Figure 4-4. Injection sites for regional anesthetics.
(1) Paracervical block. Paracervical block (see figures. 4-4 and 4-5) is an
injection of a dilute local anesthetic into the paracervical nerve endings through the
vagina. There is relief within five minutes after administration and is good for about 45
to 60 minutes. The patient doesn't feel the cervical pain related to the uterine
contractions. When the anesthetic is injected into the tissues lateral to the cervix, it is
picked up by the circulation, which quickly involves the uterus and placenta. When
overdosage occurs, the fetus may exhibit bradycardia because of the quinidine-like
effect of the anesthetic on the myocardium or quinidine due to a reduction in uterine
blood flow. In addition, CNS medullary depression may develop and the neonate may
show vascular collapse and apnea at delivery. These are potential complications and
continuous fetal monitoring is required.
(2) Pudendal block. Pudendal block (see figures. 4-4 and 4-6) is an
injection of local anesthetic on both sides of the vagina. It is administered just prior to
delivery. It numbs the perineal area, vulva, and the vagina. It is used frequently in labor
and delivery in combination with local anesthesia.