Should You Order Groin Ultrasound?
No, you should not order groin ultrasound as the next imaging study—instead, order MRI of the hip without IV contrast to evaluate for occult stress fracture, labral tear, or other structural hip pathology that is the most likely cause of persistent groin pain 3 months after a fall. 1
Why MRI Hip is the Correct Next Step
The Clinical Picture Points to Hip Pathology, Not Hernia
Persistent groin pain after trauma with normal hip radiographs is a classic presentation for occult hip pathology, particularly stress fractures of the pelvis/hip or labral tears that are radiographically occult. 1
The ACR Appropriateness Criteria rate MRI hip without IV contrast as 9/9 (usually appropriate) for suspected stress fracture with negative radiographs, making it the gold standard next imaging study. 1
Hip pathology commonly refers pain to the groin, and the absence of a palpable hernia on examination makes an occult inguinal hernia far less likely than structural hip disease in this trauma context. 1, 2
Why Ultrasound is Inappropriate Here
The ACR Appropriateness Criteria explicitly rate ultrasound of the hip/pelvis as 1/9 (usually not appropriate) for suspected stress fracture with negative radiographs. 1
Ultrasound cannot detect stress fractures, bone marrow edema, labral tears, or intra-articular cartilage pathology—the most likely diagnoses given the mechanism (fall on hip) and timeline (3 months of persistent pain). 1
While ultrasound has 86% sensitivity for detecting occult inguinal hernias 3, this patient has no clinical signs of hernia (no bulge, no palpable defect), and the trauma mechanism strongly suggests skeletal/intra-articular pathology rather than abdominal wall defect. 4, 5
The Diagnostic Algorithm for Post-Traumatic Groin Pain
Step 1: Recognize the Red Flags for Occult Hip Fracture
Pain persisting 3 months after direct hip trauma is abnormal and suggests either incomplete healing of an occult fracture or progressive intra-articular damage. 1
Normal hip radiographs do not exclude stress fractures or labral pathology—radiographs have low sensitivity for these conditions, particularly in the early weeks after injury. 1
Groin pain with certain movements suggests mechanical hip pathology (labral tear, femoroacetabular impingement, or cartilage injury) rather than hernia, which typically causes pain with Valsalva or standing. 1
Step 2: Order MRI Hip Without IV Contrast
MRI detects stress fractures within hours of injury via bone marrow edema, even when the fracture line itself is not yet visible. 1
MRI is rated 9/9 for chronic hip pain with negative radiographs when suspecting extra-articular soft tissue abnormality (tendonitis) or intra-articular pathology (labral tear). 1
MRI will also identify alternative diagnoses including avascular necrosis, occult femoral neck fracture, iliopsoas tendonitis, or adductor muscle injury—all of which can cause groin pain after trauma. 1, 2, 6
Step 3: Consider Diagnostic Hip Injection if MRI is Equivocal
If MRI shows mild findings or is inconclusive, image-guided intra-articular hip injection with anesthetic ± corticosteroid (rated 5/9, may be appropriate) can confirm whether the hip joint is the pain source. 1, 2
Complete pain relief after injection confirms intra-articular hip pathology as the cause, even if imaging findings are subtle. 1, 2
Why the Patient's Hernia Concern is Likely Wrong
Clinical Examination Trumps Patient Self-Diagnosis
The absence of a palpable hernia on examination makes occult inguinal hernia unlikely—most hernias are detectable clinically, and imaging is reserved for equivocal cases. 3, 4
When both clinical examination and ultrasound are negative for hernia, only 5.1% of patients ultimately require surgery, suggesting that negative clinical findings are highly predictive. 4
In patients with ultrasound-detected hernias but no clinical hernia, 54.1% have spontaneous pain resolution within 2 months, and 39.6% ultimately receive an alternative musculoskeletal diagnosis. 5
The Mechanism Doesn't Fit Hernia
Hernias develop from chronic increased intra-abdominal pressure or congenital weakness—not from acute trauma like falling on the hip. 3, 5
Pain "with certain movements" is more consistent with mechanical hip pathology (labral tear, impingement) than hernia, which typically causes pain with coughing, straining, or prolonged standing. 1
Common Pitfalls to Avoid
Don't Let 3 Months of Chiropractic Care Delay Definitive Diagnosis
Persistent pain after 3 months of conservative care warrants structural imaging—this timeline suggests either missed diagnosis or progressive pathology requiring different management. 1, 2
Chiropractic manipulation cannot address stress fractures, labral tears, or cartilage damage, and continued manipulation without imaging risks worsening an underlying structural problem. 1
Don't Order Ultrasound Just Because the Patient Requests It
Imaging should be guided by clinical likelihood and diagnostic accuracy, not patient preference. 1
Ordering the wrong imaging study delays diagnosis and may lead to false reassurance if negative, while the true pathology remains undetected. 1, 3
Don't Assume Normal Hip X-rays Rule Out Hip Pathology
Hip radiographs are insensitive for stress fractures, labral tears, and early cartilage damage—these require MRI for detection. 1
The ACR guidelines emphasize that diagnosis should never be made on imaging alone, but in this case, the clinical presentation (trauma + persistent groin pain + normal X-ray) strongly indicates the need for advanced imaging. 1
What to Tell the Patient
Explain that her groin pain is most likely coming from the hip joint or surrounding bone/soft tissue, not from a hernia, given the mechanism of injury and examination findings. 1
MRI is the best test to identify the cause of her pain and will show whether there is a stress fracture, labral tear, tendon injury, or other structural problem that needs specific treatment. 1
If MRI shows significant pathology, she may need orthopedic referral for consideration of physical therapy, injections, or potentially surgery depending on the findings. 1, 6