A 52-year-old man with acute severe low back pain now reports bilateral leg pain, numbness around the perineum and inner thighs, and inability to pass urine since morning despite a full bladder sensation. What is the immediate next step?
- A Nerve conduction studies of both lower limbs
- B Urgent MRI of the lumbosacral spine ✓
- C Analgesics and review after six weeks of physiotherapy
- D CT urogram to exclude renal colic
Correct answer: B. Urgent MRI of the lumbosacral spine
Explanation
Saddle anesthesia with bilateral sciatica and urinary retention indicates cauda equina syndrome, usually from a massive central disc prolapse. It is a surgical emergency requiring urgent MRI and decompression within 48 hours to preserve sphincter and sexual function. Delaying with conservative care risks permanent bladder and bowel paralysis, and nerve conduction studies add nothing once retention is established clinically.
Reference: Bailey and Love's Short Practice of Surgery, 27th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.