Abdominal Distension

Related Subjects: |Abdominal Masses: Clinical Approach and Considerations |Abdominal Distension |Vomiting

🫃 Abdominal distension refers to abnormal enlargement or bloating of the abdomen, often associated with discomfort or pain. Causes range from benign (dietary gas, constipation) to life-threatening (bowel obstruction, malignancy, liver failure). A structured approach using history, examination, and targeted investigations is essential.

📏 Abdominal Distension – “The Fs” (High-Yield Framework)

Abdominal distension is not the same as a focal abdominal mass. A classic and exam-friendly way to structure the differential is the “Fs” — asking what is filling the abdomen: gas, fluid, solid tissue, or physiological states. This mirrors real surgical and medical reasoning and works well in OSCEs and on the ward.

🔢 The Core Fs

• 💨 Flatus – gas (ileus, obstruction, aerophagia)
• 💩 Faeces – constipation, megacolon
• 💧 Fluid – ascites
• 🟣 Fetus – pregnancy
• 🟤 Fat – obesity
• 🎗️ Fatal growth – malignancy

🧠 Expanded Fs (Clinically Important)

• 🚻 Full bladder – urinary retention (very common, very reversible)
• 🦠 Flare (infection/inflammation) – ileus, peritonitis
• 🫀 Failure of organs – liver (cirrhosis), heart (right-sided HF)
• 🟦 Foreign contents – large cysts, pseudocysts, ovarian masses

🔍 Pathophysiology by “F”

• Flatus: Obstruction or ileus → proximal gas accumulation.
• Faeces: Chronic stool retention → colonic dilatation and bloating.
• Fluid: Portal hypertension, malignancy, infection → peritoneal fluid shift.
• Fetus: Physiological uterine enlargement.
• Fat: Uniform, longstanding distension.
• Fatal growth: Tumour mass effect ± ascites.
• Full bladder: Outflow obstruction or neurogenic bladder.

🩺 Common Causes (Mapped to the Fs)

• 💨 Gas Accumulation (Flatus): Swallowed air, fizzy drinks, beans, bacterial fermentation.
• 🚧 Bowel Obstruction (Flatus + Fluid): Adhesions, tumours, hernias, volvulus.
• 🚽 Constipation (Faeces): Chronic stool loading with bloating.
• 💧 Ascites (Fluid): Cirrhosis, heart failure, malignancy.
• 🤰 Pregnancy (Fetus): Physiological, progressive enlargement.
• 🫀 Liver Disease (Failure): Portal HTN + hypoalbuminaemia → ascites.
• 🌱 IBS (Functional Flatus): Post-prandial bloating, altered bowel habit.
• 🥛 Malabsorption: Coeliac disease, pancreatic insufficiency.
• ⚪ Ovarian Cysts/Tumours (Foreign/Fatal growth): Pelvic space-occupying lesions.
• 🚻 Urinary Retention (Full bladder): BPH, anticholinergics, neurological disease.

📊 Summary Table: Abdominal Distension

⚠️ Red Flags

• Sudden severe abdominal pain.
• Bilious or faeculent vomiting.
• Fever, peritonism, or sepsis.
• Unexplained weight loss or anaemia.
• Rapidly progressive distension.

🔬 Diagnostic Approach

• 📖 History + exam → bowel habit, urinary symptoms, liver disease, malignancy risk.
• 🩻 Imaging → US for fluid; CT for obstruction/masses.
• 🧪 Bloods → FBC, CRP, LFTs, U&E.
• 📹 Endoscopy → if coeliac, IBD, or malignancy suspected.

🛠️ Management Principles

• 🎯 Treat the underlying “F”.
• 🚻 Exclude urinary retention early.
• 🚧 Gas + pain + vomiting = obstruction until proven otherwise.
• 🥦 Diet tailored to cause (low-FODMAP, high-fibre, gluten-free).
• 👨‍👩‍👦 Safety-net and reassure when benign.

🧑‍⚕️ Case Examples

Case 1: 👨 55-year-old man with alcohol-related cirrhosis and progressive abdominal swelling. 🔎 US: ascites; paracentesis: transudate. 🧠 F: Fluid / Failure. ✅ Managed with spironolactone, salt restriction, paracentesis.

Case 2: 👩 35-year-old woman with bloating and alternating diarrhoea/constipation, worse after bread. 🔎 Positive tTG-IgA → duodenal biopsy confirms coeliac disease. 🧠 F: Functional flatus / malabsorption. ✅ Gluten-free diet with symptom resolution.

Case 3: 👴 82-year-old man, confused, distended abdomen, suprapubic fullness. 🔎 Bladder scan: 1.2 L retained urine. 🧠 F: Full bladder. ✅ Catheterisation → rapid improvement.