During a pudendal nerve block performed for perineal analgesia in labor, the needle is directed toward which bony landmark using the transvaginal approach?

• A Ischial tuberosity in the gluteal region
• B Pubic symphysis for bilateral blockade
• C Sacral foramina S2–S4 for proximal pudendal nerve blockade
• D Ischial spine, with the pudendal nerve passing medial to the sacrospinous ligament at this point ✓

Explanation

The pudendal nerve (S2–S4) exits the greater sciatic foramen below the piriformis, crosses the ischial spine, and passes medial to the sacrospinous ligament to re-enter the perineum via the lesser sciatic foramen into the pudendal (Alcock's) canal. For a transvaginal pudendal nerve block, the guiding finger palpates the ischial spine transvaginally and the needle is directed just medial and posterior to the ischial spine, where the nerve is accessible as it crosses the sacrospinous ligament. This provides analgesia to the perineum, vulva, and lower vagina.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.