Surgeon Questions Bariatric Surgery

What are the side effects of bariatric surgery?

I am 250 lb and 6 ft tall. I am planning to undergo bariatric surgery and would like to know what are the side effects of the surgery?

5 Answers

Good day here is a synopsis of complications. Remember that all patients are seen an prepared by a multidisciplinary team and are very well prepared for the procedure. Therefore is carries a very very low mortality and modest morbidity. Gastric bypass surgery is of the same magnitude as a Hysterectomy, Hip or knee replacement and it is safer than colon surgery.


Complications that occur during bariatric operations can be divided into three categories:

1. Bleeding
2. Inadvertent injury to the GI tract
3. Stapling misadventures

Incidence of intra-operative complications range between 0-1.4% in best series
• intra-operative complications generally can be avoided by unabated concentration and careful technique
• Injuries can be successfully corrected or repaired if recognized intra- operatively.
• Splenectomy rate is about 0.3-0.5%
• Intra-operative complications should be rare in experienced hands.

Complication rates in the early post-operative period, such as infection, dehiscence, leaks from staple breakdown, stomal stenosis, ulcers and DVT with PTE is as high as 10% or more. However, the combined risk of the most serious complications (gastrointestinal leak and deep vein thrombosis) is less than 3 %

1. Pulmonary Embolism
Is the leading cause of peri-operative death in bariatric surgical patients.
The incidence of pulmonary embolism is reported in the range of 1% to 2% in most large series of bariatric operations. Nearly one-third the bariatric patients who suffer pulmonary embolism die. Unfortunately, the incidence of pulmonary embolism does not seem to be altered much by routine use of methods of peri-operative DVT prophylaxis and of anticoagulant therapy. However it remains important to use all methods available to reduce the risk

2. Gastrointestinal leaks
Primary gastric bypass operations - 1% to 2% .
Leaks are sometimes difficult to recognize after gastric bypass because fever and abdominal tenderness are frequently absent.
The leukocyte count and CRP is often elevated but may be within normal limits. Left shoulder pain and anxiety are early symptoms. Persistent tachycardia and progressive tachypnea are the most common early signs. Hence, it is common to initially suspect pulmonary embolism in a patient with a gastric leak. Most surgeons attempt to identify leaks using radiographic GI contrast studies. However, a normal contrast study by no means excludes a leak, since extravasation from the gastric staple line is often not identified by GI contrast studies. An isolated left-sided pleural effusion is a common finding on the plain chest radiograph.
Because failure to recognize a leak can result in the patient's death, exploratory laparoscopy/tomy should be empirically performed in patients with progressive tachypnea and tachycardia in whom pulmonary embolism has been ruled out. In patients who are rapidly deteriorating, exploratory surgery should be undertaken without GI radiographs.
The incidence of leaks following revision procedures is 5 to 10 times higher than after primary operations, presumably because of problems with ischemic damage to the stomach.

3. Major wound infection
The incidence of major wound infection after gastric bypass is reported in the range of 1% to 3%. Conversely, seromas in the subcutaneous fatty layer are common, with an incidence approaching 40%. The potential for wound dehiscence after gastric bypass is greatly increased because of the tension placed on the closure by massive overweight. Hence, the abdominal fascia should be closed with heavy nonabsorbable suture. The incidence of fascial dehiscence is in the range of 1.0% in large published series.

4. Gastrointestinal bleeding within the 30-day perioperative interval
There are various causes, including marginal ulceration, ulcers in the bypassed stomach or duodenum, gastritis, and bleeding from fresh staple lines. Ulceration of the anastomosis occurs in 1-16% of patients.[12]
Possible causes of such ulcers are restricted blood supply to the anastomosis (compared to the blood supply available to the original stomach) in addition to:-
• Anastomosis tension
• Gastric acid
• Helicobacter pylori
• Smoking
• Use of Non-steroidal anti-inflammatory drugs
This condition can be treated as follows:
• Proton pump inhibitors, e.g., Nexiam
• Cytoprotectant and acid Buffering agent, e.g., Sucralfate
• Temporary restriction of consumption of solid foods

5. Small bowel obstruction (SBO)
Within the first several weeks postoperatively may occur in 1% to 2% of patients. Most cases of early obstruction can be treated successfully by tube decompression, which is best accomplished using fluoroscopy. Early obstruction may follow dehiscence of the primary trocar site with bowel entrapment like a Richter hernia

6. Cardiorespiratory complications
These are surprisingly uncommon after gastric bypass.
Sudden cardiac arrest is quite rare in the postoperative period, and death after cardiac arrest is often the result of inability to intubate patients who develop acute respiratory distress. Intubation under these difficult circumstances may require flexible bronchoscope assisted awake intubation and may be lifesaving.

7. Mortality
Important risk factors for complications and premature death following gastric bypass include:
• the physical condition of the patient - including weight and specific co-morbid conditions,
• the complexity of the bariatric procedure and
• the skill and experience of the surgeon.

Laparoscopic gastric bypass typically leads to less pain, and fewer incisional hernias (1-2%) than open surgery bypass. However, laparoscope-assisted surgery is more demanding and inexperienced bariatric surgeons can expect an initial increase in peri-operative and post-operative complications. Mortality is affected by complications, which in turn are affected by pre-existing risk factors such as degree of obesity, heart disease, obstructive sleep apnea, diabetes mellitus, and history of prior pulmonary embolism. It is also affected by the experience of the operating surgeon: the "learning curve" for laparoscopic bariatric surgery is estimated to be about 100 cases. Unfortunately, the way a surgeon becomes experienced in dealing with problems is by encountering those problems over time.
The long-term mortality rate of gastric bypass patients has been shown to be reduced by up to 40% [13,14]
At present, the general death rate from bariatric surgery seems to vary between 0.2 and 1 percent. The rate is lowest for Lapband procedure (0-0.2%) and highest for the BPD procedure (0.2 -0.8%) with gastric bypass at 0.5%

A recent Canadian study revealed that severely obese patients who chose bypass surgery, reduced their risk of premature death by up to 89 percent, compared to equally overweight patients who did not get surgical treatment. Mortality for cardiac disease was reduced from 5% in the control group to 0.45% in the study group. In another study of 66,000 obese patients, about 3 % of gastric-bypass patients (under 40) died in the 13.6 years after the surgery, compared with 14 % of obese patients who were not treated surgically.
In experienced hands, the overall complication rate of this type of surgery ranges from 7% for laparoscopic procedures to 14.5% for operations through open incisions, during the 30 days following surgery. Mortality for this study was 0% in 401 laparoscopic cases, and 0.6% in 955 open procedures. Similar mortality rates – 30-day mortality of 0.11%, and 90-day mortality of 0.3% – have been recorded in the U.S. Centers of Excellence program, the results from 33,117 operations at 106 centers.

In the first three to six months after surgery, as the body reacts to rapid weight loss, the patient may experience one or more of the following changes:

• Body aches
• Dumping syndrome
• Feeling tired (flulike) / Malaise
• Feeling cold when others feel comfortable
• Dry skin
• Hair thinning and hair loss
• Changes in mood and relationship issues

Some changes are due to a slowing of the body's metabolism from weight loss and usually resolve with time.

Normally, the pyloric valve at the lower end of the stomach regulates the release of food into the bowel. When the Gastric Bypass patient eats a sugary food, the sugar passes rapidly into the bowel due to the absence of a pilorus, where it gives rise to a physiological reaction called dumping syndrome. The body will flood the intestines in an attempt to dilute the sugars. An affected person may feel their heart beating rapidly and forcefully, break into a cold sweat, get a feeling of butterflies in the stomach, and may have a "sky is falling" type of anxiety. He/she usually has to lie down, and could be very uncomfortable for about 30 to 45 minutes. Diarrhea may then follow. Traditionally there are two explanations or 2 types of dumping namely mesenteric blood shunting and fluid shifts or vasomotor type and the hypoglycaemic type due to excessive insulin release following ingestion of high calorie sugary foods.


1. Incisional hernia
Is the most common late complication after open gastric bypass, with an incidence ranging from 10% to 20% in most large series. Incidence for laparoscopic surgery is 1-2%

2. Internal hernia with obstruction = Petersen space herniation. This is small bowel herniation through the mesenteric defect between the 2 loops of the Y anastomoses. This space should be closed at the time of primary surgery. This accounts for only 7% of all hernias but can be a potentially lethal complication due to late diagnosis

3. Symptomatic gallbladder disease
Range from 3% to 30%.
The practice of removing the gallbladder prophylactically at the time of surgery has been a controversial issue among bariatric surgeons.
Several surgeons who have recommended prophylactic cholecystectomy report histological evidence of gallbladder pathology in 90% of cases.
It is acceptable practice to remove the gallbladder for asymptomatic gallstones at the time of bypass surgery

4. Vomiting and dehydration
Although vomiting is a common side effect of gastric bypass in the early postoperative period, severe intractable vomiting is rare.
Most cases of severe vomiting are caused by stenosis of the outlet stoma. Patients with vomiting who cannot tolerate liquids should be hospitalized and placed on intravenous fluids. In many cases the edema of the outlet stoma, which results from protracted vomiting, will resolve without further intervention. Patients who cannot tolerate liquids after several days of nothing by mouth and intravenous fluids should undergo upper endoscopy and stomal dilatation using endoscopic ballons.
Stomal dilatation is usually successful, except in patients with prosthetic stomal reinforcement. Many patients with prosthetic stomal reinforcement require re-operation for intractable stomal stenosis.

5. Late disruption (breakdown) of the stapled gastric partition
Is responsible for patients regaining lost weight after gastric bypass.
However, the incidence of staple-line breakdown varies widely in clinical reports from 2% to 23%. This finding led to a prospective trial of stapling versus transsection of the upper stomach. The East Carolina group abandoned transsection after 100 cases when they observed that dividing the stomach neither eliminated subsequent gastro-gastric fistulae nor reduced the incidence of leaks. Despite conflicting data, most surgeons now routinely divide the stomach during gastric bypass.
The incidence of staple-line leaks and gastro-gastric fistulae after transsection are reported in the range of 1% to 2%.

6. Marginal ulceration after RYGB
Ranges from 3% to 10%.
These ulcers typically develop on the jejunal side of the gastroenterostomy and are caused by excessive production of gastric acid. Many cases of marginal ulcers are associated with breakdown of the gastric staple line. Marginal ulcers that are not associated with disruption of the stapled partition almost always respond to proton pump inhibitors. Conversely, ulcers that occur in patients with staple-line breakdown are often intractable to medications and require operative treatment.

7. Intestinal obstruction
Is relatively uncommon after gastric bypass but it may be life threatening.
The incidence of SBO after RYGB and other malabsorptive procedures is in the range of 2% to 3%. Because gastric capacity is greatly reduced after RYGB, vomiting is often not a prominent symptom.
Although most cases of late SBO are caused by adhesions, volvulus related to internal hernia is a recognized, occasionally fatal type of obstruction = Petersen hernia = 7% of all hernias
Because obstruction of the bypassed bowel may not be obvious on plain abdominal radiographs, CT scanning should be promptly performed when abdominal films are non-diagnostic.
Aggressive operative treatment is warranted in patients whose symptoms are not quickly improved with tube decompression.

8. Metabolic Sequelae - Nutritional effects of Bariatric surgery

After surgery, patients feel fullness after ingesting only a small volume of food, followed soon thereafter by a sense of satiety and loss of appetite. Total food intake is markedly reduced. Due to the reduced size of the newly created stomach pouch, and reduced food intake, adequate nutrition demands that the patient follow the surgeon's instructions for food consumption, including the number of meals to be taken daily, adequate protein intake, and the use of vitamin and mineral supplements. The total food intake and absorbance rate of food will rapidly decline after gastric bypass surgery. After gastric bypass surgery there is an increase in the number of acid producing cells in the lining of the stomach. Acid lowering medications are prescribed to counteract the high acidity levels. Many patients then experience Achlorhydia where there is not enough acid in stomach. This can lead to an overgrowth of bacteria as a result of the low acidity levels. A study conducted on 43 post operative patients revealed that almost all of the patients tested positive for a hydrogen breath test, which determined an overgrowth of bacteria in the small intestine[15] The overgrowth of bacteria will cause the gut ecology to change and will induce nausea and vomiting. Recurring nausea and vomiting will change the absorbance rate of food which contributes to the vitamin and nutrition deficiencies common in post operative gastric bypass patients. It has become very clear that routine follow up by a surgeons is not even closely adequate and that these patients should attend an obesity clinic regularly for at least the first 2 years after surgery. It should actually be a lifelong follow up program managed by a Bariatric clinic with involved Endocrinologists.
Protein nutrition
Proteins are essential food substances, contained in foods such as meat, fish and poultry, dairy products, soy, nuts, and eggs. With reduced ability to eat a large volume of food, gastric bypass patients must focus on eating their protein requirements first, and with each meal. In some cases, surgeons may recommend use of a liquid protein supplement.

Calorie nutrition
The profound weight loss which occurs after bariatric surgery is due to taking in much less energy (calories) than the body needs to use every day. Fat tissue must be burned, to offset the deficit, and weight loss results. Eventually, as the body becomes smaller, its energy requirements are decreased, while the patient simultaneously finds it possible to eat somewhat more food. When the energy consumed is equal to the calories eaten, weight loss will stop. Proximal GBP typically results in loss of 60 to 80% of excess body weight, and very rarely leads to excessive weight loss. The risk of excessive weight loss is slightly greater with Distal GBP and BPD
Vitamins are normally contained in the foods we eat, as well as any supplements we may choose to take. The amount of food which will be eaten after GBP is severely reduced, and vitamin content is correspondingly reduced. Supplements should therefore be taken, to completely cover minimum daily requirements of all vitamins and minerals. Absorption of most vitamins is not seriously affected after proximal GBP, although vitamin B12 is not be well-absorbed. Sublingual preparations of B12 will provide adequate absorption. Some studies suggest that GBP patients who took probiotics after surgery were able to absorb and retain higher amounts of B12 than patients who did not take probiotics after surgery. After the distal GBP, fat-soluble vitamins A, D and E may not be well-absorbed, particularly if fat intake is large. Water-dispersed forms of these vitamins may be indicated, on specific physician recommendation.
All versions of the GBP bypass the duodenum, which is the primary site of absorption of both iron and calcium. Iron replacement is essential in menstruating females, and supplementation of iron and calcium is preferable in all patients. Ferrous sulfate is poorly tolerated. Alternative forms of iron (fumarate, gluconate, chelates) are less irritating and probably better absorbed. Calcium carbonate preparations should also be avoided; calcium as citrate or gluconate, 1200 mg as calcium, has greater bioavailability independent of acid in the stomach, and will likely be better absorbed. Vit C is a co-factor for conversion of iron between the ferri to ferro form for absorption.
Alcohol Metabolism
There was a study that confirmed post operative gastric bypass patients will absorb alcohol at a faster rate than people who have not undergone the surgery. It will also take a post operative patient longer to reach sober levels after consuming alcohol than those who have not undergone the surgery. A study was conducted on 36 post operative patients and a control group of 36 subjects who have not undergone the surgery. Each subject was given a 5 oz of glass of red wine and the alcohol in their breath was measured to evaluate their alcohol metabolism. The gastric bypass group had an average peak alcohol breath level at 0.08%. The control group had an average peak alcohol breath level of 0.05%. It took on average 108 minutes for the gastric bypass patients group to return to an alcohol breath of zero, while it took the control group an average of 72 minutes to return to an alcohol breath of zero[16] . Patients who have undergone gastric bypass surgery will have a lower tolerance than people who have not gone through the surgery. It will also take a gastric bypass patient longer to return to a sober level after drinking alcohol than a person who has consumed alcohol that has not had the surgery.
There was a study conducted that confirmed the development of pica after gastric bypass surgery due to iron deficiencies. Pica is a compulsive tendency to eat substances other than normal food. Some examples would be people eating paper, clay, plaster, ashes, or ice. A study was conducted on a female post operative gastric bypass patient who was consuming eight to ten 32oz glasses of ice a day. The patients blood test revealed iron levels of 2.3 mmol/L and hemoglobin level of 5.83 mmol/L. The patient was then given iron supplements that brought her hemoglobin and iron blood levels to a normal level. After one month the patient's eating diminished to two to three glasses per day. After one year of taking iron supplements the patient's iron and hemoglobin levels remained in a normal range and the patient reported that she did not have any further cravings for ice. The patient was eating ice due to the iron deficiencies that occurred after gastric bypass surgery. Low levels of iron and hemoglobin are common in patients who have undergone gastric bypass. Pica is more common in gastric bypass patients who have a history of the condition prior to the surgery[17] .

It should therefore be clear that patients who have bariatric surgery are at risk of developing several metabolic sequelae.

• Iron:-
Since iron absorption occurs primarily in the duodenum, malabsorption of ingested iron is the primary cause of post-gastric bypass iron deficiency. Iron frequently is seriously deficient, particularly in menstruating females, and must be supplemented. Ferrous sulfate can cause considerable GI distress in normal doses; alternatives include ferrous fumarate, or a chelated form of iron. Occasionally, a female patient develops severe anemia, even with supplements, and must be treated with parenteral iron(Venofer , Cosmofer).

• Vitamin B12 deficiency
After gastric bypass there is a failure to cleave food-bound Vit B12 from its protein moiety in the upper gastric pouch. Conversely, crystalline B12 is absorbed normally in the distal ileum. Vitamin B12 requires intrinsic factor from the gastric mucosa to be absorbed. In patients with a small gastric pouch, it may not be absorbed, even if supplemented orally, and deficiencies can result in pernicious anemia and neuropathies including Wernecke encephalopathy. Sublingual B12 appears to be adequately absorbed. Vit B12 deficiency occurs in up to 39% of patients where supplementation is not followed. Vit B12 injections every 2 months may be all that is required in the majority of cases.

• Folate:-
Although the etiology of folate deficiency after gastric bypass is unknown, inadequate dietary intake is probably the most common cause. Deficiencies in each of these micronutrients can result in anemia.
• Thiamine deficiency (also known as beriberi) will, rarely, occur as the result of its absorption site in the jejunum being bypassed. This deficiency can also result from inadequate nutritional supplements being taken post operatively.

• Fat Malabsorption:-
Because fat malabsorption is a goal of the distal "malabsorptive" gastric bypass, patients who have these procedures are prone to develop diarrhea, malodorous flatus, and deficiencies in fat-soluble vitamins. It is a problem with the Long loop or distal RYGB and BPD procedure but not usually with standard LRYGB.
Fat malabsorption leads to deficiency in fat soluble vitamins including Vit A, D, E and K. There are reports of night blindness as well as deterioration of general eyesight due to deficiency in Vit A levels occurring after 2 years. Vit D deficiency is seen very regularly after LRYGB and requires prudent supplementation and testing.
• Hyperparathyroidism, due to inadequate absorption of calcium, may occur in GBP patients. Calcium is primarily absorbed in the duodenum, which is bypassed by the surgery. Most patients can achieve adequate calcium absorption by supplementation with Vitamin D and Calcium Citrate (carbonate may not be absorbed - it requires an acidic stomach, which is bypassed). Calcium and Magnesium deficiency can lead to bone demineralization and osteoporisis. Supplementation and establishing of levels regularly is vital.

• Hypoproteinemia
Can occur after the BPD procedure but is not seen after LRYGB . In cases of severe malnutrition revision with lengthening of the alimentary limb is necessary.
Rarely it may also occur sometimes after distal long loop RYGB.

• Trace elements
Deficiencies such as Copper, Zinc and Molybdenum may occur.

• Most severe or problematic deficiencies develop after BPD procedures due to the aggressive nature of the bowel bypass and these are usually not seen with the other types of procedures. Of note is the severe and irreversible metabolic derangements following the JIB procedure that has lead to this procedure being abandoned 2 decades ago. Fortunately, the majority of post-gastric bypass vitamin and mineral deficiencies are mild and are easily corrected by taking oral supplements of the deficient micronutrient.

9. Revision surgery
• Patients who have a bariatric procedure occasionally require revision, either for inadequate weight loss or for complications.
• About 10-20 percent of patients undergoing open stomach bypass require follow-up operations to correct complications, the most common complaints being abdominal hernias. Incisional hernia rate following open surgery may be a high as 23.9%
• The incidence of major postoperative complications following revisional bariatric procedures is substantially higher compared to primary operations.
• More than one-third of patients who have gastric bypass surgery develop gallstones.
• Early morbidity rates for revisional surgery range from 15% to 50%.
• The mortality rate reported after revision operations ranges as high as 10%.
• The most common complication resulting in re-operation in the laparoscopic group is intractable marginal ulcer.
• RYGB patients with stomal stenosis and an intact staple line who fail endoscopic dilatation should have revision of the gastroenterostomy.

10. Weight regain after 2 years
• Undoing any bariatric operation without conversion to another weight-reduction procedure is invariably associated with the patient's promptly regaining the lost weight.
• Gastric bypass patients with anatomically intact operations and unsatisfactory weight loss have probably "out eaten" the operation.
• These bypass patients with unsatisfactory weight loss are best converted to a more malabsorptive modification of RYGB, or in some cases biliopancreatic diversion.
• Unfortunately, some patients who are converted to a malabsorptive procedure suffer severe metabolic complications.
• Patients with staple-line breakdown after RYGB should have transection of the stomach between staple lines because of the high incidence of subsequent disruption observed in patients who have had restapling in continuity.
• Large-volume gastric pouches should be reduced when technically feasible.
• A small number of morbidly obese patients will out-eat any bariatric operation.
• Whenever a patient has failed a second technically sound and intact operation, surgeons should approach the prospect of a further revision with considerable caution and skepticism. Rejection of such patients for another operation is frequently a prudent decision.

11. Neurological complications
Includes confusion, auditory hallucinations, optic neuropathy, weakness and loss of sensation in the legs, and pain in the feet, among other conditions. Wernecke encephalopathy can occur in the presence of severe vitamin deficiency. These patients seldom have prior neurological symptoms. Many of the patients also experienced multiple nutritional abnormalities, especially low serum copper, vitamin B12, vitamin D, iron and calcium. Depression may develop in up to 15% but the opposite is usually the norm namely resolution of depression.[18]

This is a seemingly rare but serious complication following gastric bypass called NIPHS (non-insulinoma pancreatogenous hypoglycemia syndrome) or post- bariatric surgery hypoglycemia. After a person eats, this condition can result in very low blood sugar levels that lead to severe neurologic symptoms, including visual disturbances, confusion and (rarely) seizures.
Mayo physicians in Minnesota have evaluated and treated several patients with NIPHS. When medical and diet therapies do not work, surgical removal of the distal part of the pancreas has resulted in marked improvement of symptoms for most patients. Serial Insulin and Glucose post-prandial monitoring will establish the diagnosis in most cases. If the symptoms described above occur, patients should notify their physician immediately. Until this condition is controlled, patients should avoid driving motorized vehicles or performing tasks that could affect the safety of those around them.

13. GORD and regurgitation
This is a very common problem among morbid obese patients and it actually improves after bypass surgery. However in some instances patients experience ongoing and symptomatic reflux that requires long-term PPI therapy.

14. Pregnancy and Bariatric surgery
It is absolutely contra-indicated for any woman of childbearing age to fall pregnant within 18-24months of having bariatric surgery due to the many metabolic, electrolyte and mineral derangements that occurs. This may lead to fetal distress, mal-development, fetal malnutrition, congenital defects and miscarriage. It is paramount that these women take effective birth control for up to 2 years after surgery.
There are different complications depending on the type of surgery that you are having done. Most operations are restrictive, meaning they decrease the size of your stomach and restrict the amount of food you can eat at any given time. Your ability to eat a normal-sized meal will forever be altered. The operations are essentially irreversible. Other side effects, at least for the first 9-18 months, include a decreased appetite and early satiety (feeling full quickly).

If you do not maintain a low-fat, low-sugar diet, you will be at risk for dumping syndrome, which is characterized by nausea, bloating, and diarrhea. Many people develop acid reflux after a sleeve gastrectomy, but this may improve over time. Nausea, vomiting, and bloating are all common effects, especially in the early phases after surgery.
There are also specific risks of surgery related to each procedure that are not necessarily long-term side effects.
I would get on a good eating program and work out about 30 min a day. Surgery should always be the last thing you do and then only to save your life.
So like any surgery bariatric surgery also has the generic complications such as bleeding, infection, pain etc, along with complications that might arise from general anesthesia. Some specific complications to bariatric surgery will be dictated by the type of surgery you are getting eg sleeve vs bypass vs banding. I would talk to the surgeon to get a specific side effect profile.
This information is very important for you to discuss with your surgeon amd his pre-op team.