Definitions
Abdominal pain is a subjective unpleasant sensation felt in any of the abdominal regions. Acute abdominal pain is usually used to refer to pain of sudden onset, and/or short duration. Referred pain is the perception of pain in an area remote from the site of origin of the pain.
KEY POINTS
The level of abdominal pain generally relates to the origin: foregut— upper; midgut—middle; hindgut—lower.
• Generally, colicky (visceral) pain is caused by stretching or contracting
a hollow viscus (e.g. gallbladder, ureter, ileum).
• Generally, constant localized (somatic) pain is caused by peritoneal
irritation and indicates the presence of inflammation/infection
(e.g. pancreatitis, cholecystitis, appendicitis).
• Associated back pain suggests retroperitoneal pathology
(aortic aneurysm, pancreatitis, posterior DU, pyelonephritis).
• Associated sacral or perineal pain suggests pelvic pathology
(ovarian cyst, PID, pelvic abscess).
• Generally, very severe pain indicates ischaemia or generalized
peritonitis (e.g. mesenteric infarction, perforated duodenal ulcer).
• Pain out of proportion to the physical signs suggests ischaemia
without perforation.
• Remember referred causes of pain: pneumonia (right lower lobe),
myocardial infarction, lumbar nerve root pathology.
KEY INVESTIGATIONS
• EBO: leucocytosis, infective/inflammatory diseases, anaemia, occult
malignancy, PUD.
• LETs: usually abnormal in cholangitis, may be abnormal in acute
cholecystitis.
• Amylase: serum level >1000 iu diagnostic of pancreatitis. Serum level
500—1000 iu, ?pancreatitis, perforated ulcer, bowel ischaemia, severe
sepsis. Serum level raised <500 iu, non-specific indicator of pathology.
• 3-HOG (serum): ectopic pregnancy.
• Arterial blood gases: metabolic acidosis—?bowel ischaemia,
peritonitis, pancreatitis.
• MSU: urinary tract infection (++ve nitrites, blood, protein), renal stone
(++ve blood).
• EGG: myocardial infarction.
• Chest X-ray: perforated viscus (free gas), pneumonia.
• Abdominal X-ray:
ischaemic bowel (dilated, thickened oedematous loops)
pancreatitis (‘sentinel’ dilated upper jejunum)
cholangitis (air in biliary tree)
acute colitis (dilated, oedematous, featureless colon)
acute obstruction (dilated loops, ‘string of pearls’ sign)
renal stones (radiodense opacity in renal tract).
• Ultrasound:
intra-abdominal abscesses (diverticular, appendicular, pelvic)
acute cholecystitis/empyema
ovarian pathology (cyst. ectopic pregnancy)
trauma (liver/spleen haematoma)
renal infections.
• OGD:
PUD, gastritis.
• CT scan:
pancreatitis, trauma (liver/spleen/mesenteric njuries), diverNcuhtis, leaking aortic aneurysm.
• IVU: renal stones, renal tract obstruction.