ANESTHETIC OPTIONS DURING LABOR
Intravenous Agents
This includes narcotics and sedatives, which are frequently given in the active phase of labor. Advantages include ease of administration and inexpensive cost. Disadvantages include neo-natal depression if given close to delivery. The neonate may need administration of naloxone to reverse the effect.
Paracervical Block
This is a mode of conduction anesthesia that involves bilateral transvaginal local anesthetic injection to block Frankenhauser’s ganglion lateral to the cervix. It is administered in the active phase of labor. Disadvantages include temporary high levels of local anesthetic in the uterus which may lead to transitory fetal bradycardia, which is managed conservatively.
Pudendal Block
This is a mode of conduction anesthesia that involves bilateral transvaginal local anesthetic injec-tion to block the pudendal nerve as it passes by the ischial spines. It is administered in stage 2 of labor to provide perineal anesthesia.
S2 OB-GYN.indb 123
OB Triad
Paracervical Block Effect
• Term pregnancy in active labor
• Local anesthetic injection into cervix
• Immediate fetal bradycardia
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USMLE Step 2 l Obstetrics/Gynecology
OB Triad
Epidural Block Side Effect
• Pregnancy in active labor
• Conduction anesthesia given
• ½ body numb; ½ body pain
OB Triad
High Spinal (Intrathecal)
• Pregnancy in active labor
• Conduction anesthesia given
• Patient stops breathing
Epidural Block
This is a mode of conduction anesthesia that involves injection of local anesthetic into the epidural space to block the lumbosacral nerve roots during both stages 1 and 2 of labor. Advantages include use for either vaginal delivery or cesarean section. Disadvantages include patchy block from non-uniform spread of the local anesthetic around the nerve roots. Complications include hypoten-sion from peripheral vascular dilation owing to sympathetic blockade and spinal headache from inadvertent dural puncture, as well as CNS bleeding or infection (rare). Hypotension is treated with IV fluids and IV ephedrine. Spinal headache is treated with IV hydration, caffeine, or blood patch.
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Spinal Block
This is a mode of conduction anesthesia that involves injection of local anesthetic into the sub-arachnoid space to block the lumbosacral nerve roots. It is used as a saddle block for stage 2 of labor and for cesarean delivery. Advantages are complete predictable anesthesia. Complications include hypotension from peripheral vascular dilation because of sympathetic blockade (common) and spinal headache (rare), as well as CNS bleeding or infection (rare).
| T10 | ||
| T11 | Spinal cord | |
| T12 |
L1
L2
| L4 | Needle in subarachoid space | |
| L5 | Needle in epidural space | |
Needle for pudendal block
S2
S4
Epidural needle
Catheter 
Ligamentum flavium 
Subarachoid space 
Dura mater
Figure I-15-1. Anesthetic Options During Labor
General Anesthesia
This is seldom used for vaginal delivery and rarely for cesarean section. Indications include need for rapid emergency delivery, maternal medical conditions in which conduction anes-thesia is unsafe (e.g., blood dyscrasia, thrombocytopenia). Complications include aspiration pneumonia, atelectasis, and uterine atony (associated with inhalation agents, e.g., halothane, enflurane).
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Intrapartum Fetal Monitoring 16
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