The pudendal nerve leaves the pelvis through the greater sciatic foramen and re-enters via the lesser sciatic foramen to run in Alcock's canal. The pudendal nerve block for perineal analgesia is best performed at which landmark?

• A Medial to the greater sciatic foramen, above the piriformis
• B At the pubic symphysis
• C At the inferior margin of the sacrotuberous ligament posteriorly
• D Medial to the ischial spine, transvaginal or transperineal route ✓

Explanation

The pudendal nerve runs directly posterior and lateral to the ischial spine as it transitions from the greater to the lesser sciatic foramen and enters Alcock's canal (pudendal canal in the obturator internus fascia). The pudendal nerve block is performed by directing a needle transvaginally (or transperineally) to a point just medial and posterior to the ischial spine, where the nerve is most accessible and superficial. Local anaesthetic deposited here blocks all three branches (dorsal nerve of clitoris/penis, perineal nerve, and inferior rectal nerve), providing effective perineal analgesia for obstetric or perineal procedures.

Reference: BD Chaurasia's Human Anatomy, 8th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.