Abnormalities or difficulties in pregnancy or during labor and delivery can necessitate alternative delivery methods.

Operative vaginal delivery

Operative vaginal delivery involves application of forceps or a vacuum extractor to the fetal head to assist during the 2nd stage of labor and facilitate delivery.

Forceps delivery and vacuum extraction have essentially the same indications:

• Prolonged 2nd stage of labor (from full cervical dilation until delivery of the fetus)
• Suspicion of fetal compromise (eg, abnormal heart rate pattern)
• Need to shorten the 2nd stage for maternal benefit—eg, if maternal cardiac dysfunction (eg, left-to-right shunting) or neurologic disorders (eg, spinal cord trauma) contraindicate pushing or maternal exhaustion prevents effective pushing

A prolonged 2nd stage is defined in nulliparous women as lack of continuing progress for 3 h with a regional anesthetic or 2 h without a regional anesthetic or in multiparous women as lack of continuing progress for 2 h with a regional anesthetic or 1 h without a regional anesthetic.

Choice of device depends largely on user preference and operator experience and varies greatly. These procedures are used when the station of the fetal head is low (2 cm below the maternal ischial spines [station +2] or lower); then, minimal traction or rotation is required to deliver the head.

Before starting an operative vaginal delivery, the clinician should do the following:

• Confirm complete cervical dilation
• Confirm an engaged fetal vertex at station +2 or lower
• Confirm rupture of membranes
• Confirm that fetal position is compatible with operative vaginal delivery
• Drain the maternal bladder
• Clinically assess pelvic dimensions (clinical pelvimetry) to determine whether the pelvis is adequate

Also required are informed consent, adequate support and personnel, and adequate analgesia or anesthesia.

Contraindications include unengaged fetal head, unknown fetal position, and certain fetal disorders such as hemophilia. Vacuum extraction is typically considered contraindicated in preterm pregnancies of < 34 wk because risk of intraventricular hemorrhage is increased.

Major complications are maternal and fetal injuries and hemorrhage, particularly if the operator is inexperienced or if candidates are not appropriately chosen. Significant perineal trauma and neonatal bruising are more common with forceps delivery; shoulder dystocia, cephalohematoma, and retinal bleeding are more common with vacuum-assisted delivery.

Induction of Labor

Induction of labor is stimulation of uterine contractions before spontaneous labor to achieve vaginal delivery.

Indications

Induction of labor can be medically indicated (eg, for preeclampsia or fetal compromise) or elective (to control when delivery occurs). Before elective induction, gestational age and fetal lung maturity must be assessed. Elective induction is not done before 39 wk.

Contraindications to induction include having or having had the following:

• Fundal uterine surgery
• Myomectomy involving entry into the uterine cavity
• Prior classic or vertical cesarean incision in the thickened, muscular portion of the uterus
• Active genital herpes
• Placenta or vasa previa
• Abnormal fetal presentation (eg, transverse lie, umbilical cord presentation, certain types of fetopelvic disproportion)

Multiple prior uterine scars and breech presentation are relative contraindications.

Technique

If the cervix is closed, long, and firm (unfavorable), the goal is to cause the cervix to open and become effaced (favorable). Various pharmacologic or mechanical methods can be used. Misoprostol 25 mcg vaginally q 3 to 6 h is effective. Alternatives include prostaglandin E₂ given intracervically (0.5 mg) or as an intravaginal pessary (10 mg). Prostaglandins are contraindicated in women with prior cesarean delivery or uterine surgery because these drugs increase the risk of uterine rupture. Oxytocin in low or high doses can also be given. Effective mechanical methods include use of laminaria and transcervical balloon catheters, which may be useful when other methods are ineffective or contraindications exist.

Once the cervix is favorable, labor is induced. Constant IV infusion of oxytocin is the most commonly used method; it is safe and cost-effective. Low-dose oxytocin is given at 0.5 to 2 milliunits/min, increased by 1 to 2 milliunits/min, usually q 15 to 60 min. High-dose oxytocin is given at 6 milliunits/min, increased by 1 to 6 milliunits/min q 15 to 40 min to a maximum of 40 milliunits/min. With doses > 40 milliunits/min, excessive water retention may lead to water intoxication. Use of oxytocin must be supervised to prevent hypertonic uterine contractions, which may compromise the fetus. External fetal monitoring (see Normal Pregnancy, Labor, and Delivery: Fetal Monitoring) is routine; after amniotomy (deliberate rupture of the membranes), internal monitoring may be indicated if fetal status cannot be assessed externally. Amniotomy can be done to augment labor when the fetal head is applied to a favorable cervix and not ballotable (not floating).

Cesarean Delivery

Cesarean delivery is surgical delivery by incision into the uterus.

Up to 30% of deliveries in the US are cesarean. The rate of cesarean delivery fluctuates. It has recently increased, partly because of concern about increased risk of uterine rupture in women attempting vaginal birth after cesarean delivery (VBAC). (See also the American College of Obstetricians and Gynecologists practice guideline: Vaginal birth after previous cesarean delivery.)

Indications

Although morbidity and mortality rates of cesarean delivery are low, they are still several times higher than those of vaginal delivery; thus, cesarean delivery should be done only when it is safer for the woman or fetus than vaginal delivery. The most common specific indications are

• Previous cesarean delivery
• Protracted labor
• Fetal dystocia (particularly breech presentation)
• A nonreassuring fetal heart rate pattern, which requires rapid delivery

Many women are interested in elective cesarean delivery on demand. The rationale includes avoiding damage to the pelvic floor (and subsequent incontinence) and serious intrapartum fetal complications. However, such use is controversial, has limited supporting data, and requires discussion between the woman and her physician; the discussion should include immediate risks and long-term reproductive planning (eg, how many children the woman intends to have).

Many cesarean deliveries are done in women with previous cesarean deliveries because for them, vaginal delivery increases risk of uterine rupture; however, risk of rupture with vaginal delivery is only about 1% overall (risk is higher for women who have had multiple cesarean deliveries or a vertical incision, particularly if it extends through the thickened, muscular portion of the uterus). Vaginal birth is successful in about 60 to 80% of women who have had a single prior cesarean delivery and should be offered to those who have had a single prior cesarean delivery by lower uterine transverse incision. Success of VBAC depends on the indication for the initial cesarean delivery. VBAC should be done in a facility where an obstetrician, anesthesiologist, and surgical team are immediately available, which makes VBAC impractical in some situations.

Technique

During cesarean delivery, practitioners skilled in neonatal resuscitation should be readily available. The uterine incision can be classic or lower segment.

• Classic: The incision is made vertically in the anterior wall of the uterus, ascending to the upper uterine segment or fundus. This incision typically results in more blood loss than a lower-segment incision and is usually done only when placenta previa is present, fetal position is transverse with the back down, the fetus is preterm, or the lower uterine segment is poorly developed.
• Lower segment: Lower-segment incisions are done most often. A low transverse incision is made in the thinned, elongated lower portion of the uterine body under the bladder reflection. A vertical lower-segment incision is used only for certain abnormal presentations and for excessively large fetuses. In such cases, a transverse incision is not used because it can extend laterally into the uterine arteries, sometimes causing excessive blood loss. Women who have had deliveries by a low transverse uterine incision are advised about the safety of a trial of labor in subsequent pregnancies.

Last full review/revision March 2013 by Julie S. Moldenhauer, MD