What is the differential diagnosis for a 20-year-old female with hip and low back pain, radiating to the anterior right hip, with associated nausea, fatigue, and stress, and negative appendicitis tests, normal range of motion (ROM), and normal vital signs, including a normal total cholesterol level of hypercholesterolemia?

Differential Diagnosis

Based on the clinical presentation with a positive Yeoman's test, negative other SI joint provocation tests, and constitutional symptoms in a young female with stress and menstrual history, the primary differential includes sacroiliac joint dysfunction, endometriosis, and functional/stress-related pain amplification, with endometriosis being a critical consideration given the demographic and symptom pattern.

Primary Diagnostic Considerations

Sacroiliac Joint Dysfunction

• The positive Yeoman's test suggests possible SI joint involvement, though the diagnosis typically requires at least 3 out of 6 provocation tests to be positive for reliable diagnosis 1, 2.
• In this case, only one provocation test is positive, which significantly reduces the likelihood of classic SI joint dysfunction 1.
• The FABER test, which was negative in this patient, shows the highest positivity (91.4%) in confirmed SI joint dysfunction cases 1.
• The lack of pain on palpation and normal ROM further argue against typical SI joint pathology 2.

Endometriosis

• This is a critical diagnosis to consider in a 20-year-old female with low back and anterior hip pain, nausea, fatigue, and appetite changes 3.
• Endometriosis commonly presents with lumbopelvic pain that mimics musculoskeletal disorders and is frequently misdiagnosed 3.
• Key red flags in this case include:
  • Young fertile female demographic 3
  • Pain radiating to anterior hip and groin region 3, 4
  • Constitutional symptoms (nausea, fatigue, appetite changes) 3
  • Pain that changes with position but doesn't respond to NSAIDs 3
  • Regular menses (endometriosis can occur with regular cycles) 3
• Referral to gynecology for evaluation is warranted, as laparoscopy may be needed for definitive diagnosis 3.

Functional Pain Syndrome/Stress-Related Pain Amplification

• The patient's high-stress job that she "hates," combined with fatigue, nausea, and appetite changes, suggests possible stress-related pain amplification.
• The constant pain with waxing and waning intensity, lack of objective findings on examination, and failure to respond to typical analgesics support this consideration.
• However, this should be a diagnosis of exclusion after ruling out organic pathology, particularly endometriosis.

Secondary Considerations

Early Inflammatory Arthropathy

• While less likely given normal vitals and age, early seronegative spondyloarthropathy can present with SI joint region pain in young adults 4.
• The lack of morning stiffness pattern and single positive provocation test make this less probable.

Musculoskeletal Strain

• The negative physical examination findings, normal ROM, and lack of response to NSAIDs argue strongly against simple musculoskeletal strain.
• The two-week duration with worsening symptoms and constitutional features elevate concern beyond mechanical causes.

Recommended Diagnostic Approach

Immediate next steps:

• Gynecological referral for endometriosis evaluation, including pelvic ultrasound and consideration of laparoscopy if clinical suspicion remains high 3.
• Inflammatory markers (ESR, CRP) to evaluate for inflammatory arthropathy.
• Consider pelvic MRI if gynecological evaluation is inconclusive but suspicion for endometriosis remains 3.

If initial workup is negative:

• Reassess for functional pain syndrome in context of occupational stress.
• Consider trial of SI joint block only if additional provocation tests become positive, as diagnostic accuracy requires multiple positive tests 1, 2, 5.

Critical Pitfall to Avoid

Do not dismiss this as simple musculoskeletal pain or SI joint dysfunction based on a single positive provocation test 1, 5. The combination of constitutional symptoms, young female demographic, and anterior hip/groin radiation pattern mandates evaluation for endometriosis before concluding this is a benign musculoskeletal condition 3.