What initial investigations should I consider for a patient with chronic abdominal pain to rule out serious underlying conditions?

For a patient presenting with chronic abdominal pain, initial investigations should focus on identifying red flag symptoms and considering specific tests to exclude serious underlying conditions, particularly cancer ¹,².

• Clinical Assessment and Red Flags: It is crucial to assess for red flag indicators such as unexplained weight loss, unexplained rectal bleeding, persistent blood in the stool, an abdominal or rectal mass, severe abdominal pain, iron deficiency anaemia, raised inflammatory markers, nocturnal or continuous diarrhoea, fever, tachycardia, hypotension, or dehydration ². A physical examination, including abdominal and digital rectal examination, should be performed to identify distension, masses, organomegaly, or tenderness ²,³.
• Faecal Immunochemical Testing (FIT):
  • Quantitative FIT should be offered for abdominal pain with unexplained weight loss in individuals aged 40 and over [1. 3. 1].
  • It is also offered for unexplained abdominal pain with rectal bleeding in adults under 50, or for unexplained abdominal pain in those aged 50 and over [1. 3. 1].
  • FIT is also recommended for any abdominal mass or unexplained change in bowel habit [1. 3. 1].
  • A positive quantitative FIT result, when requested due to specific age and symptom criteria (e.g., 40+ with unexplained weight loss and abdominal pain, 50+ with unexplained rectal bleeding, or 60+ with iron deficiency anaemia or change in bowel habit), warrants a suspected cancer pathway referral for colorectal cancer ².
• Blood Tests:
  • A full blood count should be requested to detect anaemia ².
  • Other routine blood tests include urea and electrolytes, liver function tests (including albumin), calcium, vitamin B12 and red blood cell folate, iron status (ferritin), thyroid function tests, ESR (erythrocyte sedimentation rate), and CRP (C-reactive protein) ².
  • If hepatosplenomegaly is present, a very urgent full blood count (within 48 hours) should be considered for suspected leukaemia [1. 10. 1].
• Ovarian Cancer Investigations (for women aged 18 and over):
  • For persistent or frequent abdominal or pelvic pain (particularly more than 12 times per month) in women, especially if 50 and over, primary care tests should be carried out, including measuring serum CA125 [1. 5. 2, 1. 5. 6].
  • CA125 testing should be considered if symptoms are suggestive of ovarian cancer ².
  • If irritable bowel syndrome symptoms present for the first time in women aged 50 and over, appropriate tests for ovarian cancer, including serum CA125, should be carried out [1. 5. 5, 1. 5. 6].
  • For unexplained change in bowel habit in women, primary care tests and serum CA125 measurement should be considered [1. 5. 3, 1. 5. 6].
• Imaging:
  • An urgent direct access ultrasound scan (to be done within 2 weeks) should be considered for an upper abdominal mass consistent with an enlarged gall bladder or liver [1. 2. 10, 1. 2. 11].
  • For abdominal pain with weight loss in those aged 60 and over, or diarrhoea/constipation with weight loss in those aged 60 and over (suggesting pancreatic cancer), an urgent direct access CT scan (within 2 weeks) should be considered, or an urgent ultrasound scan if CT is unavailable [1. 2. 5].
• Endoscopy:
  • Non-urgent, direct access upper gastrointestinal endoscopy should be considered for upper abdominal pain with low haemoglobin levels or raised platelet count or nausea or vomiting in those aged 55 and over [1. 2. 3, 1. 2. 9].
  • It should also be considered for treatment-resistant dyspepsia in those aged 55 and over [1. 2. 3, 1. 2. 9].
• Stool Tests (if diarrhoea is a prominent symptom):
  • Routine microbiology investigation and examination for ova, cysts, and parasites should be considered if an infectious cause is suspected or there is a history of exotic foreign travel ².
  • Clostridioides difficile testing is relevant, particularly if there has been recent hospital admission, antibiotic use, or proton pump inhibitor use, or if symptoms have recurred ².
  • Faecal calprotectin testing can help differentiate between irritable bowel syndrome and inflammatory bowel disease in people under 40 years if specialist assessment is being considered and cancer is not suspected ². However, it should not be used for people with new onset rectal bleeding or bloody diarrhoea, or when there is a need to rule out cancer ².
• Coeliac Disease Testing:
  • Testing for coeliac disease involves immunoglobulin A (IgA) and IgA tissue transglutaminase (tTG), or IgA endomysial antibody (EMA) ². These tests should be performed while the person is consuming a gluten-containing diet ².
• Suspected Cancer Pathway Referrals:
  • A suspected cancer pathway referral should be made for upper abdominal pain with weight loss in those aged 55 and over [1. 2. 1, 1. 2. 7].
  • Women with an abdominal or pelvic mass identified by physical examination (not obviously uterine fibroids) should be referred via a suspected cancer pathway [1. 5. 1].
  • A suspected cancer pathway referral should be considered for unexplained splenomegaly in adults, especially if associated with fever, night sweats, shortness of breath, pruritus, or weight loss [1. 10. 7].
  • Consider a suspected cancer pathway referral for a rectal mass [1. 3. 5] or an upper abdominal mass consistent with stomach cancer [1. 2. 6].
  • Adults with a rectal or abdominal mass, or those under 50 with rectal bleeding and any unexplained abdominal pain, change in bowel habits, weight loss, or iron-deficiency anaemia, should also be considered for a suspected cancer pathway referral ².