What is the initial management for a female patient presenting with nausea, vomiting, suprapubic and left iliac fossa pain and tenderness, with a negative pregnancy test, normal urine dipstick, and normal White Blood Cell (WBC) counts?

Initial Management of Female Patient with Abdominal Pain and Normal Investigations

The most appropriate initial management for a female patient presenting with nausea, vomiting, suprapubic and left iliac fossa pain and tenderness, negative pregnancy test, normal urine dipstick, and normal WBC counts is CT abdomen and pelvis with contrast (option B). 1

Rationale for CT Imaging

CT imaging is indicated in this scenario for several key reasons:

• Despite normal laboratory findings, the patient's localized pain and tenderness in the left iliac fossa and suprapubic region requires cross-sectional imaging to identify potential serious pathology
• CT abdomen and pelvis has superior diagnostic accuracy (>90%) for identifying causes of abdominal pain when clinical assessment is inconclusive 2
• Normal WBC counts do not exclude serious pathology - appendicitis can present with normal WBC counts in up to 8.4% of cases 1
• Misdiagnosis based on clinical assessment alone for conditions like diverticulitis has been reported to be between 34% and 68% 2

Why Other Options Are Less Appropriate

• Abdominal X-Ray (Option A): Radiography is not useful as the initial imaging test for patients with left lower quadrant pain because CT is more accurate. While X-rays can identify large volume extraluminal air, ileus, or bowel obstruction, CT is more sensitive and specific for each of these entities 2

• Diagnostic Laparoscopy (Option C): This is invasive and should be reserved for cases where imaging is inconclusive or when there is high suspicion for surgical pathology despite negative imaging

• Analgesia & Discharge (Option D): Given the patient's localized tenderness and concerning symptoms, discharge without imaging could miss serious pathology requiring intervention

Differential Diagnosis to Consider

The patient's presentation could represent several conditions:

• Diverticulitis: Left-sided pain is classic, though only about 25% present with the triad of left lower quadrant pain, fever, and leukocytosis 2
• Appendicitis: Can present atypically, especially with retrocecal appendix
• Gynecological causes: Including ovarian cyst complications, PID, and endometriosis
• Small bowel obstruction: Can present with nausea, vomiting and abdominal pain

CT Protocol Considerations

• IV contrast should be used as it significantly increases diagnostic accuracy for conditions like appendicitis 3
• Oral contrast is generally not required for suspected high-grade obstruction as non-opacified fluid provides adequate intrinsic contrast 2
• CT can accurately identify complications requiring urgent intervention such as perforation, abscess, or bowel ischemia

Management Algorithm

1. Obtain CT abdomen and pelvis with IV contrast

2. If CT shows diverticulitis:

   • Uncomplicated: Medical therapy (antibiotics)
   • Complicated with abscess >3cm: Consider catheter drainage
   • Free perforation/peritonitis: Surgical consultation 2

3. If CT shows other pathology:

   • Appendicitis: Surgical consultation
   • Gynecological pathology: Gynecology consultation
   • Small bowel obstruction: Surgical consultation if high-grade or signs of ischemia

4. If CT is negative but symptoms persist:

   • Consider ultrasound for further evaluation of gynecological causes
   • Consider MRI if suspicion remains high for specific conditions

Important Caveats

• While ultrasound may be considered in premenopausal women to evaluate gynecological causes, the patient's left-sided pain makes diverticulitis more likely, which is better evaluated by CT
• The patient's negative pregnancy test is important as it eliminates ectopic pregnancy from consideration
• Normal WBC counts should not provide false reassurance when symptoms and physical findings suggest serious pathology

By obtaining a CT scan as the initial management step, you can accurately diagnose the cause of the patient's symptoms and guide appropriate treatment, potentially avoiding missed diagnoses and complications.