What are the evaluation and treatment options for right lower quadrant abdominal pain?

Right Lower Quadrant Abdominal Pain: Evaluation and Treatment

Immediate Imaging Strategy

Order CT abdomen and pelvis with IV contrast as your first-line imaging study for right lower quadrant pain—this achieves 95% sensitivity and 94% specificity for appendicitis while identifying alternative diagnoses in approximately 50% of cases. 1

• Use IV contrast alone without oral contrast, as IV contrast provides equivalent diagnostic accuracy without treatment delays 1
• Image the entire abdomen and pelvis, not just the pelvis—limiting CT to pelvis only misses 7% of surgical pathology located in the abdomen 1
• CT has reduced negative appendectomy rates from 16.7% to 1.7-7.7% when used preoperatively 1

When to Consider Alternative Imaging

Reserve ultrasound only for pregnant patients and children where radiation exposure is a primary concern—ultrasound has limited utility as the initial study for general RLQ pain with sensitivity of only 71.4-87.1% and specificity of 78.5-89.2%. 1, 2

• In reproductive-age females where gynecologic pathology is the primary concern, pelvic ultrasound is appropriate 3
• Ensure radiologist interpretation rather than emergency physician interpretation (59.2% vs 33.3% detection rate, P=0.001) 1
• MRI with diffusion-weighted imaging achieves 97-99% sensitivity and 100% specificity for appendicitis, but reserve this for pregnant patients or when radiation is contraindicated 2

Essential Pre-Imaging Clinical Assessment

Obtain beta-hCG in all women of reproductive age before imaging to exclude pregnancy and guide imaging choices. 1

Critical Physical Examination Findings to Document:

• Right lower quadrant tenderness at McBurney's point (most reliable finding) 1
• Rebound tenderness indicating peritoneal inflammation 1
• Involuntary guarding in the RLQ suggesting peritoneal involvement 1
• Pain migration pattern—classically from periumbilical to RLQ 1
• Fever >38°C, though absence does not exclude appendicitis 1

Laboratory Tests to Order:

• White blood cell count with differential and C-reactive protein, though normal values do not exclude appendicitis 1
• Leukocytosis with fever increases likelihood of appendicitis but is present in only ~50% of classic presentations 3, 1

Critical Management Algorithm

For High-Risk Presentations (fever, leukocytosis, peritoneal signs):

1. Immediate CT abdomen/pelvis with IV contrast 3, 1
2. If appendicitis confirmed: surgical consultation and antimicrobial therapy 1
3. If perforated appendicitis with abscess >3cm: percutaneous catheter drainage followed by delayed surgery or drainage with antibiotics only 1

For Presentations Without Leukocytosis:

Never rely on normal WBC alone to exclude appendicitis or other surgical pathology—CT imaging is mandatory. 2

• CT abdomen and pelvis with IV contrast remains first-line even without leukocytosis, as the "classic" presentation occurs in only 50% of patients 2
• CT identifies the cause of RLQ pain in the majority of cases, with 41% of non-appendiceal diagnoses requiring hospitalization and 22% requiring surgical or image-guided intervention 2

Differential Diagnosis Beyond Appendicitis

Maintain a broad differential diagnosis—approximately 50% of patients with RLQ pain have non-appendiceal diagnoses requiring different management. 1, 4

Common alternative diagnoses detected by CT include: 1, 2, 4

• Right colonic diverticulitis
• Bowel obstruction
• Inflammatory bowel disease
• Gynecologic conditions (ovarian torsion, ectopic pregnancy, tubo-ovarian abscess)
• Ureteral stones
• Epiploic appendagitis
• Mesenteric adenitis

Special Population Considerations

Pregnant Patients:

• Physical examination may be less reliable due to anatomical changes, but right-sided abdominal pain remains consistent 1
• Ultrasound is first-line, but proceed to MRI or low-dose CT if ultrasound is non-diagnostic 1

Elderly Patients:

• May present with less pronounced physical findings despite more advanced disease 1, 5
• Maintain a lower threshold for CT imaging 1

Obese Patients:

• Physical examination findings are less reliable 1
• CT is particularly valuable in this population 1

Immunocompromised Patients:

• Consider typhlitis (neutropenic enterocolitis) in the differential diagnosis 6
• Contrast-enhanced CT is mandatory to differentiate typhlitis from other intra-abdominal pathologies 6

Critical Pitfalls to Avoid

Do not assume appendicitis is the only diagnosis—CT changes management in 43% of patients initially suspected to have appendicitis clinically. 2

• Do not delay CT for oral contrast in suspected appendicitis—IV contrast alone is sufficient 1
• Do not order plain radiography as initial imaging—it has minimal diagnostic value except when concerned for perforation and free air 3
• Do not discharge patients without clear return precautions and 24-hour follow-up plan 1
• Do not overlook atypical presentations in elderly, pregnant, or obese patients 1