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Complicated Deliveries


Key Points

  • Cesarean section occurs in approximately one-third of all births in the United States, with substantial variation among hospitals that cannot be entirely accounted for by preexisting maternal or fetal comorbidities.

  • Multidisciplinary team training can reduce infant morbidity after shoulder dystocia.

  • Operative vaginal birth with either forceps or vacuum has declined to a multi-decade low despite the low frequency of infant complications directly attributable to this method of delivery.

  • Regardless of mode of delivery, both the obstetrician and pediatrician must be aware that the infant in breech presentation requires careful attention upon birth for the presence of hip dislocation and traumatic morbidity (soft tissue trauma, fracture, facial nerve paralysis, and brachial plexus palsy).

  • Twin gestations account for 3% of total births, however the twin birth rate decreased from 2018 (32.6/1000 births) to 2019 (32.1/1000 births). Twin gestations account for 17% of preterm births and approximately 25% of infants of low birth weight and very low birth weight.

  • Vaginal birth after cesarean (VBAC) section should occur in delivery facilities capable of rapidly performing an emergent cesarean section because this improves the likelihood of minimizing adverse neonatal sequelae.

Overview

Historically, childbirth was often regarded as a perilous undertaking. However, over the past century in the United States, many advancements in perinatal medicine have improved modern obstetric care, such as widespread use of antibiotics, easy access to expedient cesarean delivery, and better understanding of the proper use of instruments, such as forceps and vacuum extraction. Despite the improvements in obstetric care, and in contrast to the global trend in decreased maternal mortality, maternal mortality has been increasing in the United States (from 10 deaths per 100,000 livebirths in 1990 to a high of 18 deaths per 100,000 live births in 2014). Indeed, adverse outcomes are generally uncommon in modern obstetrics and, unlike in the past, most labor and delivery concludes with a healthy mother and neonate. Nevertheless, complicated deliveries still exist, and knowledge of their conduct and sequelae is still required for the administration of proper maternal and infant care.

In this chapter we will address:

  • Brief overview of normal labor and delivery. A comprehensive discussion of labor and delivery is beyond the scope of this chapter, and the interested reader is directed to Williams Obstetrics , 25th ed., Chapter 22 on normal labor.

  • The complicated vaginal delivery, with particular attention to neonatal outcomes.

  • Cesarean delivery and vaginal birth after cesarean (VBAC) delivery and associated neonatal implications.

Vaginal Delivery

Labor begins with the onset of regular uterine contractions with concomitant cervical dilation and effacement. The first stage of labor is subdivided into a latent phase, the length of which is variable and can last for several hours, and an active phase. Historically, the active phase was defined as beginning when the cervix is dilated 4 cm and is marked by more rapid cervical dilation ( Fig. 13.1 ). The second stage begins with complete cervical dilation and terminates with expulsion of the fetus from the birth canal. The third stage of labor concludes with delivery of the placenta ( Table 13.1 ).

Fig. 13.1, Friedman Labor Curve.

Table 13.1
Stages of Labor
Stage
First (latent and active phase) Onset of labor to complete (10 cm) cervical dilation
Second Complete cervical dilation to fetal expulsion
Third Fetal expulsion to placental expulsion

In 2010, data from the Consortium on Safe Labor stimulated debate regarding whether the 60-year-old data of Friedman apply to currently laboring women. Based on this research, the active phase became defined as beginning at 6 cm of cervical dilation ( Fig. 13.2 ). In 2012, a summary was published by a joint committee including the Eunice Kennedy Shriver National Institute of Child Health and Human Development, Society for Maternal-Fetal Medicine, and American College of Obstetricians and Gynecologists (ACOG), regarding labor management guidelines largely based on the work of Zhang, and these guidelines have been largely adopted as the standard of care for labor management.

Fig. 13.2, Contemporary Labor Curve.

Disorders of labor progress involve either protraction, with a slower rate of cervical dilation or fetal descent than expected, or arrest. Both disorders are addressed by operative delivery if they are unresponsive to active medical management; this can be performed abdominally through cesarean section or vaginally by obstetric forceps or vacuum extraction if the cervix is fully dilated and specific criteria are fulfilled (see later discussion on operative vaginal delivery). All these modalities can have neonatal and maternal adverse effects, and the choice of instrument or mode of delivery must always be selected when taking these potential morbidities into account.

Cesarean Section

A cause-and-effect relationship between cesarean delivery and improved neonatal outcomes in the United States has never been demonstrated. Currently, almost one in three mothers gives birth by cesarean section in the United States. The rate of cesarean delivery in the United States, which peaked in 2009 at 32.9%, had declined to 31.7% in 2019. Since 1985, the World Health Organization (WHO) had recommended cesarean section rates not exceed 10% to 15%. However, international data called the safety of this low projection into question, demonstrating that national cesarean section rates up to 19% were associated with lower maternal and neonatal mortality among WHO member states. Recent recommendations from the US Department of Health and Human Services Healthy People 2030 have targeted a cesarean section rate of 23.6% for first-time pregnancies.

There are, however, wide variations in cesarean delivery rates among individual states within the United States and among individual hospitals within a given state. This cesarean section variability was shown to be 10-fold (7% to 70%) among birthing hospitals in the United States and varied from 17.5% to 31.8% among the 50 states. This suggests that factors other than pregnancy risk indicators may heavily influence the current cesarean delivery rate. Liability fears have been suggested as a leading cause of the variability in cesarean section rates. One study has lent validity to this concern, showing that higher cesarean section rates were associated with reduced risk of litigation. The incidence of cesarean delivery on maternal request and its contribution to the overall increase in cesarean delivery rate are not well known, but it has been estimated that 2.5% of all births in the United States are due to maternal request for cesarean delivery. The ACOG has recommended that, in the absence of a maternal or fetal indication for cesarean delivery, vaginal delivery should be recommended. After counseling the patient about risks, benefits, and alternatives to cesarean delivery, if the patient decides to pursue an elective cesarean delivery, the delivery should not be performed before 39 weeks gestation. Women should also be informed that the risk of placental complications (which could lead to a gravid hysterectomy) will increase with each subsequent cesarean delivery. This rise in cesarean delivery has been associated with a parallel drop in the vaginal operative delivery rate to less than 5%.

Cesarean section is usually performed through either a Pfannenstiel or vertical skin incision. The uterine incision is often made transversely in the lower uterine segment because it minimizes intraoperative blood loss and future risk of rupture during subsequent labor, compared with a vertical or classical incision. The risk of rupture in future labor is thought to be 0.5% to 0.9% for a low transverse incision. However, risks of uterine rupture with previous classical incision have ranged from 1% to 12% in women undergoing a trial of labor.

Cesarean delivery is also performed for disorders of protraction or arrest in the first stage of labor when conservative measures, such as oxytocin or amniotomy, fail to augment delivery or in the second stage when assisted or operative vaginal delivery is deemed unfeasible or unsafe.

A partial list of other accepted indications for cesarean delivery is as follows:

  • Fetal malpresentation (e.g., shoulder or breech)

  • Placenta previa

  • Prior classical uterine incision

  • Fetal status not reassuring, remote from vaginal delivery

  • Higher-order multiple gestation (triplet or greater)

  • Fetal contraindications to labor (alloimmune thrombocytopenia)

  • Maternal contraindication to labor (e.g., history of rectal or perineal fistulas from inflammatory bowel disease, large lower-uterine segment, or cervical leiomyoma preventing vaginal delivery).

  • Maternal choice after counseling regarding risks versus benefits.

Operative Vaginal Delivery: Obstetric Forceps and Vacuum Extraction

Description of the Obstetric Forceps

Obstetric forceps have been used to facilitate vaginal deliveries since 1500 bce . More recently, their invention has been credited to Peter Chamberlen and his brother, both obstetricians from England. Designed originally as a means of extracting fetuses from women who were at high risk of dying during childbirth, forceps now are an alternative to cesarean delivery in women with a protracted second stage of labor. Originally, many of these instruments were furnished with hooks and other accessories of destruction, and they were intended to save the mother but not the fetus. Over the last 500 years, the modern instruments in current use have been through hundreds of modifications, safer techniques have been established, and the overriding goal now includes delivering an intact, living baby and a healthy mother.

Current obstetric forceps were first devised for practical use in the 16th and 17th centuries and were perfected over the past 300 years into the models in current use. Although there are many variations on the standard blueprint, depending on the indication for its use, all obstetric forceps have a similar design.

Forceps are made of stainless steel and consist of two blades (each approximately 37.5 cm long, crossing each other), a lock at the site of crossing, and a handle, whereby the instrument is grasped by the obstetrician. The part of the forceps that grasps the fetal head is the blade; this is further divided into the heel, which is the part closest to the lock, and the toe, which is the most distal part of the blade. The blade can be either fenestrated—meaning the body of the blade is hollow—or solid to prevent fetal head compression. A further modification is pseudofenestration, in which a solid blade has a ridged edge, combining the advantages of easier applicability and reduced fetal trauma that a solid blade affords with the ease of traction of a fenestrated blade. Obstetric forceps also possess a rounded cephalic curve, which accommodates the fetal vertex, and a pelvic curve that mirrors the maternal pelvic curve ( Fig. 13.3 ).

Fig. 13.3, Simpson forceps: a standard obstetric forceps with features common to all such instruments.

There are more than 60 different types of obstetric forceps described in the literature, but most of them are not used currently. The forceps used most often today are described in Table 13.2 , along with their indications for use and the variations in anatomy, which distinguish one from the other.

Table 13.2
Types of Obstetric Forceps in Most Common Use
Type Anatomic Modification General Use
Classic
Tucker–McClane Solid blade Nonmolded vertex
Simpson Parallel shanks Molded vertex or significant caput
Elliot Convergent shanks Nonmolded vertex
Laufe Pseudofenestrated blade; divergent shanks For preterm infants or EFW <2500 g
Rotational
Kielland English lock; absent pelvic curve For rotation of fetal vertex ≥45°
Breech
Piper Long handles with no pelvic curvature For after-coming head in breech vaginal delivery
EFW , Estimated fetal weight.

Indications for Use of Obstetric Forceps

To an individual without obstetric training, the use of forceps can appear to be a dangerous and difficult undertaking, fraught with potential trauma for both the mother and fetus. It is true that the use of this instrument, if not performed carefully or appropriately, can have serious consequences. Nevertheless, with properly trained hands, and a proper appreciation of its use, forceps have traditionally been lifesaving for both mother and fetus.

The criteria for the safe application of obstetric forceps are as follows:

  • The cervix must be fully dilated.

  • The position of the fetal vertex must be known. Forceps should not be applied when the fetal presentation is in doubt.

The fetal vertex must be engaged within the maternal pelvis. Often in difficult or challenging labors, significant caput can lead to the false impression that fetal station is lower than it actually is. For this reason, the obstetrician must be confident that the biparietal diameter has passed the pelvic inlet (engagement) as evidenced by the leading part of the fetal skull beyond the level of the ischial spines. In addition, when the presentation is occiput posterior, the leading point of the fetal skull may appear to be lower in the pelvis, although the biparietal diameter has not yet passed through the pelvic inlet, and can lead to an erroneous conclusion about fetal station. When the forceps are properly applied, the sagittal suture must be exactly midway between the blades, and the lambdoidal sutures should be equidistant from the edge of the blade. If these conditions are not met, the delivery with forceps should be reconsidered.

ACOG has revised its 1988 classification of the type of forceps delivery, according to the station of the fetal vertex before forceps application which are as follows:

  • Outlet forceps—the fetal vertex is visible at the labia without manually separating them, and the fetal skull has reached the pelvic floor.

  • Low forceps—the leading point of the fetal skull is greater than 2 cm beyond the ischial spines.

  • Mid forceps—the fetal head is engaged (0 to +1 station). The forceps should be applied only if cesarean delivery is not quickly or imminently possible with the fetus in distress, or there should be a high likelihood that the forceps operation will be successful.

  • High forceps—the vertex is not engaged (leading part not at the level of the ischial spines or beyond). Under these circumstances, the forceps must never be applied.

    The usual indications for use of the obstetric forceps are:

  • Maternal exhaustion or inability to push (endotracheal intubation with sedation or paralysis, neuromuscular disease)

  • Fetal heart tracing not reassuring

  • Maternal contraindications to pushing (cardiopulmonary disease, cerebrovascular aneurysm)

  • After-coming head in a vaginal breech delivery

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