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Normal Labor and Delivery

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Title: Normal Labor and Delivery


1
Normal Labor and Delivery
  • The Obstetrics and Gynecology Hospital of Fudan
    University
  • Jing-Xin Ding

2
  • According to the New Shorter Oxford English
    Dictionary (1993), toil, trouble, suffering,
    bodily exertion, especially when painful, and an
    outcome of work are all characteristics of labor.

3
Definition
  • Labor is the period from the onset of regular
    uterine contractions until expulsion of the fetus
    and the placenta, and it is defined as that
    occurring after 28 completed weeks of gestation.

4
  • Preterm delivery occurring after 28 weeks and
    before 37 completed weeks of gestation. In some
    developing countries, this time point has been
    advanced to 20 gestational weeks.
  • Term delivery occurring after 37 weeks and
    before 42 completed weeks of gestation.
  • Postterm delivery occurring after 42 completed
    weeks of gestation.

5
CHAPTER 1 THE HYPOTHESIS OF PARTURITION
INITIATION
  • 1. Mechanic theory
  • UTERINE QUIESCENCE During the early stage of
    pregnancy, a remarkably period of myometrial
    quiescence is imposed.
  • CERVICAL SOFTENING By the end of pregnancy,
    easily distensible, increase in tissue compliance

6
Uterine awakening or activation
  • During the end stage of pregnancy, the fetus
    compressed the lower segment and cervix of the
    uterus, and mechanic effect induced the
    initiation of labor.
  • There is no doubt that multifetal pregnancy and
    hydramnios lead to an increased risk of preterm
    birth.
  • It is likely that uterine distension acts to
    initiate expression of
  • contraction-associated proteins (CAPs) in the
    myometrium.

7
  • 2. Endocrine theory
  • The myometrial changes preparing it for labor
    contractions probably results from alterations in
    the expression of key endocrine proteins that
    control contractility. These proteins include the
    oxytocin and its receptor, prostaglandin and its
    receptor, estrogen, progesterone, and endothelin.

8
Prostagladin,PG
  • PG can promote the ripening of the cervix, and
    start the contraction of the uterine.
  • It can be synthesized in uterine muscle,
    placenta, etc.

9
Oxytocin and oxytocin receptor
  • Induce labor and promote the contraction of the
    uterine muscle.
  • The uterine sensitivity to oxytocin is increased
    before the initiation of labor.

10
Classical Progesterone Withdrawal and Parturition
  • In species that exhibit progesterone withdrawal,
    progression of parturition to labor can be
    blocked by administering progesterone to the
    mother.
  • In pregnant women, however, there are conflicting
    reports as to whether or not progesterone
    administration can delay the timely onset of
    parturition or prevent preterm labor.
  • Further research may help explain its
    differential action and how it could be better
    used to prevent preterm labor.

11
Endothelin, ET
  • Induce the contraction of the uterus.
  • Induce the synthesis and release of PG.

12
Fetal Contributions to Initiation of Parturition
  • The ability of the fetus to provide endocrine
    signals that initiate parturition has been
    demonstrated in several species.
  • This signal was shown to come from the fetal
    hypothalamic-pituitary-adrenal axis .

13
3. Neuromediator theory
  • The uterine contraction is controlled by the
    autonomic nerve.
  • It is still uncertain the role of autonomic nerve
    in the initiation of labor.

14
Summary
  • Labor onset represents the culmination of a
    series of biochemical changes in the uterus and
    cervix.
  • These result from endocrine and paracrine signals
    emanating from both mother and fetus.
  • Not fully defined.

15
CHAPTER 2 THE FACTORS DECIDING LABOR AND
DELIVERY
Force of the labor
Birth canal
Fetus
Mental and psychological factors
16
I Force of the labor
  • Uterine Contractions Main force
  • Maternal intra-abdominal pressure and the
    contranction of levator ani Ancillary forces

17
Characteristics of the uterine contractions
  • Rhythmicity
  • Symmetry
  • Polarity
  • Retraction effect

18
  • 1. Rhythmicity
  • Each contraction increase progressively in
    intensity and maintains the maxium intensity and
    then diminishes gradually.

19
  • the uterine baseline tone -- from 8 to 12 mm Hg
  • 25 mm Hg at commencement of labor to 50 mm Hg at
    the end of first stage
  • During second-stage labor, aided by maternal
    pushing, contractions of 100 to 150 mm Hg are
    typical.

20
  • At the beginning, the contracts occurs every 5-6
    minutes, and last 30 s. With the progression of
    labor, frequency increases to every 1-2 min and
    the duration increases to 60 s when the cervix is
    fully dilated.

21
  • 2. Symmetry
  • The normal contractile wave of labor originates
    near the uterine end of the fallopian tubes.
    Thus, these areas act as "pacemakers".

Contractions spread from the pacemaker area
throughout the uterus at 2 cm/sec, depolarizing
the whole uterus within 15 seconds.
22
  • 3. Polarity
  • Intensity is greatest in the fundus
  • Diminishes in the lower uterus.
  • Presumably, this descending gradient of pressure
    serves to direct fetal descent toward the cervix
    as well as to efface the cervix.
  • 4. Retraction effect
  • The muscle fiber retracts after contractions, and
    the cavity of the uterus becomes small, and the
    fetus is forced to descend.

23
Maternal intra-abdominal pressure -- pushing
  • Contraction of the abdominal muscles
    simultaneously with forced respiratory efforts
    with the glottis closed is referred to as
    pushing.
  • Similar to that with defecation, but the
    intensity usually is much greater.
  • After the cervix is dilated fully, the most
    important force in fetal expulsion is that
    produced by maternal intra-abdominal pressure.
  • Accomplishes little in the first stage. It
    exhausts the mother, and its associated increased
    intrauterine pressures may be harmful to the
    fetus.

24
The contraction of levator ani
  • The contraction of levator ani muscle contributes
    to
  • the internal rotation, extention and expulsion of
    the fetal head in the 2nd stage of labor
  • the delivery of placetenta in the 3rd stage of
    labor.

25
II Birth canal
  • Bony Pelvis
  • The soft birthing canal

26
Bony Pelvis
27
Pelvic Planes
  • 1.The pelvic inlet plane
  • 2.The mid plane of pelvis--the plane of least
    diameter
  • 3.The pelvic outlet plane

28
The pelvic inlet plane
  • bordered by the pubic crest anteriorly, the
    iliopectineal line of the innominate bones
    laterally, and the promontory of the sacrum
    posteriorly.

29
Four diameters anteroposterior, transverse, and
two oblique diameters.
  • The obstetric conjugate of the inlet -- distance
    between the promontory of the sacrum and the
    symphysis pubis. Normally, this measures 11 cm.

30
  • The transverse diameter is constructed at right
    angles to the obstetrical conjugate and
    represents the greatest distance between the
    linea terminalis on either side.
  • Each of the two oblique diameters extends from
    one of the sacroiliac synchondroses to the
    iliopectineal eminence on the opposite side.

31
The mid plane of pelvis--the plane of least
diameter
  • the most important from a clinical standpoint,
    because most instances of arrest of descent occur
    at this level.
  • It is bordered by the lower edge of the pubis
    anteriorly, the ischial spines and sacrospinous
    ligaments laterally, and the lower sacrum
    posteriorly.

32
  • The interspinous diameter, 10 cm or slightly
    greater, is usually the smallest pelvic diameter.
    The anteroposterior diameter through the level of
    the ischial spines normally measures at least
    11.5 cm.

33
The plane of the pelvic outlet
  • two approximately triangular areas with a common
    base
  • The apex of the posterior triangle is at the tip
    of the sacrum, and the lateral boundaries are the
    sacrosciatic ligaments and the ischial
    tuberosities.
  • The anterior triangle is formed by the area under
    the pubic arch.

34
  • The obstetric anteroposterior diameter extends
    from the inferior margin of the pubis to the
    sacrococcygeal joint.
  • The transverse (bituberous) diameter extends
    between the inner surfaces of the ischial
    tuberosities an average of 9 cm
  • The posterior sagittal diameter extends from the
    middle of the transverse diameter to the
    sacrococcygeal joint an average of 8.5 cm
  • The bituberous diameter the posterior sagittal
    diameter gt15 cm, then the fetus can be delivered
    through the posterior triangle.

35
Pelvic axis
  • -- an imaginary curved line that passes through
    the centers of the various diameters of the
    pelvis.
  • The pelvic axis first goes inferior and
    posterior, and then inferior, and then inferior
    and anterior.

36
Inclination of pelvis
  • The angle which the plane of the pelvic inlet
    makes with the horizontal plane when the patient
    is standing. The degree is usually 60 , if it is
    too much, the engagement and delivery is
    difficult.

37
The soft birthing canal
  • the lower uterine segments
  • the cervix
  • the vagina
  • the pelvic floor

38
Formation of the Lower Uterine Segments
  • The lower uterine segment is derived from the
    isthmus which is about 1 cm in nonpregnant
    uterus, and when the labor is started, with
    regular contractions of the upper uterine
    segment, it distended to 7 to 10cm.

39
  • the Physiological Retraction Ring
  • As a result of the lower segment thinning and
    concomitant upper segment thickening, a boundary
    between the two is marked by a ridge on the inner
    uterine surfacethe physiological retraction ring.

40
Cervical Changes
  • two fundamental changeseffacement and dilatation
  • For an average-sized fetal head to pass through
    the cervix, its canal must dilate to a diameter
    of approximately 10 cm.

41
Effacement of cervix
  • Cervical effacement is "obliteration" or "taking
    up" of the cervix.
  • It is manifest clinically by shortening of the
    cervical canal from a length of about 2-3 cm to a
    mere circular orifice with almost paper-thin
    edges.

42
Dilatation of cervix
  • The process of cervical effacement and dilatation
    causes the formation of the forebag of amnionic
    fluid, which is the leading portion of the
    amnionic sac and fluid located in front of the
    presenting part.
  • As uterine contractions cause pressure on the
    membranes, the hydrostatic action of the amnionic
    sac in turn dilates the cervical canal.
  • In the absence of intact membranes, the pressure
    of the presenting part against the cervix and
    lower uterine segment is similarly effective.

43
  • A. Before labor, the primigravid cervix is long
    and undilated in contrast to that of the
    multipara, which has dilatation of the internal
    and external os.
  • B. As effacement begins, the multiparous cervix
    shows dilatation and funneling of the internal
    os. This is less apparent in the primigravid
    cervix.
  • C. As complete effacement is achieved in the
    primigravid cervix, dilation is minimal. The
    reverse is true in the multipara.

44
Pelvic Floor Changes during Labor
  • The most marked change consists of the stretching
    of levator ani muscle fibers. This is accompanied
    by thinning of the central portion of the
    perineum, which becomes transformed from a
    wedge-shaped, 5-cm-thick mass of tissue to a
    thin, almost transparent membranous structure
    less than 1 cm thick.
  • The extraordinary number and size of the blood
    vessels that supply the vagina and pelvic floor
    result in substantive blood loss if these tissues
    are torn.

45
III Fetus
  • Size of fetus
  • Fetal lie, presentation and position
  • Fetal abnormalities

46
FETAL HEAD Important sutures and fontanelles
  • two frontal, two parietal, and two temporal
    bones, along with the occipital bone.

47
Sutures
The membrane-occupied spaces between the cranial
bones are known as sutures.
  • The sagittal suture lies between the parietal
    bones and extends in an anteroposterior direction
    between the fontanelles, dividing the head into
    right and left sides.
  • The lambdoid suture extends from the posterior
    fontanelle laterally and serves to separate the
    occipital from the parietal bones.
  • The coronal suture extends from the anterior
    fontanelle laterally and serves to separate the
    parietal and frontal bones.
  • The frontal suture lies between the frontal bones
    and extends from the anterior fontanelle to the
    glabella (the prominence between the eyebrows).

48
Fontanelles
  • The membrane-filled spaces located at the point
    where the sutures intersect are known as
    fontanelles.
  • The anterior fontanelle (bregma) is at the
    intersection of the sagittal, frontal, and
    coronal sutures. It is diamond shaped and
    measures approximately 23cm, and it is much
    larger than the posterior fontanelle.
  • The posterior fontanelle is Y- or T-shaped and
    is found at the junction of the sagittal and
    lambdoid sutures.

49
  • Clinically, they are useful in diagnosing the
    fetal head position.

50
Diameters
  • Occipitofrontal Diameter (11.3cm), extends from
    the external occipital protuberance to the
    glabella. The fetus usually engage by this
    diameter.
  • Suboccipitobregmatic Diameter (9.5cm), the
    presenting anteroposterior diameter when the head
    is well flexed, and it is the shortest
    anteroposterior diameter . It extends from the
    undersurface of the occipital bone at the
    junction with the neck to the center of the
    anterior fontanelle.

51
  • Occipitomental Diameter (13.3cm), the presenting
    anteroposterior diameter in a brow presentation
    and the longest anteroposterior diameter of the
    head it extends from the vertex to the chin.

52
  • Biparietal Diameter (9.3cm), the largest
    transverse diameter it extends between the
    parietal bones.
  • This diameter detected by antenatal ultrasonic
    examination was used to estimate the size of the
    fetus.

53
2. Fetal lie and presentation
  • Fetal Lie. The lie is the relation of the long
    axis of the fetus to that of the mother, and is
    either longitudinal or transverse.

54
  • Fetal Presentation. The presenting part is that
    portion of the fetal body that is either foremost
    within the birth canal or in closest proximity to
    it.

55
3. Fetal abnormalities
  • When certain part of fetus is enlarged in fetal
    abnormalities, for example, conjoined twins,
    hydrocephalus, dystocia will occur.

56
IV Maternal mental and psychological factors
  • Psychologic support to the women during labor is
    very important.
  • The provision of continuous psychologic support
    during labour by doulas, as well as nurses,
    family or friends is associated with improved
    maternal and fetal health and a variety of other
    benefits.
  • A doula, also known as a labour coach, is a
    nonmedical person who assists a woman before,
    during or after childbirth, as well as her
    partner and/or family by providing information,
    physical assistance and emotional support.

57
CHAPTER 3 MECHANISM OF LABOR WITH OCCIPUT
PRESENTATION
  • The positional changes in the presenting part
    required to navigate the pelvic canal constitute
    the mechanisms of labor.
  • Left occiput anterior (LOA) position is the most
    common fetal position
  • The cardinal movements of labor are engagement,
    descent, flexion, internal rotation, extension,
    external rotation, and expulsion.

58
ENGAGEMENT
  • The mechanism by which the biparietal
    diameterthe greatest transverse diameter in an
    occiput presentationpasses through the pelvic
    inlet is designated engagement.
  • In nulliparous women, the fetal head engage 1 or
    2 weeks before labor.
  • In multiparous women, the fetal head usually
    engage after the onset of labor.

59
  • 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.

60
DESCENT
  • This movement is the first requisite for birth of
    the newborn.
  • In nulliparas, engagement may take place before
    the onset of labor, and further descent may not
    follow until the onset of the second stage.
  • In multiparous women, descent usually begins with
    engagement.

61
  • 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
  • (4) extension and straightening of the fetal
    body.

62
FLEXION
  • As soon as the descending head meets resistance,
    whether from the cervix, walls of the pelvis, or
    pelvic floor, flexion of the head normally
    results.

63
  • In this movement, the chin is brought into more
    intimate contact with the fetal thorax, and the
    appreciably shorter suboccipitobregmatic diameter
    is substituted for the longer occipitofrontal
    diameter.

64
INTERNAL ROTATION
  • 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.

65
EXTENSION
  • After internal rotation, the sharply flexed head
    reaches the vulva and undergoes extension.
  • When the head presses upon the pelvic floor,
    however, two forces come into play.

66
  • The first, 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.

67
  • With progressive distention of the perineum and
    vaginal opening, an increasingly larger portion
    of the occiput gradually appears. The head is
    born as the occiput, bregma, forehead, nose,
    mouth, and finally the chin pass successively
    over the anterior margin of the perineum.

68
EXTERNAL ROTATION
  • The delivered head next undergoes restitution.
  • If the occiput was originally directed toward the
    left, it rotates toward the left. This movement
    apparently is brought about by the same pelvic
    factors that produced internal rotation of the
    head..

69
  • Restitution of the head to the oblique position
    is followed by completion of external rotation to
    the transverse position, a movement that
    corresponds to rotation of the fetal body,
    serving 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.

70
EXPULSION
  • Almost immediately after external rotation, the
    anterior shoulder appears under the symphysis
    pubis, and the perineum soon becomes distended by
    the posterior shoulder. After delivery of the
    shoulders, the rest of the body quickly passes.

71
  • During labor, these movements are sequential but
    also show great temporal overlap.
  • For example, as part of the process of
    engagement, there is both flexion and descent of
    the head.
  • As a result, the fetus is transformed into a
    cylinder, with the smallest possible cross
    section passing through the birth canal.

72
HAVE A REST
73
CHAPTER 4 DIAGNOSIS OF THREATENED LABOR AND
LABOR
  • THREATENED LABOR
  • Before actual labor begins, a number of
    physiologic preparatory events usually occur. And
    these are called threatened labor.

74
The manifestation of threatened labor
  • Lightening
  • False Labor
  • Bloody show

75
Lightening
  • Lightening may be noted by the mother as a
    flattening of the upper abdomen and an increased
    prominence of the lower abdomen.
  • Two or more weeks before labor, the fetal head in
    most primigravid women settles into the brim of
    the pelvis. In multigravida, this often does not
    occur until early in labor.

76
False Labor
  • During the last 4 to 8 weeks of pregnancy, the
    uterus undergoes irregular contractions that
    normally are painless.
  • Such contractions appear unpredictably and
    sporadically and can be rhythmic and of mild
    intensity. In the last month of pregnancy, these
    contractions may occur more frequently, and with
    greater intensity.
  • These Braxton Hicks contractions are considered
    false labor in that they are not associated with
    progressive cervical dilatation or effacement.
  • They may serve, however, a physiologic role in
    preparing the uterus and cervix for true labor.

77
Bloody show
  • Prior to the onset of parturition, the cervix is
    frequently noted to soften as a result of
    increased water content and collagen lysis.
  • Simultaneous effacement, or thinning of the
    cervix, occurs as it is taken up into the lower
    uterine segment.
  • Consequently, patients often present in early
    labor with a cervix that is already partially
    effaced.
  • As a result of cervical effacement, the mucous
    plug within the cervical canal may be released.
    The onset of labor may thus be heralded by the
    passage of a small amount of blood-tinged mucus
    from the vagina (bloody show).

78
In Labor
  • It is defined as progressive cervical effacement
    and dilatation resulting from regular uterine
    contractions that occur at least every 5 minutes
    and last 30 to 60 seconds.

79
STAGES OF LABOR
  • Total stage of labor is from the onset of regular
    uterine contractions to the delivery of the baby
    and placenta.

80
3 stages of labor
  • The first stage is from the onset of true labor
    to complete dilation of the cervix.
  • primiparous patients 11-12h, multiparous
    patients 6-8h.
  • The second stage is from complete dilation of the
    cervix to the birth of the baby.
  • primiparous patients 1-2h, less than 2 h.
    multiparous patients much faster, less than 1h.
  • The third stage is from the birth of the baby to
    delivery of the placenta.
  • 5-15min, less than 30 minutes.

81
CHAPTER 5 CLINICAL MANIFESTATION AND
MANAGEMENT OF FIRST STAGE OF LABOR
82
CLINICAL MANIFESTATION OF THE FIRST STAGE
  • Regular uterine contraction.
  • From the onset of labor, it occur every 5-6
    minutes and last about 30 seconds.
  • With the progression of labor, the uterine
    contractions increase progressively in intensity.
    At the same time, frequency increases to every
    2-3 min, and the duration increases to 50-60
    seconds.
  • When the cervix is nearly fully dilated, the
    contractions last to 1min or even longer, and
    rest for only 1-2 min.

83
2. Dilatation of cervix
  • Dilatation of the cervix is determined by vaginal
    examination.
  • If progress is slow, evaluation for uterine
    dysfunction, fetal malposition, or cephalopelvic
    disproportion should be undertaken.

84
3. Descent of fetal head
  • Determined by vaginal examination.
  • The level of the lowest presenting fetal part in
    the birth canal is described in relationship to
    the ischial spines.

85
4. Rupture of membranes
  • Rupture of membranes usually occurs when the
    cervix is nearly fully dilated.

86
MANAGEMENT OF THE FIRST STAGE OF LABOR
  • On admission the general condition of the
    patient is assessed, her pulse rate and blood
    pressure are recorded, and her urine is tested
    for protein.
  • By abdominal examination the presentation and
    position ot the fetus, and the relation of the
    presenting part to the brim of the pelvis, are
    determined.

87
  • Abdominal examination will also show the
    frequency and strength of the uterine
    contractions. The fetal heart rate is counted for
    a full minute, and any abnormality of rate or
    rhythm is noted.
  • A vaginal examination will show the degree of
    dilatation of the cervix, whether the membrane
    are intact or ruptured, and the level and
    position of the presenting part.

88
Partogram
  • Once the labor has become established, all events
    during labor are noted on a partograma most
    useful graphical record of the course of labor.

89
  • Routine observations of the mothers pulse rate
    and blood pressure, with an assessment of the
    strength of the uterine contractions are entered
    on it. Records of the findings at successive
    vaginal examinations are plotted on a graph,
    showing the dilatation of the cervix and the
    descent of the fetal head in centimeters against
    the time in hours.

90
  • The curve obtained is compared with an average
    normal curve for primigravidae or multigravidae
    as may be appropriate. If the patients progress
    is normal her curve will correspond with the
    normal curve, or lie to the left of it.
  • If for any reason labor is not progressing
    normally dilatation of the cervix will become
    slower or may cease, and the patients partogram
    will be to the right of the normal curve.
  • Certain steps should be taken in the clinical
    management of the patient during the first stage
    of labor.

91
Uterine Activity
  • Uterine contractions should be monitored every 30
    minutes by palpation for their frequency,
    duration, and intensity. 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.
  • For high-risk pregnancies, uterine contractions
    should be monitored continuously along with the
    fetal heart rate. This can be achieved
    electronically using either an external
    tocodynamometer or an internal pressure catheter
    in the amniotic cavity.

92
Fetal Monitoring
  • The fetal heart rate should be evaluated by
    either auscultation with a DeLee stethoscope, by
    external monitoring with Doppler equipment, or by
    internal monitoring with a fetal scalp electrode.
  • In patients with no significant obstetric risk
    factors, the fetal heart rate should be
    auscultated or the electronic monitor tracing
    evaluated every 1-2h in the latent phase of
    labor, and at least every 15-30 minutes in the
    active phase of the first stage of labor and at
    least every 15 minutes in the second stage of
    labor.

93
DILATION OF CERVIX AND DESCENT OF FETAL HEAD
  • Measurement of progress
  • During the first stage, the progress of labor may
    be measured in terms of cervical effacement,
    cervical dilatation, and descent of the fetal
    head.

94
Phases
  • The first stage of labor consists of two phases
    a latent phase, during which cervical effacement
    and early dilatation(to 3cm) occur, and an active
    phase, during which more rapid cervical
    dilatation occurs, the cervix dilate from 3cm to
    10cm.

95
And the active phase has 3 component parts
  • acceleration phase the cervix dilates from
    3-4cm, normally takes 1h and 30 min.
  • maximum acceleration phase the cervix dilates
    from 4-9cm, normally takes 2h.
  • deceleration phase the cervix dilates from
    9-10cm, normally takes 30 min.

96
Length
  • The length of the first stage may vary in
    relation to parity primiparous patients
    generally experience a longer first stage than do
    multiparous patients.
  • Because the latent phase may overlap considerably
    with the preparatory phase of labor, its duration
    is highly variable.
  • It may also be influenced by other factors, such
    as sedation and stress.
  • This phase normally takes 8h, and the maximum is
    16 h in primiparous patients.

97
  • The active phase begins when the cervix is 3 cm
    dilated in the presence of regularly occurring
    uterine contractions. The minimal dilatation
    during the active phase of the first stage is
    nearly the same for primiparous and multiparous
    women 1 and 1.2cm/hour, respectively.
  • This phase normally takes 4h, and the maximum is
    8 h.

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Descent of fetal head
  • The levelor stationof the presenting fetal part
    in the birth canal is described in relationship
    to the ischial spines.
  • When the lowermost portion of the presenting
    fetal part is at the level of the spines, it is
    designated as being at zero (0) station.
  • As the presenting fetal part descends from the
    inlet toward the ischial spines, when it is
    3,2and 1 cm above the ischial spines, the
    designation is 3, 2, 1. When it is 1, 2,3 and
    4cm blow the spines, as the presenting fetal part
    descends, it is then 1, 2, 3, 4.

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  • The descent of fetal head is not obvious in the
    latent phase, and is accelerated in the active
    phase, usually 0.86cm/h.

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Rupture of membranes
  • Rupture of membranes usually occurs when the
    cervix is nearly fully dilated.
  • Once the membrane is ruptured, the fetal heart
    should be monitored, and the color and amount of
    Amnionic Fluid should be noted.
  • And the time of rupture should be recorded.

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Blood Pressure
  • During uterine contractions, the maternal blood
    pressure usually elevated 5-10 mmHg. The blood
    pressure should be monitored every 4-6 hours once
    the labor is started.

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Maternal Position.
  • If the head is engaged there is no need for the
    patient to remain in bed during early labor. If
    she is up and about, the weight of the liquor and
    fetus helps to dilate the cervix, and pressure on
    the lower segment stimulates the uterus to
    contract.
  • If she is lying in bed, the lateral recumbent
    position should be encouraged to ensure perfusion
    of the uteroplacental unit.

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  • There may be a frequent desire to pass water
    during the first stage. If the bladder becomes
    full and the patient cannot empty it a soft
    catheter should be passed, as a full bladder has
    an inhibiting effect on the uterine contractions.
  • Although it is common practice to give an enema
    and to clip or shave the vulval hair, there is
    little to show that either of these practices is
    necessary, and many women dislike them.

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Vaginal Examination
  • During the latent phase, particularly when the
    membranes are ruptured, vaginal examinations
    should be done sparingly to decrease the risk of
    an intrauterine infection. In the active phase,
    the cervix should be assessed approximately every
    2 hours to determine the progress of labor.
    Cervical effacement and dilatation, the station
    and position of the presenting part, and the
    presence of molding or caput in vertex
    presentations should be recorded.

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Amniotomy
  • The artificial rupture of fetal membranes may
    provide information on the volume of amniotic
    fluid and the presence or absence of meconium. In
    addition, rupture of the membranes may cause an
    increase in uterine contractility.
  • Amniotomy incurs risks of chorioamnionitis if
    labor is prolonged and of umbilical cord
    compression or cord prolapse if the presenting
    part is not engaged.

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CHAPTER 6 CLINICAL MANIFESTATION AND MANAGEMENT
OF SECOND STAGE OF LABOR
  • This stage begins when cervical dilatation is
    complete and ends with fetal delivery.

107
CLINICAL MANIFESTATION
  • With full cervical dilatation, which signifies
    the onset of the second stage, a woman typically
    begins to bear down. With descent of the
    presenting part, she develops the urge to
    defecate. Uterine contractions and the
    accompanying expulsive forces may now last
    1minute or longer and recur at an interval no
    longer than 1 minute. The abdominal pressure,
    together with the uterine contractile force,
    combines to expel the fetus. During the second
    stage of labor, fetal descent must be monitored
    carefully to evaluate the progress of labor.

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  • With each contraction, the perineum bulges
    increasingly. The vulvovaginal opening is dilated
    by the fetal head, and the fetal head is seen at
    the vulva at the height of each contraction.
    Between the contractions the elastic tone of the
    perineal muscles push the head back , and this is
    called head visible on vulval gapping.

109
  • The perineal body and vulval outlet become more
    and ore stretched, and the encirclement of the
    largest head diameter by the vulvar ring is known
    as crowning of head.

110
  • Six movements of the baby enable it to adapt to
    the maternal pelvis descent, flexion, internal
    rotation, extension, external rotation, and
    expulsion.
  • The second stage generally takes from 1 to 2
    hours in primigravid women and from 5 to 60
    minutes in multigravid women.

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MANAGEMENT OF THE SECOND STAGE
  • Fetal Monitoring
  • During the second stage, the fetal heart rate
    should be monitored continuously or evaluated
    every 5-10 minutes. Fetal heart rate
    decelerations (head compression or cord
    compression) with recovery following the uterine
    contraction may occur normally during this stage.

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Bearing Down
  • With each contraction, the mother should be
    encouraged to hold her breath and bear down with
    expulsive efforts.

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Vaginal Examination
  • Progress should be recorded approximately every
    30 minutes during the second stage. Particular
    attention should be paid to the descent and
    flexion of the presenting part, the extent of
    internal rotation. During the second stage of
    labor, the retracted cervix is no longer
    palpable.

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Delivery of the Fetus
  • When delivery is imminent, the patient is usually
    placed in the lithotomy position, and the skin
    over the lower abdomen, vulva, anus, and upper
    thighs is cleansed with an antiseptic solution.

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The modified Ritgen maneuver
  • The midwife must control the head to prevent it
    being born suddenly, and it must be kept flexed
    until the largest diameter has passed the vulval
    outlet. A towel-draped, gloved hand may be used
    to exert forward pressure on the chin of the
    fetus through the perineum just in front of the
    coccyx. Concurrently, the other hand exerts
    pressure superiorly against the occiput. The
    downward pressure increases flexion of the head
    and allows a controlled delivery. This maneuver
    is simpler than that originally described by
    Ritgen (1855), and it is customarily designated
    the modified Ritgen maneuver.

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  • Once the head is delivered, the airway is cleared
    of blood and amniotic fluid using a bulb suction
    device. The oral cavity is cleared initially and
    then the nares are cleared. A second towel is
    used to wipe secretions from the face and head.

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  • After the airway has been cleared, an index
    finger is used to check whether the umbilical
    cord encircles the neck. If so, the cord can
    usually be slipped over the infants head. If the
    cord is too tight, it can be cut between two
    clamps.

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CHAPTER 7 CLINICAL MANIFESTATION AND MANAGEMENT
OF THIRD STAGE OF LABOR
119
clinical manifestation placental separation
120
Management
  • the care of the newborn
  • assist the delivery of placenta
  • to exam the placenta and fetal membranes
  • to check the soft birth canal
  • to prevent PPH
  • to observe the general state of health
  • manual removal of placenta

121
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