What is the initial workup for a patient presenting with lower abdominal pain?

Initial Workup for Lower Abdominal Pain

The initial workup for a patient presenting with lower abdominal pain should include targeted laboratory testing and imaging based on pain location, with ultrasonography recommended for right-sided pain and CT with contrast recommended for left lower quadrant or nonlocalized pain. 1, 2

Clinical Assessment

• Determine the exact location of pain as this guides both diagnosis and appropriate imaging selection 2
• Evaluate for alarm signs including severe pain, sudden onset, high fever, abdominal distension, or rebound tenderness which may indicate serious pathology requiring urgent intervention 2
• Check vital signs to detect fever, tachycardia, hypotension, or tachypnea that may indicate infection, bleeding, or other complications 2

Essential Laboratory Tests

• Complete blood count to evaluate for leukocytosis, which may suggest infection or inflammation 2
• Beta-hCG test in all women of childbearing age before proceeding with imaging to rule out pregnancy-related conditions 2
• Note that CRP and WBC count alone are insufficient to definitively discriminate between urgent and non-urgent diagnoses 3

Imaging Selection by Pain Location

Right Lower Quadrant Pain

• Ultrasonography is the most appropriate initial imaging method 1, 2
• Consider CT with contrast if ultrasonography is inconclusive or if appendicitis is strongly suspected 1, 2

Left Lower Quadrant Pain

• CT with contrast is the recommended initial imaging test 1
• Particularly useful for suspected diverticulitis, which is the most common cause of left lower quadrant pain in adults 1

Nonlocalized Abdominal Pain

• CT with contrast is the optimal initial imaging choice, especially if fever or serious pathology is suspected 1, 2
• CT has been shown to change the leading diagnosis in 49% of patients and alter management plans in 42% of patients with nontraumatic abdominal pain 1

Right Upper Quadrant Pain

• Ultrasonography is the recommended initial imaging test 1, 2
• Cholescintigraphy may follow if ultrasound findings suggest gallbladder disease 1

Special Populations

• In premenopausal women, consider transvaginal ultrasound if gynecologic pathology is suspected 1, 2
• In elderly patients, be aware that symptoms may be atypical and require more thorough evaluation even with normal laboratory tests 2

Radiation Considerations

• Avoid unnecessary CT scans, especially in younger patients, to minimize radiation exposure 2
• Consider unenhanced CT for suspected urolithiasis, which has sensitivity and specificity near 100% 1
• Conventional radiography has limited diagnostic value for abdominal pain and rarely changes patient treatment 1

Common Pitfalls to Avoid

• Relying solely on clinical assessment without appropriate imaging when serious pathology is suspected 3
• Failing to consider gynecologic causes in women of childbearing age 2
• Delaying antibiotic treatment in patients with signs of sepsis (should be started within the first hour) 3
• Withholding pain medication due to concerns about masking physical examination findings (opioids do not affect diagnostic accuracy) 3