Acute Abdominal Pain in Adults
The sudden onset of severe abdominal pain represents a genuine emergency in general practice and is a common out-of-hours call. In the true acute abdomen, the patient is obviously ill, and as the clinical condition may deteriorate rapidly, ensure that you examine the patient as soon as possible. NOTE: Upper and mid-abdominal pain are dealt with here. Lower abdominal pain is dealt with under ‘pelvic pain, acute’ and specifically epigastric-type pain is covered in more detail in the epigastric pain section.
Differential diagnosis
Common Diagnoses
- Peptic Ulcer
- Biliary Colic
- Appendicitis
- Gastroenteritis
- Renal Colic
Occasional Diagnoses
- Cholecystitis (May Follow Biliary Colic, but Pain is Constant and Fever Present)
- Diverticulitis
- Acute or Subacute Bowel Obstruction (Adhesions, Carcinoma, Strangulated Hernia, Volvulus)
- Pyelonephritis
- Muscular Wall Pain
- Pancreatitis
- Meckel’s Diverticulum
Rare Diagnoses
- Perforation (e.g. Duodenal Ulcer [DU], Carcinoma) Resulting in Peritonitis
- Hepatitis
- Crohn’s and Ulcerative Colitis
- Ischaemic Bowel
- Dissecting/Leaking Aneurysm
- Diabetic Ketoacidosis (DKA) and other Occasional Medical Causes (e.g. Myocardial Infarction [MI], Pneumonia, Sickle Cell Crisis)
Ready reckoner
Key distinguishing features of the most common diagnoses
| Peptic Ulcer | Renal Colic | Biliary Colic | Appendicitis | Gastroenteritis | |
|---|---|---|---|---|---|
| Colicky Pain | No | Yes | Yes | No | Yes |
| Localised Pain | Yes | Yes | Yes | Yes | No |
| Abdominal Tenderness | Yes | No | Possible | Yes | Possible |
| Fever | No | No | No | Yes | Possible |
| Diarrhoea | No | No | No | Possible | Yes |
Possible investigations
- The only test likely to help the GP is urinalysis: This may reveal haematuria (renal colic), evidence of urinary infection or glycosuria in DKA. In general, the following investigations will be done in hospital after acute admission.
- Full blood count: WCC raised in many causes and confirms acute inflammation or infection.
- U&E essential as abnormalities common with diarrhoea or vomiting. Amylase raised in ischaemic bowel and acute pancreatitis.
- LFT may show raised bilirubin in biliary obstruction, and widespread derangement in hepatitis.
- Helicobacter pylori testing: Strong association with peptic ulcer disease.
- Upper GI endoscopy: To visualise upper GI tract.
- Plain erect abdominal X-ray invaluable to confirm perforated viscus (air under diaphragm). Supine also necessary if obstruction suspected. Ninety percent of renal or ureteric stones will be revealed with a plain abdominal X-ray.
- Ultrasound: Helpful to confirm gallstones.
- Renal imaging: For ureteric stones.
Top Tips
- The aim of assessment is correct disposal rather than an exact diagnosis. Colicky pain may be appropriate to manage at home; constant pain with tenderness is likely to need admission.
- If treating a patient at home, arrange for review as appropriate and ensure that the patient is aware of the symptoms which should prompt urgent reassessment.
- The examination is likely to contribute significantly to making the diagnosis – so take particular care and don’t forget the basics such as pulse rate, temperature, bowel sounds and a rectal examination.
Red Flags
- Beware ‘gastroenteritis’ masking or developing into an acute appendicitis. Make arrangements for follow-up and emphasise that constant pain needs urgent review
- Prejudice is easy if the patient has a history of functional problems or irritable bowel. Surgical pathology can happen to anyone, so be objective.
- Beware the elderly patient with an irregular pulse: Mesenteric infarction causes severe pain but few signs
- Don’t forget to examine the hernial orifices, especially if obstruction is a possibility.