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INTRODUCTION

KEY QUESTIONS

  • When should one consider a pudendal block as opposed to, or as an adjunct to, alternative pain or anesthetic options?

  • What considerations should be made surrounding complications that may arise after pudendal block placement?

  • What are the anatomical structures that the pudendal block innervates?

  • What are the key steps to the procedure?

CASE 69-1

A 30-y.o. G2P1 presents at 39 3/7 weeks gestation in active labor. Initial cervical exam shows her to be 8 cm dilated. She rapidly progresses to complete. She reflexively starts pushing in an uncoordinated manner due to severe pain. She strongly desires pain control and relief as she cries in pain. FHR tracing at this time is notable for deeply variable decelerations. The recommendation is made for an urgent assisted vaginal delivery.

Pudendal nerve blocks are an efficient and easy mode of peripheral analgesia that can be used for a variety of obstetric and gynecologic procedures. It was first introduced in 1908 by Mueller, who injected a local anesthetic directly into the perineum, vulvar, and perianal fossa.1 King described the technique in more detail in 1916 in a trial of 100 patients undergoing spontaneous delivery and perineal repair.1,2 However, the technique did not become popular or widely used until 1953, after development of the modified technique by Klink and Kohl, with the focus shifting to targeting specific nerve branches.3

The classical method of pudendal block involved a transperineal approach with local infiltration. This was best described by Gate and Dutton (1955). The technique that we use today, with a transvaginal approach, was first described in 1956 by Kobak, Evans, and Johnson.1 This technique dispensed with the original local infiltration of anesthetic, evolving to a true peripheral nerve block and targeting of the pudendal nerve.

Pudendal nerve blocks are still used for certain obstetric and gynecologic indications, but they have been displaced by an increase in the use of neuraxial anesthesia (such as epidurals or spinals), especially in the context of treatment for pain in the second stage of labor. However, many would argue that it is important for practitioners to remain competent in this method of anesthesia, especially for urgent or emergent deliveries when quick pain control and analgesia are indicated.

ANATOMY AND PHYSIOLOGY

A pudendal nerve block provides anesthesia to the lower vagina, vulva, and surrounding tissues, with some relaxation of the pelvic floor (Fig. 69-1).

FIGURE 69-1.

Pudendal nerve and vessels. (Reproduced with permission from Hoffman BL, Schorge JO, Bradshaw KD, et al: Williams Gynecology, 3rd ed. New York, NY: McGraw-Hill; 2016.)

The goal of this particular nerve block is to target the pudendal nerve distal to its formation by the anterior divisions of the S2–S4 ...

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