gynecology and obstetrics
Management of Normal Delivery
Anesthesia
Options include regional, local, and general anesthesia. Local anesthetics and opioids are commonly used. These drugs pass through the placenta; thus, during the hour before delivery, such drugs should be given in small doses to avoid toxicity (eg, central nervous system [CNS] depression, bradycardia) in the neonate. Opioids used alone do not provide adequate analgesia and so are most often used with anesthetics. Several methods are available. Analgesia None Spinal injection(into the paraspinal subarachnoid space) may be used for cesarean delivery, but it is used less often for vaginal deliveries because it is short-lasting (preventing its use during labor) and has a small risk of spinal headache afterward. When spinal injection is used, patients must be constantly attended, and vital signs must be checked every 5 minutes to detect and treat possible hypotension. Methods include pudendal block, perineal infiltration, and paracervical block. Pudendal block,rarely used because epidural injections are typically used instead, involves injecting a local anesthetic through the vaginal wall so that the anesthetic bathes the pudendal nerve as it crosses the ischial spine. This block anesthetizes the lower vagina, perineum, and posterior vulva; the anterior vulva, innervated by lumbar dermatomes, is not anesthetized. Pudendal block is a safe, simple method for uncomplicated spontaneous vaginal deliveries if women wish to bear down and push or if labor is advanced and there is no time for epidural injection. Complications of pudendal block include intravascular injection of anesthetics, hematoma, and infection. Infiltration of the perineumwith an anesthetic is commonly used, although this method is not as effective as a well-administered pudendal block. 10% ( Anesthesia reference ). It is used mainly for 1st- or early 2nd-trimester abortion. The technique involves injecting 5 to 10 mL of 1% Because potent and volatile inhalation drugs (eg,isoflurane) can cause marked depression in the fetus, general anesthesia is not recommended for routine delivery. Rarely, nitrous oxide 40% with oxygen may be used for analgesia during vaginal delivery as long as verbal contact with the woman is maintained. Thiopental, a sedative-hypnotic, is commonly given IV with other drugs (eg,succinylcholine, nitrous oxide plus oxygen) for induction of general anesthesia during cesarean delivery; used alone, thiopental provides inadequate analgesia. With thiopental, induction is rapid and recovery is prompt. It becomes concentrated in the fetal liver, preventing levels from becoming high in the central nervous system (CNS); high levels in the CNS may cause neonatal depression. Epidural analgesia, which can be rapidly converted to epidural anesthesia, has reduced the need for general anesthesia except for cesarean delivery. 1.LeFevre ML: Fetal heart rate pattern and postparacervical fetal bradycardia.Obstet Gynecol64 (3):343–6, 1984. 