Abdominal Distension

Abdominal distension can be due to a huge number of conditions.  A detailed history and examination is crucial to formulating even an accurate differential diagnosis.

History

  • Ask the patient to define/describe the symptom:
    • Is it a mass/swelling?  Is it generalised/localised (if so, where?)? Is it a sensation (bloatedness) e.g. gassiness, satiety, pain?  Is it a physical enlargement (do their clothes feel tight?)?
      • How long has it been there? Onset, duration, progression, timings etc?
        • Is it associated with eating (if so, any particular foods)?
    • What associated symptoms are there?
      • Abdominal Pain
        • Is this associated with eating and/or defaecation?
      • Flatus
      • Nausea/vomiting
      • Malaise/Lethargy
      • Weight loss/Weight gain
      • Change in Bowel Habit
        • Including any blood?
      • Jaundice
      • Any trauma/bruising?
      • Amenorrhoea/Menorrhagia
      • Lower Urinary Tract Symptoms
    • Take a detailed medical history and drug history; family history; social history and travel history
      • Remember to ask in particular about alcohol consumption; IV drug use; FHx of breast/ovarian cancer (or any cancer)

Examination

(see abdominal examination)

Investigations

  • Pregnancy test (where appropriate)
  • FBC to check for
    • WCC ?infection
    • Hb ?anaemia of chronic disease/malignancy
  • U&Es
    • Renal function: hypokalaemia/uraemia may cause non-mechanical bowel obstruction
  • LFTs
    • Any liver dysfunction may be a cause of ascites
    • Other abnormalities e.g. suggestive of cholestasis, may be a feature of malignancy
  • Abdominal imaging (X-ray, USS +/- CT)
  • Colonoscopy/sigmoidoscopy +/- endoscopy may be appropriate to rule out a primary GI malignancy

Differential Diagnosis

The five F’s account for the majority of causes:

  • Fat
  • Flatus
  • Fluid
  • Faeces
  • Foetus

I.e.

  • Obesity
  • Pregnancy
  • Gas
    • Can (not uncommonly) be due to Irritable bowel syndrome
  • Ascites
    • Liver cirrhosis
    • Peritoneal carcinomatosis
    • Nephrotic syndrome (i.e. renal cause)
    • Others including peritoneal TB, pancreatitis, ovarian hyperstimulation syndrome
  • Constipation
  • Fibroids
  • Enlarged bladder

Generalised- Non-obstructive causes

  • Obesity
    • Ask about lifestyle
  • Pregnancy
    • Ask about menstrual/sexual history
  • Irritable bowel syndrome
    • Ask about symptoms of bloating, distension and if they change with bowel movements/eating
  • Ascites
    • Ask about alcohol, history of malignancy (inc FHx); heart problems; kidney problems; oedema in the legs/any SOB; any abdominal pain; jaundice
  • Lymphadenopathy
  • Intra-abdominal bleeding e.g. ruptured abdominal aortic aneurysm
    • Ask about pain e.g. sudden onset

Obstructive causes (ask about pain, vomiting, passing wind)

  • neoplasms
    • Ask about change in bowel habit?  Any weight loss, night sweats?
  • Adhesions
    • Ask about previous surgery.
  • Infections (diverticular disease, intra-abdominal abscess
    • Pain, fever, nausea
  • Foreign bodies (including a bezoar)
  • Miscellaneous
    • adhesions, endometriosis, pregnancy, strangulated herniavolvulus,intussusceptiongallstones, faecalith/meconium ileus, haematoma, pneumatosis intestinalis (pneumatosis coli), superior mesenteric artery syndrome, annular pancreas, Hirschsprung’s disease, stenosis (radiation, surgical anastomosis site, Crohn’s disease, tuberculous).

Nonmechanical 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 ulcerpancreatitis, 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).
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