Gastric bypass complications: symptoms and treatment

Although gastric bypass surgery can lead to weight loss and improved health, it is important to note that, even though very rare, there is a complication risk. Gastric bypass surgery can result in both short-term and long-term complications that may have an effect on patients’ quality of life and health. This chapter will cover the common gastric bypass complications that may occur with the surgery, including both short-term and long-term problems.

By being aware of possible complications, gastric bypass patients can make informed choices about whether or not gastric bypass surgery is a suitable option for them and what they can expect during their recovery.

Gastric Bypass Complications

Immediate post-op gastric bypass complications

Some complications after gastric bypass can occur immediately after the surgery. To prevent and also treat them straight away, you will be staying in the hospital for observation for a few nights.

These gastric bypass complications can be due to the surgery or the anesthesia. During your hospital stay, your vitals will be regularly checked and in the case of any signs of these complications, the medical team will take action to treat them.


Bleeding can happen immediately after the surgery due to a surgical complication on the staple lines, infection, or stomach or small intestine ulcers.

It can present itself with the following symptoms:

  • Abdominal pain
  • Low blood pressure
  • Tachycardia (rapid heartbeat – generally over 100 BPM)
  • Difficulty breathing
  • Nausea and vomiting
  • Fever

If these complications are present, a CT scan or an endoscopy will be performed to identify the source of the bleeding. In the incidence of this complication, surgical intervention might be needed if the patient has a hemodynamic compromise (unstable blood flow) or does not respond to transfusion, and patients whose source of bleeding cannot be identified nonoperatively.

As a preventative method, a specialized diet and activity program will be given to you along with a list of medications to take and avoid.


You need to keep in mind that an infection can occur after any surgical procedure. Naturally, infection after gastric bypass is a possibility and it may have various reasons. An infection can occur if:

  1. The patient had a pre-op infection in their body
  2. Prescribed antibiotics were not used properly
  3. The incisions were not dressed appropriately or long enough and are exposed to bacteria
  4. Utilization of hot tubs or swimming pools before the incisions were healed
  5. The incision site was not kept dry and clean

Infection can be seen on the skin around the incision site or in the stomach. Possible symptoms of infection after gastric bypass are:

  • Fever
  • Redness, swelling, and pain around the incision site
  • Abdominal pain
  • Nausea and vomiting

To prevent infection, you will be given antibiotics from the beginning of your surgery until you are discharged. Afterward, you will be prescribed additional antibiotics to take for about 10 days after your date of discharge. However, if an infection does occur and antibiotics do not work, the surgeon might need to intervene and drain the infection out.

Blood clots

To heal its injured tissue, our bodies start forming blood clots. However, in the case of us not being mobile enough and dehydration, and indirectly causing excessive clotting, it might become an issue. It generally forms on the legs, known as deep vein thrombosis (DVT). And sometimes, it can detach and travel to the lungs, leading to an incident called pulmonary embolism (PE).

DVT and PE symptoms can be different. Let’s review.

Symptoms of DVT (on the leg)

Symptoms of PE (on the lungs)




Difficulty breathing


Coughing up blood

Severe pain

Sharp chest pain

To prevent the formation of blood clots, you will be given surgical stockings that apply pressure on your legs. During and after your surgery, you will be given blood thinners and you will be prescribed additional blood thinners to take after being discharged.

If the patient does suffer from blood clots and thinners are not effective, they will be given thrombolytic drugs that break up and dissolve blood clots. Another treatment may include a minimally invasive intervention called catheterdirected thrombolysis. Inserting a catheter in the vein where the clot is, the surgeon will inject a thrombolytic drug directly into the clot to break it up and dissolve it.

Anesthesia-related complications

Anesthesia-related complications can occur after any procedure that requires anesthesia. The risks of it are generally super low because the anesthesiologist carefully monitors your vitals during the surgery. The possible risks of anesthesia can be the following:

  • Allergic reaction
  • Difficulty breathing
  • Nerve damage
  • Nausea and vomiting
  • Stroke
  • Heart attack
  • Short-term memory loss

If you have any underlying medical conditions or you are using medications or used medications recently, please let your healthcare provider know beforehand. These circumstances can affect the anesthesia.

As an anesthesia process, intubation is performed to aid your breathing during the surgery, and extubation is performed to remove the breathing-aid tools. These procedures are generally safe, but on rare occasions, some complications that are temporary may occur.

Intubation complication symptoms can be the following:

  • Sore throat
  • Difficulty breathing
  • Bleeding
  • Infection
  • Damage to lips, gums, or teeth

Extubation complication symptoms may be:

  • Nausea and vomiting
  • Bleeding
  • Infection
  • Coughing or gagging
  • Hoarseness
  • Laryngospasm (temporary spasm of the vocal cords that can cause difficulty speaking and/or breathing)

Short-term gastric bypass complications

Short-term gastric bypass complications can range from mild discomfort to more serious issues that require medical intervention, including dumping syndrome, and bowel obstruction.

Dumping syndrome

Dumping syndrome occurs when food passes rapidly from the stomach to the small intestine, leading to a sudden release of hormones and a drop in blood sugar levels.

You will know if you are “dumping” immediately, as the symptoms that can be observed within 20-30 minutes after eating are:

  • Diarrhea
  • Nausea and vomiting
  • Abdominal cramps and pain
  • Fatigue
  • Flushing
  • Tachycardia
  • Dizziness

The prevention of dumping syndrome is in the hand of the patient. The planned diet program should be followed, but along with that, there are a few more instructions. You should eat small, frequent meals that are NOT high in fat and sugar. Take your time while eating and chew your food thoroughly.

If the patient is experiencing dumping syndrome, they should contact their healthcare provider for further management of it. If it is severe, hospitalization may be required to treat and manage the symptoms and prevent further complications that can be caused by them.

Bowel obstruction & constipation

Bowel obstruction is a blockage in the intestines that can happen because of adhesions or internal hernia(s). It requires immediate action as it can prevent the passage of food, waste, and fluids. It can be managed or treated by bowel rest, fluid resuscitation, hospitalization, or surgery.

The possible symptoms of bowel obstruction are:

  • Abdominal cramps or pain
  • Constipation
  • Diarrhea
  • Bloating
  • Nausea and vomiting

Symptoms of constipation may include:

  • Abdominal pain
  • Inability to defecate
  • Hard stools
  • Bloating
  • Builtup gas

Constipation can occur also because of changes in diet, inadequate mobility, and dehydration. To prevent constipation, you need to drink enough water (2 liters a day), eat fiberrich food, and keep yourself mobile.

Long-term complications

Patients who have undergone gastric bypass surgery may experience long-term complications that can affect their quality of life and health. Gastric bypass long-term complications can include hernias, gastrointestinal problems, nutritional deficiencies, and more.

Hiatal hernia

Because of the proceeding of the procedure, the newly shaped pouch and the rerouted small intestine can cause the stomach to move up to the esophageal hiatus (the hole on the diaphragm where the esophagus passes through). This occurrence is called a hiatal hernia. It can present itself with the following symptoms:

  • Heartburn
  • Acid reflux
  • Chest pain
  • Difficulty swallowing

The management and/or treatment options for hiatal hernia can include PPI inhibitors, H2 blockers, or surgery.


The formation of scar tissue at the surgical site is the most common cause of stricture after gastric bypass, leading to a narrowing of the opening. Other possible factors that could lead to strictures are infection, inflammation, or errors in the surgical technique.

Possible symptoms can be the following:

  • Nausea and vomiting
  • Abdominal pain
  • Difficulty swallowing

If a stricture is present, the patient might need to go for treatments such as endoscopic dilation, stent placement, or, in severe cases, revision surgery.


Gallstones after gastric bypass can occur because of the rapid weight loss that is expected after the surgery. Gallstones are hardened digestive juices that formed in the gallbladder. They can later lead to pancreatitis, inflammation of the gallbladder, and infections.

Gallstone symptoms are:

  • Fever
  • Nausea and vomiting
  • Abdominal pain
  • Clay-colored stools
  • Jaundice (yellow skin and/or sclera – the white part of the eye)

To prevent gallstones to form, you will be prescribed bile acid supplements. In the case of gallstones being formed, the patient may be given medications that help dissolve them. Although rare, it may not be managed with medication and a surgical intervention might be needed to remove the gallbladder.


Because of the nature of gastric bypass surgery, nutrient, and calorie absorption will be reduced. If this is not managed via supplements or it is severe, patients might face malabsorption.

The symptoms can include:

  • Diarrhea
  • Nutritional deficiencies
  • Anemia
  • Fatigue
  • Muscle weakness/muscle loss
  • Weight loss
  • Steatorrhea (fatty stools)

To prevent malabsorption, while following dietary instructions, you should take additional supplements for nutrients, vitamins, and minerals. Your healthcare provider will ask for followup appointments regularly to observe your blood levels to see if there are any deficiencies. If there are, your dietary plans and supplements will be modified accordingly.

Complications specific to revision surgery

A revision surgery for gastric bypass is a correction or a modification procedure. It can be effective and resolve problems related to the previous surgery, but it carries heightened risks as it puts more stress on the body.

Complications specific to revision surgery may include:

Malnutrition: A revision surgery may further limit the food intake and/or the nutrient and calorie absorption.

Wound complications: Revision surgeries may increase the risks of infection and scarring. It can also cause incisions to heal poorly.

Scar tissue formation: There are already scar tissues present on the patient’s body from the previous surgery. These scar tissues can make it difficult to access the stomach.

Inadequate weight loss: Revision surgery can be more challenging. And as a result, the desired outcome may not be met. This can lead to inadequate weight loss.

It is especially crucial to follow the instructions given after revision surgery. Such as keeping up with a diet and exercise plan and follow-up appointments. In case of any symptoms, the patient needs to contact their healthcare provider as soon as possible to prevent, manage, and treat the complications to remove the obstacles on the way of their journey.


(1) Lim R, Beekley A, Johnson DC, Davis KA. Early and late complications of bariatric operation. Trauma Surgery & Acute Care Open. 2018;3(1):e000219. doi: Link

(2) Concors SJ, Ecker BL, Maduka R, et al. Complications and Surveillance After Bariatric Surgery. Current Treatment Options in Neurology. 2016;18(1). doi: Link

(3) Seeras K, Acho RJ, Lopez PP. Roux-en-Y Gastric Bypass Chronic Complications. PubMed. Published 2022. Link

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