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.

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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 .

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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.

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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.

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• 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.

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II Birth canal

• Bony Pelvis
• The soft birthing canal

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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.

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• 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.

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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.

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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.

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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.

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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.

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

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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.

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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.

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3. Fetal abnormalities

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

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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.

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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.

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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.

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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.

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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.

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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.

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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.

98
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.

99

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

100
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.

101
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.

102
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.

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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.

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• 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.

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• 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
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clinical manifestation placental separation
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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

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