An acute abdomen is severe abdominal pain lasting less than 24 hours with signs of tenderness. It requires rapid diagnosis and treatment as some causes like perforation require urgent surgery. Common causes are hemorrhage, infection, perforation, blockage, and ischemia. Physical exam, lab tests, imaging like CT scans, and diagnostic tools help determine the cause. Indications for urgent surgery include signs of peritonitis, shock, deterioration on conservative care, and radiologic findings suggestive of a condition like perforation requiring operation. Preoperative preparation focuses on IV access, fluid resuscitation, antibiotics, and correcting electrolyte abnormalities.