Paracervical blocks are waning in popularity as they have been found to cause fetal bradycardia (which is associated with increased neonatal morbidity and mortality). Usually, paracervical block-induced bradycardia lasts < 15 minutes and is treated with lateral positioning and administration of oxygen. Regardless, paracervical blocks should be avoided in all patients with suspected uteroplacental insufficiency. The block is performed by injecting local anesthetic (usually chloroprocaine, as it is quickly degraded) lateral and posterior to the uterocervical junction (waiting 5 minutes between sides), and usually only lasts 45-60 minutes.
Normally performed by obstetricians who inject transvaginally, aiming for the sacrospinous ligament medial and posterior to the ischial spine. When successful, the pudendal block is sufficient for an uncomplicated vaginal or instrumented delivery, but is limited by its high failure rate.
Perineal infiltration is accomplished by the obstetrician, normally to provide analgesia for an episiotomy and subsequent repair. Care should be taken to avoid the fetal scalp.