Bloating and abdominal distension
By Dr. Bahir Hadi — Consultant Surgeon, PhD
Bloating and abdominal distension: causes, work-up and treatment
Bloating is one of the most frequent gastrointestinal complaints in adults. Up to 30 % of the population experience bloating regularly, and it accounts for around 10 % of all referrals to a gastroenterology specialist [1]. Bloating may be functional (no demonstrable disease) or organic (with an underlying cause requiring treatment).
What does "bloating" actually mean?
The term covers two distinct phenomena that are often confused:
- Bloating (subjective sensation): the feeling of a tight abdomen, often without visible change.
- Distension (objective measurement): an actual increase in abdominal girth - measurable or visible.
Both arise from an imbalance between gas production, gas transport and abdominal wall tone.
Most common causes
| Cause | Share | Characteristics |
|---|---|---|
| Irritable bowel syndrome (IBS) | 30-40 % | Bloating + altered bowel habit + pain |
| Functional bloating | 15-20 % | Without other IBS criteria |
| SIBO | 10-15 % | Symptoms 30-90 min after meals |
| Lactose/fructose intolerance | 10 % | Tied to specific foods |
| Constipation | 10 % | Infrequent, hard stools |
| Coeliac disease | 1-3 % | Gluten-related, often with weight loss, iron deficiency |
| Gastroparesis | <2 % | Early satiety, nausea, diabetes history |
| Ovarian/gynaecological pathology | - | Persistent uniform distension in women >50 |
Red flags requiring prompt investigation:
- Weight loss, rectal bleeding, fever
- Persistent distension in women >50 (ovarian cancer suspicion)
- Nocturnal symptoms or progression over weeks
- Family history of colorectal cancer
Pathophysiology - why does it happen?
Three mechanisms may occur alone or in combination:
- Increased gas production - bacterial fermentation of carbohydrates (especially FODMAPs) in the colon or small bowel (SIBO).
- Delayed gas transit - reduced motility, often in IBS-C or diabetes.
- Visceral hypersensitivity - normal gas perceived as uncomfortable - classic in IBS [2].
- Abdomino-phrenic dyssynergy - diaphragm descends while abdominal wall relaxes, pushing the belly out.
Work-up
First-line (GP):
- History: diet, bowel habit, weight, medication, gynaecological status.
- Blood tests: haemoglobin, CRP, TSH, coeliac antibodies (anti-tTG IgA), ferritin.
- Faecal calprotectin if diarrhoea (excludes IBD).
- Urine hCG in women of reproductive age.
Second-line (specialist):
- Colonoscopy for age >50, weight loss, rectal bleeding or positive calprotectin.
- Gastroscopy for concurrent dyspepsia, vomiting or iron deficiency.
- SIBO breath test (lactulose or glucose) for postprandial bloating.
- Pelvic ultrasound/MRI for women >50 or abnormal gynaecological exam.
Treatment
Diet first-line - low-FODMAP diet:
FODMAP restriction reduces symptoms in 70-75 % of patients with IBS-related bloating [3]. The diet consists of three phases: elimination (4-6 weeks) → reintroduction → personalised maintenance. Should be supervised by a dietitian.
Medication:
- Simethicone - defoaming agent, eases gas symptoms.
- Enteric-coated peppermint oil - antispasmodic, evidence in IBS.
- Probiotics - Bifidobacterium infantis 35624 has the best evidence.
- Rifaximin 550 mg three times daily for 14 days - for confirmed SIBO.
- Linaclotide/prucalopride - for IBS-C with predominant bloating.
Lifestyle:
- Eat slowly, avoid chewing gum and carbonated drinks.
- Reduce refined carbohydrates and sugar alcohols (sorbitol, xylitol).
- Regular physical activity - even 20 min daily walking improves gas transit.
- Diaphragmatic breathing training for abdomino-phrenic dyssynergy.
When to see a specialist
Contact your GP or Kirurgen.dk if:
- Bloating persists >3 weeks despite dietary changes
- Symptoms worsen or wake you at night
- Weight loss, rectal bleeding, fever or anaemia
- Age >50 with new-onset bloating
Treatment at Kirurgen.dk
We offer full work-up of chronic bloating - colonoscopy, gastroscopy, coeliac screening and SIBO testing. See also: IBS, SIBO, Chronic constipation, Coeliac disease.
References
- Lacy BE, Cangemi D, Vazquez-Roque M. Management of chronic abdominal distension and bloating. Clin Gastroenterol Hepatol 2021;19(2):219-31.
- Mari A, Abu Backer F, Mahamid M, et al. Bloating and abdominal distension: clinical approach and current treatment. Adv Ther 2019;36(5):1075-84.
- Halmos EP, Power VA, Shepherd SJ, Gibson PR, Muir JG. A diet low in FODMAPs reduces symptoms of irritable bowel syndrome. Gastroenterology 2014;146(1):67-75.
More on this topic at Kirurgen.dk
Category: Gastrointestinal