Acute Abdomen

Differential Diagnoses Based on Location of Pain

Right Upper Quadrant

  • Biliary Colic
  • Acute Cholecystitis
  • Acute Cholangitis

Right Iliac Fossa

  • Acute Appendicitis
  • Ectopic Pregnancy
  • Ovarian Cyst
  • Meckel’s Diverticulitis


  • Pancreatitis
  • Peptic Ulcer Disease
  • Abdominal Aortic Aneurysm

Central / Generalised

  • Abdominal Aortic Aneurysm
  • Intestinal Obstruction
  • Ischaemic Colitis

Left Iliac Fossa

  • Diverticulitis
  • Ectopic Pregnancy
  • Ovarian Cyst


  • Acute Urinary Retention
  • Pelvic Inflammatory Disease

Loin to Groin

  • Renal Colic (kidney stones)
  • Abdominal Aortic Aneurysm
  • Pyelonephritis



  • Inflammation of the peritoneum (the lining of the abdomen)
  • Localised peritonitis is caused by underlying organ inflammation (e.g. appendicitis or cholecystitis)
  • Generalised peritonitis is caused by perforation of an abdominal organ (e.g. perforated duodenal ulcer or ruptured appendix)
  • Spontaneous bacterial peritonitis is associated with spontaneous infection of ascites in cirrhotic liver disease, is treated with antibiotics and carries a poor prognosis


Investigations for obtaining a diagnosis and preparing the patient for theatre

  • FBC gives an indication of bleeding (drop in Hb) and infection / inflammation (raised WBC)
  • U&E gives an indication of electrolyte imbalance and kidney function (useful prior to CT scans, as they require a contrast injection that can damage kidneys)
  • LFTs give an indication of the state of the biliary and hepatic system
  • CRP gives an indication of inflammation and infection
  • Amylase gives an indication about inflammation of the pancreas in acute pancreatitis
  • INR gives an indication of the synthetic function of the liver and is essential in establishing their coagulation prior to procedures
  • PO2 (on an ABG) and blood calcium are required in scoring acute pancreatitis
  • Group and Save is essential prior to theatre in case the patient requires a blood transfusion
  • Blood lactate gives an indication of tissue ischaemia
  • Abdominal xray can provide evidence of bowel obstruction by showing dilated bowel loops
  • Erect chest xray can demonstrate air under the diaphragm when there are intraabdominal perforation
  • Ultrasound abdomen can be useful in checking for gallstones, biliary duct dilatation and gynaecological pathology
  • CT scans are often required to identifying the cause of an acute abdomen and determine correct management


Initial Management of an Acute Abdomen

  • ABCDE approach to priorise resuscitation
  • Nil by mouth
  • IV access (the bigger the cannula the better)
  • IV fluids
  • IV antibiotics (if evidence of infective cause)
  • Analgesia and antiemetics
  • NG tube if vomiting and suspected obstruction
  • Catheterise for fluid balance monitoring
  • Obtain investigations as above
  • Escalate to registrar / consultant / critical care as appropriate to severity of the patient’s condition
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