Acute Abdomen

Acute abdomen is a sudden onset of severe abdominal pain that may indicate a life-threatening pathology. It can be due to many different pathologies:

• Conditions requiring urgent laparotomy:

  • Organ rupture - AAA, Spleen, Ectopic pregnancy

  • Peritonitis - Perforation of Ulcer, Diverticulum, Appendix, Bowel, Gallbladder

    • Presents with guarding, abdominal rigidity, and pneumoperitoneum on CXR

• Conditions not requiring urgent laparotomy:

  • Colic - Bile duct, Bowels, Ureter

    • Unlike peritonitis, the pt will be restless

  • Local peritonism - Diverticulitis, Cholecystitis, Appendicitis

Any patient presenting with acute abdomen needs immediate investigations to rule out the life-threatening pathologies that require urgent surgical intervention. Investigations to do include:

• Pregnancy test - rule out ectopic pregnancy

• Bloods - FBC, U&E, CRP, LFT, Lactate (mesenteric ischaemia), Amylase (acute pancreatitis)

• Erect CXR - for pneumoperitoneum

• ECG - to rule out cardiac pathology

Any pain that's originating from the visceral peritoneum (covers organ itself) of the abdominal organs causes poorly-localised pain as the organs themselves have fewer nerve endings; patients complain of generalised abdominal pain. In contrast, when this begins to irritate or cause inflammation to the parietal peritoneum (cover inner lining of abdominal wall), the pain becomes well-localised; patients begin to complain of a more specific area of the abdomen that's painful.

• A good example of this is in appendicitis where there's migratory pain from the umbilical region to the right iliac fossa as it progresses. The initial inflammtion stimulates the visceral afferent pain fibres, producing poorly-localised umbilical pain (appendix is a midgut structure). As the appendix becomes more inflamed, it irritates the parietal peritoneum, which activates somatic nerve fibres and produces more localised pain, most often felt in the right iliac fossa.