What diagnostic exams are recommended for patients presenting with right lower quadrant (RLQ) abdominal pain?

Diagnostic Imaging for Right Lower Quadrant Abdominal Pain

Primary Recommendation

CT of the abdomen and pelvis with contrast is the initial imaging study of choice for evaluating patients presenting with right lower quadrant (RLQ) abdominal pain. 1

Clinical Context and Imaging Selection

The approach to RLQ pain depends on whether appendicitis is the primary clinical concern or if the presentation is nonspecific with multiple diagnostic possibilities:

For Nonspecific RLQ Pain (Appendicitis Not Primary Concern)

• CT abdomen and pelvis with contrast is the preferred initial study because it has high diagnostic yield for both appendicitis (sensitivity 95%, specificity 94%) and alternative diagnoses 1
• CT identifies the cause of RLQ pain in the majority of cases, with 94.3% concordance between CT diagnosis and final clinical diagnosis for non-appendiceal conditions 1
• Common alternative diagnoses detected include right colonic diverticulitis (8%), bowel obstruction (3%), benign adnexal masses, gastroenteritis, colitis, inflammatory bowel disease, and ureteral stones 1
• Among patients with non-appendiceal CT diagnoses, 41% require hospitalization and 22% undergo surgical or image-guided intervention, demonstrating the clinical impact of accurate diagnosis 1

For Suspected Appendicitis (Fever, Leukocytosis, Classic Presentation)

• CT abdomen and pelvis with contrast remains the gold standard, with negative appendectomy rates dropping from 16.7% with clinical evaluation alone to 8.7% with preoperative CT 1
• CT use for appendicitis diagnosis increased from 7.2% in 1997 to 83.3% in 2016, reflecting its established role 1
• Contrast-enhanced CT without oral contrast achieves sensitivity of 90-100% and specificity of 94.8-100%, avoiding delays associated with oral contrast administration 1

Critical Imaging Considerations

CT Protocol Specifics

• Both abdomen AND pelvis must be included in the CT examination 2
• Scanning only the pelvis (focused appendiceal CT) decreases overall sensitivity from 99% to 88% and misses 7% of patients with abnormalities outside the pelvis requiring surgery 2
• Contrast-enhanced CT with intravenous contrast (without oral contrast) is preferred to avoid treatment delays while maintaining diagnostic accuracy 1

Alternative Imaging Modalities

Ultrasonography has limited utility as the initial study for general RLQ pain:

• Average sensitivity of 87.1% and specificity of 89.2% for appendicitis 3
• Should be reserved for specific populations where radiation is a concern (pregnant patients, children) 1, 4, 5
• May miss non-appendiceal pathology that CT would detect 1

Plain radiography has minimal diagnostic value and should not be routinely obtained 1

MRI may be appropriate when CT is contraindicated but is not a first-line study 4

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 including onset, migration pattern, associated symptoms (fever, nausea, vomiting), and presence of peritoneal signs 1
• Check for leukocytosis and perform urinalysis to help stratify likelihood of appendicitis versus other diagnoses 3

Common Pitfalls to Avoid

• Do not limit CT to pelvis only - this misses 7% of surgical pathology located in the abdomen 2
• Do not delay CT for oral contrast administration in suspected appendicitis, as IV contrast alone provides equivalent diagnostic accuracy 1
• Do not assume appendicitis is the only diagnosis - approximately 50% of RLQ pain patients have alternative diagnoses requiring different management 1
• Do not rely on ultrasound as the primary modality in adults with nonspecific RLQ pain, as it has lower sensitivity and may miss critical alternative diagnoses 1, 3

Special Population Considerations

For pregnant patients or children where radiation exposure is a primary concern, ultrasound may be considered first-line, but CT should not be withheld if ultrasound is nondiagnostic and clinical suspicion remains high 1, 5