Surgical complications

BOMSS have made a handy chart for primary care management of post-operative bariatric patients, which can be found on their website

Please refer back to the bariatric surgery service at the Homerton University Hospital if support and guidance are required regarding complications.





Treatment options

Anastomotic and stomach ulcers

Upper abdominal pain, vomiting, hematemesis

Upper GI endoscopy in chronic presentation.  (Chest X-ray and CT abdomen in acute setting).

  1. high dose of proton pump inhibitors
  2. stop smoking
  3. eradiation of helicobacter pylori infection
  4. surgery in acute presentation (last option for refractory ulcers) – refer back to Homerton

Reflux / Heartburn

Acid reflux, heartburn, coughing at night, reflux on bending


Proton pump inhibitors. If problem is persistent, refer back to Homerton.

Strictures / Stenosis

Nausea, vomiting, dysphagia, regurgitation.

Radiological investigations such as barium studies and upper GI endoscopy.

Most strictures can be managed safely with endoscopic dilation.

Internal hernias (gastric bypass)

Cramping, intermittent abdominal pain, nausea with or without vomiting.

Based on clinical suspicion; it can be missed on CT abdomen.

Diagnostic laparoscopy and repair of hernia defects, refer back to Homerton.


Right upper quadrant abdominal pain, some nausea/vomiting

Abdominal ultrasound

Symptomatic gallstones require laparoscopic cholecystectomy, refer to hospital.

Gastric band slippage / erosion

(Slippage) Abdominal pain, vomiting

(Erosion) Pain, vomiting, bleeding, intra-abdominal abscess, fistula formation, weight regain, loss of restriction

Plain X-ray, barium studies, CT abdomen and upper GI endoscopy

Often removal of gastric band, refer back to Homerton. 1 in 5 patients with gastric band will need revisional surgery at some point following their original operation.


Medical complications

Adjustment of regular medications

Improvement in conditions such as type 2 diabetes, hypertension, hyperlipidaemia and obstructive sleep apnoea are often seen following weight loss from bariatric surgery.  People with these conditions should therefore have regular monitoring and adjustments of medications after bariatric surgery.  For people who have type 2 diabetes and no longer require medication, it is still recommended that they have other checks including eye tests and foot health checks on a long term basis, especially if they have had diabetes for a long time as a percentage of patients do relapse.

Patients on thyroxine might require dose reduction following high amounts of weight loss and should be monitored regularly in first year for dose optimisation.

Please refer back to the bariatric surgery service at the Homerton University Hospital if support and guidance is required regarding complications.

Table of medical complications

Dumping syndrome / Hypoglycaemia

More common after a gastric bypass or duodenal switch procedure.

Symptoms  - dizziness, shaking, sweating, palpitations, light headedness, nausea, diarrhoea

Treatment - Dietary modification such as avoiding high sugar and high fat foods and drinks, separating eating and drinking, avoiding long gaps between meals and opting for low glycaemic index (GI) foods. For severe hypoglycaemia a referral back to Homerton University Hospital is recommended.

Kidney stones

Increased risk of kidney stone formation due to enteric hyperoxaluria (increased oxalate absorption) from the gut due to altered gut structure post-surgery (especially gastric bypass and duodenal switch).

Advice - keep water intake to 1.5-2L minimum, low oxalate diet if possible (reduces risk of calcium oxalate kidney stones), calcium supplements should be taken with food (helps binding to oxalate).

In high risk patients (reduced eGFR, history of kidney stones, single kidney), a 24 urine collection to assess risk of urinary stone formation by measuring stone promoters (calcium, oxalate, sodium) and inhibitors (citrate and magnesium) will be helpful post-surgery.

Osteomalacia and fracture

Prolonged vitamin D deficiency can lead to secondary hyperparathyroidism, which increases loss of bone mass. Patients are then pre-disposed to bone pains, long bone and vertebral fracture.

In high risk patients (post-menopausal, on steroids, on thyroxine) regular monitoring of vitamin D and PTH will help in assessing bone metabolism along with DEXA scans, if scans are felt to be indicated.

Wernicke’s encephalopathy (prolonged vomiting)

Patients with prolonged vomiting/diminished food intake can develop severe thiamine deficiency as body thiamine stores lasts for only couple of weeks.

 If patient experiences prolonged vomiting always prescribe additional thiamine (thiamine 200–300 mg daily, vitamin B co strong 1 or 2 tablets, three times a day) and urgent referral to bariatric centre.

Those patients who are symptomatic or where there is clinical suspicion of acute deficiency should be admitted immediately via A&E for administration of IV thiamine/referred to specialist bariatric unit at HUH.

Neurological complications

Severe neurological deficits can occur due to concomitant multiple nutritional deficiencies e.g. copper, vitamin B12, thiamine.

Symptoms - loss of sense of vibration and touch, sub-acute combined degeneration of spinal cord, loss of deep tendon reflexes, severe depression.

Urgent referral to specialist bariatric unit recommended.

Nutritional complications

The BOMSS guidelines for biochemical monitoring and micronutrient replacements can be found here.

Please refer back to the bariatric surgery service at the Homerton University Hospital if support and guidance is required regarding complications.

table of nutritional complications

Protein energy malnutrition

It can present at any point after bariatric surgery.

Possible causes – poor dietary protein intake, malabsorption

Symptoms – muscle wasting, weight loss, oedema (although other causes of oedema should also be excluded).

Advice – increase protein intake to >80g/d, if not improve then refer back to Homerton.

Severe iron deficiency anaemia

Patients on PPIs are at increased risk.

Long-standing deficiency, particularly in females with menorrhagia, can become refractory to oral therapy and require injectable iron preparations.

Severe prolonged undiagnosed vitamin B12 deficiency

Patients on PPIs and metformin are at increased risk.

It can lead to sub-acute combined degeneration of the spinal cord.

Inappropriate folate supplementation in a vitamin B12 deficient patient can aggravate vitamin B12 deficiency related neurological complications – start treating vitamin B12 deficiency before commencing folate treatment.

Severe folic acid deficiency

Patients on anti-folate drugs, with psoriasis or a condition with high cell turnover (including pregnancy and lactation), are at increased risk.

A higher dose may be required due to malabsorptive nature of surgery.

Vitamin A deficiency

Most likely with duodenal switch procedure, or after prolonged diarrhoea and vomiting.  It can lead to problems with vision unless supplemented with high doses of vitamin A.