Normal Labor Flashcards
At the onset of labor, the position of the fetus with respect to the birth canal is critical to the route of delivery and thus should be determined in early labor. Important relationships include_______________________________.
fetal lie,
presentation,
attitude,
and position.
“FPAP”
The relation of the fetal long axis to that of the mother is termed ________and is either longitudinal or transverse.
Fetal Lie
The relation of the fetal long axis to that of the mother is termed fetal lie and is either______________
longitudinal or transverse.
Occasionally, the fetal and the maternal axes may cross at a 45-degree angle, forming an _________ This lie is unstable and becomes longitudinal or transverse during labor.
oblique lie.
A _____________ is present in more than 99 percent of labors at term.
longitudinal lie
Predisposing factors for transverse fetal position include ________________(Chap. 23, p. 468).
multiparity,
placenta previa,
hydramnios, and
uterine anomalies
“HUMP”
The __________ is that portion of the fetal body that is either foremost within the birth canal or in closest proximity to it.
It typically can be felt through the cervix on vaginal examination.
Fetal Presentation
Accordingly, in___________, the presenting part is either the fetal head or breech, creating cephalic and breech presentations, respectively.
longitudinal lies
When the fetus lies with the long axis transversely, the______________ is the presenting part. Table 22-1 describes the incidences of the various fetal presentations.
shoulder
Cephalic Presentation
Such presentations are classified according to the relationship between the head and body of the fetus (Fig. 22-1). Ordinarily, the head is flexed sharply so that the chin is in contact with the thorax. The occipital fontanel is the presenting part, and this presentation is referred to as a______________
vertex or occiput presentation.
less commonly, the fetal neck may be sharply extended so that
the occiput and back come in contact,and theface is foremost
in the birth canal—__________ (Fig. 23-6, p. 466).
face presentation
The fetal head may assume a position between these extremes, partially flexed in some cases, with the anterior (large) fontanel, or bregma, presenting—__________
sinciput presentation
—or partially extended in other cases, to have a_________ (Fig. 23-8, p. 468).
brow presentation
These latter two presentations are usually__________.
As labor progresses, sinciput and brow presentations almost always convert into vertex or face presentations by neck flexion or extension, respectively. Failure to do so can lead to dystocia, as discussed in Chapter 23 (p. 455).
transient
The term fetus usually presents with the vertex, most logically
_______________.
because the uterus is piriform or pear shaped
Although the fetal head at term is slightly larger than the breech, the entire podalic pole of the fetus—that is, the _________________—is bulkier and more mobile than the cephalic pole.
breech and its flexed extremities
The____________ is composed of the fetal head only. Until approximately 32 weeks, the amnionic cavity is large compared with the fetal mass, and the fetus is not crowded by the uterine walls. Subsequently, however, the ratio of amnionic fluid volume decreases relative to the increasing fetal mass. As a result, the uterine walls are apposed more closely to the fetal parts.
cephalic pole
If ____________, the fetus often changes polarity to make use of the roomier fundus for its bulkier and more mobile podalic pole. As discussed in Chapter 28 (p. 559), the incidence of breech presentation decreases with gestational age. It approximates 25 percent at 28 weeks, 17 percent at 30 weeks, 11 percent at 32 weeks, and then decreases to approximately
3 percent at term.
presenting by the breech
The high incidence of breech presentation in
hydrocephalic fetuses is in accord with this theory, as the larger
fetal cephalic pole requires more room than its podalic pole.
Breech Presentation
When the fetus presents as a breech, the three general configurations are_____________and are described in Chapter 28 (p. 559).
NOTE :
Breech presentation may result from circumstances that prevent normal version from taking place. One example is a septum that protrudes into the uterine cavity (Chap. 3, p. 42). A peculiarity of fetal attitude, particularly extension of the vertebral column as seen in frank breeches, also may prevent the fetus from turning.
If the placenta is implanted in the lower uterine segment, it may distort normal intrauterine anatomy and result in a breech presentation.
frank, complete, and footling presentations
■ Fetal Attitude or Posture
In the later months of pregnancy, the fetus assumes a characteristic posture described as attitude or habitus as shown in Figure 22-1. As a rule, the fetus forms an ovoid mass that corresponds roughly to the shape of the uterine cavity. The fetus becomes folded or bent upon itself in such a manner that the back becomes markedly convex; the head is sharply flexed so that the chin is almost in contact with the chest; the thighs are flexed over the abdomen; and the legs are bent at the knees.
In all cephalic presentations, the arms are usually crossed over the thorax or become parallel to the sides.
The umbilical cord lies in the space between them and the lower extremities. This characteristic posture results from the mode of fetal growth and its accommodation to the uterine cavity.
Abnormal exceptions to this attitude occur as the ____________ from the vertex to the face presentation (see Fig. 22-1). This results in a progressive change in fetal attitude from a convex (flexed) to a concave (extended) contour of the vertebral column.
fetal head becomes progressively more extended
■ ___________________ refers to the relationship of an arbitrarily chosen portion of the fetal presenting part to the right or left side of the birth canal.
Accordingly, with each presentation there may be two positions—right or left.
Fetal Position Position
The________________________ are the determining points in vertex, face, and breech presentations, respectively (Figs. 22-2 to 22-6). Because the presenting part may be in either the left or right position, there are left and right occipital, left and right mental, and left and right sacral presentations. These are abbreviated as LO and RO, LM and RM, and LS and RS, respectively.
fetal occiput, chin (mentum), and sacrum
For still more accurate orientation, the relationship of a given portion of the presenting part to the anterior, transverse, or posterior portion of the maternal pelvis is considered. Because the presenting part in right or left positions may be directed ________________, there are six varieties of each of the three presentations as shown in Figures 22-2 to 22-6. Thus, in an occiput presentation, the presentation, position, and variety may be abbreviated in clockwise fashion as:
anteriorly (A), transversely (T), or posteriorly (P)
Approximately two thirds of all vertex presentations are in the _________, and one third in the _______________
left occiput position
Right
In shoulder presentations, the __________is the portion of the fetus arbitrarily chosen for orientation with the maternal pelvis. One example of the terminology sometimes employed for this purpose is illustrated in Figure 22-7. The acromion or back of the fetus may be directed either posteriorly or anteriorly and superiorly or inferiorly. Because it is impossible to differentiate exactly the several varieties of shoulder presentation by clinical examination and because such specific differentiation serves no practical purpose, it is customary to refer to all transverse lies simply as shoulder presentations. Another term used is transverse lie, with back up or back down, which is clinically important when deciding incision type for cesarean delivery (Chap. 23, p. 468).
acromion (scapula)
Diagnosis of Fetal Presentation and Position Several methods can be used to diagnose fetal presentation and position. These include _______________.
Rarely, plain radiographs, computed tomography, or magnetic resonance imaging may be used.
abdominal palpation,
vaginal examination,
auscultation,
and,
in certain doubtful cases, sonography
______________examination can be conducted systematically employing the four maneuvers described by Leopold in 1894 and shown in Figure 22-8. The mother lies supine and comfortably positioned with her abdomen bared. These maneuvers may be difficult if not impossible to perform and interpret if the patient is obese, if there is excessive amnionic fluid, or if the placenta is anteriorly implanted.
Abdominal Palpation—Leopold Maneuvers Abdominal
What are the reasons for the difficulty in perfoming the Leopods maneuver?
These maneuvers may be difficult if not impossible to perform and interpret if the patient is :
obese,
if there is excessive amnionic fluid,
or if the placenta is anteriorly implanted.
The first maneuver permits______________
identification of which fetal pole—that is, cephalic or podalic—occupies the uterine fun-dus.
In the first maneuver, The breech gives the sensation of a__________
whereas the head feels____________
large, nodular mass,
hard and round and is more mobile and
ballottable.
Performed after determination of fetal lie, the second maneuver is accomplished as the ________________
palms are placed on either side of the maternal abdomen, and gentle but deep pressure is exerted.
In the second maneuver, what can be felt is:
On one side, a _____________—the back.
On the other,_______________t—the fetal extremities.
hard, resistant structure is felt
numerous small, irregular, mobile parts are fel
By noting whether the is__________ directed anteriorly, transversely, or posteriorly, fetal orientation can be determined.
back
The third maneuver is performed by _________________.
grasping with the thumb and fingers of one hand the lower portion of the maternal abdomen just above the symphysis pubis
What is felt in the 3rd maneuver?
If the presenting part is not engaged, a **movable mass will be felt, **usually the___________. The differentiation between head and breech is made as in the first maneuver. If the presenting part is deeply engaged, however, the findings from this maneuver are simply indicative that the lower fetal pole is in the pelvis, and details are then defined by the fourth maneuver.
head
To perform the fourth maneuver, the________________
In many instances, when the head has descended into
the pelvis, the anterior shoulder may be differentiated readily
by the third maneuver.
examiner faces the mother’s feet and, with the tips of the first three fingers of each
hand, exerts deep pressure in the direction of the axis of the pelvic inlet.
Abdominal palpation can be performed throughout the latter months of pregnancy and during and between the contractions of labor. With experience, it is possible to estimate the size of the fetus. According to Lydon-Rochelle and colleagues (1993), experienced clinicians accurately identify fetal malpresentation using Leopold maneuvers with a high sensitivity—88 percent, specificity—94 percent, positive-predictive value—74 percent, and negative-predictive value—97 percent.
Before labor, the diagnosis of fetal presentation and position by _________ is often inconclusive because the presenting part must be palpated through a closed cervix and lower uterine segment. With the onset of labor and after cervical dilatation, vertex presentations and their positions are recognized by palpation of the various fetal sutures and fontanels. Face and breech presentations are identified by palpation of facial features and fetal sacrum, respectively.
vaginal examination
In attempting to determine
presentation and position by vaginal
examination, it is advisable to
pursue a definite routine, comprising
four movements.
First, the
examiner inserts two fingers into
the vagina and the presenting part
is found.
Differentiation of vertex,
face, and breech is then accomplished
readily.
Second, if the vertex
is presenting, the fingers are
directed posteriorly and then swept
forward over the fetal head toward
the maternal symphysis (Fig. 22-9).
During this movement, the fingers
necessarily cross the sagittal suture
and its linear course is delineated.
Next, the positions of the two fontanels are ascertained. For this, fingers are passed to the most anterior extension of the sagittal suture, and the fontanel encountered there is examined and identified. Then, with a sweeping motion, the fingers pass along the suture to the other end of the head until the other fontanel is felt and differentiated (Fig. 22-10).
Last, the station, or extent to which the presenting part has descended into the pelvis, can also be established at this time (p. 449). Using these maneuvers, the various sutures and fontanels are located readily (Fig. 7-11, p. 139).
Sonography and Radiography Sonographic techniques
can aid fetal position identification, especially in obese women or in women with rigid abdominal walls. Zahalka and associates (2005) compared digital examinations with transvaginal and transabdominal sonography for fetal head position determination during second-stage labor and reported that _______________
transvaginal sonography was superior.
__________________
In most cases, the vertex enters the pelvis with the sagittal suture
lying in the transverse pelvic diameter
. The fetus enters the pelvis
in the left occiput transverse (LOT) position in 40 percent
of labors and in the right occiput transverse (ROT) position in
20 percent (Caldwell, 1934).
In occiput anterior positions—LOA
or ROA—the head either enters the pelvis with the occiput
rotated 45 degrees anteriorly from the transverse position, or
this rotation occurs subsequently.
The mechanism of labor in
all these presentations is usually similar.
The positional changes of the presenting part required to
navigate the pelvic canal constitute the mechanisms of labor.
Occiput Anterior Presentation
The cardinal movements of labor are ___________________ (Fig. 22-11). During labor, these movements not only are sequential but also show great temporal overlap.
For example, as part of engagement, there is both flexion and descent of the head. It is impossible for the movements to be completed unless the presenting part descends simultaneously.
Concomitantly, uterine contractions effect important modifications in fetal attitude, or habitus, especially after the head has descended into the pelvis. These changes consist principally of fetal straightening, with loss of dorsal convexity and closer application of the extremities to the body. As a result, the fetal ovoid is transformed into a cylinder, with the smallest possible cross section typically passing through the birth canal.
engagement,
descent,
flexion,
internal rotation,
extension,
external rotation,
and expulsion
\
The mechanism by which the biparietal diameter—the greatest transverse diameter in an occiput presentation—passes through the pelvic inlet is designated __________
engagement.
The fetal head may engage during the last few weeks of pregnancy or not until after labor commencement.
In many multiparous and some nulliparous women, the fetal head is freely movable above the pelvic inlet at labor onset.
In this circumstance, the head is sometimes referred to as ___________” A normal-sized head usually does not engage with its sagittal suture directed anteroposteriorly. Instead, the fetal head usually enters the pelvic inlet either transversely or obliquely. Segel and coworkers (2012) analyzed labor in 5341 nulliparous women and found that fetal head engagement before labor onset did not affect vaginal delivery rates in either spontaneous or induced labor.
“floating.
The fetal head tends to accommodate to the transverse axis of the pelvic inlet, whereas the sagittal suture, while remaining parallel to that axis, may not lie exactly midway between the symphysis and the sacral promontory.
The sagittal suture frequently is deflected either posteriorly toward the promontory or anteriorly toward the symphysis (Fig. 22-12). Such lateral deflection to a more anterior or posterior position in the pelvis is called ___________
Asynclitism.
If the sagittal suture approaches the sacral promontory, more of the anterior parietal bone presents itself to the examining fingers, and the condition is called _________________
.
anterior asynclitism
If, however, the sagittal suture lies close to the symphysis, more of the posterior parietal bone will present, and the condition is called ______________
. With extreme posterior asynclitism, the posterior ear may be easily palpated.
posterior asynclitism
With extreme posterior asynclitism, the ____________-may be easily palpated. Moderate degrees of asynclitism are the rule in normal labor. However, if severe, the condition is a common reason for cephalopelvic disproportion even with an otherwise normalsized pelvis. Successive shifting from posterior to anterior asynclitism aids descent.
posterior ear
This movement is the first requisite for birth of the newborn.
Descent
In nulliparas, engagement may take place __________, and further descent may __________
before the onset of labor
not follow until the onset of the second stage.
In multiparas, descent usually begins with ____________-
engagement.
Descent is brought about by one or more of four forces:
(1) pressure of the amnionic fluid,
(2) direct pressure of the fundus upon the breech with contractions
, (3) bearing-down efforts of maternal abdominal muscles, and
(4) extension and straightening of the fetal body.
As soon as the descending head meets
resistance,whether from the cervix, pelvic
walls, or pelvic floor, it normally flexes.
With this movement, the chin is brought
into more intimate contactwith thefetal
thorax, and the appreciably shorter suboccipitobregmatic
diameter is substituted
for the longer occipitofrontal diameter
Flexion
This movement consists of a turning of the head in such a manner
that the occiput gradually moves toward the symphysis
pubis anteriorly from its original position or, less commonly,
posteriorly toward the hollow of the sacrum(Figs. 22-15 to
22-17).
___________ is essential for completion of labor,
except when the fetus is unusually small.
Internal Rotation
Calkins (1939) studied more than 5000 women in labor to
ascertain the time of internal rotation. He concluded that in
approximately two thirds, internal rotation is completed by the
time the head reaches the pelvic floor;
in about another fourth,
internal rotation is completed shortly after the head reaches the
pelvic floor;
and in the remaining 5 percent, rotation does not
take place. When the head fails to turn until reaching the pelvic
floor, it typically rotates during the next one or two contractions
in multiparas.
In nulliparas, rotation usually occurs during the next________________
three to five contractions.
After internal rotation, the sharply flexed head reaches the vulva and undergoes extension. If the sharply flexed head, on reaching the pelvic floor, did not extend but was driven farther downward, it would impinge on the posterior portion of the perineum and would eventually be forced through the perineal tissues.16).
Extension
When the head presses on the pelvic floor, however, two forces come into play.
The first force, exerted by the uterus, acts more posteriorly, and the second, supplied by the resistant pelvic floor and the symphysis, acts more anteriorly. The resultant vector is in the direction of the vulvar opening, thereby causing head extension. This brings the base of the occiput into direct contact with the inferior margin of the symphysis pubis (see Fig. 22-
With progressive distention of the perineum and vaginal opening, an increasingly larger portion of the occiput gradually appears. The head is born as the _____________________pass successively over the anterior margin of the perineum (see Fig. 22-17). Immediately after its delivery, the head drops downward so that the chin lies over the maternal anus.
occiput, bregma, forehead, nose, mouth, and finally the chin
The delivered head next undergoes restitution (see Fig. 22-11). If the occiput was originally directed toward the left, it rotates toward the left ischial tuberosity. If it was originally directed toward the right, the occiput rotates to the right. Restitution of the head to the oblique position is followed by______________ completion to the transverse position. This movement corresponds to rotation of the fetal body and serves to bring its bisacromial diameter into relation with the anteroposterior diameter of the pelvic outlet. Thus, one shoulder is anterior behind the symphysis and the other is posterior. This movement apparently is brought about by the same pelvic factors that produced internal rotation of the head.
External Rotation
Almost immediately after external rotation, the anterior shoulder appears under the symphysis pubis, and the perineum soon becomes distended by the posterior shoulder.
Expulsion
After delivery of the ____________ the rest of the body quickly passes.
shoulders,
In approximately 20 percent of labors, the fetus enters the pelvis in an_______________ (Caldwell, 1934).
The right occiput posterior (ROP) is slightly more common than the left (LOP)
Occiput Posterior Presentation
. It appears likely from radiographic evidence tha occiput posterior presentation are more often associated with a ____________. They also are more commonly seen in association with anterior placentation (Gardberg, 1994a)
.
narrow forepelvis
In most occiput posterior presentations, the mechanism of labor is identical to that observed in the transverse and anterior varieties, except that the occiput has to internally rotate to the symphysis pubis through 135 degrees, instead of 90 and 45 degrees, respectively (see Fig. 22-17).
______________ together permit most posteriorly positioned occiputs to rotate promptly as soon as they reach the pelvic floor, and labor is not lengthened appreciably.
Effective contractions, adequate head flexion, and average fetal size
In perhaps 5 to 10 percent of cases, however, rotation may be incomplete or may not take place at all, especially if the fetus is large (Gardberg, 1994b).
______________which diminishes abdominal muscular pushing
and relaxes pelvic floor muscles, may predispose to incomplete
rotation.
If rotation is incomplete, transverse arrest may
result. If no rotation toward the symphysis takes place, the
occiput may remain in the direct occiput posterior position, a
condition known as persistent occiput posterior. Both persistent
occiput posterior and transverse arrest represent deviations
from the normal mechanisms of labor and are considered further
in Chapter 23.
Poor contractions, faulty head flexion, or epidural analgesia,
In vertex presentations, labor forces alter fetal head shape.
In prolonged labors before complete cervical dilatation, the
portion of the fetal scalp immediately over the cervical os
becomes edematous (Fig. 33-1, p. 647). This swelling, known
as the ____________, is shown in Figures 22-18 and
22-19. It usually attains a thickness of only a few millimeters,
but in prolonged labors it may be sufficiently extensive to
prevent differentiation of the various sutures and fontanels.
More commonly, it is formed when the head is in the
lower portion of the birth canal andfrequently only after the
resistance of a rigid vaginal outlet is encountered. Because it
develops over the most dependent area of the head, one may
deduce the original fetal head position by noting the location
of the caput succedaneum.
Caput Succedaneum
In addition to soft tissue changes, the bony fetal head shape is also altered by external compressive forces and is referred to as ___ (see Fig. 22-19).
Molding
NOTE : Possibly related to Braxton Hicks contractions, some molding develops before labor. Most studies indicate that there is seldom overlapping of the parietal bones. A “locking” mechanism at the coronal and lambdoidal connections actually prevents such overlapping (Carlan, 1991).
Molding results in a shortened suboccipitobregmatic diameter and a lengthened mentovertical diameter. These changes are of greatest importance in women with contracted pelves or asynclitic presentations.
In these circumstances, the degree to which the head is capable of molding may make the difference between spontaneous vaginal delivery and an operative delivery. Some older literature cited severe head molding as a cause for possible cerebral trauma. Because of the multitude of associated factors, for example, prolonged labor with fetal sepsis and acidosis, it is impossible to link molding to any alleged fetal or neonatal neurological sequelae. Most cases of molding resolve within the week following delivery, although persistent cases have
been described
The strict definition of ___________—uterine contractions that bring about demonstrable effacement and dilatation of the cervix—does not easily aid the clinician in determining when labor has actually begun, because this diagnosis is confirmed only retrospectively. Several methods may be used to define its start. One defines onset as the clock time when painful contractions become regular. Unfortunately, uterine activity that causes discomfort, but that does not represent true labor, may develop at any time during pregnancy.
False labor often stops spontaneously, or it may proceed rapidly into effective contractions.
labor
The greatest impediment to understanding normal labor is __________________.
recognizing its start
When can we define the onset of labor?
- One defines onset as the clock time when painful contractions become regular. Unfortunately, uterine activity that causes discomfort, but that does not represent true labor, may develop at any time during pregnancy. False labor often stops spontaneously, or it may proceed rapidly into effective contractions.
- A second method defines the onset of labor as beginning at the time of admission to the labor unit. In the United States, admission for labor is frequently based on the extent of cervical dilatation accompanied by painful contractions. If a woman has intact membranes, then a cervical dilatation of 3 to 4 cm or greater is presumed to be a reasonably reliable threshold for the diagnosis of labor. In this case, labor onset commences
with the time of admission. This presumptive method obviates many of the uncertainties in diagnosing labor during earlier stages of cervical dilatation. Laughon and colleagues (2012) compared the duration of spontaneous labor at term in nulliparas delivered in the United States between 1959 and 1966 to that of those delivered from 2002 to 2008. As shown in Figure 22-20, the length of labor increased by approximately 2 hours during those 50 years
First Stage of Labor
Assuming that the diagnosis has been confirmed, what then are the expectations for the progress of normal labor? A scientific approach was begun by Friedman (1954), who described a characteristic sigmoid pattern for labor by graphing cervical dilatation against time. This graphical approach, based on statistical observations, changed labor management. Friedman
developed the concept of three functional labor divisions to
describe the physiological objectives of each division as shown
in Figure 22-21.
- preparatory division
- dilatational division
- pelvic division
First, during the ______________, although the cervix dilates little, its connective tissue components change considerably (Chap. 21, p. 410). Sedation and conduction analgesia are capable of arresting this labor division
preparatory division
The______________, during which dilatation proceeds at its most rapid rate, is unaffected by sedation.
dilatational division
Last, the ___________ commences with the deceleration phase of cervical dilatation. The classic labor mechanisms that involve the cardinal fetal movements of the cephalic presentation take place principally during this division.
In actual practice, however, the onset of the this division is seldom clearly identifiable.
pelvic division
As shown in Figure 22-21, the pattern of cervical dilatation during the preparatory and dilatational divisions of normal labor is a sigmoid curve. Two phases of cervical dilatation are defined.
The latent phase corresponds to the ______________, and the active phase to the ___________
preparatory division
dilatational division
. And as shown in Figure 22-22, Friedman subdivided the active phase into the_____________,_________________ and ____________
acceleration phase,
the phase of maximum slope,
and the deceleration phase.
Latent Phase
The onset of ___________, as defined by Friedman (1972), is the point at which the mother perceives regular contractions.
latent labor
The latent phase for most women ends once dilatation of _________ is achieved. This threshold may be clinically useful, for it defines dilatation limits beyond which active labor can be expected. This concept of a latent phase has great significance in understanding normal human labor, because labor is considerably longer when a latent phase is included. To better illustrate
3 to 5 cm
_______________ Friedman and Sachtleben (1963) defined this by a latent phase exceeding 20 hours in the nullipara and 14 hours in the multipara. These times corresponded to the 95th percentiles.
Prolonged Latent Phase.
Factors that affected latent phase duration include________________________
In those who had been administered heavy sedation, 85 percent of women eventually entered active labor. In another 10 percent, uterine contractions ceased, suggesting that they had false labor. The remaining 5 percent experienced persistence of an abnormal latent phase and required oxytocin stimulation. Amniotomy was discouraged because of the 10-percent incidence of false labor. Sokol and associates (1977) reported a 3- to 4- percent incidence of prolonged latent phase, regardless of parity. Friedman (1972) reported that latent phase prolongation did not adversely influence fetal or maternal morbidity or mortality rates. However, Chelmow and coworkers (1993) disputed the long-held belief that prolongation of the latent phase is benign.
excessive sedation or epidural analgesia;
unfavorable cervical condition, that is, thick, uneffaced, or undilated;
and false labor.
The progress of labor in nulliparas has particular significance because these curves all reveal a rapid change in the slope of cervical dilatation rates between 3 and 5 cm (see Fig. 22-23).Thus, cervical dilatation of 3 to 5 cm or more, in the presence of uterine contractions, can be taken to reliably represent the threshold for _______. Similarly, these curves provide useful guideposts for labor management.
Active Labor
Turning again to Friedman (1955), the mean duration of active-phase labor in nulliparas was__________.
But the standard deviation of 3.4 hours is large, hence, the active phase was reported to have a statistical maximum of 11.7 hours.
4.9 hours
Indeed, rates of cervical dilatation ranged from a minimum _______________
1.2 up to 6.8 cm/hr.
Friedman (1972) also found that multiparas progress somewhat faster in active-phase labor, with a minimum normal rate of_____________ His analysis of active-phase labor concomitantly describes rates of fetal descent and cervical dilatation (see Fig. 22-21). Descent begins in the later stage of active dilatation, commencing at 7 to 8 cm in nulliparas and becoming most rapid after 8 cm.
1.5 cm/hr.
Active-Phase Abnormalities. These have bee reported to occur in 25 percent of nulliparous and 15 percent of multiparous labors (Sokol, 1977). Friedman (1972) subdivided active-phase problems into __________________
protraction and arrest disorders.
___________ is defined as a slow rate of cervical dilatation or descent, which for nulliparas was < 1.2 cm dilatation per hour or < 1 cm descent per hour.
Protraction
For multiparas, protraction was defined as _______________.
< 1.5 cm dilatation per hour or < 2 cm descent per hour
Friedman defined___________as a complete cessation of dilatation or descent.
arrest
____________ was defined as 2 hours with no cervical change,
Arrest of dilatation
_______________as 1 hour without fetal descent.
The prognosis for protraction and arrest disorders differs considerably. Friedman found that approximately 30 percent of women with protraction disorders had cephalopelvic disproportion (CPD). This compared with a 45-percent CPD rate for women in whom an arrest disorder developed. Abnormal labor patterns, diagnostic criteria, and treatment methods are summarized in Chapter 23 (p. 456).
arrest of descent
Hendricks and colleagues (1970) challenged Friedman’s conclusions about the course of normal human labor. Their principal differences included:
(1) absence of a latent phase,
(2) no deceleration phase,
(3) brevity of labor, and
(4) dilatation at similar rates for nulliparas and multiparas after 4 cm.
Note: They disputed the concept of a latent phase because they observed that the cervix dilated and effaced slowly during the 4 weeks preceding labor. They contended that the latent phase actually progressed over several weeks. They also reported that labor was relatively rapid. Specifically, the average time from admission to complete dilatation was 4.8 hours for nulliparas and 3.2 hours for multiparas.
There have been other reports in which investigators have reassessed the Friedman labor curves. Zhang and associates (2010) studied electronic labor records from 62,415 parturients with spontaneous labor at term and vaginal birth.
They found that normal labor may take more than ______________________. Thereafter, labor accelerated much faster in multiparas. In a study performed at Parkland Hospital, epidural analgesia was found to lengthen the active phase of the Friedman labor curve by 1 hour (Alexander, 2002). This increase was the result of a slight but significant decrease in the rate of cervical dilatation—1.4 cm/hr in women given epidural analgesia compared with 1.6 cm/hr in those without such analgesia.
6 hours to progress from 4 to 5 cm and more than 3 hours to progress from 5 to 6 cm dilation
There are now several reports that_____________ lengthens the first stages of labor by 30 to 60 minutes (Chin, 2012; Kominiarek, 2011). Finally, Adams and coworkers (2012) found that_______________increased labor by approximately 45 minutes.
maternal obesity
maternal fear
This stage begins with complete cervical dilatation and ends with fetal delivery. The median duration is approximately 50 minutes for nulliparas and about 20 minutes for multiparas, but it is highly variable (Kilpatrick, 1989).
In a woman of higher parity with a previously dilated vagina and perineum, two or three expulsive efforts after full cervical dilatation may suffice to complete delivery. Conversely, in a woman with a contracted pelvis, with a large fetus, or with impaired expulsive efforts from conduction analgesia or sedation, the second stage may become abnormally long. Robinson and colleagues (2011) found that increasing maternal body mass index did not interfere with the second stage of labor. Abnormalities of this labor stage are described in Chapter 23 (p. 456).
Second Stage of Labor
Duration of Labor
Our understanding of the normal duration of labor may be clouded by the many clinical variables that affect conduct of labor in modern obstetrical units. Kilpatrick and Laros (1989) reported that the mean length of first- and second-stage labor was approximately_______________, and that the 95th percentile upper limit was 18.5 hours.
9 hours in nulliparous women without regional analgesia
Corresponding times for multiparous women were a mean of_______________
These authors defined labor onset as the time when a woman recalled regular, painful contractions every 3 to 5 minutes that led to cervical change. Spontaneous labor was analyzed in nearly 25,000 women delivered at term at Parkland Hospital in the early 1990s. Almost 80 percent of women were admitted with a cervical dilatation of 5 cm or less.
6 hours with a 95th percentile maximum of 13.5 hours.
_______________________ at admission were significant determinants of the length of spontaneous labor. The median time from admission to spontaneous delivery for all parturients was 3.5 hours, and 95 percent of all women delivered within 10.1 hours. These results suggest that normal human labor is relatively short. Zhang and associates (2009a,b) described similar findings in their study of 126,887 deliveries from 12 United States institutions.
Parity—nulliparous versus multiparous— and cervical dilatation
■ Summary of Normal Labor Labor
is characterized by brevity and considerable biological variation.
Active labor can be reliably diagnosed when cervical dilatation is 3 cm or more in the presence of uterine contractions.
Once this cervical dilatation threshold is reached, normal progression to delivery can be expected, depending on parity, in the ensuing 4 to 6 hours.
Anticipated progress during a 1- to 2-hour second stage is monitored to ensure fetal safety.
Finally, most women in spontaneous labor, regardless of parity, if left unaided, will deliver within approximately 10 hours after admission for spontaneous labor. Insufficient uterine activity is a common and correctable cause of abnormal labor progress. Therefore, when the length of otherwise normal labor exceeds the expected norm, interventions other than cesarean delivery—for example, oxytocin administration—must be first considered.
:)
MANAGEMENT OF NORMAL LABOR
The ideal management of labor and delivery requires two potentially opposing viewpoints on the part of clinicians.
First, birthing should be recognized as a normal physiological process that most women experience without complications.
Second, intrapartum complications, often arising quickly and unexpectedly, should be anticipated. Thus, clinicians must simultaneously make every woman and her supporters feel comfortable, yet ensure safety for the mother and newborn should complications suddenly develop
. Principles such as these are the basis for a recent “Call to Action” by seven national organizations intended to emphasize quality patient care in labor and delivery (Lawrence, 2012). The American Academy of Pediatrics and the American College of Obstetricians and Gynecologists (2012) have collaborated in the development of Guidelines for Perinatal Care. These provide detailed information on the appropriate content of intrapartum care, including both personnel and facility requirements. Shown in Table 22-2 are the recommended nurse-to-patient ratios recommended for labor and delivery. Shown in Table 22-3 are the recommended room dimensions for these functions.
TABLE 22-2. Recommended Nurse/Patient Ratios for Labor and Delivery Ratio Clinical Setting
** 1:2 Patients in labor**
1: 1 Patients in second-stage labor
1: 1 Patients with medical/obstetrical complications
1:2 Oxytocin induction/augmentation
1: 1 During epidural analgesia initiation
1: 1 Circulation for cesarean delivery
Admission Procedures
Pregnant women should be urged to report early in labor rather than to procrastinate until delivery is imminent for fear that they might be experiencing false labor.
Early admittance to the labor and delivery unit is important, especially if during antepartum care the woman, her fetus, or both have been identified as being at risk.
Identification of Labor
Although the differentiation between false and true labor is difficult at times, the diagnosis usually can be clarified by _________________ and ________________In those instances when a diagnosis of labor cannot be established with certainty, observation for a longer period is often wise.
contraction frequency and intensity and by cervical dilatation.
Pates and associates (2007) studied the commonly used recommendations given to pregnant women that, in the absence of ruptured membranes or bleeding,____________________
Among 768 women studied at Parkland Hospital, active labor defined as cervical dilatation ≥ 4 cm was diagnosed within 24 hours in three fourths of women with ≥ 12 contractions per hour. Bailit and coworkers (2005) compared labor outcomes of 6121 women who presented in active labor defined as uterine contractions plus cervical dilatation ≥ 4 cm with those of 2697 women who presented in the latent phase. Women admitted during latent-phase labor had more active-phase arrest, more frequent need for oxytocin labor stimulation, and higher rates of chorioamnionitis. It was concluded that physician interventions in women presenting in the latent phase may have been the cause of subsequent labor abnormalities.
uterine contractions 5 minutes apart for 1 hour—that is, ≥ 12 contractions in 1 hour—may signify labor onset.
_________________________ to ensure public access to emergency services regardless of the ability to pay.
All Medicare-participating hospitals with emergency services must provide an appropriate screening examination for any pregnant woman experiencing contractions and presenting to the emergency department for evaluation. The definition of an emergency condition makes specific reference to a pregnant woman who is having contractions.
Labor is defined as “the process of childbirth beginning with the latent phase of labor continuing through delivery of the placenta. A woman experiencing contractions is in true labor unless a physician certifies that after a reasonable time of observation the woman is in false labor.” A woman in true labor is considered “unstable” for interhospital transfer purposes until the newborn and placenta are delivered. An unstable woman may, however, be transferred at the direction of the patient or by a physician who certifies that the benefits of treatment at another facility outweigh the transfer risks. Physicians and hospitals violating these federal requirements are subject to civil penalties up to $50,000 and termination from the Medicare program.
Emergency Medical Treatment and Labor Act—EMTALA Congress enacted EMTALA in 1986
__________________is routinely used for high-risk pregnancies commencing at admission.
Electronic Fetal Heart Rate Monitoring As discussed in Chapter 24 (p. 473), electronic fetal heart rate monitoring
Some investigators recommend monitoring women with low-risk pregnancies upon admission as a test of fetal well-being—the so-called____________.
fetal admission test
Note :If no fetal heart rate abnormalities are detected, continuous electronic monitoring is replaced by intermittent assessment for the remainder of labor. We are of the view that electronic fetal heart rate monitoring is reasonable in the preadmission evaluation of women, including those who subsequently are discharged. At Parkland Hospital, external electronic monitoring is performed for at least 1 hour before discharging the woman who was ascertained to have false labor.
Home Births
A major emphasis of obstetrical care during the 20th century was the movement to birthing in hospitals rather than in homes. In 2006, 98.9 percent of births in the United States took place in hospitals (Martin, 2011). Of the other 1.1 percent, 67.2 percent were in homes, and 27.6 percent were in birthing centers. Between 2004 and 2008, more than half of all states had an increase in home births (MacDorman, 2011). As discussed in Chapter 1 (p. 11) most studies suggest increased risks with home deliveries (Berghella, 2008; Cheng, 2013; de Jonge, 2013; Grunebaum, 2013). Indeed, Chervenak and colleagues (2013) have questioned the ethics of physicians voluntarily involved in home births.
Initial Evaluation________________, ______________,__________ and __________ are recorded.
Maternal blood pressure, temperature, pulse, and respiratory rate
The pregnancy record is promptly reviewed to identify complications.
Problems identified or anticipated during prenatal care should be displayed prominently in the pregnancy record.
Most often, unless there has been bleeding in excess of bloody show, a _____________ is performed.
vaginal examination
Note: The gloved index and second fingers are then introduced into the vagina while avoiding the anal region (Fig. 22-24). The number of vaginal examinations correlates with infection-related morbidity, especially in cases of early membrane rupture.
Ruptured Membranes
The woman should be instructed during the antepartum period to be aware of fluid leakage from the vagina and to report such an event promptly. Rupture of the membranes is significant for three reasons.
- First, if the presenting part is not fixed in the pelvis, the possibility of umbilical cord prolapse and compression is greatly increased.
- Second, labor is likely to begin soon if the pregnancy is at or near term.
- Third, if delivery is delayed after membrane rupture, intrauterine infection is more likely as the time interval increases (Herbst, 2007). Upon sterile speculum examination, ruptured membranes are diagnosed if amnionic fluid pools in the posterior fornix or clear fluid flows from the cervical canal.
:Although several diagnostic tests for the detection of ruptured membranes have been recommended, none is completely reliable
. If the diagnosis remains uncertain, another method involves _________________
pH determination of vaginal fluid.
Note : The pH of vaginal secretions normally ranges from 4.5 to 5.5, whereas that of amnionic fluid is usually 7.0 to 7.5.
The use of the _____________ to identify ruptured membranes is a simple and fairly reliable method.
Test papers are impregnated with the dye, and the color of the reaction between these paper strips and vaginal fluids is interpreted by comparison with a standard color chart.
A pH above 6.5 is consistent with ruptured membranes.
indicator nitrazine
False-positive test results may occur with____________,_______________ and _________ for pH testing ruptured membranes.
coexistent blood, semen, or bacterial vaginosis in
, whereas false-negative tests may result with _____________
scant fluid.
Other tests include arborization or ferning of vaginal
fluid, which suggests amnionic rather than cervical fluid.
Amnionic fluid crystallizes to form a fernlike pattern due to
its relative concentrations of sodium chloride, proteins, and
carbohydrates (Fig. 4-2, p. 49).
Detection of alpha-fetoprotein
in the vaginal vault has been used to identify amnionic
fluid (Yamada, 1998). Although rarely required, identification
may also follow injection of indigo carmine into the
amnionic sac via abdominal amniocentesis
The degree of cervical effacement usually is expressed in terms of the_____________ compared with that of an uneffaced cervix. When the length of the cervix is reduced by one half, it is 50-percent effaced. When the cervix becomes as thin as the adjacent lower uterine segment, it is completely, or
100-percent, effaced.
** length of the cervical canal**
________________ is determined by estimating the average diameter of the cervical opening by sweeping the examining finger from the margin of the cervical opening on one side to that on the opposite side. The diameter traversed is estimated in centimeters.
Cervical dilatation
The cervix is said to be dilated fully when the diameter measures _____________, because the presenting part of a term-size newborn usually can pass through a cervix this widely dilated.
10 cm
The ____________ is determined by the relationship of the cervical os to the fetal head and is categorized as posterior, mid-position, or anterior. Along with position, the consistency of cervix is determined to be soft, firm, or intermediate between these two.
position of the cervix
The ___________of the presenting fetal part in the birth
canal is described in relationship to the ischial spines, which are
halfway between the pelvic inlet and the pelvic outlet.
level—or station—
When
the lowermost portion of the presenting fetal part is at the level
of the spines, it is designated as being at ______. In
the past, the long axis of the birth canal above and below the
ischial spines was arbitrarily divided into thirds by some and
into fifths (approximately 1 cm) by other groups. In 1989, the
American College of Obstetricians and Gynecologists adopted
the classification of station that divides the pelvis above and
below the spines into fifths. Each fifth represents 1 cm above
or below the spines. Thus, as the presenting fetal part descends
from the inlet toward the ischial spines, the designation
is –5, –4, –3, –2, –1, then 0 station. Below the spines, as the
presenting fetal part descends, it passes +1, +2, +3, +4, and +5
stations to delivery. Station +5 cm corresponds to the fetal head
being visible at the introitus.
zero (0) station
If the leading part of the fetal head is at 0 station or below,
most often the fetal head has engaged—thus, the biparietal
plane has passed through the pelvic inlet. If the head is unusually
molded or if there is an extensive caput formation or both, engagement
might not have taken place although the head appears to be
at 0 station
These five characteristics: __________, ___________ , __________ and _____________ are assessed when tabulating the Bishop score. This score is commonly used to predict labor induction outcome and is discussed in Chapter 26 (p. 526). FIGURE 22-24 To perform vaginal examination, the labia have been separated with one hand, and the first and second fingers of the other hand are carefully inserted into the introitus.
cervical dilatation, effacement, consistency, position, and fetal station
■ Laboratory Studies When a woman is admitted in labor, most often the ________________ concentration should be rechecked.
The hematocrit can be measured easily and quickly. At Parkland Hospital, blood is collected in a standard collection tube with anticoagulant. From this, a heparinized capillary tube is filled to spin in a microhematocrit centrifuge in the labor and delivery unit. This provides a hematocrit value within 3 minutes. The initial collection tube is also sent to the hematology laboratory for evaluation. Another labeled tube of blood is allowed to clot and sent to the blood bank for blood type and antibody screen, if needed. A final sample is collected for syphilis and human immunodeficiency virus (HIV) serology. We obtain a urine specimen for protein determination in hypertensive women only (Chap. 40, p. 729). In some labor units, however, a clean-catch voided specimen is examined in all women for protein and glucose.
Women who have had no prenatal care should be considered to be at risk for syphilis, hepatitis B, and HIV (Chap. 65, p. 1265). In those with no prior prenatal care, these laboratory studies, as well as a blood type and antibody screen, should be performed (American Academy of Pediatrics and American College of Obstetricians and Gynecologists, 2012). Some states, for example, Texas, require routine testing for syphilis, hepatitis B, and HIV in all women admitted to labor and delivery units, even if these were done during prenatal care.
hematocrit or hemoglobin
Management of the First Stage of Labor
- Intrapartum Fetal Monitoring 2. Maternal Vital Signs 3. Subsequent Cervical Examinations 4. Oral Intake 5. Intravenous Fluids 6.Maternal Position 7. Analgesia 8. Amniotomy 9. Urinary Bladder Function
This is discussed in detail in Chapter 24. Briefly, the American Academy of Pediatrics and American College of Obstetricians and Gynecologists (2012) recommend that during first-stage labor, in the absence of any abnormalities, the fetal heart rate should be checked immediately after a contraction at least every 30 minutes and then every 15 minutes during the second stage.
If continuous electronic monitoring is used, the tracing is evaluated at least every 30 minutes during the first stage and at least every 15 minutes during second-stage labor.
Intrapartum Fetal Monitoring
For women with pregnancies at risk, _____________ is performed at least every 15 minutes during first-stage labor and every 5 minutes during the second stage.
Continuous electronic monitoring may be used with evaluation of the tracing every 15 minutes during the first stage of labor, and every 5 minutes during the second stage.
fetal heart auscultation
Uterine Contractions
Although usually assessed by electronic monitoring as also discussed in Chapter 24, contractions can be both quantitatively and qualitatively evaluated manually.
With the palm of the hand resting lightly on the uterus, the time of contraction onset is determined.
Its intensity is gauged from the degree of firmness the uterus achieves.
At the acme of effective contractions, the finger or thumb cannot readily indent the uterus during a “firm” contraction. The time at which the contraction disappears is noted next. This sequence is repeated to evaluate the frequency, duration, and intensity of uterine contractions.
Uterine Contractions
Maternal Vital Signs
Temperature, pulse, and blood pressure are evaluated at least
every ____________.
4 hours
If membranes have been ruptured for many hours before labor onset or if there is a borderline temperature elevation, the temperature is checked__________.
NOTE :
Moreover, with prolonged membrane rupture, defined as greater than 18 hours, antimicrobial administration for prevention of group B streptococcal infections is recommended. This is discussed in Chapter 64 (p. 1249).
hourly
Subsequent Cervical Examinations
During the first stage of labor, the need for subsequent vaginal examinations to monitor cervical change and presenting part position will vary considerably.
When the membranes rupture, an examination to exclude cord prolapse should be performed expeditiously if the fetal head was not definitely engaged at the previous examination.
The fetal heart rate should also be checked immediately and during the next uterine contraction to help detect occult umbilical cord compression.
At Parkland Hospital, periodic pelvic examinations are typically performed at 2- to 3-hour intervals to evaluate labor progress.
Oral Intake
Food should be withheld during ____________.
Gastric emptying time is remarkably prolonged once labor is established and analgesics are administered.
As a consequence, ingested food and most medications remain in the stomach and are not absorbed. Instead, they may be vomited and aspirated (Chap. 25, p. 519).
NOTE : According to the American Academy of Pediatrics and the American College of Obstetricians and Gynecologists (2007), sips of clear liquids, occasional ice chips, and lip moisturizers are permitted.
active labor and delivery
Intravenous Fluids
Although it has become customary in many hospitals to establish an intravenous infusion system routinely early in labor, there is seldom any real need for this in the normal pregnant woman, at least until analgesia is administered.
An intravenous infusion system is advantageous during the immediate puerperium to administer oxytocin prophylactically and at times therapeutically when uterine atony persists.
Moreover, with longer labors, the administration of glucose, sodium, and water to the otherwise fasting woman at the rate of _______________prevents dehydration and acidosis. Shrivastava and associates (2009) noted shorter labors in nulliparas delivering vaginally who were provided an intravenous normal saline with dextrose solution compared with those given saline solution only. Garite and coworkers (2000) randomly assigned 195 women in labor to receive either 125 or 250 mL/hr of lactated Ringer or
isotonic sodium chloride solution. The mean volume of total
intravenous fluid was 2008 mL in the 125 mL/hr group and
2487 mL in the 250 mL/hr group. Labor lasted > 12 hours in
significantly more (26 versus 13 percent) of the women given
a 125 mL/hr infusion compared with those given 250 mL/
hr—26 versus 13 percent, respectively.
60 to 120 mL/hr
Analgesia This is discussed in detail in Chapter 25. In general, pain relief should depend on theNext** needs and desires of the woman.** The American College of Obstetricians and Gynecologists (2009) has specified optimal goals for anesthesia care in obstetrics.
Amniotomy
If the membranes are intact, there is a great temptation, even during normal labor, to perform_____________
The presumed benefits are more rapid labor, earlier detection of meconiumstained amnionic fluid, and the opportunity to apply an electrode to the fetus or insert a pressure catheter into the uterine cavity for monitoring.
The advantages and disadvantages of amniotomy are discussed in Chapter 26 (p. 531). Importantly, the fetal head must be well applied to the cervix and not be dislodged from the pelvis during the procedure to avert umbilical cord prolapse.
amniotomy.
Urinary Bladder Function
Distention of the bladder should be _______ because it can hinder descent of the fetal presenting part and lead to subsequent bladder hypotonia and infection.
During each abdominal examination, the suprapubic region should be inspected and palpated to detect distention. If the bladder is readily seen or palpated above the symphysis, the woman should be encouraged to void. At times, those who may be unable to void on a bedpan may be able to ambulate with assistance to a toilet and successfully void.
If the bladder is distended and voiding is not possible, catheterization is indicated. Carley and coworkers (2002) found that 51 of 11,332 vaginal deliveries (1 in 200) were complicated by urinary retention. Most women resumed normal voiding before discharge from the hospital. Musselwhite and associates (2007) reported retention in 4.7 percent of women who had labor epidural analgesia. Risk factors for retention were primiparity, oxytocin-
induced or -augmented labor,perineal lacerations, operative
vaginal delivery, catheterization during labor, and labor
duration > 10 hours.
avoided
Management of the
Second Stage of Labor
Expulsive Efforts
In most cases, bearing down is reflexive and spontaneous during second-stage labor.
Occasionally, a woman may not employ her expulsive forces to good advantage and coaching is desirable.
Her legs should be half-flexed so that she can push with them against the mattress.
When the next uterine contraction begins, she is instructed to exert downward pressure as though she were straining at stool.
A woman is not encouraged to push beyond the completion of each contraction.
Instead, she and her fetus should be allowed to rest and recover.
During this period of actively bearing down, the fetal heart rate auscultated immediately after the contraction is likely to be slow but should recover to normal range before the next expulsive effort.
Several positions during the second stage have been recommended to augment pushing efforts. Eason and colleagues (2000) performed an extensive review of various positions and their effect on the incidence of perineal trauma. They found that the supported upright position had no advantages over the recumbent one.
Upright positions include sitting, kneeling, squatting, or resting with the back at a 30-degree elevation. Conversely, in their systematic review, Berghella and coworkers (2008) reported good-quality data that supported the upright position. Fetal and obstetrical outcomes appear to be unaffected whether pushing is coached or uncoached during second-stage labor (Bloom, 2006; Tuuli, 2012).
The maternal effects of coached pushing were reported by Schaffer and colleagues (2005), who performed urodynamic testing in primigravidas 3 months following delivery. Women coached to push during second-stage labor had decreased bladder capacity and decreased first urge to void compared with women encouraged to push or rest as desired. The long-term effects of this practice are yet to be defined.
As the head descends through the pelvis, the perineum begins to bulge and the overlying skin becomes stretched. Now the scalp of the fetus may be visible through the vulvar opening. At this time, the woman and her fetus are prepared for delivery, which is described in Chapter 27 (p. 537).
LABOR MANAGEMENT PROTOCOLS
An orderly and systematic approach to labor management
results in reproducible maternal and perinatal outcomes. This
was proven by Althabe and coworkers (2008), who randomized
implementation of evidence-based care in 19 hospitals in
Argentina and Uruguay. Several labor management protocols
are subsequently presented. These include those from the
National Maternity Hospital in Dublin, the World Health
Organization, and from Parkland Hospital.
More than 30 years ago, O’Driscoll and associates (1984) pioneered the concept that a disciplined, standardized labor management protocol reduced the number of cesarean deliveries for dystocia.
Their overall cesarean delivery rate was 5 percent in the 1970s and 1980s with such management. The approach is now referred to as _____________.
Two of its components—amniotomy and oxytocin— have been widely used, especially in English-speaking countries outside the United States.
With this protocol, labor is diagnosed when painful contractions are accompanied by complete cervical effacement, bloody “show,” or ruptured membranes.
Women with such findings are committed to delivery within 12 hours.
Pelvic examination is performed each hour for the next 3 hours, and thereafter at 2-hour intervals.
active management of labor
When dilatation has not increased by at least 1 cm/hr, __________ is performed.
Progress is again assessed at 2 hours and high-dose oxytocin infusion, described in Chapter 26 (p. 530), is started unless dilatation of at least 1 cm/hr is documented. Women are constantly attended by midwives. If membranes rupture before admission, oxytocin is begun for no progress at the 1-hour mark.
López-Zeno and colleagues (1992) prospectively compared such active management with their “traditional” approach to labor management at Northwestern Memorial Hospital in Chicago. They randomly assigned 705 nulliparas with uncomplicated pregnancies in spontaneous labor at term.
The cesarean delivery rate was significantly lower with active versus traditional management—10.5 versus 14.1 percent, respectively. Subsequent studies did not show this. Wei and associates (2009) in a Cochrane database review found a modest reduction in cesarean delivery rates when active management of labor was compared with standard care. Frigoletto and coworkers (1995) reported another randomized trial with 1934 nulliparous women at Brigham and Women’s Hospital in Boston. Although they found that such management somewhat shortened labor, it did not affect the cesarean delivery rate. These observations have since been reported by many others (Brown, 2008).
amniotomy
A ___________ was designed by the World Health Organization (WHO) for use in developing countries (Dujardin, 1992). According to Orji (2008), the partograph is similar for nulliparas and multiparas.
partograph
Labor is divided into a latent phase, which should last no ___________, and an active phase.
longer than 8 hours
The active phase starts at ________ and progress should be no slower than 1 cm/hr.
3 cm dilatation,
A ______________ is recommended before intervention when the active phase is slow.
Labor is graphed, and analysis includes use of alert and action lines. Lavender and colleagues (2006) randomized 3000 nulliparous women to labor interventions at 2 hours versus 4 hours as recommended by WHO. Their cesarean delivery rate was unaffected, and they concluded that interventions such as amniotomy and oxytocin were needlessly increased using the 2-hour time interval. After their Cochrane Database review, Lavender and associates (2008) do not recommend use of the partograph for standard labor management.
4-hour wait
Parkland Hospital Labor
Management Protocol
Women are admitted if active labor—defined as cervical dilatation
of 3 to 4 cm or more in the presence of uterine contractions—
is diagnosed or if ruptured membranes are confirmed
.
Management guidelines summarized in Figure 22-25 stipulate
that a pelvic examination be performed approximately
every 2 hours.
Ineffective labor is suspected when the cervix
does not dilate within approximately 2 hours of admission.
Amniotomy is then performed, and labor progress determined
at the next 2-hour evaluation. In women whose labors
do not progress, an intrauterine pressure catheter is placed
to assess uterine function.
Hypotonic contractions and no
cervical dilatation after an additional 2 to 3 hours result in
stimulation of labor using the high-dose oxytocin regimen
described in Chapter 26 (p. 530). The goal is uterine activity
of 200 to 250 Montevideo units for 2 to 4 hours before
dystocia can be diagnosed.
