Diagnostic Approach to Right Lower Quadrant Pain with Thigh Weakness
Clinical Presentation and Differential Diagnosis
- The American College of Radiology suggests that right lower quadrant pain combined with right thigh weakness requires urgent evaluation for psoas abscess or retroperitoneal pathology, as this combination of symptoms suggests iliopsoas muscle involvement rather than typical intra-abdominal pathology like appendicitis 1
- Psoas muscle involvement can cause hip flexion weakness and pain with hip extension, and retroperitoneal pathology can affect the lumbar plexus (L2-L4 nerve roots), according to the American College of Radiology 1
- Possible femoral neuropathy from compression or inflammation can also occur, as noted by the American College of Radiology, although this specific point is also mentioned in Praxis Medical Insights, the ACR guideline is preferred 1
Diagnostic Imaging
- The American College of Radiology recommends contrast-enhanced CT of the abdomen and pelvis with IV contrast as the imaging modality of choice for this presentation, with sensitivities ranging from 85.7% to 100% and specificities from 94.8% to 100% for acute abdominal pathology 3, 4
- CT can identify retroperitoneal collections, psoas abscesses, and alternative diagnoses beyond appendicitis, according to the American College of Radiology 5
Management
- The American College of Radiology suggests that if psoas or retroperitoneal abscess is identified, broad-spectrum antibiotics should be initiated immediately, and percutaneous catheter drainage (PCD) is usually appropriate for collections >3 cm 1
- For appendicitis confirmed, the American College of Radiology recommends proceeding to appendectomy as standard treatment, and for perforated appendicitis with abscess, PCD followed by delayed surgery or PCD only is usually appropriate 4, 1