Ideally, a pregnant woman has a principal, designated health care provider. Beginning with admission to the labor and delivery area, the obstetric team monitors the patient’s progress. Once the patient is in active labor, her provider should be readily available.
Walking may be more comfortable than being supine dur-ing early labor. Women in early labor are confined to bed if they are too uncomfortable to move about safely or if care maneuvers require it.
Supine labor is common in the United States. The left lateral position keeps the uterus off the infe-rior vena cava; this obstructs venous return, thence cardiac output, leading to hypotension (supine hypotensive syn-drome). Thedorsal lithotomy positionis most commonly usedfor spontaneous and operative vaginal delivery in the United “birthing chairs,” on labor balls, or in variously configured tubs of warm water.
Because labor is associated with decreased gastrointestinal peristalsis, there is concern about aspiration during the administration of anesthesia. Patients in active labor should avoid oral ingestion of anything except clear fluids (sips only), occasional ice chips, and preparations for moisten-ing the mouth and lips.
When oral intake is not possible or is insufficient, intravenous therapy with 1⁄2 normal saline or D5 1⁄2 normal saline is indicated. Normal saline can be used if increased oncotic pressure is desired, but lactated fluids are gener-ally contraindicated because of the metabolic acid deficit incurred by the lactate administration.
Measurement of the fetal heart rate and its changes dur-ing labor is the primary means of intrapartum assessment of fetal well-being. This may be done by intermittent aus-cultation with a stethoscope or hand-held Doppler, or by the use of electronic fetal monitoring. The method chosen may depend on risk assessment at admission, the prefer-ence of the patient and the obstetric staff, and department policy. Risk factors include vaginal bleeding, acute abdom-inal pain, temperature >100.4°F, preterm labor or rupture of membranes, hypertension, and nonreassuring fetal heart rate pattern.
In the absence of risk factors on admission, the standard approach to fetal monitoring is to determine, evaluate, and record the fetal heart rate every 30 minutes in the active phase in the first stage of labor, and at least every 15 minutes in the second stage. In the presence of risk factors, fetal sur-veillance should be performed using either intermittent aus-cultation or continuous fetal monitoring. During the active first stage of labor, auscultation should be performed every 15 minutes, preferably before, during, and after a contrac-tion, and continuous monitoring should be evaluated at least every 15 minutes. During the second stage of labor, the fetal heart rate should be monitored every 5 minutes using either the intermittent or continuous procedure. If electronic fetal monitoring is used, an external tocodynamometer is initially used to assess uterine activity, providing information regard-ing the frequency and duration of contractions, but not their intensity. Electronic fetal monitoring is not necessary for a low-risk term pregnancy.
Management of discomfort and pain during labor is an essential part of good obstetric practice. Some patients tolerate pain by using techniques learned in childbirth preparation programs. It is important that bedside staff be knowledgeable about these pain management techniques and be supportive of the patient’s decisions. Unless con-traindicated, pharmacologic analgesics to ameliorate pain of contractions should be made available on request to women in labor.
During the first stage of labor, pain results from the contraction of the uterus and dilation of the cervix. This pain travels along the visceral afferents, which accompany sympathetic nerves entering the spinal cord at T-10, T-11, T-12, and L-1. As the fetal head descends, there is also dis-tension of the lower birth canal and perineum. This pain is transmitted along somatic afferents that comprise por-tions of the pudendal nerves that enter the spinal cord at S-2, S-3, and S-4. To provide relief from obstetric pain, the following methods of anesthesia and analgesia are used.
· Epidural block: infusion of local anesthetics or narcoticsthrough a catheter into the epidural space. The most effective form of intrapartum pain relief in the United States, it can be used in either vaginal or abdominal deliv-eries and in postpartum procedures such as tubal ligation.
· Spinal anesthesia: a single injection of anesthetic
· Combined spinal–epidural: combination of the abovetwo techniques
· Local block: local injection of anesthetic into theperineum or vagina. A pudendal block is a local block (Fig. 8.7).
· General anesthesia: inhaled or intravenous administra-tion of anesthetic agents that results in a loss of mater-nal consciousness. This technique is reserved only for cesarean deliveries in selected cases.
To determine which method of obstetric pain control should be used, the positive and negative aspects of each should be considered. Of the regional modes of analgesia, epidural anesthesia is superior to spinal anesthesia in that it can be left as a continuous source of analgesia and anesthe-sia during both the labor and delivery process. The advan-tage of this technique is its ability to provide analgesia during labor as well as excellent anesthesia for delivery, yet main-tain the patient’s sense of touch, facilitating participation in the birth process. Spinal anesthesia provides good pain relief for procedures of limited duration, such as cesarean delivery or vaginal delivery when labor is rapidly progressing. Combined spinal–epidural anesthesia has advantages: the epidural catheter to titrate medications throughout labor and the rapid onset associated with spinal techniques. All of these types of regional anesthesia may be associated with a postdural puncture headache. However, combined spinal–epidural anesthesia avoids the risk of spinal headache in the mother and reduces the risk of sympathetic blockade, which could lead to hypotension. There is also less motor blockade than with spinal anesthesia. Local block may pro-vide anesthesia for episiotomy and repair of vaginal and per-ineal lacerations; however, paracervical block may result in fetal bradycardia. General anesthesia is associated with complications such as maternal aspiration and neonatal depression. If properly administered, it is effective for most cesarean deliveries, but regional anesthesia is preferable.