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Complications of the gastric sleeve

We pride ourselves on giving patients the maximum possible information upon which to base their decision to proceed with weight loss surgery, or not. Nowhere is this more evident than in the clear, open and frank way we explain the potential complications of surgery (in general) and the sleeve specifically.

The fact is that all providers have patients who experience complications. We are talking about the human body and not an electrical appliance. At Healthier Weight, we work tirelessly to reduce the incidence rate of complications but it can never be zero.

You should be very cautious of providers who understate their complication rates, claim not to have them or who cannot quote complication rates.

We have provided on this page a long list of complications associated with gastric sleeve. It’s a long list but the incidence rates are very low, in some cases below 1 in 10,000. 

You can click on each complication to read a fuller description.

Overall the mortality rate for sleeve patients is about 0.24% (1 in 4,000+). The post-operative complication and return to theatre rates are between 4%*. Thee rates are based on internationally published data. It’s a wide range and our rate is at the very bottom end of the range.

*Use and Outcomes of a laparoscopic Sleeve Gastrectomy versus Laparoscopic Gastric Bypass: Analysis of the American College of Surgeons NSQIP. J Am Surg. 2015 May

You can view the scientific references that the complication rates quoted in this section are drawn from in the ‘scientific references’ section at the foot of this page.

What influences the complication rate?

There are several factors that influence your complication rate, some that you are in control of. Here is a short list of the main factors:

  • The experience and expertise of your surgeon
  • Your compliance with the pre and post-operative diet guidelines including in relation to alcohol
  • Not smoking – this is very important for sleeve
  • Longer term, attending for blood tests
  • Following our guidance on post-op wound care to reduce the risk of infection
  • Looking out for any symptoms and calling us immediately you suspect any, especially in the first 14 days after surgery.
  • The support of a multi-disciplined team of weight loss specialists to meet your needs as and when they arise (surgeons, doctors, psychologists, nurses and dietitians)


General complications of surgery 

The risk of postoperative bleeding is generally reported to be about 2%. Bleeding can be intra- or extraluminal. A bleed would usually be detected while you are in hospital. It is one of the reasons we regard a 2 night stay as imperative. If you experience a bleed it is safer that you do so while still in hospital.

Intramural bleeding (bleeding inside the stomach) from the staple line usually presents with an upper gastrointestinal bleed. Common symptoms include blood in stools or in vomit. 

Extraluminal bleeding might be indicated by drop in serum hemoglobin levels or presentation of tachycardia or hypotension. 

An extraluminal bleed might originate from the spleen, staple line, liver or entry sites of the trocars used to perform the sleeve. 

Deep vein thrombosis / pulmonary embolus

Blood clots after any surgery can be life-threatening if not treated quickly. It’s important therefore for patients to inform us if they experience pain, redness, swelling or loss of sensation. If in doubt, call us. 

The incidence rate of clots is well below 1%. They can be treated with surgery but more often are treated medically to disperse the clot.

These are collections of fluids. In the case of seroma (serum without blood) and haematoma (containing blood). These usually occur at the port sites and can the result of a problem with he sutures. They will usually occur soon after surgery. 
In very rare cases patients will experience pneumonia or other breathing problems after surgery. These are usually managed medically in a high dependency unit at the hospital. In the worst-case scenario is respiratory failure. This is the inability to breathe adequately after surgery and may require support of breathing in an intensive care ward.
These are injuries to the vascular system (blood vessels) and the internal structures of the body (viscera) that can occur during surgery. They are extremely rare, fewer than 0.1% in most studies. They can occur in any type of surgery where the body’s internal organs are the subject of surgical intervention.

Complications of gastric sleeve

A stricture is when the opening to or from the stomach is blocked, often due to inflammation, and food cannot pass through the stomach as it should. Stricture can present soon or later after surgery.

Sometimes they can be treated conservatively without a return to theatre, others will require a dilatation to try and stretch the stomach. This might be repeated on more than one occasion. If the stricture is long then it may be necessary to re-operate and convert he sleeve to a bypass.

A staple line leak is the most feared complication in the first week after surgery. For this reason, surgeons usually take extra measures to test for leaks before they close, in some cases over sewing the staple line by hand. A leak present by the patient experiencing fever, increased heart rate and/or altered breathing.

If you suspect a leak you should go to A&E and call your provider. It is likely that the care you require will only be available through the multi-disciplinary services present in a major NHS hospital.

The published rate of staple line leaks is about 2% but in the best centres, it would be below this. In poor ones, it might be nearer 4 or 5%

  • Early leaks (within 3 days) are usually closed successfully through a second surgery.

  • Later leaks (after 8 days) are harder to treat as inflammation will have set in making surgical closure more difficult. A conversion to bypass may be possible but if the patient is stable the treatment is more likely to conservative through stenting the stomach and managing the patient’s nutrition.

  • A patient with a later presenting staple line leak is likely to require an extended stay in hospital that could extend to several weeks. An early presenting leak can usually be treated and the patient discharged home within a few days.

  • The prevention and early identification of leaks are two of the key attributed you need from your sleeve provider. Experience of the surgeon and hospital team is critical in this respect.

This is extremely rare and would only occur when the surgeon experiences something unexpected during the operation, for example a serious bleed might require conversion to open surgery. The incidence rate of conversion to open procedure in our practice has been below 0.05% (1 in 2,000).
A marginal ulcer is a peptic ulcer occurring at the margin of a surgical anastomosis of the stomach and small intestine or duodenum. Marginal ulcers are extremely rare in sleeve surgery with an incidence rate below 0.1% (1 in 1,000). They are a later presenting complication and when they do occur they will usually require further surgery. 

This is referred to under the stricture section. It is an endoscopic procedure that is done to widen the sleeves stomach. A complication of sleeve is that in rare cases the stomach can become blocked. This can be treated by dilating (stretching) the stomach using a simple non surgical gastroscopic technique. 

These are usually at the wound sites where the surgeon made incisions to access the abdomen.

They are usually treated effectively with anti-biotics. The key is to spot them early, so when you suspect an infection you should call us immediately. Wound care guidance is provided to all patients and its important they follow this.

You might suspect an infection when you experience fever, redness at wound sites, increased heart rate, dizziness or warmth at the wound sites.

While nutritional deficiencies are less common compared to gastric bypass. Nonetheless most patients will need to supplement their diet with daily vitamins and minerals.

The data show that about 1 in 8 sleeve patients can experience some form of nutritional deficiency. Regular blood tests and following nutritional guidance will avoid this.

As so many UK adults are vitamin and mineral deficient in some way, you may not notice any specific symptoms, hence the importance of blood tests. Our package includes a 6-month blood test and it's important you present for this. We also write to your GP to explain the blood tests that are required on an ongoing basis to monitor your health.

  • Loss of hair
  • Dizziness
  • Constipation
  • Disturbed menstrual cycle
  • Difficulty concentrating
  • Tiredness and fatigue
  • Pale skin


If you experience these, please call us and we can ensure you are eating the right things and taking the right supplements. It is usually easily treated in this way.

All surgery will bring a degree of pain and discomfort. In reality, most patients say that they are surprised that they do not experience more pain. The skill of the surgeon, anaesthetist and hospital ward team are important factors in reducing pain and discomfort post operatively.

Most patients are up and walking in the hours immediately after their surgery and home within a 2-3 days.

We are manipulating the body’s internal organs when we do your sleeve so some discomfort must be expected but this can usually be treated very effectively with pain killers. You’ll be sent home with a supply of painkillers to help with any discomfort you experience.

If you experience severe abdominal pain please call us immediately

You may experience some swelling and bruising after your surgery. Its inevitable as there is some manipulation of the tissue/organs inside your body and of the skin on he outside. Patients are often surprised at how little swelling they can see externally.

Its important you follow the correct post operative diet, we supply this, as this will aid your recovery after surgery.

Some swelling of the stomach is to be expected and this usually settles down after a few days.

Pain should not be severe and pay close attention to severe abdominal pain. Call us if you experience severe pain.

Whenever you undergo surgery and complete a consent form we have to explain that there is a risk of death. In gastric sleeve publications this risk is quantified at less than 0.3%. (less than 1 in 3,000). Please remember that some patients who undergo sleeve surgery are really in very poor health and are experiencing multiple health problems arising from their weight. They may be type 2 diabetic, experiencing cardiac problems, breathing problems, etc. These patients will have a higher mortality risk and they are included in the 0.3% rate quoted.

For patients treated in the private sector the rate will be lower as the most complex patients are likely to be treated in the NHS.


Gastro-oesophageal Reflux Disease (GORD), commonly described as heartburn, is common after gastric sleeve surgery.

If you have reflux disease we are very unlikely to accept you for sleeve surgery. The band or bypass would be the better option for these patients.

Reflux can present as heartburn, pain on swallowing, soreness in the oesophagus/back of the throat and can be worse at night. It is a side effect of the gastric sleeve because the new sleeve stomach is smaller and under higher pressure than the old stomach. It’s the pressure that can force stomach contents upwards.

It can usually be treated effectively through PPI medication. In fact, all sleeve are prescribed PPI (often Omeprazole) for a 3 month period postoperatively. 

Read more about reflux after sleeve surgery

Treatment of complications

If you experience a complication with your gastric sleeve after you have been discharged from the hospital, it is likely that you will need treatment in an NHS hospital. Most late presenting complications (after discharge) will be a leak from the staple line or a stricture. We consider that these can only safely be treated in an NHS environment where the multi-disciplinary medical support and intensity of support can be provided. 

Scientific references

We have drawn the complication rates quoted above from respected medical and scientific journals and publications. You can view these in our ‘gastric sleeve – scientific references’ section. 

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*Weight loss surgery results and benefits vary and are different for each individual. As such, Healthier Weight cannot guarantee specific weight loss goals.