Early Diagnosis of Postpartum Obturator Neuropathy with Magnetic Resonance Imaging

Early recognition of postpartum nerve injury is critical for timely intervention and recovery. However, diagnosis is challenging because deficits may mimic residual epidural anesthesia, nerve root injury, or epidural hematoma. Anesthesiologists, often first consulted, are pivotal in early evaluation and diagnosis. Figure 1 shows fat-suppressed T2-weighted pelvic magnetic resonance imaging obtained on postpartum day 7 from a 35-yr-old primiparous woman who reported difficulty lifting her right leg 1 day after vaginal delivery of a 2,670-g infant at 37 + 6 weeks under uneventful epidural labor analgesia (first stage, 12 h; second stage, 1.5 h with mediolateral episiotomy). This image demonstrates T2 hyperintensity in the right pectineus with normal contralateral signal—findings consistent with acute denervation edema and early peripheral neuropathy. Focused examination on postpartum day 1 revealed right hip flexion weakness (3/5) and unexpected adduction weakness (3/5), impairing leg crossing. Reflexes and sensation, including assessment of the obturator nerve’s medial thigh territory, were intact (Supplemental Digital Content fig. S1, https://links.lww.com/ALN/E356). Given that the pectineus may receive obturator nerve innervation, the imaging findings aligned with the adduction weakness and raised suspicion for obturator neuropathy, later confirmed by needle electromyography at 6 weeks, showing spontaneous activity in the right adductor magnus. With conservative management, hip flexion recovered from 4/5 at 1 week to 5/5 by 2 months, and adduction progressed from 4/5 at 1 month to full recovery by 3 months (Supplemental Digital Content video S1, https://links.lww.com/ALN/E357).Fig. 1.: Axial (A) and coronal (B) fat-suppressed T2-weighted fast spin echo pelvic magnetic resonance imaging obtained on postpartum day 7. Yellow arrows indicate increased T2 signal intensity in the right pectineus, with normal signal on the contralateral side (white arrows), consistent with early denervation changes.Electrodiagnostic testing is critical for evaluating peripheral nerve injury but limited within the first 1 to 2 weeks, as denervation signs typically appear 10 to 28 days after injury.1 In contrast, magnetic resonance imaging can detect muscle denervation as early as 24 h,2 is readily available, and visualizes surrounding structures to promptly exclude compressive lesions, making it a valuable tool for early diagnosis and management. Postpartum obturator neuropathy is rare, often due to fetal head or positional compression.3 Anesthesiologists should begin evaluation with a detailed peripartum history and a focused neurologic examination, carefully testing hip adduction, as subtle or compensated deficits may aid localization. Serial assessments clarify symptom evolution, guiding to the underlying cause. If deficits persist or worsen, then early magnetic resonance imaging is essential for differential diagnosis and timely rehabilitation. Competing Interests The authors declare no competing interests. Supplemental Digital Content Supplemental Figure 1. Schematic of medial thigh sensory innervation, https://links.lww.com/ALN/E356 Supplemental Video S1. Serial assessment of right lower limb function over the first 8 weeks postpartum, https://links.lww.com/ALN/E357