Gastric bypass: what is it and what can go wrong

The Roux-en-Y gastric bypass (RNY) is by far the most common of the many variations of gastric bypass operation that is performed in the world today.

During surgery, the top section of the stomach is divided off by a line of staples, creating a small ‘pouch’ stomach. A new exit from this pouch is made into a ‘Y’ loop from the small intestine so that food bypasses the old stomach and part (about 100-150cm) of the small intestine. The size of stomach pouch and the length of small intestine that is bypassed are carefully calculated to ensure that patients will be able to eat enough for their body’s needs at normal weight.

Following surgery, the weight should fall until it gets near this point, and then stabilise.

What are the risks from a gastric bypass procedure?

If someone is obese, any surgery is more risky – the death rate associated with this procedure is about 1 in 200 operations. Anaesthesia is difficult to manage, and any illnesses related to obesity can add further complications.

The most common risk of death during a gastric bypass operation is a blood clot in the lung (pulmonary embolism) or problems arising from a leak in a join made during the surgery. Any detected leak should therefore be operated on immediately, otherwise the patient is put at risk of sepsis.

Further risks include:

  • infection in the lungs, stomach or wounds from the operation
  • long-term dilation of the pouch
  • development of a hernia

Both of the second conditions can be repaired surgically.

In addition, a small proportion of patients will fail to lose more than 25% of their excess weight with a gastric bypass operation and further revisions to it may be necessary.

Finally, some surgeons will advocate removing the gallbladder at the same time because a common (and non-negligent) complication of rapid weight loss is the formation of gallstones. Removing the gallbladder at the same time therefore prevents the risk of the patient having to come back at a later date for that surgery.

How does a gastric bypass work?

Weight loss is achieved in three ways:

  • A small stomach pouch is created which reduces the amount of food a patient can eat (restriction).
  • Food leaves the new stomach pouch through a new opening and bypasses the rest of the stomach and much of the small intestine. This means that less calories are absorbed as the food passes through the body (malabsorption).
  • If the patient eats a large quantity of sugar, the body responds by overproducing insulin which makes you feel light-headed and queasy (commonly referred to as dumping syndrome). This acts as a deterrent from overeating the wrong types of food.

How long will I be in hospital?

Most surgeons do this operation by laparoscopic (keyhole) surgery in the UK and the usual length of hospital stay is 2-5 nights afterwards. The surgery takes between 1-3 hours usually.

Some people who are very obese, or who have had previous abdominal surgery may not be able to have this operation done laparoscopically and it will be done via a normal ‘open’ incision. In these circumstances, patients will take a little longer to recover from the bigger incision, but it should not adversely affect the subsequent weight loss progress

What can I expect following gastric bypass surgery?

The operation will cause some pain and discomfort but this should be manageable with pain relief medication. Initially, patients will have an intravenous drip but should be able to start drinking sips of water quite soon after the operation.

Generally speaking 2–4 days after the operation patients are allowed to start drinking freely.

Usually, 4–6 weeks after the laparoscopic bypass operation patients will be back to normal activities, already seeing some weight loss. patients will progress from a pureed diet to solid food step by step.

The weight loss following a gastric bypass is generally greater than that achieved with a gastric band and studies show that on average, people lose between 66–75% of their excess weight in the two years after gastric bypass surgery.

Because of the malabsorption component of this surgery, patients may not absorb sufficient minerals and nutrients from the food for their body’s needs. This can lead to deficiencies and problems such as fatigue, poor skin, hair and nails. Patients will therefore be required to take vitamin and mineral supplements for the rest of their life and their blood will be tested usually every six months or so to ensure they are not developing any deficiencies.

Many patients will have looser stools or diarrhoea following gastric band surgery as less water is absorbed back into the body.

As mentioned above, if a patient eats too much sugar following the surgery they will also probably suffer from dumping syndrome.

How do I know something has gone wrong?

1 – Blood clots

Common places for clots to develop are in the lower leg (deep vein thrombosis) or lungs (pulmonary embolism).

Symptoms can include:

  • your lower leg becoming painful, achy and tender
  • swelling, redness or warmth in your lower leg
  • a sharp, stabbing chest pain that may be worse when breathing in
  • shortness of breath or a cough
  • feeling faint or dizzy

2 – Wound infection

Sometimes the wounds from your surgery can become infected while they’re healing.

Signs of a wound infection can include:

  • pain in or around the wound
  • red, hot and swollen skin
  • pus coming from the wound

3 – A leak

In the days or weeks after a gastric bypass or sleeve gastrectomy, there’s a small chance that of a leak.

Symptoms of a leak can include:

  • a fever
  • a fast heartbeat
  • stomach pain
  • chills and shivering
  • fast breathing

4 – A blockage

Sometimes the stomach or small intestine can become narrower (a stricture) or blocked after weight loss surgery.

Symptoms of a blockage can include:

5 – Malnourishment

Symptoms of malnourishment following gastric bypass might not always be obvious, but can include:

6 – Gallstones

The main symptom of gallstones is episodes of severe stomach pain that come on suddenly and typically last a few minutes to a few hours.

In a few cases, they can also cause:

  • a high temperature (fever) of 38C (100.4F) or above
  • a fast heartbeat
  • yellowing of the skin and eyes (jaundice)
  • itchy skin
  • chills or shivering
  • confusion