Chapter 62. Anesthesia for Obstetric Care and Gynecologic Surgery

Lawrence C. Tsen

The use of epidural, spinal, combined spinal–epidural, and dural-puncture epidural techniques for obstetric care has increased dramatically because of the quality and safety of the analgesia and anesthesia produced, the ability to titrate the degree and duration of pain relief, and the expanding number of situations for which their use is appropriate.
Labor analgesia and obstetric anesthesia can have beneficial effects on the outcomes of external cephalic version, in utero fetal and placental surgery, and parturients with significant comorbid conditions.
Major fetal organogenesis occurs during weeks 3 to 10 of gestation. Teratogenicity is difficult to evaluate in prospective clinical trials because of the low incidence of occurrence and the number of confounding factors, but the list of proven human teratogens does not include the anesthetics commonly used in clinical practice.
Although important reductions in anesthesia-related maternal mortality have occurred in the past 5 decades, a greater risk (1.7 times) of maternal death is still witnessed with the use of general versus regional anesthesia. This finding can be partially explained by changes in the airway that occur over the course of pregnancy. Promotion of neuraxial techniques, skill with alternate airway devices, and review of difficult airway algorithms are strongly encouraged.
Antenatal and postpartum maternal hemorrhage can be masked until significant blood loss has occurred, but a cogent plan for diagnosis and response can significantly affect the outcome. Interventional radiologists may place occlusion balloons within the uterine or hypogastric arteries in high-risk parturients to allow timely control of bleeding.
Preeclampsia is a multisystem disease that raises numerous concerns for anesthesia care, but neuraxial techniques remain the preferred option unless contraindicated by coagulations disorders, severe hypovolemia, or patient preference.
Anesthetic care for gynecologic surgery requires an understanding of gender-related differences in physiology, including sensitivity to pain, and pharmacodynamics, including responses to anesthetic drugs; such differences ultimately may affect patient outcomes and satisfaction.
Both obstetric and gynecologic surgery involve positions, techniques, and organ systems that require special vigilance. The uterus and other female viscera are highly vascular. Blood loss can be sudden and profuse; air emboli can occur unexpectedly (especially in the Trendelenburg position); and in pregnancy-related procedures, amniotic fluid emboli can occur without provocation.
Hysteroscopic and laparoscopic procedures can result in significant adverse outcomes from absorption of carbon dioxide (CO2) or the distending medium. CO2 insufflation of the abdomen or pelvis may cause a number of disturbances in cardiac and respiratory physiology, which can be minimized if anticipated.
The Trendelenburg lithotomy position, which is commonly used for gynecologic procedures, may lead to a number of peripheral nerve injuries. Excessive hip flexion, abduction, and external rotation may cause femoral nerve, obturator, lateral femoral cutaneous, sciatic, and peroneal nerve injuries. Attention to positioning throughout the procedure, use of protective padding, and avoidance of contact with hard surfaces or supports are important elements of optimal care.