Abdominal Distension and Bloating

Authored by , Reviewed by Dr Jacqueline Payne | Last edited | Meets Patient’s editorial guidelines

This article is for Medical Professionals

Professional Reference articles are designed for health professionals to use. They are written by UK doctors and based on research evidence, UK and European Guidelines. You may find the Wind, Gas and Bloating article more useful, or one of our other health articles.

Treatment of almost all medical conditions has been affected by the COVID-19 pandemic. NICE has issued rapid update guidelines in relation to many of these. This guidance is changing frequently. Please visit https://www.nice.org.uk/covid-19 to see if there is temporary guidance issued by NICE in relation to the management of this condition, which may vary from the information given below.

Abdominal distension may be generalised, or may be localised to a discrete mass or enlargement of an organ. The main causes of generalised abdominal distension are easily remembered by the five Fs:

  • Fat (obesity)
  • Faeces (constipation)
  • Fetus (pregnancy)
  • Flatus (gastrointestinal)
  • Fluid (ascites)

The most common causes are:

  • Obesity
  • Pregnancy
  • Irritable bowel syndrome 
  • Constipation
  • Fibroids
  • Enlarged bladder

Non-obstructive causes

Mechanical bowel obstruction

Non-mechanical bowel obstruction

  • Vascular insufficiency: thrombosis, embolism.
  • Retroperitoneal irritation: renal colic, neoplasm, infection.
  • Extra-abdominal infection: sepsis, pneumonia, empyema, spinal osteomyelitis.
  • Metabolic/toxic: hypokalaemia, uraemia, lead poisoning.
  • Chemical irritation: perforated peptic ulcer, pancreatitis, biliary peritonitis.
  • Miscellaneous: excessive intraluminal gas, intra-abdominal infection, trauma, mechanical ventilation, other causes of peritoneal inflammation, severe pain and non-steroidal anti-inflammatory drugs (NSAIDs).

Right upper quadrant

Left upper quadrant

See the separate Right Upper Quadrant Pain and Left Upper Quadrant Pain articles for further detail.


  • Abdominal wall - eg, lipoma, hernia.
  • Stomach - eg, carcinoma, distension due to pyloric stenosis.
  • Pancreas - eg, pseudocyst, carcinoma.
  • Transverse colon - eg, carcinoma, faeces, diverticular mass.
  • Hepatomegaly.
  • Retroperitoneum - eg, aortic aneurysm, lymphadenopathy.
  • Omentum - eg, secondaries from stomach or ovary.


  • Hernia, paraumbilical or umbilical.
  • Stomach - eg, carcinoma.
  • Transverse colon - eg, carcinoma, faeces, diverticular mass.
  • Small bowel - eg, Crohn's disease.
  • Omentum - eg, secondaries from stomach or ovary.
  • Retroperitoneum - eg, aortic aneurysm, lymphadenopathy.

Right and left lower quadrants


  • Careful history taking and abdominal examination are essential. Clinical assessment will usually indicate the nature of abdominal distension (ie whether ascites, gastrointestinal gas, pregnancy, etc) but further investigations are often required to determine the precise aetiology.
  • Resonance on percussion may be misleading because there may be bowel overlying a solid tumour or enlarged organ.
  • Weight loss associated with abdominal distension suggests malignancy.
  • Constipation needs to be fully evaluated to establish any underlying cause.
  • Obesity may make examination very difficult to provide a clear assessment and an ultrasound scan may then be required, irrespective of the likely cause of distension.
  • FBC: raised white cell count in infection or malignancy, anaemia with abnormal vaginal bleeding associated with fibroids, or as a consequence of malignancy.
  • U&Es: renal dysfunction; hypokalaemia or uraemia may cause non-mechanical bowel obstruction.
  • LFTs: liver failure, cholestatic hyperbilirubinaemia with carcinoma of pancreas, hypoalbuminaemia associated with ascites.
  • Urinalysis: may show haematuria in patients with tumours of kidney or bladder.
  • Pregnancy test.
  • Abdominal X-ray, barium enema: constipation, large bowel pathology, bowel obstruction.
  • Abdominal ultrasound.
  • Sigmoidoscopy, colonoscopy.
  • Further investigations may include CT scan and paracentesis.
  • Any patient who presents with abdominal distension without a clear diagnosis requires referral.
  • Referral will also be required for any patient with a serious underlying cause but for many patients the cause is benign.

Bloating is a very common and subjective ailment which can affect patients of all ages. It can be associated with any of the causes of abdominal distension but it is most commonly associated with irritable bowel syndrome. Bloating can have a major impact both socially and psychologically. It is incompletely understood and often inadequately treated. New diet restriction strategies may be helpful[1].

For further information see the related separate Irritable Bowel Syndrome article.

Further reading and references

  1. Foley A, Burgell R, Barrett JS, et al; Management Strategies for Abdominal Bloating and Distension. Gastroenterol Hepatol (N Y). 2014 Sep10(9):561-71.