his block usually provides satisfactory pain relief during irst-stage labor. How ever, because the pudendal nerves are not blocked during paracervical blockade, addi
Ischial spine tional analgesia is required for delivery. For
Pudendal nerve paracervical blockade, usually 5 to 10 mL of lidocaine (1 to 2 percent) or chloroprocaine (3 percent) is injected into the cervix later ally at 3 and 9 o'clock. Because these anes thetics are relatively short acting, this block may have to be repeated during labor.
Fetal bradycardia is a worrisome com plication that occurs with approximately 15 percent of paracervical blocks (Rosen, FIGURE 25-2 Local infiltration of the pudendal nerve. Transvaginal technique showing 2002). Bradycardia usually develops within the needle extended beyond the needle guard and passing through the sacrospinous 10 minutes and may last up to 30 minutes.
ligament to reach the pudendal nerve.
protrude beyond its tip, and the needle is pushed beyond the introducer tip into the mucosa. A mucosal wheal is made with 1 mL of I-percent lidocaine solution or an equivalent dose of another local anesthetic (see Table 25-4). To guard against intravascular infusion, aspiration is attempted before this and all subsequent injections. The needle is then advanced until it touches the sacrospinous ligament, which is iniltrated with 3 mL of lidocaine. he needle is advanced farther through the ligament. As the needle pierces the loose areolar tissue behind the ligament, resistance against the plunger drops. Another 3 mL of solution is injected in this region. Next, the needle is withdrawn into the introducer, which is moved to a point just above the ischial spine. The needle is inserted through the mucosa and a inal 3 mL is deposited. The procedure is then repeated on the other side.
Within 3 to 4 minutes of injection, a successful pudendal block will allow pinching of the lower vagina and posterior vulva bilaterally without pain. If delivery occurs before the pudendal block becomes efective and an episiotomy is indicated, then the fourchette, perineum, and adjacent vagina can be iniltrated with 5 to 10 mL of I-percent lidocaine solution directly at the planned episiotomy site. By the time of repair, the pudendal block usually has become efective.
Pudendal block usually does not provide adequate analgesia when delivery requires extensive obstetrical manipulation. Moreover, such analgesia is usually inadequate for women in whom complete visualization of the cervix and upper vagina or manual exploration of the uterine cavity is indicated.
Infrequently, complications may follow this block. As previously described, intravascular injection of a local anesthetic agent may cause serious systemic toxicity. Hematoma formation from perforation of a blood vessel is most likely when there is a coagulopathy (Lee, 2004). Rarely, severe infection may originate Doppler studies have shown a rise in the pulsatility index of the uterine arteries following paracervical blockade. These observations support the hypothesis of drug-induced arterial vasospasm as a cause of fetal bradycardia (Manninen, 2000). For these reasons, paracervical block is not used in situations of potential fetal compromise.
Epidural, spinal, or combined spinal-epidural techniques are the most common methods used for pain relief during labor and delivery. In the United States in 2008, epidural analgesia was used in nearly 70 percent of mothers during labor and had a success rate of 98.8 percent. Neuraxial analgesia was used even more often in operative vaginal deliveries and supported 84 percent of forceps deliveries and 77 percent of vacuum extractions (Osterman, 2011).