Lower Abdominal Pain in the Emergency Department

Table of Contents

Resuscitation and Critical Diagnosis

General

Work-up for lower abdominal pain begins with resuscitation and exclusion of critical diagnoses
- AAA (Abdominal Aortic Aneurysm)
- Mesenteric Ischemia
- Perforation
- SBO (small bowel obstruction)
- ectopic pregnancy
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)

Resuscitate

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

Rule Out Critical diagnoses:

• AAA, Mesenteric Ischemia, Perforation, SBO, ectopic pregnancy

Differential Diagnosis for Abdominal Right Lower Quadrant (RLQ) Pain

Differential Diagnosis for Abdominal Left Lower Quadrant (LLQ) Pain — Differential Diagnosis for Abdominal Right Lower Quadrant (RLQ) Pain

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

Resuscitation
- Large bore IV, IV Fluids

Pain control
- Opiate administration has no significant association with management errors (JAMA 2006;296:1764-1774)

Antibiotics
- Broad spectrum, empiric
- Lower Incidence of postoperative wound infection and intra-abdominal abscess formation (Cochrane Database Syst Rev 2005;(3):CD001439)
- Antibiotics alone for treatment? (Lancet. 2011:377(9777):1573)
  - Spontaneous resolution can also occur
  - 1 year recurrence rate with antibiotics as sole therapy → 15% most within 10 days

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

Outpatient
- Indication: Mild symptoms, tolerating oral fluids, well appearing (Am Fam Physician 2005;72(7):1229)
- Antibiotics, 7-10days (Amoxicillin / Clavulanic acid, TMP/SMX (Trimethoprim / Sulfamethoxazole), ciprofloxacin/metronidazole)
- Liquid diet, may consider no antibiotics in extremely well appearing pts (Br J Surg 2012;99(4):532)
- If no improvement in 2-3 days → consider peridiverticular disease (reassessment and admission?)

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 +

Complications

May be difficult to distinguish “flare” from an acute complication → consider further diagnostic imaging
TOXIC MEGACOLON
- 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
- Ischemic vs infectious vs inflammatory
- Mesenteric Ischemia
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