Differential Diagnosis of Acute Abdominal Pain by Predominant Age
Birth to one year Two to five years Six to 11 years
Infantile colic
Gastroenteritis
Constipation
Urinary tract infection
Intussusception
Volvulus
Incarcerated hernia
Hirschsprung's disease
Gastroenteritis
Appendicitis
Constipation
Urinary tract infection
Intussusception
Volvulus
Trauma
Pharyngitis
Sickle cell crisis
Henoch-Schönlein purpure
Mesenteric lymphadenitis
Gastroenteritis
Appendicitis
Constipation
Functional pain
Urinary tract infection
Trauma
Pharyngitis
Pneumonia
Sickle cell crisis
Henoch-Schönlein purpure
Mesenteric lymphadenitis
12 to 18 years
Appendicitis
Gastroenteritis
Constipation
Dysmenorrhea
Mittelschmerz
Pelvic inflammatory disease
Threatened abortion
Ectopic pregnancy
Ovarian/testicular torsion
# Labs and Diagnostic Studies
1. Urinalysis
2. Complete Blood Count (CBC)

Leukocytosis lags other findings in elderly
3. Electrocardiogram
4. Pulse oximetry
5. Serum Phosphate (increased in Mesenteric Ischemia)
6. Liver Function Tests
7. Blood Cultures
8. Amylase
1. Pancreatitis (Lipase preferred)
2. Bowel Obstruction
3. Bowel perforation or peptic ulcer perforation
4. Mesenteric Ischemia
9. Lipase Indications
1. Pancreatitis
2. Bowel Obstruction
3. Duodenal Ulcer
10. Arterial Blood Gas
# Imaging: Protocol
1. Directed imaging where specific cause is suggested
2. Initial non-specific radiology studies
1.
Chest XRay findings a.
Abdominal free air b.
Congestive Heart Failure c.
Pneumonia
2.
Kidney, Ureter, Bladder plain XRay (KUB) findings a.
Small Bowel Obstruction b.
Incarcerated Hernia c.
Appendicitis

d.
Large Bowel Obstruction e.
Diverticulitis f.
Volvulus g.
Mesenteric Ischemia
Second-line studies where diagnosis unclear
See available studies below for specific indications
3.
Abdominal CT is most broadly useful study a.
"Workhorse" of Acute Abdomen evaluation
Sucher (2002) Semin Laparosc Surg 9(1):3
4.
Right upper quadrant ultrasound a.
First-line study if biliary tract disease suspected
5.
Angiography or MR angiography a.
Indicated for Mesenteric Ischemia
6.
Upper Endoscopy a.
Indicated if Peptic Ulcer Disease suspected
# Imaging: Available studies
A.
Chest XRay a.
Assess for cardiopulmonary process b.
Identifies 50-90% of perforated viscus c.
Free air under diaphragm d.
Increased sensitivity
B.
Left lateral decubitus XRay
C.
XRay after 500 ml air given via Nasogastric Tube
D.
Abdominal XRay (KUB) Indications a.
Bowel perforation b.
Bowel Obstruction c.
Abdominal Aortic Aneurysm d.
Volvulus e.
Nephrolithiasis f.
Abdominal trauma g.
Mesenteric Ischemia h.
Cholelithiasis
E.
Abdominal Ultrasound Indications a.
Cholecystitis b.
Appendicitis (lower efficacy than CT) c.
Abdominal Aortic Aneurysm (hemodynamically unstable)
F.
Abdominal CT Indications a.
Appendicitis b.
Diverticulitis c.
Bowel Obstruction d.
Pancreatitis e.
Abdominal Aortic Aneurysm (hemodynamically stable) f.
Mesenteric Ischemia
G.
Angiography or MR Angiography Indications a.
Mesenteric Ischemia