Imaging for Right Groin Pain Radiating to Medial Thigh
Start with plain radiographs of the pelvis and hip, followed by MRI pelvis/hip without contrast if radiographs are negative or equivocal. 1
Initial Imaging Approach
Obtain AP pelvis and lateral hip radiographs first in essentially all cases of chronic groin pain, as this provides excellent screening for common disorders like arthritis, stress fractures, and bone lesions, while guiding selection of subsequent imaging. 1
Radiographs may be sufficient for diagnosis in many cases and are essential for comparison with advanced imaging studies. 1
The clinical presentation of groin pain radiating medially suggests potential hip joint pathology, adductor tendon injury, pubic symphysis disorders, or referred pain from lumbar spine/nerve roots. 1
When Radiographs Are Negative or Equivocal
MRI pelvis/hip without IV contrast is the definitive next study, as it provides superior soft tissue contrast resolution and multiplanar capabilities to evaluate all potential pain sources. 1, 2
Why MRI Is Superior for This Presentation:
MRI achieves 91% sensitivity and 92% specificity for detecting occult groin abnormalities including hernias, tendon injuries, and muscle strains that are missed by other modalities. 3
MRI directly visualizes the adductor tendons (particularly adductor longus), iliopsoas tendon, rectus abdominis attachments, pubic symphysis, hip joint cartilage and labrum, and surrounding musculature—all potential sources of medial groin pain. 1, 2, 4
IV contrast is rarely needed for initial MRI evaluation of groin pain, as T2-weighted sequences adequately demonstrate most pathology including tendinopathy, muscle injuries, and bone marrow edema. 1
Specific Pathologies MRI Can Identify:
Adductor-related groin pain: The "superior cleft sign" (rectus abdominis-adductor longus attachment microtearing) is highly associated with chronic groin pain and predicts excellent response to targeted treatment. 5
Pubic symphysis disorders: Osteitis pubis, symphyseal instability, and secondary cleft sign (short adductor attachment injuries) are well-demonstrated on MRI. 5, 4
Occult inguinal hernias: MRI detects 91% of occult hernias missed on physical examination, whereas CT only detects 54% and ultrasound only 33%. 3
Hip joint pathology: Labral tears, femoroacetabular impingement, cartilage defects, and early arthritis that may refer pain medially. 1, 2
Iliopsoas pathology: Tendinopathy, bursitis, or snapping hip syndrome. 1, 4
Role of Other Modalities:
Ultrasound has limited utility for initial evaluation, with highly variable sensitivity (21-95.7%) depending on operator experience and patient body habitus, and cannot reliably exclude occult abnormalities. 1, 3
CT is inferior to MRI for soft tissue evaluation and should not be used as the primary modality for groin pain unless there is concern for acute fracture or when MRI is contraindicated. 1, 3
Consider lumbar spine MRI if clinical features suggest radiculopathy (L2-L4 nerve roots can refer pain to medial thigh), though lumbosacral plexus MRI may be needed if electrodiagnostic studies suggest plexopathy rather than radiculopathy. 1
Critical Pitfalls to Avoid:
Do not skip radiographs—they remain the essential first test despite being normal in many cases, as they guide subsequent imaging selection and provide baseline comparison. 1
Do not rely on ultrasound or CT to exclude pathology in groin pain with medial radiation, as both have unacceptably high false-negative rates for the spectrum of disorders causing this presentation. 3
Do not order MRI with contrast initially—it adds cost and time without improving diagnostic yield for most groin pain etiologies. 1
Recognize that clinical localization between radiculopathy and plexopathy can be challenging—if lumbar spine MRI is unrevealing but neurologic symptoms persist, consider dedicated lumbosacral plexus MRI. 1