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

Evaluation and Management of Right Lower Quadrant Abdominal Pain

Initial Diagnostic Imaging

CT abdomen and pelvis with IV contrast is the imaging study of choice for evaluating right lower quadrant (RLQ) pain, achieving 95% sensitivity and 94% specificity for appendicitis while identifying alternative diagnoses in approximately 50% of cases. 1

Why CT is Superior

• CT has become the dominant modality, with utilization increasing from 7.2% to 83.3% between 1997-2016 for suspected appendicitis, reducing negative appendectomy rates from 16.7% (clinical evaluation alone) to 1.7-7.7% with preoperative imaging 2, 1
• IV contrast alone is sufficient—do not delay imaging for oral contrast administration, as IV contrast provides equivalent diagnostic accuracy without treatment delays 1
• Whole abdomen/pelvis imaging is mandatory—limiting CT to pelvis only misses 7% of surgical pathology located in the abdomen 1

Alternative Imaging: When Ultrasound May Be Considered

• Ultrasound has limited utility as the initial study for general RLQ pain, with sensitivity of 71.4-87.1% and specificity of 78.5-89.2% for appendicitis 2, 1
• Appendix non-visualization is common (27.7-45% of cases), significantly limiting diagnostic accuracy 2
• Reserve ultrasound for specific populations where radiation is a concern: pregnant patients and children 1
• Radiologist interpretation is superior to emergency physician interpretation (59.2% vs 33.3% detection rate, P=0.001) 2

Clinical Assessment Before Imaging

Essential Pre-Imaging Steps

• Obtain beta-hCG in all women of reproductive age before imaging to exclude pregnancy and guide imaging choices 1
• Document pain characteristics: onset, migration pattern (periumbilical to RLQ suggests appendicitis), associated symptoms (nausea, vomiting, anorexia), and presence of peritoneal signs 1, 3
• Check vital signs: fever >38°C, though not always present in early appendicitis 3

Key Physical Examination Findings

• Right lower quadrant tenderness at McBurney's point is the most reliable finding 3
• Rebound tenderness (pain worsening when pressure suddenly released) indicates peritoneal inflammation 3
• Involuntary guarding (muscle rigidity) in the RLQ suggests peritoneal involvement 3
• Do not rely on a single finding—combining multiple examination findings with laboratory tests increases diagnostic accuracy 3

Laboratory Tests

• White blood cell count with differential and C-reactive protein should be obtained, though normal values do not exclude appendicitis 3
• Leukocytosis with fever increases likelihood of appendicitis but is present in only ~50% of classic presentations 2

Differential Diagnosis Beyond Appendicitis

Approximately 50% of patients with RLQ pain have non-appendiceal diagnoses requiring different management. 1

Common Alternative Diagnoses Detected by CT

• Right colonic diverticulitis (cecal diverticulitis mimics appendicitis clinically) 1, 4
• Bowel obstruction (adhesive small bowel obstruction has 85% sensitivity with history of prior abdominal surgery) 2
• Inflammatory bowel disease (Crohn's disease affecting terminal ileum) 1, 4
• Gynecologic conditions in women: ovarian torsion, tubo-ovarian abscess, ruptured ovarian cyst 1
• Ureteral stones causing referred pain 1
• Epiploic appendagitis and omental infarction 4
• Infectious colitis including typhlitis in immunocompromised patients 5

Clinical Significance

• 41% of patients with non-appendiceal CT diagnoses require hospitalization 1
• 22% undergo surgical or image-guided intervention for alternative diagnoses 1

Management Algorithm Based on Clinical Presentation

High-Risk Presentation: Fever, Leukocytosis, Peritoneal Signs

1. Immediate CT abdomen/pelvis with IV contrast 2, 1
2. If appendicitis confirmed: surgical consultation and antimicrobial therapy 6
3. If perforated appendicitis with abscess >3cm: percutaneous catheter drainage followed by delayed surgery OR drainage only with antibiotics 2

Intermediate-Risk Presentation: RLQ Pain Without Fever/Peritoneal Signs

1. Proceed with CT imaging for stable patients with mild-to-moderate symptoms 6
2. Maintain hydration while awaiting imaging 6
3. Mild pain control, avoiding opioids which can mask symptoms 6

Low-Risk Presentation: Minimal Symptoms, No Fever, Preserved Appetite

1. Discharge with mandatory 24-hour follow-up and clear return precautions 6
2. Do not reflexively order CT—clinical scoring systems (Alvarado, AIR score, Adult Appendicitis Score) should guide imaging decisions 6, 3
3. If symptoms persist or worsen at follow-up, proceed to imaging 6

Special Population Considerations

Pregnant Patients

• Physical examination may be less reliable due to anatomical changes, but right-sided abdominal pain remains consistent 3
• Ultrasound is first-line, but do not hesitate to 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 3
• Lower threshold for CT imaging given atypical presentations 3

Obese Patients

• Physical examination findings are less reliable with higher false-negative and false-positive rates 3
• CT is particularly valuable in this population 3

Immunocompromised Patients

• Consider typhlitis (neutropenic enterocolitis) in patients with AIDS or chemotherapy 5
• Contrast-enhanced CT is mandatory to differentiate from other intra-abdominal pathologies 5

Critical Pitfalls to Avoid

• Do not assume appendicitis is the only diagnosis—maintain broad differential given 50% alternative diagnosis rate 1
• Do not delay CT for oral contrast in suspected appendicitis—IV contrast alone is sufficient 1
• Do not discharge patients without clear return precautions and 24-hour follow-up plan 6
• Do not overlook atypical presentations in elderly, pregnant, or obese patients 3
• Do not order plain radiography—it has minimal diagnostic value 1