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Acute abdomen

Last updated: March 12, 2021

Summarytoggle arrow icon

Acute abdomen refers to severe abdominal pain lasting for ≤ 5 days. The underlying pathology may be intra-abdominal, thoracic, or systemic and may require urgent surgical intervention. The initial approach to acute abdomen should be to assess for immediately life-threatening causes (e.g., ruptured abdominal aortic aneurysm, bowel perforation) by checking vital signs, performing a quick physical examination, and immediately conducting the appropriate focused diagnostic tests (e.g., abdominal ultrasound, abdominal x-ray). Once emergency causes have been ruled out, a thorough history and physical examination should be performed to narrow the differential diagnoses and guide further diagnostic workup and therapy. Traumatic causes of abdominal pain, abdominal trauma, and chronic abdominal pain are not addressed here.

Approach to management [1]

Red flags for abdominal pain

Immediately life-threatening diagnoses

The diagnostic workup should be guided by the pretest probability of the diagnoses under consideration. The following list includes some commonly used diagnostic tools that can help to diagnose or rule out possible etiologies in a patient with acute abdominal pain.

Laboratory studies

A urine pregnancy test should be performed in every woman of reproductive age, regardless of current contraception use.
Patients with obvious signs of diffuse peritonitis do not require further diagnostic imaging and should proceed straight to surgical management.

Imaging [2][3][4][5][6][7][8]

Approach

  • The initial imaging modality should be guided by the working diagnosis, as based on the patient history, vital signs, and examination.
  • The following recommendations apply to nonpregnant adults.
  • In pregnant women with acute abdominal pain, ultrasound and/or MRI of the abdomen and/or pelvis without contrast are the preferred initial imaging modalities.

By suspected diagnosis [5]

Suspected diagnosis Recommended imaging modality
Acute coronary syndrome

Hemorrhagic shock [6]

Bowel perforation [2]
Small bowel obstruction [3]

Intra-abdominal abscess
  • CT abdomen and pelvis with IV contrast
Acute diverticulitis [7]
Acute appendicitis [4]

Acute mesenteric ischemia [9]
  • CTA of the abdomen
Acute pancreatitis [10]

Nephrolithiasis [11]
Acute complicated pyelonephritis [6]
  • CT abdomen and pelvis with IV contrast

Suspected symptomatic AAA in a hemodynamically stable patient [12]

By location of the pain

Site of pain
Initial test of choice

Alternatives

RUQ pain [13]

RLQ pain [4]

or

LLQ pain [7]
  • CT abdomen and pelvis with IV contrast

LUQ pain [14]
  • CT abdomen with oral and IV contrast

Suprapubic pain [14]

Pelvic pain [15]
  • Gynecological etiology suspected: Ultrasound pelvis (transabdominal and/or transvaginal)
  • Nongynecological etiology suspected and β-HCG is negative: CT abdomen and pelvis with IV contrast

Nonlocalized pain [2]
  • CT abdomen and pelvis with IV contrast
  • CT abdomen and pelvis without IV contrast
  • MRI abdomen and pelvis with/without IV contrast
  • Ultrasound abdomen and/or pelvis
  • Postoperative patients with acute abdomen: consider fluoroscopy (enema and/or upper abdominal series)

Consider diagnostic laparoscopy in hemodynamically stable patients in which the diagnosis is still unclear after complete physical examination and imaging. For patients with hemodynamic instability or severe abdominal distention, proceed to diagnostic laparotomy. [16]

In pregnant patients, regardless of the site of pain, ultrasound and MRI are the preferred initial imaging modalities.

Clinical features Diagnostic findings Acute management
Acute coronary syndrome [17][18]

Acute mesenteric ischemia

[19][20][21][22]
Rupture or impending rupture of AAA [23]

Aortic dissection

[24][25][26]
Clinical features Diagnostic findings Acute management
GI tract perforation [2][27][28]

Mechanical bowel obstruction [2][3][29][30]
  • X-ray abdomen
    • Dilated bowel loops proximal to the obstruction
    • Rectal air shadow absent
    • Multiple air-fluid levels
  • CT abdomen with IV and oral contrast
    • Similar findings as on x-ray
    • Transition point at site of obstruction

Acute appendicitis

[31][32][33][34]
Peptic ulcer disease [35][36][37]
Diverticulitis [38][39][40][41][42][43][44]
Clinical features Diagnostic findings Acute management

Acute pancreatitis

[45][46][47]
  • Severe epigastric pain that radiates to the back (circumferential pain)
  • Nausea, vomiting
  • Epigastric tenderness, guarding, rigidity
  • Hypoactive bowel sounds
  • Possibly fever
  • History of gallstones or alcohol use

Symptomatic cholelithiasis

[48][49][50]
Choledocholithiasis [48][51]

Acute cholecystitis

[48][49][54][55][56]

Acute cholangitis

[48][49][58][59] [54][60][61]
Clinical features Diagnostic findings Acute management
Ruptured ectopic pregnancy [62]
Ovarian torsion [63][64]
  • Sudden onset unilateral lower abdominal or pelvic pain
  • Nausea, vomiting
  • Unilateral iliac fossa tenderness
Testicular torsion [65]
Acute pyelonephritis [6][66][67][68][69]
Nephrolithiasis
  • Severe unilateral and colicky flank pain (renal colic)
  • Hematuria
  • Nausea, vomiting
  • Dysuria, frequency, and urgency

Approach

Community-acquired infections [70][71][72]

Severity of infection Suggested single-agent empiric regimen [70]

Suggested combination empiric regimen [70]

Mild or moderate infection
Severe infection
and/or
high-risk patient

Metronidazole is contraindicated in the first trimester of pregnancy.

Healthcare-associated infections [54][70][71][72]

Healthcare-associated infections are more likely to be antibiotic-resistant and both institutional and individual patient antibiograms should be considered when choosing an empiric regimen!

Patient and/or institutional risk factors
 Suggested empiric regimens [70]
Low risk (< 20%) of infection with resistant organism
High risk (> 20%) of infection with resistant organism
High risk of MRSA

  • Combination empiric regimen (see above)
  • PLUS vancomycin

Obtain cultures, if necessary, before the administration of empirical IV antibiotics.

For patients with a beta-lactam or carbapenem allergy, consider vancomycin with aztreonam and metronidazole.

Gastrointestinal etiologies [14] Nongastrointestinal etiologies [14]
RUQ
LUQ
RLQ
LLQ
Epigastrium
Periumbilical
Suprapubic
Diffuse abdominal pain

The differential diagnoses listed here are not exhaustive.

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