Acute Abdomen

Snapshot

A 17-year-old boy is brought to the emergency room by his parents for increasing abdominal pain. He started having periumbilical pain last night but now reports increasing right lower quadrant pain. He reports that about an hour ago, the pain acutely intensified and was not responsive to ibuprofen or acetaminophen anymore. On physical exam, his abdomen is rigid with involuntary guarding and tenderness to light percussion. A right lower quadrant ultrasound shows an enlarged appendix with possible perforation. He is emergently taken to the operating room.

Introduction

Overview
- acute abdomen is characterized by acute onset of severe abdominal pain that requires urgent surgical evaluation
  - management depends on etiology
Epidemiology
- incidence
- etiologies
  - hemorrhage
    - abdominal aortic aneurysm rupture
    - bleeding gastric ulcer
    - ruptured ectopic pregnancy
  - ischemia
    - ischemic bowel disease
  - perforated bowel/peritonitis
    - perforated peptic ulcer
    - bowel obstruction
    - diverticular disease
    - inflammatory bowel disease
    - perforated appendicitis
Pathogenesis
- mechanism
  - hemorrhage will often lead to hypovolemic shock, requiring swift intervention
  - ischemia results in elevated lactate and also requires early intervention
perforated bowel causes inflammation of the peritoneum or peritonitis

Presentation

Imaging

Chest radiograph
- indications
  - to look for free air under the diaphragm
- findings
  - free air under the diaphragm, indicating bowel perforation
Abdominal radiograph
- indications
  - if bowel obstruction is suspected
- findings
  - dilated loops of bowel
Abdominal ultrasound
- indications
  - if biliary or hepatic etiology is suspected
  - if tubo-ovarian pathology is suspected
  - if appendicitis is suspected
  - if aneurysm is suspected
  - evaluate for hemorrhage
CT abdomen and pelvis
- indications
if mesenteric ischemia, diverticulitis, or bowel perforation are suspected

Studies

Differential

Differential by Location of Abdominal Pain
Generalized
Bowel obstructionMesenteric ischemia
Right Upper Quadrant	Epigastric	Left Upper Quadrant
Acute cholecystitisHepatitisLiver abscessAcute cholangitis	Peptic ulcer diseaseMyocardial infarctionPancreatitis	Gastric ulcerSplenic rupture
Right Lower Quadrant	Periumbilical	Left Lower Quadrant
Appendicitis	Bowel obstructionAppendicitisAbdominal aortic aneurysm	Diverticulitis
Lower abdomen

Treatment

Management approach
- depends on the etiology of acute abdomen
Medical
- supportive care
  - indications
    - all patients
  - modalities
    - intravenous hydration
    - analgesia
    - anti-emetics
    - nasogastric decompression if necessary
    - bowel rest
    - NPO
    - blood transfusion if necessary
Surgical
- surgical intervention
  - indications
irreversible pathologies such as appendicitis, mesenteric ischemia, and perforated bowel

Complications