Abdominal Swelling

This presentation covers both abdominal and pelvic masses, and general abdominal swelling. The patient may complain of a general increase in girth or of a discrete mass discovered accidentally; alternatively the GP might find the swelling while performing a physical examination.

Published: 28th June 2022 | Updated: 5th September 2022

Differential diagnosis

Common Diagnoses

  • Pregnancy
  • Irritable Bowel Syndrome (IBS)
  • Constipation
  • Fibroid Uterus
  • Enlarged Bladder

Occasional Diagnoses

  • Coeliac Disease
  • Ascites (Itself has many causes)
  • Intestinal Obstruction
  • Ovarian Mass (Cyst or Malignant Tumour)
  • Carcinoma of Stomach or Colon
  • Hepatomegaly (Various Causes)

Rare Diagnoses

  • Splenomegaly (Various Causes)
  • Pancreatic Carcinoma
  • Aortic Aneurysm
  • Massive Para-Aortic Lymphadenopathy
  • Hydronephrosis, Renal Cysts and Renal Malignancy

Ready reckoner

Key distinguishing features of the most common diagnoses

PregnancyIBS ConstipationFibroid UterusBladder
Size VariesNoYesPossibleNoPossible
Poor Urinary StreamNoNoNoNoYes
Cannot Get BelowYesNoPossibleYesYes

Possible investigations

Likely: Pregnancy test, ultrasound.

Possible: Urinalysis, FBC, U&E, LFT, CA-125, anti-endomysial and anti-gliadin antibodies, plain abdomen X-ray.

Small Print: Hospital-based lower GI investigations, paracentesis, CT scan.

  • Pregnancy test essential in amenorrhoeic women.
  • Urinalysis may reveal microscopic haematuria in renal or bladder tumours.
  • Abdominal ultrasound is the quickest and most efficient way to define the source of most abdominal swellings or masses. Ultrasound of pelvis/abdomen may also be indicated according to an elevated CA-125 (see below).
  • Full blood count (FBC): Anaemia likely in malignancy, possible in fibroids with menorrhagia; also will reveal blood dyscrasias.
  • Urea and electrolytes (U&E) may be deranged in gross renal disease. Liver function tests (LFTs) may give a clue to alcoholic hepatomegaly or malignancy. Low albumin in ascites.
  • CA-125: May be indicated in women, especially those aged 50 or more, to help exclude ovarian cancer.
  • Anti-endomysial and anti-gliadin antibodies: For possible coeliac disease.
  • Hospital-based lower GI investigations: Useful to confirm or exclude colonic disease.
  • Plain abdominal X-ray: May show constipation or obstruction (in the latter case, likely to be arranged after admission).
  • Other tests are likely to be arranged after specialist referral, e.g. paracentesis (to investigate and relieve ascites), CT scanning (to establish nature of mass and its effects on surrounding structures).

Top Tips

  • Take care in the history to distinguish between intermittent or variable swelling, and progressive swelling. The former will probably not be caused by serious pathology, whereas the latter may well be.
  • Pregnancy can catch out the unwary, particularly when dealing with perimenopausal women or teenage girls. Do not accept the claim that ‘I can't be pregnant’.
  • Some ‘swellings’ turn out, on examination, to be impalpable or to represent normal anatomy. The physical examination may have a therapeutic effect. If not, explore the patient's concerns more fully and consider anxiety, depression or other psychological problems if symptoms persist.

Red Flags

  • Weight loss in conjunction with abdominal swelling should immediately suggest malignancy.
  • Acute onset of swelling with abdominal pain suggests obstruction, requiring urgent surgical attention.
  • Obesity presents difficulties in examination and can be difficult to distinguish from ascites. If in doubt, arrange an ultrasound.
  • Resonance on percussion does not rule out a solid mass: Retroperitoneal masses will push bowel anteriorly and may be apparently tympanic.
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Website disclaimer

Pulse Reference is based on the best-selling book Symptom Sorter.

The experts behind Pulse Reference are Dr Keith Hopcroft who is the co-author of Symptom Sorter, a GP in Essex and Pulse’s editorial advisor and Dr Poppy Freeman, a GP in Camden and also a clinical advisor to Pulse.

This website is for clinical guidance only and cannot give definitive diagnostic information. Practitioners should work within the limits of their individual professional practice, seek guidance when necessary and refer appropriately.