What is the best course of action for a 29-year-old female patient presenting with vomiting, left leg pain radiating to the pelvic floor area, and a negative at-home pregnancy test (human chorionic gonadotropin (hCG) test)?

Management of a 29-Year-Old Female with Vomiting and Left Leg Pain

For a 29-year-old female presenting with vomiting and left leg pain radiating to the pelvic floor with a negative home pregnancy test, immediate imaging with pelvic ultrasound followed by CT abdomen and pelvis with IV contrast is indicated to rule out potentially life-threatening conditions including deep vein thrombosis, ectopic pregnancy, and appendicitis.

Initial Assessment

Pregnancy Status Verification

• Repeat serum β-hCG test immediately despite negative home test
  • Home pregnancy tests can yield false negatives, especially early in pregnancy
  • Serum β-hCG becomes positive approximately 9 days after conception 1
  • Elevated β-hCG in a seemingly non-pregnant patient may indicate miscarriage, ectopic pregnancy, or other conditions 1

Critical Differential Diagnoses

1. Venous thromboembolism (VTE)

   • Left leg pain radiating to pelvic floor strongly suggests possible DVT
   • May present with nausea/vomiting if pulmonary embolism has developed

2. Gynecological emergencies

   • Ectopic pregnancy (despite negative home test)
   • Ovarian torsion
   • Pelvic inflammatory disease

3. Gastrointestinal causes

   • Appendicitis (can present atypically with left-sided pain)
   • Inflammatory bowel disease
   • Diverticulitis

4. Urinary tract pathology

   • Urolithiasis
   • Pyelonephritis

Diagnostic Approach

Immediate Laboratory Tests

• Complete blood count
• Comprehensive metabolic panel
• Serum β-hCG (quantitative)
• Urinalysis
• Inflammatory markers (CRP, ESR)
• Coagulation studies (D-dimer if DVT suspected)

Imaging Algorithm

1. If β-hCG positive:

   • Transvaginal ultrasound is the first-line imaging modality 1, 2
   • Evaluate for intrauterine vs. ectopic pregnancy
   • Assess adnexal structures for masses, torsion, or free fluid

2. If β-hCG negative:

   • Doppler ultrasound of left leg to evaluate for DVT
   • CT abdomen and pelvis with IV contrast for comprehensive evaluation 1, 2
     • CT has higher sensitivity (89% vs 70%) than ultrasound for urgent diagnoses 2
     • Can detect appendicitis (94% sensitivity), diverticulitis, bowel obstruction, and urolithiasis 2

Management Based on Findings

If DVT Confirmed

• Immediate anticoagulation therapy
• Consider inferior vena cava filter if contraindications to anticoagulation exist

If Gynecological Emergency

• Ectopic pregnancy: Methotrexate or surgical intervention based on location and stability 3
• Ovarian torsion: Immediate surgical consultation for detorsion
• PID: Broad-spectrum antibiotics

If Gastrointestinal Pathology

• Appendicitis: Surgical consultation for appendectomy 1
• Diverticulitis: Antibiotics, bowel rest

If Urinary Tract Pathology

• Urolithiasis: Pain management, hydration, possible urological intervention
• Pyelonephritis: Antibiotics, hydration

Symptomatic Management of Vomiting

• First-line: Non-pharmacological approaches

  • Small, frequent meals
  • Avoiding triggers
  • Adequate hydration

• Second-line: Pharmacological options

  • Vitamin B6 (pyridoxine) 10-25 mg every 8 hours 1
  • Doxylamine 10-25 mg every 8 hours (if not pregnant) 1
  • Ondansetron 4-8 mg every 8 hours for persistent symptoms 1

Important Caveats

• Do not dismiss negative home pregnancy test - serum β-hCG is essential
• Do not delay imaging if clinical suspicion for DVT or other emergent conditions is high
• Consider radiation exposure if pregnancy is confirmed - MRI may be preferable in first trimester 1
• Beware of atypical presentations - appendicitis can present with left-sided pain
• Monitor for clinical deterioration - vital sign changes may indicate rupture of ectopic pregnancy or other emergency

The combination of vomiting and unilateral leg pain radiating to the pelvis is concerning for serious pathology requiring prompt evaluation and management to prevent significant morbidity and mortality.