Abdominal pain

Also see the separate articles on Acute Abdomen, Abdominal Pain in Pregnancy, Abdominal Pain in Children and Recurrent Abdominal Pain in Children. For abdominal pain by regions see the separate articles on Right Upper Quadrant Pain, Left Upper Quadrant Pain, Epigastric Pain, Loin Pain, Right Iliac Fossa Pain and Left Iliac Fossa Pain.

What is abdominal pain?

Abdominal pain is a common presenting problem in primary care or A&E. Symptoms may be acute (an 'acute abdomen'), subacute or chronic. There are many possible causes - often it is not possible to reach a definite diagnosis in primary care. What is more important is to assess how ill the patient is, to identify any life-threatening problems or 'red flags' and to decide the next step in management - eg, whether to monitor, investigate or refer, and how urgently.¹

Urgent or easily missed causes of acute abdominal pain

Assessment of patients with abdominal pain

• How ill is the patient?

  • For acute abdominal pain:¹
    

    • Always check - and document - vital signs, particularly pulse rate, temperature and blood pressure.

    • Subtle changes in vital signs may indicate serious illness - eg, unexplained tachycardia may be the main/only clue to a serious abdominal/pelvic condition.

    • If the patient is shocked, arrange immediate hospital assessment and management.

    • Give analgesia if needed: intravenous (IV) opiates may be given if needed, and do not affect clinical assessment; titrate small doses and monitor blood pressure.

    • Aim to identify urgent problems (see under 'Urgent or easily missed causes of acute abdominal pain', above).

    Always consider ectopic pregnancy in any woman of childbearing age.

  • For subacute or chronic abdominal pain - look for 'red flags' and other alerting features such as:
    

    • Age >60 years.

    • Relevant family history - ovarian or bowel cancer, familial polyposis coli.

    • History suggesting gastrointestinal (GI) bleed.

    • Unexplained weight loss (or poor growth in children).

    • Repeated consultations for the same problem; change in pattern of consultation ('beware the patient with thin notes').

    • Anaemia.

    • Masses or organomegaly.

• History and examination ± initial investigations (see 'History' and 'Examination' sections, below).

• Decide initial management:
  

  • Have a low threshold for admission/referral of young children, the elderly, the immunocompromised and those with learning difficulties - these groups are more likely to present late or without classical symptoms and signs and may deteriorate quickly.

  • Symptoms and signs may evolve over time - reassessment is an important tool.

  • If the patient is discharged, ensure they know when to seek further help.

History

• Location, nature and severity of pain:
  

  • Colicky (waves of pain): suggests obstructed viscus - eg, intestinal obstruction, renal colic, biliary colic.

  • Tearing pain: suggests aortic dissection or rupture.

  • Constant sharp pain, worse on movement or coughing: suggests peritonitis.

  • Constant dull ache: suggests inflammation - eg, appendicitis, diverticulitis.

  • The pattern of pain may change over time - eg, early appendicitis, mesenteric ischaemia or bowel strangulation may begin as colicky pain and then become constant as the condition progresses; pain may localise as the parietal peritoneum becomes involved.

• Any radiation or referred pain?
  

  • Aortic aneurysm, renal and pancreatic pain: may radiate to the back.

  • Renal colic: may radiate to the groin.

  • Diaphragmatic irritation: may cause shoulder tip pain.

  • Gallbladder pain: may radiate to the scapula.

• Onset of pain:
  

  • Very sudden onset suggests rupture or torsion of an organ (eg, ruptured aneurysm, ectopic pregnancy, torsion of testis or ovary).

• Other symptoms:
  

  • Systemic symptoms: fever, night sweats, weight loss.

  • Vomiting: may be due to severe pain (eg, testicular torsion), gastroenteritis or obstruction.

  • Bleeding: upper GI (haematemesis or melaena) or lower GI (rectal bleed).

  • Constipation or diarrhoea.

  • Vaginal bleeding or discharge: consider gynaecological/obstetric causes.

• Past medical history:
  

  • Note any similar episodes.

  • Note previous illness or surgery.

  • Note Medication/allergies/last meal.

Examination

See the separate Abdominal Examination article.

Investigations

Initial investigations in primary care

• A urine pregnancy test should be offered to women of childbearing age who have abdominal pain (to help rule out ectopic pregnancy).³ If ectopic pregnancy is suspected, the woman should be referred for urgent hospital assessment, even if the urine test is negative.⁴

• Urinalysis ± microscopy and culture.

• Depending on the clinical scenario, consider:
  

  • Blood tests:
    

    • FBC (for occult bleeding).

    • Erythrocyte sedimentation rate (ESR)/C-reactive protein (CRP) - for inflammatory bowel disease.

    • Coeliac antibodies (anti-endomysial antibody or tissue transglutaminase test).

    • U&E, glucose, LFT, amylase, calcium.

  • ECG.

  • Ultrasound of the abdomen and pelvis.

Initial investigation in A&E

• Urine pregnancy test.

• Urinalysis ± microscopy and culture.

• Depending on the clinical scenario, consider:
  

  • ECG.

  • Blood tests:
    

    • FBC.

    • Group/crossmatch blood.

    • ESR/CRP

    • U&E, glucose, amylase, calcium.

  • Erect CXR (looking for air under the diaphragm).

  • Plain abdominal X-ray (or erect and supine abdominal X-rays if an obstruction is suspected) - may show up obstruction, volvulus, ischaemia, severe constipation.

  • Ultrasound or CT scans.

Further investigations

Further investigations will depend on initial assessment findings and initial investigation results, but may include:

• Upper or lower GI endoscopy.

• Ultrasound or CT scans targeted at suspected pathology.

• Diagnostic laparoscopy.

• Laparotomy.

What causes abdominal pain? (Aetiology)

Abdominal pain in particular patient groups

Elderly patients⁹

Presentation tends to be different from younger patients - it may lack classical symptoms and signs and it tends to present later.

Common causes of abdominal pain in the elderly are:

• Peptic ulcer disease.

• Cholecystitis.

• Acute pancreatitis.

• Mesenteric ischaemia/infarction.

• Aortic aneurysm.

• Bowel obstruction - small or large bowel.

• Diverticular disease/diverticulitis.

• Constipation.

• Urinary retention.

• Medical causes (see table 'Causes of abdominal pain by regions', above).

Immunocompromised patients¹⁰

The classical signs of an acute abdomen may be absent in the immunocompromised patient.

Patients with the most severe immunocompromise are chemotherapy patients with neutropenia and HIV patients with CD4+ cell count <200/mm³. Mild-to-moderate immune deficiency occurs in those who are:

• Malnourished.

• Taking steroids.

• Elderly.

• Patients with diabetes.

• Patients with cancer.

• HIV-positive with CD4+ cell count >200/mm³.

Particular causes of abdominal pain in this group include:

• Gastritis - can be due to pathogens such as Candida spp., Cryptosporidium spp. and cytomegalovirus (CMV).

• Hepatic pathology - cholecystitis with atypical pathogens, AIDs-related cholangitis, liver abscess.

• Pseudomembranous colitis.

• Typhlitis (neutropenic enterocolitis) - fever and abdominal pain, particularly right iliac fossa pain.

• CMV colitis - a small-vessel vasculitis mainly affecting the colon; it affects AIDS and renal transplant patients.

• Abdominal tuberculosis - usually ileocaecal.

• Disseminated Mycobacterium avium intracellulare (MAI) - usually in AIDS patients, affecting the jejunum or small bowel; severe abdominal pain and systemic symptoms.

• Acute graft-versus-host disease - after bone marrow transplant.

• Bowel obstruction or intussusception - due to lymphoma or Kaposi's sarcoma.

• Side-effects of antiretrovirals, chemotherapy or other treatments.

Athletes

Abdominal pain during exertion is a common symptom among endurance sports athletes such as long-distance runners. There are many possible causes which may need careful evaluation. These are discussed in the literature.¹¹