleen. Sometimes, though, the spleen must be removed. A person can live normally without a spleen, but will have to receive a vaccine after the surgery.
Some patients will need a blood thinner to prevent the formation of blood clots. This blood thinner can interfere with normal blood clotting and may increase the risk of bleeding during and after surgery. If bleeding occurs, you would be closely monitored and the blood thinner may have to be stopped.

Heart and Lung Complications

Patients with significant heart disease, lung disease, or very severe obesity are at greater risk of developing complications such as heart attack or lung failure after surgery. Such complications could require a breathing tube to be placed in the lungs leading to an extended stay in the ICU while on a ventilator.
Patients who have had prior heart attacks, congestive heart failure, or who are severely deconditioned (bedridden or limited to minimal activity) are at higher risk and would need clearance from the specialists. Pneumonia, atelectasis, or other problems with lungs happen about ten percent of the time. This is why patients are encouraged to walk the day of surgery.

Anastomotic Leak

The risk of developing a leak at the staple line (where the new connections are made) is 1.5%. This may result in more surgeries, revisions, and prolonged hospitalization with rehabilitation.

Pulmonary Embolism

This problem affects the lungs and the heart, but it usually starts in the legs, with the formation of blood clots. Although these can occur at any time, and are more likely in overweight patients, they are especially likely at the time of and soon after surgery, because people who have an operation don’t like to move around, or exercise their legs. The blood becomes stagnant and clots in the leg veins, and if a clot breaks off and floats through the veins to the lungs, it is called a pulmonary embolism. The blood clot blocks the arteries in the lungs, and can cause a part of the lung to lose its circulation and die – a pulmonary infarction. If the circulation to a large part of the lung is affected, the heart is placed under a lot of strain, and it may fail suddenly, which can be fatal. The likelihood of pulmonary embolism is decreased by thinning the blood with heparin, which makes it less likely to clot. Pneumatic compression devices are used to compress the legs and keep the blood flowing faster in the veins. Patients are asked to get up to walk as soon as possible. The nurses caring for you have been specially trained to take care of bariatric surgery patients and will have you walking soon after the surgery.

Post-surgical Infection

Infection can occur in the wound or in the abdominal cavity. Abdominal infection can be very serious and indicate a leakage of stomach contents from the point at which the small intestine is connected to the small stomach pouch. This can be a serious and life-threatening complication requiring reoperation, prolonged hospitalization, and long ICU stays. Infection can occur in the wound about 5% of the time. You are given antibiotics at the time of surgery to decrease this risk. If infection in the wound occurs, the skin and fatty layers of the wound need to be opened slightly. Healing usually occurs within 3 to 6 weeks.

Inability to Perform the Surgery

Unexpected situations may be encountered that make the surgery excessively risky. For example, a patient with a heavy drinking history may have cirrhosis so severe that it is impossible to perform gastric bypass surgery due to the excessive risk of bleeding.


For most patients, the risk of death from the surgery is less than 1%. It is higher in patients who have severe heart or lung disease or patients who are having revision of gastric bypass surgery. The most common causes of death after the surgery are infection and blood clots that travel to the lungs.

Longer Term Risks


Hernias are weaknesses in wounds and lead to a sometimes-painful bulge that tends to enlarge with time. This continues to be a problem when the gastric bypass is done using an incision. The risk of a wound hernia occurring is 10-20% greater with open surgery. If a wound hernia occurs, another operation is required to repair it. We typically wait one year until maximum weight loss has occurred before repair.

Ulcers or strictures

The opening of the stomach may develop an ulcer or may narrow requiring dilation or even reoperation.


Up to one-third of obese patients who have bariatric surgery may develop gallstones. Gallstones are clumps of cholesterol and other matter that form in the gallbladder. During rapid or substantial weight loss a person’s risk of developing gallstones increases. Additional surgery to remove the gallbladder may be necessary. Some patients may have their gallbladder removed at the time of the obesity surgery if they have gallstones.

Vitamin and mineral deficiencies

Nearly 30 percent of patients who have weight-loss surgery develop nutritional deficiencies such as anemia, osteoporosis, and metabolic bone disease. These can be prevented by taking vitamins, minerals, and having careful follow up with your primary care physician and a nutritionist. Women of childbearing age should avoid pregnancy until their weight becomes stable because rapid weight loss and nutritional deficiencies can harm a developing fetus. Most patients are required to take daily multivitamins and calcium with vitamin D. Some patients may require vitamin B12 or iron supplements as well.

Side Effects:

Certain side-effects are seen with weight-loss operations simply because of the amount of weight loss in such a short period of time. These are seen also in people who have had successful weight loss without surgery.

Dumping Syndrome

The “dumping syndrome” in which food moves too quickly through the small intestine can cause nausea, weakness, sweating, faintness, and sometimes diarrhea after eating. There can also be an inability to eat sweets without severe weakness and sweating causing patients to lie down to let the symptoms pass. “Dumping syndrome” is a good side effect because it encourages patients not to eat sweets. Dairy intolerance, constipation, headache, hair loss and depression are other possible side effects.

Transient Hair Loss

Hair loss and thinning is a common side-effect which may occur during the first 6 months. Although it is alarming, it will not lead to baldness and is reversible. Once your weight stabilizes and you take in more protein, the hair will grow back. Hair treatments and permanents should be avoided. Be sure to take in an adequate amount of protein. Twenty percent of our patients have inadequate protein intake. Most patients report that their hair returns fuller and thicker than before.


Since the new stomach pouch is smaller, it will not be able to hold as much food as it used to. If you get full but continue to eat more or eat quickly without chewing thoroughly, chances are an episode of vomiting will result. These habits will change after several episodes of vomiting occur. You will have to “re-learn” your way of eating by eating slower, chewing food well and stopping when you feel full. If you have had no problems with eating during the first month after surgery and then suddenly experience vomiting after eating or drinking, you may have developed a “stricture” or narrowing at the point where the stomach pouch connects with the small intestine. You should call your surgeon for further evaluation.

Lactose Intolerance

The enzyme needed to digest milk and other dairy products (lactase) does not reach food in the usual fashion and may not be able to fully digest milk. Undigested milk can lead to gas, cramping and diarrhea. You may need to avoid dairy products and eat foods which do not contain lactose (i.e. soy milk, lactaid).

Loss of Muscle Mass

Since the amount of calories eaten is drastically reduced after surgery, the body will look to burn other energy stores to maintain itself. Surprisingly, the body prefers to use up muscle for energy before using up fat. Therefore, most of the weight you lose will be muscle and then fat. However, this can be avoided. The way to prevent muscle loss is to exercise every day. It is extremely important to perform both aerobic activity and weightlifting regularly after surgery. These activities can be alternated, but should last for 20-30 minutes at least 3 or 4 times a week. Exercising everyday, however, is ideal and should be the goal.

Excess Skin

After a large amount of weight lost, you may find yourself with excess skin in places you never knew existed. The logical question is “What happens to the excess skin?” Weight loss after surgery continues for about 18-24 months. After that, your body is equilibrated and ready for additional surgery for excess skin removal. This is typically performed by a plastic surgeon experienced in this field. The plastic surgeon will evaluate you and help you decide what areas need “tightening” up. Documentation in your chart (at your surgeon’s office) at each visit about problems such as rashes under the skin folds and the weight of the skin on your abdomen causing backaches will ‘sometimes’ persuade your insurance company that removal is medically necessary. This usually applies to the loose abdominal skin only. Alternatively, there are many plastic surgeons who are flexible and may be able to work out a payment schedule with you.

Benefits of Obesity Surgery

Patients will often see improvements in obesity-related medical conditions that they had before surgery such as diabetes mellitus, glucose intolerance, high cholesterol/triglycerides, hypertension and sleep apnea. In general, 70 – 95% of patients with obesity-related medical conditions are no longer on medication for these conditions three years after surgery.

Patients have reported an enhanced quality of life, improved mobility and stamina, better mood, self- esteem and interpersonal effectiveness, and lessened self-consciousness.

Cardiovascular Disease

Although it can’t be said for sure that heart disease is reduced, the improvement in problems such as high blood pressure, high blood cholesterol, and diabetes suggests that improvement in risk is very likely. In a recent study, the risk of death from cardiovascular disease was reduced in diabetic patients, who are particularly susceptible to this problem.

High Blood Pressure

At least 70% of patients who have high blood pressure, and who are taking medications to control it, are able to stop all medications and have a normal blood pressure, usually within 2 – 3 months after surgery. When medications are still required, their dosage can be lowered, with reduction of their side-effects.

High Blood Cholesterol

Over 80% of patients will develop normal cholesterol levels within 2 – 3 months after operation.

Stress Incontinence

This condition responds dramatically to weight loss, usually by becoming completely controlled. A person who is still troubled by incontinence can choose to have specific corrective surgery later, with much greater chance of a successful outcome, with a reduced body weight.

Low Back Pain and Joint and Disc Disease

Patients usually experience considerable relief of pain and disability from arthritis and from pain in the weight-bearing joints. This tends to occur early, with the first 30 to 40 pounds lost, usually within about a month after surgery. Of course, if there is nerve irritation, or structural damage already present, it may not be reversed by weight loss, and some pain symptoms can persist.


Most people with asthma find that they have fewer and less severe attacks, and sometimes none at all.

Sleep Apnea

Dramatic relief of sleep apnea occurs as our patients lose weight. Many report that within a year of surgery, their symptoms were completely gone, and they had even stopped snoring completely – and their spouses agree.

Type 2 Diabetes Mellitus

Over 90% of Type II diabetics obtain excellent results, usually within a few days after surgery and normal blood sugar levels, allowing freedom from all medications, including insulin injections. There is no medical treatment for diabetes which can achieve as complete and profound an effect. This has led some physicians to suggest that surgery may be the best treatment for diabetes, in the severely obese patient. Borderline Diabetes is even more reliably reversed by gastric bypass. Since this condition becomes diabetes in many cases, the operation can frequently prevent diabetes, as well.

Gastroesophageal Reflux Disease

Relief of all symptoms of reflux usually occurs within a few days of gastric bypass surgery, for nearly all patients. A study is now beginning to determine if the changes in the esophageal lining membrane, called Barrett’s esophagus, may be reversed by the surgery as well – thereby reducing the risk of esophageal cancer.


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