Key distinguishing features of the most common diagnoses
|High Abdominal Pain||Possible||No||Yes||Possible||Possible|
Likely:Urinalysis, FBC, ESR/CRP, MSU, H. pylori testing
Possible:U&E, LFT, amylase, coeliac screen, CA-125, FIT, faecal calprotectin, plain abdominal X-ray, ultrasound, renal imaging, hospital-based lower GI investigations, gastroscopy.
Small Print:Specialised investigations such as mesenteric angiography and further tests for rare medical causes.
- Urinalysis: Blood alone with stone; blood, pus cells and nitrite in UTI.
- MSU: To confirm urinary infection and guide treatment.
- FBC and ESR/CRP: May suggest inflammatory bowel disease, PU or malignancy. Raised platelets associated with oesophageal or stomach cancer.
- U&E may be deranged in hydronephrosis, renal stones or Addison’s disease.
- LFT and amylase: LFT may be abnormal if carcinoma present. Amylase may be raised in pancreatitis and bowel ischaemia.
- Coeliac screen: Anti-endomysial and anti-gliadin antibodies – suggest coeliac disease if positive.
- CA-125: Especially in women aged 50 or more, may help exclude ovarian cancer.
- H. pylori testing: Strong association with peptic ulcer disease.
- FIT: A useful colorectal cancer ‘rule out’ test in patients at low risk. Also commonly required now when arranging a two-week referral to help secondary care stratify urgency of investigation.
- Faecal calprotectin: To help rule out inflammatory bowel disease, especially if recurrent or persistent diarrhoea is also a feature.
- Plain abdominal X-ray: May reveal constipation, subacute obstruction or kidney stones.
- Renal imaging: For renal stones or recurrent UTI.
- Ultrasound: Will show hydronephrosis and gallstones. Pelvic/abdominal ultrasound also indicated if CA-125 elevated.
- Hospital-based lower GI investigations: For various lower bowel disorders.
- Gastroscopy: May be required to confirm PU and exclude gastric carcinoma.
- Further tests such as angiography (for mesenteric ischaemia) or investigations for rare medical causes may be arranged after specialist referral.
- Simply establishing what provokes or relieves the problem can provide helpful pointers – pain occurring after eating suggests gallstones, PU, gastric carcinoma or mesenteric ischaemia; if relieved by defecation, the likely diagnoses are IBS or constipation.
- In an otherwise well patient, the longer the history the less likely there is to be significant underlying disease.
- Avoid repeated investigation if a patient has already been thoroughly assessed in the past – unless the individual becomes unwell or develops new symptoms. Be frank with the patient by explaining about the ‘law of diminishing returns’ in investigating chronic unexplained abdominal pain.
- Be prepared to make a positive diagnosis of IBS in a fit young patient if the symptoms are classical and basic investigations are negative; explanation and education are the keys to effective management.
- Weight loss in association with recurrent abdominal pain suggests significant pathology.
- Hard enlarged left supraclavicular nodes (Troisier’s sign) are pathognomic of gastric carcinoma.
- Beware that constipation itself is often a symptom rather than a diagnosis. Be sure to establish and treat any underlying cause if it doesn’t respond to simple treatment.
- IBS is the commonest diagnosis – but consider other possibilities if the pain is always in the same site, wakes the patient at night or is associated with rectal bleeding or weight loss.