Lower Abdominal Pain in the Emergency Department

Resuscitation and Critical Diagnosis


  • Work-up for lower abdominal pain begins with resuscitation and exclusion of critical diagnoses
  • Then, through a detailed history and physical, consider all the causes of lower abdominal pain
  • Rule out Genitourinary causes (pyelonephritis vs kidney stone) if possible with Urine Analysis
  • The differential may then come down to GI (appendicitis, diverticulitis) vs pelvic etiology (in females) → will need further imaging based on suspicion (CT A/P vs pelvic ultrasound)


• IV/O2/Monitor, IV Fluids, Labs as needed, pregnancy test

Rule Out Critical diagnoses:

AAA, Mesenteric Ischemia, Perforation, SBO, ectopic pregnancy

Lower Abdominal Pain Algorithm
Lower Abdominal Pain Algorithm

Emergent Causes of Lower Abdominal Pain

1. Appendicitis

Clinical Presentation of Appendicitis

  • General
    • Abdominal pain
      • Periumbilical colicky pain
      • Migration to right iliac fossa → constant and sharp
      • Localized peritoneal irritation (McBurney’s point)
      • Rovsing’s (palpation in LLQ elicits pain in RLQ)
      • Psoas (passive extension of thigh or active flexion of hip → pain → retrocecal appendicitis)
      • Obturator signs (flexion and internal rotation of hip → pain)
    • Anorexia, nausea / vomiting, constipation / diarrhea
    • Fever, tachycardia, High WBC, High CRP
  • Strongest predictors of appendicitis (Meta-analysis Brit J Surg 2004;91:28-37)
    • Inflammatory response variables (PMN, WBC, CRP)
    • Peritoneal irritation (rebound, percussion tenderness, guarding, rigidity)
    • Migration of pain (epigastric/periumbilical → RLQ (right lower quadrant))
  • Patients at extremes of age may have non-specific symptoms → diagnostic difficulty

Appendicitis Triad

□ Inflammatory markers
□ Peritoneal irritation
□ Migration of pain

Appendicitis - Pathogenesis and Clinical Findings
Appendicitis – Pathogenesis and Clinical Findings

Work-up for Appendicitis (Ann Intern Med 2004;141:537-46)

  • Ultrasound
    • Aperistaltic and non-compressible structure > 6mm
    • Sensitivity 86%; Specificity 81%
  • CT
    • Abnormal appendix, calcified appendicolith + periappendiceal inflammation or diameter >6mm
    • Sensitivity 94%; Specificity 95%

Treatment of Appendicitis

  • Surgery
    • Risk of rupture: 0-36h → <2%;
    • Each ensuing 12h period after 36h → 5%
    • Timing (Arch Surg 2006;141:504-7)
      • No significant difference between early (<12h after presentation) and later (12- 24h) appendectomy

2. Diverticulitis

Clinical Presentation

  • Presents like appendicitis, but of the LLQ (lower left quadrant)
  • Hypogastric pain migrates to LLQ (93-100%)
  • Fever, High WBC
  • Diarrhea, guaiac + stools
Acute Diverticulitis - Pathogenesis and Clinical Findings
Acute Diverticulitis – Pathogenesis and Clinical Findings

Work-up for Diverticulitis (Am J Roentgenol 2002;178:1313-8)

  • Empiric treatment ?
    • No imaging studies needed if diagnosis is clear-cut → can begin empiric treatment
  • CT
    • Sensitivity 69-95%, Specificity 75-100%
    • Use for uncertain diagnosis, exclude other causes of abdominal pain, rule out diverticular complications, or clinical deterioration
    • Findings: bowel wall thickening (96%), fat stranding (95%), detects complications (free air, abscess, phlegmons, cancer)
  • Ultrasound
    • Sensitivity 84%, Specificity 93%
    • Rule out AAA, hypoechoic bowel wall thickening, diverticula, abscess, hypoechoic around bowel wall

Complications of Diverticulitis (Emerg Med Clin N Am 2003;21:937-969)

  • Abscess
    • Can lead to fistula formation, sepsis
  • Free perforation, peritonitis
    • Rupture of diverticular abscess → acute surgical abdomen
    • More common In elderly and immunosuppressed, high mortality (6-25%)
  • Fistula
    • Fistula between colon and surrounding structures → colovesicular, colovaginal, colocutaneous, coloenteric
    • Colovesicular most common (dysuria, pyuria, pneumaturia, fecaluria)
  • Obstruction
    • Uncommon-2% of cases
    • May cause Small-Bowel Obstruction when loops of bowel entangled in peridiverticular adhesions

Treatment of Diverticulitis

  • Inpatient
    • Indication: Severe symptoms requiring narcotics, unable to tolerate oral fluids, elderly, comorbid illnesses, ill/septic, no home support or follow-up
    • IV antibiotics (gram negative/anaerobes), bowel rest
    • Laparotomy? → generalized peritonitis, sepsis, visceral perforation, clinical deterioration

3. Pyelonephritis

See Low Back Pain Algorithm

4. Nephrolithiasis

See Low Back Pain Algorithm

5. Torsion / PID / TOA

6. Acute Scrotum

Other Causes of Lower Abdominal Pain

1. IBD (Inflammatory bowel disease)

Clinical Presentation

  • RLQ pain → terminal ileitis ?
    • Diffuse abdominal pain, diarrhea, guaiac +
Inflammatory bowel diseases
Inflammatory bowel diseases


  • May be difficult to distinguish “flare” from an acute complication → consider further diagnostic imaging
    • Define: Lethal complication of IBD or infectious colitis → total or segmental nonobstructive colonic dilatation plus systemic toxicity
    • Clinical: abrupt onset bloody diarrhea, fever, High WBC, tachycardia, third space losses, ill appearing, abdominal distension → perforation (peritoneal signs may be masked by steroids)
    • Therapy: Resuscitation, blood transfusion, broad spectrum antibiotics, corticosteroids, +/- immunosuppressants, bowel rest and bowel decompression
    • Surgery: indicated if no improvement on medical therapy (subtotal colectomy with endileostomy)
  • Hemorrhage: (CD > UC) → Resuscitation, blood transfusion, surgery consult (bowel resection?)
  • Other: Obstruction, Perforation, Abscess

2. Colitis

  • Etiology
  • Clinical Presentation
    • Gastroenteritis ?
    • N/V/D
    • Guaiac + stools

Other Appendicitis Mimics

  • Mesenteric adenitis (diagnosis of exclusion)
  • Typhlitis
  • Intussusception
  • Ileocecitis
  • Omental infarct
  • Epiploic appendigitis (L>R)
  • Spigelian hernia