Admission Assessment of the Laboring Woman
Diane J. Angelini
E. Jean Martin
Donna J. Ruth
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As you complete this module, you will learn:
Key questions to ask the woman being admitted to the labor unit
To identify factors that make the laboring woman a high-risk patient
To recognize those characteristics that help to distinguish between true labor and false labor
Physical assessment skills used in admitting the laboring woman
How to use the Fern test, the Nitrazine paper test, and a sterile speculum examination to evaluate pooling of fluid in determining if membranes have ruptured
To evaluate cervical effacement, dilatation, station, and fetal presentation during labor.
The importance of preparing for and informing the expectant mother of examination and test procedures
When you have completed this module, you should be able to recall the meaning of the following terms. You should also be able to use the terms when consulting with other health professionals. The terms are defined in this module or in the glossary at the end of this book.
amniotic fluid index (AFI)
group B streptococcus (GBS)
herpes simplex virus (HSV) type 1, type 2
meconium aspiration syndrome (MAS)
Identifying Critical Information
What critical information must be identified for the woman being admitted to the labor unit?
Certain information is needed immediately to evaluate the following:
The extent of the woman’s labor
Her general physical condition
Her risk status
Her preparation for labor and delivery
This assessment must be carried out quickly to determine how active the labor is and to become alert to women with a history of rapid deliveries or those with problems denoting risk.
Guidelines for History Taking
Maintain eye contact.
Introduce yourself and confirm the name by which the woman wishes to be called.
Inform the woman that you need to ask several questions and that you will stop whenever a contraction begins.
Ask open-ended questions when possible. For example, “Can you tell me about any problems you have had during this pregnancy?” instead of “Have you had an infection (or problem) during this pregnancy?” and “What preparation have you had for your labor and delivery?” instead of “Have you attended childbirth preparation classes?”
You might need to ask specific questions to follow up on the answers to your open-ended questions.
Identifying the High-Risk Mother and Fetus
How can you identify a mother and fetus who are at risk?
Mothers with high-risk pregnancies tend to have high-risk infants. These patients need to be identified as early as possible on admittance to the labor unit. Women who begin pregnancy as a low-risk patient may develop complications that make them high risk during the labor and delivery process. Assessment on admission and throughout the labor process will help to identify these women in a timely manner.
Taking a good history and reviewing the prenatal record of the woman when she is admitted to the labor unit is necessary for identifying the high-risk intrapartal patient. Risk status may have changed in the period between the last prenatal visit and admission for delivery.
Maternal smoking is associated with preterm labor and delivery, growth restriction, birth defects, and other pregnancy complications.2
Risk Factors for Laboring Women
The hepatitis B virus can be transmitted to the fetus during delivery and, perhaps, in rare cases, transplacentally.
Any woman with an undocumented HIV status at the time of labor should be offered screening with a rapid HIV test.6
A preterm birth is one that occurs before 37 completed weeks of gestation. Gestational age is more important than weight in determining perinatal morbidity or mortality.
Can women who are clearly at risk for problems during labor be identified ahead of time?
The following factors are associated with the development of complications for either the mother or the baby both during and after labor and delivery.
Factors Identified From the Mother’s History
Preeclampsia or eclampsia
Sickle cell disease
Sexually transmitted infections
Previous perinatal loss
Carrier state for blood-borne infectious disease (e.g., hepatitis B, syphilis, or HIV)
Group B streptococcus (GBS) carrier status
Women who are partners of intravenous drug abusers, bisexual males, or those who have multiple partners exhibit high-risk behavior for sexually transmitted diseases, some of which could be life threatening to both the mother and the fetus. Screening for syphilis, hepatitis B, and HIV infection, and possibly Hepatitis C, is strongly recommended.
Factors That Develop During Pregnancy
Factors Related to the Fetus
Irregularity in fetal heart rate (FHR) or nonreassuring FHR patterns
Intrauterine growth restriction
Significant increase or decrease in current fetal activity
Meconium-stained amniotic fluid
Factors Developing During Early Labor
Premature rupture of membranes (PROM) at term
Fresh meconium-stained fluid
Abnormal fetal heart tones or nonreassuring FHR patterns
Suspected cephalopelvic disproportion
The presence of any high-risk factors requires that the mother and fetus be continually evaluated throughout labor.
Determining True Labor
Is the woman in true labor?
The uterus undergoes intermittent contractions once pregnancy is established. These contractions are called Braxton–Hicks contractions, and they are often associated with false labor. After the 28th week of pregnancy, these contractions become definite and more noticeable by the woman.
As the 37th week of pregnancy approaches, contractions can be strong and are sometimes perceived by the expectant mother as a sign of true labor. Braxton–Hicks contractions usually stop or become highly irregular with a change of activity.
When the mother is discharged home, instruct her to return if any of the following occur:
Membranes rupture, even without contractions
Contractions become more frequent
Headache, visual complaints, epigastric pain
Decrease fetal movement
Evaluating the Status of Membranes
What is meant by “membranes”?
While developing inside the uterus, the fetus lives in a sac. The sac has two layers: the inner layer, called the amnion, and the outer covering, called the chorion. This sac is filled with fluid that is made up of water, various chemicals (e.g., salts), and particles that come from the fetus itself (e.g., body cells and hair).
What is normal amniotic fluid like?
By the end of pregnancy, the uterus contains approximately 1 L of amniotic fluid. The fluid is clear or straw colored and has a characteristic (not foul) odor. When tested for its acid–base content, it ranges from neutral to slightly alkaline. A close relationship exists between the status of the fluid and the health of the fetus. By studying various components of amniotic fluid, one can learn much about the gender, health, and maturity of the baby.
Does the fluid serve a special purpose?
The fetus derives many benefits from amniotic fluid, which does the following:
Protects the fetus from a direct blow. Pressure from a blow spreads in all directions within the fluid-filled sac, so the fetus does not receive the full impact of the blow.
Provides a fluid environment in which the fetus moves. This fluid continually changes in amount and consistency, promoting the growth and development of the fetus.
Prevents loss of heat and permits the fetus to maintain a constant body temperature.
Provides a source of oral intake. The fetus swallows amniotic fluid from approximately the fourth month until delivery.
Acts as a collection system for the waste products of the fetus. The fetus urinates into the amniotic fluid from the fourth month until delivery.
What can happen to the amniotic fluid and membranes that indicates a problem?
A. Premature Rupture of Membranes (PROM) Before Labor Begins With a Term Fetus at 37 Completed Weeks or More Gestational Age
Membranes (“bag of waters”) can rupture before labor begins. The break in the membranes can be complete, with a large gushing of fluid from the birth canal, or a small tear with a slow leak.
Many women go into labor spontaneously within a few hours after membranes rupture.
B. Preterm Premature Rupture of Membranes (PPROM) Before Labor Begins With a Preterm Fetus Less than 37 Weeks’ gestation
When rupture occurs before the fetus has reached the 37th completed week of gestation, perinatal morbidity and mortality increase. These women should be monitored for signs and symptoms of infection.
C. Meconium-Stained Amniotic Fluid
Fetal stool is referred to as meconium. It is largely made up of water, but also contains proteins, cholesterol, lipids, vernix, and other substances. Large concentrations of bile pigments give meconium its green color. Meconium present for more than 24 hours begins to turn yellow-green.
Almost all fetuses and newborn infants who pass meconium are at term or postterm gestation. From 20 to 34 weeks’ gestation, fetal passage of meconium remains infrequent.7 Although 12% to 22% of labors are complicated by meconium, only a few are linked to infant mortality.2
The significance of meconium-stained amniotic fluid as a predictor of fetal compromise may depend on the following:
Concentration and type of meconium (e.g., thick or thin, color, amount)
Stage of labor when the meconium is passed (often not known)
The presence of other fetal compromise markers such as FHR abnormalities or oligohydramnios
Birth of a depressed infant occurs in 20% to 33% of infants born through meconium-stained amniotic fluid. It is likely caused by pathologic intrauterine processes, primarily chronic asphyxia and infection.7
Meconium aspiration syndrome (MAS) is thought to be caused by an initial hypoxic event resulting in the release of meconium into the amniotic fluid. The normal fetal response to hypoxemia is to gasp, and thus in this instance, the meconium is aspirated and can be seen below the vocal cords on examination.
The pathophysiologic process set up in MAS often leads to a poor perinatal outcome.
NOTE: MAS is significantly associated with fetal acidemia at birth.8
Meconium is rarely passed before the 34th gestational week.
Clinical studies indicate an association between the passage of meconium and high-risk clinical situations, including the following:
Meconium alone is not an indicator of fetal hypoxia. Look at other fetal assessment parameters.
Electronic fetal monitoring maybe recommended when meconium-stained amniotic fluid is present. Meconium-stained infants should not have suctioning on the perineum. They should be handed directly to pediatrics for evaluation.
Be prepared for the birth of a high-risk infant.
The presence of meconium is managed differently at different institutions. In most scenarios, neonatology is called for the birth to assess for meconium aspiration. In most situations, there is no suctioning of the fetus during the birth process and the infant is handed to neonatology for evaluation. If the infant is vigorous, no evaluation below the vocal cords is necessary.
Postterm pregnancies are defined as those lasting beyond 42 weeks’ gestation. Most women are offered induction early in the 41st week.
In postterm laboring women, you should look for the following:
Amniotic membranes and fluid can become infected, especially after 24 hours of ruptured membranes. Infection can be detected by the presence of a foul odor, fundal tenderness, and an elevated temperature in the mother of 100.4 or greater.
E. Port Wine–Colored Amniotic Fluid—AN EMERGENCY
Port wine–colored amniotic fluid is an indicator of a premature separation of the placenta from the uterine wall, called abruptio placentae or vasa previa.
Signs of Abruptio Placentae
The following signs indicate that the placenta has partially or totally separated from the uterine wall:
Hard or rigid tone to abdomen
Bradycardia or absence of fetal heart tones
External bright red bleeding or concealed bleeding, shock
Vasa previa is noted when placental vessels overlie the cervix or portions of the cervix and are covered only with membrane. These vessels are vulnerable to compression which can lead to fetal anoxia and to laceration leading to fetal exsanguination. Vasa previa is relatively uncommon, 1 in 5,200 pregnancies.9
Abruptio placentae occurs in approximately 1 in 160 to 290 deliveries,10,11 although most people consider it to be 1 in 200. Factors that may predispose a woman to developing abruptio placentae include the following:
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