Labor Evaluation

Labor Evaluation

Elisabeth D. Howard

The process of childbirth at term is normally initiated by regular uterine contractions, spontaneous rupture of membranes, or both (Cunningham, Leveno, & Bloom, 2014). Safe, thorough evaluation of the pregnant woman at term who presents to an obstetric triage setting requires knowledge of the necessary components of maternal and fetal assessment, including history, physical examination, and clinical management. This chapter presents a review of clinical management of the main presenting concerns of women at term, including premature rupture of membranes (PROM), latent labor, active labor, and imminent delivery.

PROM AT TERM

The incidence of PROM at term is 8% to 10% of all pregnancies (American College of Obstetricians and Gynecologists [ACOG], 2007) and refers to spontaneous rupture of membranes at term (≥37 weeks of gestation) occurring before the onset of labor (Cunningham et al., 2014; Hannah et al., 1996). The management of PROM at term remains somewhat controversial and is based primarily on results from the Term PROM Study (1996). Managed expectantly, 95% of women with PROM will labor and deliver within 72 hours (Hannah et al., 1996). More recent data from the ACOG (2007) recommend induction of labor for women with term or near-term PROM upon presentation, whereas the position of the American College of Nurse Midwives (ACNM, 2008) suggests that with appropriate counseling and informed consent, under specific conditions and absence of risk factors, selected patients may be offered expectant management as a safe alternative to induction of labor. This is predicated on the preference of the woman and provider evaluation (Cunningham et al., 2014; Dare et al., 2006).

PRESENTING SYMPTOMATOLOGY

A history of a sudden gush of fluid or continued trickling of fluid is suggestive, but not confirmatory evidence, of ruptured membranes. Time of leakage, color of fluid (i.e., blood tinged, meconium stained), consistency, and odor are important to ascertain, including recent intercourse. Associated cramping, contractions, and presence of fetal movement need to be noted.

192HISTORY AND PHYSICAL EXAMINATION

Ruptured membranes are confirmed by a sterile speculum examination and the visualization of a pool of amniotic fluid in the vaginal vault or observed leakage of fluid from the cervical os. If there is scant fluid present in the vaginal vault, a swab may be taken. It is critical to obtain fluid from the vaginal vault rather than the cervical os, where mucus may be present and confound findings. Vaginal secretions are normally slightly acidic, whereas amniotic fluid is basic, thus turning nitrazine paper dark blue. By itself, this finding is nonspecific, as red blood cells and semen can also turn nitrazine paper dark blue. Additionally, the fluid should be dried on a slide and studied under a microscope. Dried amniotic fluid forms crystals (ferning) on a microscope slide, whereas vaginal secretions do not. Cervical dilation and effacement are estimated visually only during the sterile speculum examination (Cunningham et al., 2014).

Gestational age is determined by standard parameters. Maternal vital signs including blood pressure, temperature, and pulse are assessed. In addition, abdominal examination is performed to determine fetal presentation, lie, estimated fetal weight, and presence or absence of contractions. The fetal heart rate (FHR) may be evaluated with a fetoscope, Doppler, or an external fetal monitor for baseline FHR, variability, and presence or absence of decelerations and accelerations. It is critical that confirmation of fetal presentation be obtained. Group B Streptococcus (GBS) status will need to be determined.

DIFFERENTIAL DIAGNOSIS

If spontaneous rupture of membranes is not confirmed by examination, other possibilities need to be considered. These include normal leukorrhea of pregnancy, loss of mucus plug, involuntary loss of urine, ejaculatory fluid from sexual intercourse, and vaginal infections.

CLINICAL MANAGEMENT

When PROM is confirmed by physical examination, the risks and benefits of both induction of labor and expectant management may be reviewed with the pregnant woman. The maternal risks of ruptured membranes at term are low (Cunningham et al., 2014; Saccone, 2016). The risks to the fetus include ascending infection and umbilical cord compression (ACOG, 2007). In general, these risks may be mitigated with delay of baseline vaginal examination and minimal vaginal examinations (ACNM, 2008).

The largest prospective study to date that has investigated management of PROM is the Term PROM study. This was a multicenter, randomized trial that consisted of over 5,000 women at term with PROM (Hannah et al., 1996). In the expectant management arm of this trial, there was a higher incidence of chorioamnionitis and endometritis (Seaward et al., 1997). The incidence of neonatal infection was not statistically significant in any of the groups. It is recommended that women receive counseling and informed consent about the risks and benefits of induction of labor versus expectant management. According to ACNM (2008), women who select expectant management as a safe alternative to induction of labor must meet the following conditions: a term, 193uncomplicated pregnancy, single vertex pregnancy with clear amniotic fluid, absence of identified infection, absence of fever, a Category 1 FHR tracing, and minimization of digital vaginal examinations (including delay of a baseline vaginal examination). Observation of the woman for the onset of spontaneous labor includes documentation of the rationale of care, informed consent/patient counseling, and clinical circumstances (ACNM, 2008).

Visualization and estimation of cervical dilation and length are appropriate for planning for cervical ripening versus Pitocin induction, although no studies have proven the superiority of prostaglandin induction over Pitocin in the setting of PROM. Confirmation of fetal presentation via abdominal examination and ultrasound are crucial in the absence of a digital examination. Although there may be a role for observation after PROM, the most standard recommendation, based on the current evidence with term PROM, is that labor is preferentially induced at the time of presentation (ACOG, 2007; Cunningham et al., 2014; Saccone & Berghella, 2015).

There are times when the woman’s stated history of spontaneous rupture is inconsistent with the physical examination findings, yet the history is compelling. If examination results are equivocal, it may be appropriate to repeat the sterile speculum examination in 20 to 30 minutes or longer after the woman has been reclining, to assess for reaccumulation of pooling or ferning, and repeat nitrazine testing.

LATENT LABOR

The first stage of labor comprises both latent and active phases. Labor is a normal physiologic process characterized by sequential and rhythmic changes that result in birth of the newborn. While it is typically a gradual, continuous process that takes place over time, it is divided into first, second, and third stages of labor. This section addresses the diagnosis of the latent phase of the first stage of labor.

The initial phase of labor begins when a woman perceives regular contractions that effect changes in the consistency, position, dilation, and effacement of the cervix (King et al., 2015). This latent phase of labor is complex and is not well understood or well studied. There is a wide range of variation in the duration of the latent phase (Zhand, Landy, et al., 2010). This is partially due to the subjective nature of a patient’s perception as to the onset of contractions. In addition, this is the time when the clinician makes the determination between early and false labor (Braxton Hicks contractions).

Clinically, it is crucial to recognize when a woman is still in the latent phase of labor and not yet active because this has several management implications (Greulich & Tarrant, 2007; King et al., 2015). Latent labor admission to a labor unit is associated with higher risk for overuse of multiple labor interventions, such as administration of oxytocics, operative birth for abnormal labor progress, and cesarean delivery (Greulich & Tarrant, 2007; King et al., 2015; Tilden et al., 2016). In addition to these outcomes, the estimated gestational age (EGA) is a critical determinant of neonatal outcome as the data on late-term infants (37–39 weeks EGA) show a higher incidence of morbidity (Parikh et al., 2014). In addition, for women to adequately distinguish latent from active labor, it is helpful to provide detailed and specific guidance. Instruction about comfort measures at home is an important aspect of care that contributes to patient satisfaction (Hosek, Faucher, Lankford, & Alexander, 2014).

194PRESENTING SYMPTOMATOLOGY

Women may present with regular contractions that are still infrequent in timing. The contractions may be irregular and the intervals between them long. Discomfort may be chiefly in the lower abdomen and is likely to be relieved by sedation. In latent labor, the contractions, though infrequent, are becoming coordinated and increasing in intensity. Women present in early labor for a variety of reasons, including pain, need for reassurance, and partner’s urging (Cheyne et al., 2007). Anxiety and uncertainty are factors that influence the decision to seek care as well as the desire to shift responsibility to the hands of a clinician (Cheyne et al., 2007).

PHYSICAL EXAMINATION

A review of the medical record, including the medical and obstetric histories, is obtained. Additional data include the following: frequency, duration and intensity of contractions, time established, discomfort, any mitigating factors, status of membranes, vaginal bleeding, and leakage of fluid. Maternal coping resources are reviewed, and these include the amount of recent sleep, support persons available, level of hydration, and alimentation. Vital signs, including blood pressure, temperature, and pulse, are noted, as well as an abdominal examination to determine fetal presentation and position. The FHR is evaluated and a cervical examination is performed.

CLINICAL MANAGEMENT

Pregnant women in the latent phase of labor need support, encouragement, and advice if they are discharged from an obstetric triage unit (Greulich & Tarrant, 2007; King et al., 2015; Tilden et al., 2016). Ideally, the discussion of latent labor takes place prenatally, and healthy pregnant women are encouraged to spend the latent phase at home (Greulich & Tarrant, 2007; Tilden et al., 2016). The role of psychologic factors on pain perception is well known (King et al., 2015). Educational interventions may be most effective in decreasing the number of women admitted in early labor (Tilden et al., 2016). Anticipatory guidance and written instructions on the length of latent phase, comfort measures, and guidelines regarding when to call the provider are helpful for the pregnant woman to have (King et al., 2015).

Cognitive pain management techniques such as guided imagery and relaxation techniques decrease anxiety and promote comfort, thereby decreasing the catecholamine response. Encouragement of freedom of movement enhances uterine activity and increases sense of personal control over labor. Sensory stimuli such as music of one’s choosing, aromatherapy, touch, acupressure, and hydrotherapy all decrease anxiety, thereby reducing pain and promoting comfort and progress (Janssen, Shroff, & Jaspar, 2012). The therapeutic presence of family, a doula, and a calm physical environment promote comfort and decrease anxiety (King et al., 2015). Overall suggested comfort measures for women in latent labor include tub baths, hydration, alimentation, ambulation, therapeutic touch, encouragement, and support of family (ACNM, 2012; Hanada, Matsuzake, Ota, & Mori, 2015).

195It is important to review the risks of early admission including Pitocin augmentation, need for epidural anesthesia, and the potentially higher cesarean section rate. If the gestational age is less than 39 weeks, supportive, rather than active, management is warranted. The opportunity and time for the woman in early labor to ask questions and to be comfortable with the discharge plan of care is vital. In addition, it is essential that discharge documentation explicitly state that she is not in active labor in compliance with the Emergency Medical Treatment and Active Labor Act (EMTALA) guidelines. Table 18.1 reviews nonpharmacologic coping strategies.

If a woman is particularly anxious or fatigued, she may benefit additionally from the following medications for outpatient support and management as noted in Table 18.2.

TABLE 18.1 Nonpharmacologic Coping Strategies for Laboring Women

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