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263
1. What is the definition of labor?
Labor begins when uterine contractions of sufficient frequency, intensity, and duration are attained to
bring about effacement and progressive dilation of the cervix.
2. What two steps are theorized to be crucial to the initiation of labor in human
pregnancy?
1. Retreat from pregnancy maintenance
2. Uterotonic induction
Despite extensive investigation into the associated physiologic and biochemical changes, the
physiologic processes in human pregnancy that result in the onset of labor are still not defined.
3. In which patients is induction of labor considered?
Awaiting the onset of normal labor may not be an option in certain circumstances. At preterm
gestations, indications for labor induction include severe preeclampsia, fetal growth restriction
with abnormal antepartum surveillance or other evidence of fetal compromise, and deterioration
of maternal disease to the point that continuation of pregnancy is believed to be detrimental.
In cases of rupture of membranes without labor (i.e., premature rupture of membranes) at term
(37 to 42 weeks) or postterm (≥42 weeks), induction of labor is often performed.
4. What is a Bishop score, and how is it used?
A Bishop score is a quantifiable method to assess the likelihood of a successful induction. Elements include
dilation, effacement, station, consistency, and position of the cervix (Table 61-1). A score of 6 or less trans-
lates into a need to ripen the cervix and is associated with less successful inductions. A score 8 or greater
generally means the cervix does not need ripening and induction is more likely to be successful.
5. What methods are available for cervical ripening?
Mechanical methods provide local pressure and stimulate endogenous release of prostaglandins,
which results in cervical ripening. Options include a transcervical Foley catheter (filled with
30 to 60 mL after insertion) or hydroscopic dilators (laminaria or a similar synthetic product).
Pharmacologic methods include low-dose oxytocin, prostaglandin E
2
(dinoprostone), and
prostaglandin E
1
(misoprostol). Prostaglandin E
1
can be administered intravaginally or orally, and
prostaglandin E
2
can be applied within the vagina in either gel or suppository form.
6. When is cervical ripening contraindicated?
Contraindications to labor induction are the same as those for spontaneous labor and vaginal delivery.
They include—but are not limited to—vasa previa, placenta previa, fetal malpresentation (e.g., breech
CHAPTER 61
LABOR AND VAGINAL
DELIVERY
Kelly A. Best, MD
Table 61-1. Bishop Scoring System for Assessment of Inducibility
SCORE
DILATION
(cm)
EFFACEMENT
(%)
STATION
(-3 TO +3 SCALE)
CERVICAL
CONSISTENCY
CERVICAL
POSITION
0 Closed 0-30 −3 Firm Posterior
1 1-2 40-50 −2 Medium Midposition
2 3-4 60-70 −1, 0 Soft Anterior
3 ≥5 ≥80 +1, +2 — —
VI LABOR, DELIVERY, AND POSTPARTUM
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264 LABOR, DELIVERY, AND POSTPARTUM
or transverse lie), umbilical cord prolapse, and previous transfundal uterine surgical procedures.
Because of an increased risk of uterine rupture during induction of labor with prostaglandins among
women with previous low-transverse cesarean sections, the American College of Obstetricians and
Gynecologists (ACOG) advises against the use of prostaglandins in these cases. For more information
on a trial of labor after cesarean section (TOLAC), see Chapter 63.
7. How is the pelvis assessed clinically?
Historically, clinical assessment of the pelvis (known as pelvimetry) was used to predict whether
vaginal birth was possible and provide information about a patient’s overall pelvic dimensions and
configuration. However, this has been shown not to be reliable; the best way to assess whether a
pelvis is adequate is to allow for a trial of labor.
• The pelvic inlet is bounded in the anteroposterior dimension (obstetric conjugate) by the sacral
promontory and the pubic symphysis. Laterally, it is bound by the linea terminalis. The size
of the pelvic inlet can be estimated by palpating the sacral promontory, which provides the
measurement for the diagonal conjugate, which is approximately 1.5 to 2 cm greater than the
obstetric conjugate.
• The pelvic midplane is bounded laterally by the inferior margins of the ischial spines, anteriorly by
the lower margin of the symphysis pubis, and posteriorly by the sacrum (usually S4 or S5).
• The pelvic outlet consists of two triangular areas that are not in the same plane but share a common
base, which is the distance between the two ischial tuberosities. The apex of the posterior triangle is at
the tip of the sacrum, and the anterior triangle is formed by the area under the pubic arch (Fig. 61-1).
Most patients have an intermediate form of the four classically described pelvic types (Fig. 61-2).
8. What are the three stages of labor?
The first stage begins with the onset of labor and ends when the cervix is fully dilated (10 cm). The
second stage begins when dilation of the cervix is complete and ends with delivery of the infant. The
third stage begins immediately after delivery of the infant and ends with delivery of the placenta.
9. How are uterine contractions monitored?
Uterine monitoring can be either external or internal.
• External monitoring: performed by securing a displacement transducer to the maternal abdomen.
When the uterus contracts, the transducer moves; this movement is translated into an electronic
signal and is transcribed as a vertical displacement from the resting uterine tone. This form of
monitoring provides information only about the frequency of contractions.
Transverse
diameter
(bituberous)
Ant. triangle
Post. triangle
Sacrotuberous
ligt.
Figure 61-1. The pelvic outlet. Ant., Anterior; ligt., ligament; post., posterior. (From Hobel CJ, Chang AB. Normal labor,
delivery, and postpartum care. In: Hacker NF, Moore JG, Gambone JC, eds. Essentials of Obstetrics and Gynecology. 4th ed.
Philadelphia: Saunders; 2004:108.)
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LABOR AND VAGINAL DELIVERY 265
• Internal monitoring: performed by threading a pressure catheter through the cervix, around the
presenting part of the fetus, and into the uterine cavity. This method provides information on both
the strength and frequency of contractions.
10. What is a normal contraction pattern?
A normal contraction pattern during labor consists of three to five contractions in 10 minutes, aver-
aged over a 30-minute period.
11. What is an “adequate” contraction pattern?
An adequate contraction pattern refers to contractions of sufficient frequency and strength to cause
cervical change.
Uterine contractions can be measured in Montevideo units. To calculate Montevideo units,
total vertical displacement above resting uterine tone is multiplied by contraction frequency over
a 10-minute period (Fig. 61-3). An intrauterine pressure catheter must be used. Contractions are
considered adequate when they reach 200 Montevideo units or greater.
Anthropoid
Gynecoid Android
Platypelloid
Figure 61-2. The four basic pelvic types (Caldwell-Moloy classification). The dotted line indicates the transverse
diameter of the inlet. (From Hobel CJ, Chang AB. Normal labor, delivery, and postpartum care. In: Hacker NF, Moore JG,
Gambone JC, eds. Essentials of Obstetrics and Gynecology. 4th ed. Philadelphia: Saunders; 2004:109.)
100
12
10
8
6
4
2
0 kPa
75
50
25
UA 0 mm Hg
100
12
10
8
6
2
0 kPa
75
50
25
UA 0 mm Hg
Figure 61-3. Calculation of Montevideo units. UA, Uterine activity. (From Bashore RA, Koos BJ. Fetal surveillance during
labor. In: Hacker NF, Gambone JG, Hobel CJ, eds. Hacker and Moore’s Essentials of Obstetrics and Gynecology. 5th ed.
Philadelphia: Saunders; 2010.)
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266 LABOR, DELIVERY, AND POSTPARTUM
12. What are the two phases of the first stage of labor?
The first stage is divided into a latent phase and an active phase. The duration of the latent phase is
variable and has little bearing on the subsequent course of labor, whereas the characteristics of the
active phase are usually predictive of the outcome of a particular labor.
13. What is the Friedman curve?
In the 1950s, Emanuel A. Friedman popularized the use of an objective measure of labor progres-
sion. He constructed a graphic representation of expected cervical dilation against time, with varying
expectations for nulliparous and multiparous patients. Used in conjunction with fetal descent, these
curves were used to provide clinical feedback about the normalcy of a patient’s labor progress.
“Labor curves” have since been updated in light of changing demographics, improved statistical
and experimental methods, and more robust study designs.
14. What cervical changes generally take place during the latent phase of labor?
Although little cervical dilation occurs during this time, considerable changes take place in the
extracellular matrix (collagen and other connective tissue components) of the cervix. Cervical ripening
generally includes palpable softening, effacement, and anterior rotation of the cervix in the pelvic axis.
15. When does conversion from the latent to active phase occur?
During labor, the transition is characterized by increased regularity and intensity of contractions,
accompanied by progressive and predictable cervical change. The active phase of labor begins at
6 cm dilation and accelerates at different rates based on parity.
16. What is the duration of the first stage of labor?
• Latent phase: The median duration and 95th percentile duration of the latent phase depend on
baseline cervical dilation and are similar between nulliparous and parous women. If a patient is
admitted to the hospital at 2 cm dilation, the median duration of the latent phase is approximately
6 hours, and the 95th percentile is 15.7 hours. If a patient is admitted at 3 cm, the median duration is
approximately 4 hours, and the 95th percentile is 12.5 hours. The term prolonged latent phase is used
to indicate that a patient has been in the latent phase of labor for longer than the 95th percentile.
• Active phase: The median duration and 95th percentile duration of the active phase in nulliparous
women are 2.1 and 8.6 hours, respectively. In parous women, these times are 1.5 and 7.5 hours.
The term prolonged active phase is used to indicate that cervical dilation is occurring at a rate of
less than the 5th percentile.
17. What is the management of a prolonged latent phase?
Options include maternal sedation (also known as “therapeutic rest”), augmentation with oxytocin, or
discharge home if the patient and fetus are stable.
18. What is the management of a prolonged active phase?
Treatment is either observation or augmentation with oxytocin.
19. How is arrest of the active phase defined, and how is it managed?
Arrest of the active phase is defined as cessation of dilation when an adequate contraction pattern
(≥200 Montevideo units in a 10-minute period) has been present for 2 hours. Cesarean section is
generally indicated in these cases.
20. At how many centimeters is a cervix considered to be fully dilated?
At 10 cm, it is considered fully dilated because this is the approximate diameter of the fetal vertex at
term. For preterm infants, however, full dilation may be less than 10 cm; the cervix will not dilate past
the maximal point of the presenting part.
21. What are the two possible abnormalities of the second stage of labor?
Prolonged descent and arrest of descent. Although prolonged descent has traditionally been defined
as descent occurring at less than 1 cm/hour in nulliparas and more than 2 cm/hour in multiparas, it
does not usually affect clinical management. Arrest of descent is defined as generally considered to
occur when there has been no progress (descent or rotation) for a specified amount of time based on
parity and whether regional anesthesia is being used:
• 4 hours or longer in nulliparous women with an epidural
• 3 hours or longer in nulliparous women without an epidural
• 3 hours or longer in multiparous women with an epidural
• 2 hours or longer in multiparous women without an epidural
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LABOR AND VAGINAL DELIVERY 267
If the patient is a candidate for operative vaginal delivery, this may be an acceptable option as long as
fetal macrosomia and cephalopelvic disproportion are not suspected; otherwise, cesarean delivery is
indicated.
22. What should be assessed during a vaginal examination?
• Cervical dilation
• Degree of effacement (thinning of the cervix, usually expressed as a percentage)
• Fetal station (presenting part described in centimeters in relation to the maternal ischial spines)
• Presenting part (e.g., vertex, breech, shoulder) and orientation
23. What are the cardinal movements of labor?
Engagement
Descent
Flexion
Internal rotation
External rotation
Extension
Restitution
Expulsion
Figure 61-4 illustrates the cardinal movements of labor.
24. What is the Ritgen maneuver?
Moderate upward pressure is applied to the fetal chin by the operator’s posterior hand, which is
covered with a sterile towel, while the vertex is held against the symphysis (Fig. 61-5). This maneuver
allows control of the delivery of the head and favors extension, so that the head is delivered with its
smallest diameter passing through the introitus and over the perineum.
25. What is shoulder dystocia and how is it managed?
Shoulder dystocia is impaction of the fetal shoulders within the maternal pelvis after delivery of the
fetal head, thus preventing further expulsion of the infant. Special maneuvers are required to free the
anterior shoulder:
• McRobert maneuver (acute flexion of the maternal legs)
• Suprapubic pressure
• Woods corkscrew maneuver (rotating the posterior shoulder of the fetus 180 degrees in a cork-
screw fashion)
• Delivery of the posterior shoulder (by sweeping the posterior arm of the fetus across the chest)
• Rubin maneuver (displacing the anterior shoulder toward the chest of the fetus within the pelvis)
• Deliberate fracture of the clavicles
• Zavanelli maneuver (involving flexion of the fetal head, replacement of the fetus within the uterine
cavity, and emergency cesarean section delivery)
26. How often does shoulder dystocia occur?
Although it has traditionally been associated with fetal macrosomia, up to 50% of cases of shoulder
dystocia occur in neonates weighing less than 4000 g. Among infants weighing 4000 to 4499 g, the
incidence of shoulder dystocia is 1% to 10% in nondiabetic women and 5% to 23% in diabetic women.
These numbers rise to 3% to 23% and 20% to 50%, respectively, for infants weighing more than 4500 g.
27. What are the potential complications of shoulder dystocia?
For the fetus, shoulder dystocia may be associated with transient brachial plexus palsies, clavicular
fractures, humeral fractures, and neonatal death. For the mother, severe perineal lacerations and
postpartum hemorrhage can occur.
28. What is an episiotomy, and why is it performed?
An episiotomy is incision of the perineum to enlarge the vaginal opening. It was historically thought
to prevent excessive stretching of the perineum, but it has now been abandoned for lack of evidence.
Episiotomy has been associated, however, with an increased risk of injury to the rectal sphincter. The
two types of episiotomy are median (midline) and mediolateral. A median episiotomy is considered
easier to repair and to have a less painful recovery, but it also has a higher rate of extension into the
rectum. Mediolateral episiotomies are made at a 45-degree angle to the base of the introitus; they
have a lower extension rate and may be considered for large infants, a small perineal body, and in
some cases of operative vaginal delivery.
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268 LABOR, DELIVERY, AND POSTPARTUM
29. What tissue layers are involved in each of the four types of obstetric laceration?
• First-degree: the fourchette, perineal skin, and vaginal mucosa, but not the underlying fascia and
muscle
• Second-degree: as in first-degree lacerations, with the addition of the fascia and muscles of the
perineal body
• Third-degree: as in second-degree lacerations, with the addition of the anal sphincter
• Fourth-degree: as in third-degree lacerations, with the addition of the rectal mucosa (exposing the
lumen of the rectum)
A Before engagement
C Descent, rotation
E Complete extension
G
Anterior shoulder delivery
B Engagement, flexion, descent
D Complete rotation, early extension
F Restitution
H
Posterior shoulder delivery
Figure 61-4. The cardinal movements of labor. Although labor is a continuous process, eight discrete cardinal move-
ments of labor occur. A, Before engagement. B, Engagement, flexion, and descent. C, Descent and rotation. D, Complete
rotation and early extension. E, Complete extension. F, Restitution. G, Anterior shoulder delivery. H, Posterior shoulder
delivery. (From Norwitz ER, Robinson JN, Repke JT. Labor and delivery. In: Gabbe SG, Niebyl JR, Simpson JL, eds.
Obstetrics: Normal and Problem Pregnancies. 4th ed. Philadelphia: Churchill Livingstone; 2002:365.)
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LABOR AND VAGINAL DELIVERY 269
30. What are the indications for operative vaginal delivery?
The indications for operative vaginal delivery include any condition threatening the mother or fetus
during the second stage of labor that is likely to be relieved by delivery. Examples of maternal
indications are heart disease, pulmonary injury or compromise, certain neurologic conditions, and
maternal exhaustion. An common fetal indication is a nonreassuring fetal heart rate pattern.
31. What are general prerequisites for performing an operative vaginal delivery (ABCs)?
• There must be adequate anesthesia.
• The maternal bladder should be emptied.
• The cervix must be completely dilated.
• The fetal head must be engaged.
• The fontanels and direction of the occiput must be precisely known.
• Membranes must be ruptured (“gush of amniotic fluid”).
• The maternal pelvis must be assessed to be adequate (“hips”).
• An indication should be present.
32. What is asynclitism?
Asynclitism is failure of the vertex to descend with the sagittal suture in the middle plane between
the front and back of the pelvis. It is detected clinically on examination when either the anterior or
posterior parietal bones precede the sagittal suture. When accompanied by molding, asynclitism can
lead to erroneous assessments of the true fetal position.
33. How are the different levels of operative delivery described?
• In a high operative delivery, the fetal head is not engaged; this type of operative delivery is no
longer performed.
• A mid operative delivery is when the fetal station is greater than +2 cm but the head is
engaged.
• A low operative delivery is when the leading point of the fetal skull is at station +2 cm or greater
and not on the pelvic floor.
• An outlet operative delivery is when the fetal skull has reached the pelvic floor; scalp should be
visible at the introitus without separating the labia, the sagittal suture is in an anteroposterior
orientation, and rotation of the fetal head does not exceed 45 degrees (i.e., in right or left occiput
anterior or posterior position).
34. What are the two general types of operative delivery?
Vacuum-assisted delivery and forceps-assisted delivery.
Figure 61-5. Ritgen maneuver. The fingers of the right hand, pressing posterior to the rectum, are used to extend the
head while counterpressure is applied to the occiput by the left hand to allow controlled delivery of the fetal head. (From
Hobel CJ, Chang AB. Normal labor delivery and postpartum care. In: Hacker NF, Moore JG, Gambone JC, eds. Essentials of
Obstetrics and Gynecology. 4th ed. Philadelphia: Saunders; 2004:118.)
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270 LABOR, DELIVERY, AND POSTPARTUM
35. What are following forceps: Simpson, Elliot, Tucker-McLane, Kielland, and Piper?
• Simpson: fenestrated blades with divergent handles. The greater cephalic curve of the blade
is suited for the molded head and when traction is desired. The Luikart modification employs a
pseudofenestrated or semifenestrated blade.
• Elliot: fenestrated blades with convergent handles. The lesser cephalic curve is suited for the
unmolded head and when traction is desired.
• Tucker-McLane: solid blades with convergent handles. The lesser cephalic curve is suited for
the unmolded head in situations requiring minimal traction; the Luikart modification employs a
pseudofenestrated or semifenestrated blade.
• Kielland: minimal pelvic curve. It is ideal for rotation of the vertex from the occiput posterior or
transverse position to the occiput anterior position.
• Piper: used for delivering the aftercoming head of the breech fetus. The pelvic curve is opposite
that of other forceps so that the handles are below the level of the blades
Figure 61-6 illustrates the classification of forceps.
1
Classial forceps
Cephalic curvature
Tucker-McLane
Simpson
Elliot
Sliding lock
Sliding lock
Kiellands
Longhandles
Kiellands
Piper
Piper
Elliot
Simpson
Tucker-McLane
Pelvic curvature
Locking
handles
2
Rotational forceps
No pelvic curvature
No pelvic curvature
3
Forceps for delivery of aftercoming head of the breech
Figure 61-6. Classification of forceps. (From Norwitz ER, Robinson JN, Repke JT. Labor and delivery. In: Gabbe SG.
Niebyl JR, Simpson JL, eds, Obstetrics: Normal and Problem Pregnancies. 4th ed. Philadelphia: Churchill Livingstone;
2002:381.)
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LABOR AND VAGINAL DELIVERY 271
BiBliography
1. American College of Obstetricians and Gynecologists. Induction of labor. ACOG practice bulletin no. 107. Obstet
Gynecol. 2009;114:386–397.
2. American College of Obstetrics and Gynecologists. Vaginal birth after previous cesarean delivery. ACOG practice
bulletin no. 115. Obstet Gynecol. 2010:1143–1156.
3. Ananth CV, et al. Electronic fetal monitoring in the US: temporal trends and adverse perinatal outcomes. Obstet
Gynecol. 2013;121:927–933.
4. Baskett TF, Allen AC. Perinatal implications of shoulder dystocia. Obstet Gynecol. 1995;86:15.
5. Bishop EH. Pelvic scoring for elective induction. Obstet Gynecol. 1964;24:266–268.
6. Buser D, Mora G, Arias F. A randomized comparison between misoprostol and dinoprostone for cervical ripening and
labor induction in patients with unfavorable cervices. Obstet Gynecol. 1997;89:581–585.
7. Creasy RK, Resnik RI, Iams JD, Lockwood CJ, Moore TR, eds. Creasy and Resnik’s Maternal-Fetal Medicine: Principles
and Practice. 6th ed. Philadelphia: Saunders; 2009.
8. Cunningham F, Leveno KJ, Bloom SL, et al., eds. Williams Obstetrics. 24th ed. New York: McGraw-Hill; 2013.
9. Frigoletto FD, Lieberman E, Lang J, et al. A clinical trial of active management of labor. N Engl J Med.
1995;333:745–750.
10. Gherman RB, Ouzounian JG, Goodwin TM. Obstetric maneuvers for shoulder dystocia and associated fetal morbidity.
Am J Obstet Gynecol. 1998;178:1126.
11. Gilson GJ, Russell DJ, Izquiedero LA. A prospective randomized evaluation of a hygroscopic cervical dilator, Dilapan,
in the preinduction ripening of patients undergoing induction of labor. Obstet Gynecol. 1996;175:145.
12. Kazzi FM, Bottoms SF, Rosen MG. Efficacy and safety of laminaria digitata for preinduction ripening of the cervix.
Obstet Gynecol. 1982;60:440–443.
13. Lydon-Rochelle M, Holt VL, Easterling TR, Martin DP. Risk of uterine rupture during labor among women with a prior
cesarean delivery. N Engl J Med. 2001;345:3–8.
14. Osterman MJ, Martin JA. Recent declines in induction of labor by gestational age. NCHS Data Brief. 2014;155:1–8.
15. Spong CY, Berghella V, Wenstrom KD, Mercer BM, Saade GR. Preventing the first cesarean delivery: sum-
mary of a joint Eunice Kennedy Shriver National Institute of Child Health and Human Development, Society for
Maternal-Fetal Medicine, and American College of Obstetricians and Gynecologists Workshop. Obstet Gynecol.
2012;120:1181–1193.
16. Ventura SJ, Martin JA, Curtin SC, Mathews TJ. Births: final data for 1997. Natl Vital Stat Rep. 1999;47:1–96.
17. Zhang J, Landy HJ, Branch DW, et al. Contemporary patterns of spontaneous labor with normal neonatal outcomes.
Obstet Gynecol. 2010;116:1281–1287.
KEY POINTS: LABOR AND VAGINAL DELIVERY
1. Labor begins when uterine contractions of sufficient frequency, intensity, and duration are attained
to bring about effacement and progressive dilation of the cervix.
2. A Bishop score is a quantifiable method to assess the likelihood of a successful induction. If unfa-
vorable, cervical ripening can be done by mechanical (e.g., large Foley catheter) or pharmacologic
(e.g., prostaglandins, oxytocin) means.
3. Labor has three stages. The first stage (from the onset of contractions to complete dilation) is
divided into latent and active phases. Stage 2 is from complete dilation to delivery of fetus, and
stage 3 is from delivery of the fetus to delivery of the placenta.
4. The cardinal movements of labor are engagement, descent, flexion, internal rotation, extension,
external rotation, and expulsion.
5. Indications for operative vaginal delivery include any condition threatening the mother or fetus
during the second stage of labor that is likely to be relieved by delivery.
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272
1. What is intrapartum fetal surveillance, and why is it done?
Intrapartum fetal surveillance is how obstetricians monitor the fetal response to labor, and the goals
are to identify fetal hypoxia or acidemia and intervene early enough to prevent neurologic injury
or death. It most frequently refers to fetal heart rate monitoring. Additional, less common tech-
niques include fetal pulse oximetry, fetal scalp blood sampling, vibroacoustic stimulation, and fetal
electrocardiography.
2. How is fetal heart rate monitoring performed?
Fetal heart rate monitoring can be divided into intermittent and continuous monitoring. Continuous
monitoring can then be further classified as external or internal (Fig. 62-1).
• Intermittent auscultation: Intermittent auscultation is performed using a handheld Doppler device
to assess the fetal heart rate periodically. The optimal frequency has not been established, but the
most commonly cited protocol involves auscultation every 30 minutes during the first stage of labor
and every 15 minutes during the second stage.
• Electronic fetal monitoring, external: An ultrasound transducer and detector device are secured
to the maternal abdomen over an area where the fetal heart rate is best detected. The transducer
sends out ultrasound waves that are reflected from the motion of the fetal heart back to the
transducer. A microprocessor analyses these reflections and transcribes them onto a moving paper
reel or through a computer program that displays the fetal heart tracing on a computer screen. The
provider can then evaluate the fetal heart pattern.
• Electronic fetal monitoring, internal: A bipolar electrode is attached directly to the fetal
scalp, inserted just under the skin. The electrical fetal cardiac signal is then amplified, and the
heart rate is calculated. Because the fetal heart rate is measured directly, as opposed to being
measured through the maternal abdomen, internal monitoring is a more precise measure of
fetal status.
3. Is electronic fetal monitoring superior to intermittent auscultation?
Multiple clinical trials comparing electronic monitoring with intermittent auscultation showed no clear
benefit. However, these studies were limited to normal, uncomplicated pregnancies. Data also suggest
that the protocol for intermittent auscultation is successfully followed only a small percentage of the
time. For these reasons, electronic monitoring is most frequently the method of intrapartum surveil-
lance in labor and delivery units.
CHAPTER 62
INTRAPARTUM FETAL
SURVEILLANCE
Laurin Cristiano, MD
Fetal heart
rate monitoring
Intermittent
auscultation
Continuous fetal
monitoring
External – ultrasound
doppler
Internal – fetal
scalp electrode
Figure 62-1. Fetal heart rate monitoring.
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