Normal Labor and Normal Labor and DeliveryDelivery

The Obstetrics and Gynecology The Obstetrics and Gynecology Hospital of Fudan University Hospital of Fudan University

Jing-Xin Ding Jing-Xin Ding

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

DefinitionDefinition

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

Preterm deliveryPreterm delivery occurring after 28 weeks an occurring after 28 weeks and before 37 completed weeks of gestation. In sd before 37 completed weeks of gestation. In some developing countries, this time point has ome developing countries, this time point has been advanced to 20 gestational weeks.been advanced to 20 gestational weeks.

Term deliveryTerm delivery occurring after 37 weeks and b occurring after 37 weeks and before 42 completed weeks of gestation.efore 42 completed weeks of gestation.

Postterm deliveryPostterm delivery occurring after 42 complet occurring after 42 completed weeks of gestation.ed weeks of gestation.

CHAPTER 1 CHAPTER 1 THE HYPOTHESIS OF THE HYPOTHESIS OF PARTURITION INITIATIONPARTURITION INITIATION

1. Mechanic theory1. Mechanic theoryUTERINE QUIESCENCEUTERINE QUIESCENCE During the early During the early

stage of pregnancy, a remarkably pestage of pregnancy, a remarkably period of myometrial quiescence is impriod of myometrial quiescence is imposed.osed.

CERVICAL SOFTENINGCERVICAL SOFTENING By the end of preg By the end of pregnancy, easily distensible, increase in tisnancy, easily distensible, increase in tissue compliance sue compliance

Uterine awakeningUterine awakening or or activationactivation

During the end stage of pregnancy, the fetus compressed During the end stage of pregnancy, the fetus compressed the lower segment and cervix of the uterus, and mechanic the lower segment and cervix of the uterus, and mechanic effect induced the initiation of labor. effect induced the initiation of labor.

There is no doubt that multifetal pregnancy and hydramniThere is no doubt that multifetal pregnancy and hydramnios lead to an increased risk of preterm birth.os lead to an increased risk of preterm birth.

It is likely that uterine distension acts to initiate expressioIt is likely that uterine distension acts to initiate expression ofn of

contraction-associated proteins (CAPs) in the myometrium.contraction-associated proteins (CAPs) in the myometrium.

2. Endocrine theory2. Endocrine theoryThe myometrial changes preparing it foThe myometrial changes preparing it fo

r labor contractions probably results fr labor contractions probably results from alterations in the expression of kerom alterations in the expression of key endocrine proteins that control conty endocrine proteins that control contractility. Theseractility. These proteins proteins include the include the oxoxytocin and its receptor, prostaglandin ytocin and its receptor, prostaglandin and its receptor, estrogen, progesteroand its receptor, estrogen, progesterone, and endothelin.ne, and endothelin.

Prostagladin,PGProstagladin,PG

PG can promote the ripening of the PG can promote the ripening of the cervix, and start the contraction of cervix, and start the contraction of the uterine.the uterine.

It can be synthesized in uterine It can be synthesized in uterine muscle, placenta, etc.muscle, placenta, etc.

Oxytocin and oxytocin receptorOxytocin and oxytocin receptor

Induce labor and promote the contractiInduce labor and promote the contraction of the uterine muscle.on of the uterine muscle.

The uterine sensitivity to oxytocin is incrThe uterine sensitivity to oxytocin is increased before the initiation of labor.eased before the initiation of labor.

Classical Progesterone Classical Progesterone Withdrawal and ParturitionWithdrawal and Parturition

In species that exhibit progesterone In species that exhibit progesterone withdrawal, progression of parturition to withdrawal, progression of parturition to labor can be blocked by administering labor can be blocked by administering progesterone to the mother. progesterone to the mother.

In pregnant women, however, there are In pregnant women, however, there are conflicting reports as to whether or not conflicting reports as to whether or not progesterone administration can delay the progesterone administration can delay the timely onset of parturition or prevent timely onset of parturition or prevent preterm labor. preterm labor.

Further research may help explain its Further research may help explain its differential action and how it could be better differential action and how it could be better used to prevent preterm labor. used to prevent preterm labor.

Endothelin, ETEndothelin, ET

Induce the contraction of the uterus.Induce the contraction of the uterus. Induce the synthesis and release of Induce the synthesis and release of

PG.PG.

Fetal Contributions to Initiation Fetal Contributions to Initiation of Parturitionof Parturition

The ability of the fetus to provide endocrine signals that initiThe ability of the fetus to provide endocrine signals that initiate parturition has been demonstrated in several species.ate parturition has been demonstrated in several species.

This signal was shown to come from the fetal hypothalamic-pThis signal was shown to come from the fetal hypothalamic-pituitary-adrenal axisituitary-adrenal axis . .

3. Neuromediator theory3. Neuromediator theory

The uterine contraction is controlled The uterine contraction is controlled by the autonomic nerve. by the autonomic nerve.

It is still uncertain the role of It is still uncertain the role of autonomic nerve in the initiation of autonomic nerve in the initiation of labor. labor.

SummarySummary

Labor onset represents the culmination Labor onset represents the culmination of a series of biochemical changes in the of a series of biochemical changes in the uterus and cervix. uterus and cervix.

These result from endocrine and paracriThese result from endocrine and paracrine signals emanating from both mother ne signals emanating from both mother and fetus. and fetus.

Not fully defined. Not fully defined.

CHAPTER 2CHAPTER 2 THE FACTORS THE FACTORS DECIDING LABOR AND DELIVERYDECIDING LABOR AND DELIVERY

Birth canalBirth canal

FetusFetus

Mental and psychological factorsMental and psychological factors

Force of the laborForce of the labor

I Force of the laborI Force of the labor

Uterine ContractionsUterine Contractions — Main force — Main force Maternal intra-abdominal pressure Maternal intra-abdominal pressure

and the contranction of levator aniand the contranction of levator ani — — Ancillary forcesAncillary forces

Characteristics of the uterine Characteristics of the uterine contractionscontractions

RhythmicityRhythmicity SymmetrySymmetry PolarityPolarity Retraction effectRetraction effect

1. Rhythmicity1. Rhythmicity Each contraction increase progressively iEach contraction increase progressively i

n intensity and maintains the maxium in intensity and maintains the maxium intensity and then diminishes gradually.ntensity and then diminishes gradually.

the uterine baseline tone -- from 8 to the uterine baseline tone -- from 8 to 12 mm Hg 12 mm Hg

25 mm Hg at commencement of 25 mm Hg at commencement of labor to 50 mm Hg at the end of first labor to 50 mm Hg at the end of first stage stage

During second-stage labor, aided by During second-stage labor, aided by maternal pushing, contractions of maternal pushing, contractions of 100 to 150 mm Hg are typical.100 to 150 mm Hg are typical.

At the At the beginningbeginning, the contracts , the contracts occurs occurs every 5-6 minutes, and last every 5-6 minutes, and last 30 s30 s. With the progression of labor, . With the progression of labor, frequency increases to frequency increases to every 1-2 minevery 1-2 min and the duration increases to and the duration increases to 60 s60 s when the cervix is fully dilated. when the cervix is fully dilated.

2. Symmetry2. Symmetry The normal The normal

contractile wave of contractile wave of labor originates labor originates near the uterine near the uterine end of the fallopian end of the fallopian tubes. Thus, these tubes. Thus, these areas act as areas act as "pacemakers"."pacemakers".

Contractions spread from the pacemaker area Contractions spread from the pacemaker area throughout the uterus at 2 cm/sec, throughout the uterus at 2 cm/sec, depolarizing the whole uterus within 15 depolarizing the whole uterus within 15 seconds.seconds.

3. Polarity3. Polarity Intensity is greatest in the fundusIntensity is greatest in the fundus Diminishes in the lower uterus.Diminishes in the lower uterus. Presumably, this descending gradient of pressure Presumably, this descending gradient of pressure

serves to direct fetal descent toward the cervix as serves to direct fetal descent toward the cervix as well as to efface the cervix.well as to efface the cervix.

4. Retraction effect 4. Retraction effect The muscle fiber retracts after contractions, and The muscle fiber retracts after contractions, and

the cavity of the uterus becomes small, and the fethe cavity of the uterus becomes small, and the fetus is forced to descend.tus is forced to descend.

Maternal intra-abdominal Maternal intra-abdominal pressure -- pushingpressure -- pushing

Contraction of the abdominal muscles Contraction of the abdominal muscles simultaneously with forced respiratory efforts simultaneously with forced respiratory efforts with the glottis closed is referred to as pushing. with the glottis closed is referred to as pushing.

Similar to that with defecation, but the Similar to that with defecation, but the intensity usually is much greater.intensity usually is much greater.

After the cervix is dilated fully, the most After the cervix is dilated fully, the most important force in fetal expulsion is that important force in fetal expulsion is that produced by maternal intra-abdominal produced by maternal intra-abdominal pressure. pressure.

Accomplishes little in the first stageAccomplishes little in the first stage. It . It exhausts the mother, and its associated exhausts the mother, and its associated increased intrauterine pressures may be increased intrauterine pressures may be harmful to the fetusharmful to the fetus..

The contraction of levator aniThe contraction of levator ani

The contraction of levator ani muscle contThe contraction of levator ani muscle contributes to:ributes to:

the internal rotation, extention and expthe internal rotation, extention and expulsion of the fetal head in the 2nd stage ulsion of the fetal head in the 2nd stage of laborof labor

the delivery of placetenta in the 3rd stathe delivery of placetenta in the 3rd stage of labor.ge of labor.

II Birth canalII Birth canal

Bony PelvisBony Pelvis The soft birthing canalThe soft birthing canal

Bony PelvisBony Pelvis

Pelvic PlanesPelvic Planes

1.The pelvic inlet plane1.The pelvic inlet plane

2.The mid plane of pelvis--the plane of 2.The mid plane of pelvis--the plane of least diameterleast diameter

3.The pelvic outlet plane3.The pelvic outlet plane

The pelvic inlet planeThe pelvic inlet plane

bordered by the pubic crest anteriorly, tbordered by the pubic crest anteriorly, the iliopectineal line of the innominate bhe iliopectineal line of the innominate bones laterally, and the promontory of thones laterally, and the promontory of the sacrum posteriorly. e sacrum posteriorly.

Four diameters: anteroposterior, transvFour diameters: anteroposterior, transverse, and two oblique diameters.erse, and two oblique diameters.

The obstetric conjugate of the inlet -- disThe obstetric conjugate of the inlet -- distance between the promontory of the satance between the promontory of the sacrum and the symphysis pubis. Normally,crum and the symphysis pubis. Normally, this measures 11 cm. this measures 11 cm.

The The transverse diametertransverse diameter is constructed at righ is constructed at right angles to the obstetrical conjugate and repret angles to the obstetrical conjugate and represents the greatest distance between the linea tsents the greatest distance between the linea terminalis on either side.erminalis on either side.

Each of the two oblique diameters extends froEach of the two oblique diameters extends from one of the sacroiliac synchondroses to the ilm one of the sacroiliac synchondroses to the iliopectineal eminence on the opposite side.iopectineal eminence on the opposite side.

the most important from a clinical the most important from a clinical standpoint, because most instances of standpoint, because most instances of arrest of descent occur at this level. arrest of descent occur at this level.

It is bordered by the loIt is bordered by the lower edge of the pubis wer edge of the pubis anteriorly, the ischial santeriorly, the ischial spines and sacrospinoupines and sacrospinous ligaments laterally, as ligaments laterally, and the lower sacrum pnd the lower sacrum posteriorly. osteriorly.

The mid plane of pelvis--the The mid plane of pelvis--the plane plane of least diameterof least diameter

The The interspinous diameterinterspinous diameter, 10 cm or slig, 10 cm or slightly greater, is usually the smallest pelvihtly greater, is usually the smallest pelvic diameter. The anteroposterior diametc diameter. The anteroposterior diameter through the level of the ischial spines er through the level of the ischial spines normally measures at least 11.5 cm. normally measures at least 11.5 cm.

TheThe plane of the pelvic outlet plane of the pelvic outlet two approximately triangular areas with a common btwo approximately triangular areas with a common b

asease The apex of the posterior triangle is at the tip of the saThe apex of the posterior triangle is at the tip of the sa

crum, and the lateral boundaries are the sacrosciatic lcrum, and the lateral boundaries are the sacrosciatic ligaments and the ischial tuberosities. igaments and the ischial tuberosities.

The anterior The anterior triangle is triangle is formed by the formed by the area under the area under the pubic arch. pubic arch.

The The obstetric anteroposterior diameterobstetric anteroposterior diameter exte extends from the inferior margin of the pubis to thnds from the inferior margin of the pubis to the sacrococcygeal joint. e sacrococcygeal joint.

The The transverse (bituberous) diametertransverse (bituberous) diameter exten extends between the inner surfaces of the ischial tuds between the inner surfaces of the ischial tuberosities —an average of 9 cmberosities —an average of 9 cm

The The posterior sagittal diameterposterior sagittal diameter extends from extends from the middle of the transverse diameter to the sthe middle of the transverse diameter to the sacrococcygeal joint —an average of 8.5 cmacrococcygeal joint —an average of 8.5 cm

The bituberous diametThe bituberous diameter + the posterior sagitter + the posterior sagittal diameter >15 cm, theal diameter >15 cm, then the fetus can be delivn the fetus can be delivered through the posteered through the posterior triangle.rior triangle.

Pelvic axisPelvic axis

-- an imaginary curved line that passes -- an imaginary curved line that passes through the centers of the various through the centers of the various diameters of the pelvis. diameters of the pelvis.

The pelvic axis first goes inferior and The pelvic axis first goes inferior and posterior, and then inferior, and then posterior, and then inferior, and then inferior and anterior.inferior and anterior.

Inclination of Inclination of pelvispelvis

The The angleangle which the which the planeplane of the of the pelvicpelvic inlet inlet makesmakes with the with the horizontal planehorizontal plane when the patient is standing. The when the patient is standing. The degree is usually 60 °, if it is too much, degree is usually 60 °, if it is too much, the engagement and delivery is difficult.the engagement and delivery is difficult.

The soft birthing canalThe soft birthing canal

the lower the lower uterine uterine segmentssegments

the cervixthe cervix the vagina the vagina the pelvic the pelvic

floorfloor

Formation of the Lower Uterine Formation of the Lower Uterine SegmentsSegments

The lower uterine segment is derived fThe lower uterine segment is derived from the isthmus which is about 1 cm irom the isthmus which is about 1 cm in nonpregnant uterus, and when the ln nonpregnant uterus, and when the labor is started, with regular contractiabor is started, with regular contractions of the upper uterine segment, it dions of the upper uterine segment, it distended to 7 to 10cm.stended to 7 to 10cm.

the Physiological Retraction the Physiological Retraction RingRing

As a result of the lower segment As a result of the lower segment thinning and concomitant upper thinning and concomitant upper segment thickening, a boundary segment thickening, a boundary between the two is marked by a ridge between the two is marked by a ridge on the inner uterine surface—the on the inner uterine surface—the physiological retraction ring.physiological retraction ring.

Cervical ChangesCervical Changes

two fundamental changes—two fundamental changes—effacement and dilatationeffacement and dilatation

For an average-sized fetal head For an average-sized fetal head to pass through the cervix, its to pass through the cervix, its canal must dilate to a diameter canal must dilate to a diameter of approximately 10 cm.of approximately 10 cm.

Effacement of cervixEffacement of cervix

Cervical effacement is "obliteration" Cervical effacement is "obliteration" or "taking up" of the cervix. or "taking up" of the cervix.

It is manifest clinically by shortening It is manifest clinically by shortening of the cervical canal from a length of of the cervical canal from a length of about 2-3 cm to a mere circular about 2-3 cm to a mere circular orifice with almost paper-thin edges. orifice with almost paper-thin edges.

Dilatation of Dilatation of cervixcervix

The process of cervical effacement and dilatation The process of cervical effacement and dilatation causes the formation of the causes the formation of the forebagforebag of amnionic f of amnionic fluid, which is the leading portion of the amnionic luid, which is the leading portion of the amnionic sac and fluid located in front of the presenting pasac and fluid located in front of the presenting part.rt.

As uterine contractions cause pressure on the meAs uterine contractions cause pressure on the membranes, the hydrostatic action of the amnionic mbranes, the hydrostatic action of the amnionic sac in turn dilates the cervical canal.sac in turn dilates the cervical canal.

In the absence of intact membranes, the pressure In the absence of intact membranes, the pressure of the presenting part against the cervix and loweof the presenting part against the cervix and lower uterine segment is similarly effective. r uterine segment is similarly effective.

A. Before labor, the primiA. Before labor, the primigravid cervix is long angravid cervix is long and undilated in contrast d undilated in contrast to that of the multiparto that of the multipara, which has dilatation a, which has dilatation of the internal and extof the internal and external os.ernal os.

B. As effacement begins, B. As effacement begins, the multiparous cervix the multiparous cervix shows dilatation and fshows dilatation and funneling of the internaunneling of the internal os. This is less apparel os. This is less apparent in the primigravid cnt in the primigravid cervix. ervix.

C. As complete effacemeC. As complete effacement is achieved in the print is achieved in the primigravid cervix, dilatiomigravid cervix, dilation is minimal. The revern is minimal. The reverse is true in the multipse is true in the multipara. ara.

Pelvic Floor Changes during Pelvic Floor Changes during LaborLabor

The most marked change consists of the stretcThe most marked change consists of the stretching of levator ani muscle fibers. This is accomhing of levator ani muscle fibers. This is accompanied by thinning of the central portion of thpanied by thinning of the central portion of the perineum, which becomes transformed from e perineum, which becomes transformed from a wedge-shaped, 5-cm-thick mass of tissue to a wedge-shaped, 5-cm-thick mass of tissue to a thin, almost transparent membranous structa thin, almost transparent membranous structure less than 1 cm thick. ure less than 1 cm thick.

The extraordinary number and size of the blooThe extraordinary number and size of the blood vessels that supply the vagina and pelvic flod vessels that supply the vagina and pelvic floor result in substantive blood loss if these tissuor result in substantive blood loss if these tissues are torn.es are torn.

III FetusIII Fetus

Size of fetusSize of fetus Fetal lie, presentation and Fetal lie, presentation and

positionposition Fetal abnormalitiesFetal abnormalities

FETAL HEADFETAL HEAD Important sutures and fontanellesImportant sutures and fontanelles two frontal, two parietal, and two temptwo frontal, two parietal, and two temp

oral bones, along with the occipital bonoral bones, along with the occipital bone. e.

SuturesSutures

The The sagittal suturesagittal suture lies between the parietal bones an lies between the parietal bones and extends in an anteroposterior direction between the d extends in an anteroposterior direction between the fontanelles, dividing the head into right and left sides.fontanelles, dividing the head into right and left sides.

The The lambdoid suturelambdoid suture extends from the posterior fonta extends from the posterior fontanelle laterally and serves to separate the occipital fronelle laterally and serves to separate the occipital from the parietal bones.m the parietal bones.

The The coronal suturecoronal suture extends from the anterior fontane extends from the anterior fontanelle laterally and serves to separate the parietal and frolle laterally and serves to separate the parietal and frontal bones. ntal bones.

The frontal sutureThe frontal suture lies between the frontal bones and lies between the frontal bones and extends from the anterior fontanelle to the glabella (thextends from the anterior fontanelle to the glabella (the prominence between the eyebrows). e prominence between the eyebrows).

The membrane-The membrane-occupied spaces occupied spaces between the cranial between the cranial bones are known as bones are known as sutures.sutures.

FontanellesFontanellesThe membrane-filled spacThe membrane-filled spac

es located at the point es located at the point where the sutures interwhere the sutures intersect are known as fontasect are known as fontanellesnelles..

The anterior fontanelle (bregma)The anterior fontanelle (bregma) is at the intersection is at the intersection of the sagittal, frontal, and coronal sutures. It is diamoof the sagittal, frontal, and coronal sutures. It is diamond shaped and measures approximately 2×3cm, and ind shaped and measures approximately 2×3cm, and it is much larger than the posterior fontanelle.t is much larger than the posterior fontanelle.

The posterior fontanelleThe posterior fontanelle is Y- or T-shaped and is foun is Y- or T-shaped and is found at the junction of the sagittal and lambdoid sutures. d at the junction of the sagittal and lambdoid sutures.

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

DiametersDiameters

Suboccipitobregmatic Suboccipitobregmatic DiamDiametereter (9.5cm), (9.5cm), the presenting the presenting anteroposterior diameter whanteroposterior diameter when the head is well flexed, anen the head is well flexed, and it is d it is the shortest the shortest anteroposanteroposterior diameter . It extends frterior diameter . It extends from the undersurface of the oom the undersurface of the occipital bone at the junction ccipital bone at the junction with the neck to the center of with the neck to the center of the anterior fontanelle.the anterior fontanelle.

Occipitofrontal Occipitofrontal DiameterDiameter (11.3c (11.3cm),m), extends from the external oc extends from the external occipital protuberance to the glabelcipital protuberance to the glabella. The fetus usually engage by thla. The fetus usually engage by this diameter.is diameter.

Occipitomental Occipitomental DiametDiameterer (13.3cm), (13.3cm), the present the presenting anteroposterior diaing anteroposterior diameter in a brow presentmeter in a brow presentation and the longest anation and the longest anteroposterior diameter oteroposterior diameter of the head; it extends frof the head; it extends from the vertex to the chin. m the vertex to the chin.

Biparietal Biparietal DiameterDiameter (9.3cm), (9.3cm), the largest transverse the largest transverse diameter; it extends between the parietal bones. diameter; it extends between the parietal bones.

This diameter detected by antenatal ultrasonic examiThis diameter detected by antenatal ultrasonic examination was used to estimate the size of the fetus.nation was used to estimate the size of the fetus.

2. Fetal lie and presentation2. Fetal lie and presentation

Fetal Lie.Fetal Lie. The lie is the relation of The lie is the relation of the long axis of the fetus to that of the long axis of the fetus to that of the mother, and is either the mother, and is either longitudinallongitudinal or or transverse.transverse.

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

3. Fetal abnormalities3. Fetal abnormalities

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

IV Maternal mental and IV Maternal mental and psychological factorspsychological factors

Psychologic support to the women during laPsychologic support to the women during labor is very important. bor is very important.

The provision of continuous pThe provision of continuous psychologicsychologic support during labour by doulas, as well as support during labour by doulas, as well as nurses, family or friends is associated with nurses, family or friends is associated with improved maternal and fetal health and a improved maternal and fetal health and a variety of other benefits.variety of other benefits.

A A douladoula, also known as a labour coach, is , also known as a labour coach, is a nonmedical person who assists a woman a nonmedical person who assists a woman before, during or after before, during or after childbirthchildbirth, as well , as well as her partner and/or family by providing as her partner and/or family by providing information, physical assistance and information, physical assistance and emotional support. emotional support.

CHAPTER 3 MECHANISM OF LABOR CHAPTER 3 MECHANISM OF LABOR WITH OCCIPUT PRESENTATIONWITH OCCIPUT PRESENTATION

The positional changes in the presenting The positional changes in the presenting part required to navigate the pelvic canapart required to navigate the pelvic canal constitute l constitute the mechanisms of laborthe mechanisms of labor..

LLeft occiput anterior (LOA)eft occiput anterior (LOA) position is th position is the most common fetal position e most common fetal position

The The cardinal movements of laborcardinal movements of labor are e are engagement, descent, flexion, internal rongagement, descent, flexion, internal rotation, extension, external rotation, and tation, extension, external rotation, and expulsion. expulsion.

ENGAGEMENTENGAGEMENT

The mechanism by which the biparietal The mechanism by which the biparietal diameter—the greatest transverse diamdiameter—the greatest transverse diameter in an occiput presentation—passes eter in an occiput presentation—passes through the pelvic inlet is designated through the pelvic inlet is designated enengagement.gagement.

In nulliparous women, the fetal head enIn nulliparous women, the fetal head engage 1 or 2 weeks before labor.gage 1 or 2 weeks before labor.

In multiparous women, the fetal head usIn multiparous women, the fetal head usually engage after the onset of labor. ually engage after the onset of labor.

A normal-sized heaA normal-sized head usually does nd usually does not engage with itot engage with its sagittal suture s sagittal suture directed anteropdirected anteroposteriorly. Insteaosteriorly. Instead, the fetal head d, the fetal head usually enters thusually enters the pelvic inlet eithe pelvic inlet either transversely oer transversely or obliquely.r obliquely.

DESCENTDESCENT

This movement is the first requisite for bThis movement is the first requisite for birth of the newborn. irth of the newborn.

In nulliparas, engagement may take placIn nulliparas, engagement may take place before the onset of labor, and further de before the onset of labor, and further descent may not follow until the onset of escent may not follow until the onset of the second stage. the second stage.

In multiparous women, descent usually In multiparous women, descent usually begins with engagement. begins with engagement.

Descent is brought about by one or more Descent is brought about by one or more of four forces: of four forces:

(1) pressure of the amnionic fluid, (1) pressure of the amnionic fluid, (2) direct pressure of the fundus upon the (2) direct pressure of the fundus upon the

breech with contractions, breech with contractions, (3) bearing down efforts of maternal abdo(3) bearing down efforts of maternal abdo

minal musclesminal muscles (4) extension and straightening of the feta(4) extension and straightening of the feta

l body. l body.

FLEXIONFLEXION

As soon as the descending head meets rAs soon as the descending head meets resistance, whether from the cervix, walls esistance, whether from the cervix, walls of the pelvis, or pelvic floor, flexion of thof the pelvis, or pelvic floor, flexion of the head normally results. e head normally results.

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

INTERNAL INTERNAL ROTATIONROTATION

This movement consiThis movement consists of a turning of the sts of a turning of the head in such a mannhead in such a manner that the occiput grer that the occiput gradually moves towaradually moves toward the symphysis pubid the symphysis pubis anteriorly from its os anteriorly from its original position. riginal position.

EXTENSIONEXTENSION

After internal rotation, the sharply After internal rotation, the sharply flexed head reaches the vulva and flexed head reaches the vulva and undergoes extension. undergoes extension.

When the head presses upon the When the head presses upon the pelvic floor, however, two forces pelvic floor, however, two forces come into play. come into play.

The first, exerted by the uterus, acts morThe first, exerted by the uterus, acts more posteriorly, and the second, supplied be posteriorly, and the second, supplied by the resistant pelvic floor and the sympy the resistant pelvic floor and the symphysis, acts more anteriorly. hysis, acts more anteriorly.

The resultant vector is in the direction of The resultant vector is in the direction of the vulvar opening, thereby causing heathe vulvar opening, thereby causing head extension. d extension.

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

EXTERNAL ROTATIONEXTERNAL ROTATION

The delivered head next undergoes The delivered head next undergoes restirestitution.tution.

If the occiput was originally directed towIf the occiput was originally directed toward the left, it rotates toward the left. Thiard the left, it rotates toward the left. This movement apparently is brought abous movement apparently is brought about by the same pelvic factors that product by the same pelvic factors that produced internal rotation of the head.. ed internal rotation of the head..

Restitution of the head to the oblique position Restitution of the head to the oblique position is followed by completion of external rotation is followed by completion of external rotation to the transverse position, a movement that cto the transverse position, a movement that corresponds to rotation of the fetal body, servinorresponds to rotation of the fetal body, serving to bring its bisacromial diameter into relatiog to bring its bisacromial diameter into relation with the anteroposterior diameter of the peln with the anteroposterior diameter of the pelvic outlet. Thus, one shoulder is anterior behinvic outlet. Thus, one shoulder is anterior behind the symphysis and the other is posterior.d the symphysis and the other is posterior.

EXPULSIONEXPULSION

Almost immediately afteAlmost immediately after external rotation, the ar external rotation, the anterior shoulder appears nterior shoulder appears under the symphysis puunder the symphysis pubis, and the perineum sobis, and the perineum soon becomes distended bon becomes distended by the posterior shoulder. y the posterior shoulder. After delivery of the shouAfter delivery of the shoulders, the rest of the bodlders, the rest of the body quickly passes. y quickly passes.

During labor, these movements are During labor, these movements are sequential but also show great sequential but also show great temporal overlap. temporal overlap.

For example, as part of the process For example, as part of the process of engagement, there is both flexion of engagement, there is both flexion and descent of the head. and descent of the head.

As a result, the fetus is transformed As a result, the fetus is transformed into a cylinder, with the smallest into a cylinder, with the smallest possible cross section passing possible cross section passing through the birth canal. through the birth canal.

CHAPTER 4 DIAGNOSIS OF CHAPTER 4 DIAGNOSIS OF THREATENED LABOR AND LABORTHREATENED LABOR AND LABOR

THREATENED LABORTHREATENED LABOR Before actual labor begins, a Before actual labor begins, a

number of physiologic number of physiologic preparatory events usually preparatory events usually occur. And these are called occur. And these are called threatened labor.threatened labor.

The manifestation of threatened laborThe manifestation of threatened labor

LighteningLightening False LaborFalse Labor Bloody showBloody show

LighteningLightening

LighteningLightening may be noted by the mother may be noted by the mother as a flattening of the upper abdomen anas a flattening of the upper abdomen and an increased prominence of the lower d an increased prominence of the lower abdomen.abdomen.

Two or more weeks before labor, the fTwo or more weeks before labor, the fetal head in most primigravid women etal head in most primigravid women settles into the brim of the pelvis.settles into the brim of the pelvis. In m In multigravida, this often does not occur untultigravida, this often does not occur until early in labor.il early in labor.

False LaborFalse Labor During the last 4 to 8 weeks of pregnancy, the During the last 4 to 8 weeks of pregnancy, the

uterus undergoes irregular contractions that uterus undergoes irregular contractions that normally are painless.normally are painless.

Such contractions appear unpredictably and Such contractions appear unpredictably and sporadically and can be rhythmic and of mild sporadically and can be rhythmic and of mild intensity. In the last month of pregnancy, these intensity. In the last month of pregnancy, these contractions may occur more frequently, and with contractions may occur more frequently, and with greater intensity. greater intensity.

These Braxton Hicks contractions are These Braxton Hicks contractions are considered false labor in that they are not considered false labor in that they are not associated with progressive cervical dilatation associated with progressive cervical dilatation or effacement.or effacement.

They may serve, however, a physiologic role in They may serve, however, a physiologic role in preparing the uterus and cervix for true labor.preparing the uterus and cervix for true labor.

Bloody showBloody show Prior to the onset of parturition, the cervix is frequPrior to the onset of parturition, the cervix is frequ

ently noted to soften as a result of increased water ently noted to soften as a result of increased water content and collagen lysis.content and collagen lysis.

Simultaneous effacement, or thinning of the cervix,Simultaneous effacement, or thinning of the cervix, occurs as it is taken up into the lower uterine segm occurs as it is taken up into the lower uterine segmentent..

Consequently, patients often present in early labor wiConsequently, patients often present in early labor with a cervix that is already partially effaced.th a cervix that is already partially effaced.

As a result of cervical effacement, the mucous plug witAs a result of cervical effacement, the mucous plug within the cervical canal may be released. The onset of lahin the cervical canal may be released. The onset of labor may thus be heralded by the passage of a small abor may thus be heralded by the passage of a small amount of blood-tinged mucus from the vagina mount of blood-tinged mucus from the vagina (“blo(“bloody show”)ody show”)..

In LaborIn Labor

It is defined as progressive cervical effIt is defined as progressive cervical effacement and dilatation resulting from acement and dilatation resulting from regular uterine contractions that occuregular uterine contractions that occur at least every 5 minutes and last 30 tr at least every 5 minutes and last 30 to 60 seconds.o 60 seconds.

STAGES OF LABORSTAGES OF LABOR

Total stage of labor Total stage of labor is from the is from the onset of regular uterine contractions onset of regular uterine contractions to the delivery of the baby and to the delivery of the baby and placenta.placenta.

3 stages of labor3 stages of labor The first stage is from the onset of true labor tThe first stage is from the onset of true labor t

o complete dilation of the cervix.o complete dilation of the cervix.primiparous patients: 11-12h, multiparous patieprimiparous patients: 11-12h, multiparous patie

nts 6-8h.nts 6-8h. The second stage is from complete dilation of The second stage is from complete dilation of

the cervix to the birth of the baby. the cervix to the birth of the baby. primiparous patients: 1-2h, less than 2 h. multipprimiparous patients: 1-2h, less than 2 h. multip

arous patients much faster, less than 1h.arous patients much faster, less than 1h. The third stage is from the birth of the baby to The third stage is from the birth of the baby to

delivery of the placenta. delivery of the placenta. 5-15min, less than 30 minutes.5-15min, less than 30 minutes.

CHAPTER 5 CLINICAL CHAPTER 5 CLINICAL MANIFESTATION AND MANAGEMENT MANIFESTATION AND MANAGEMENT

OF FIRST STAGE OF LABOROF FIRST STAGE OF LABOR

CLINICAL MANIFESTATION OF THE CLINICAL MANIFESTATION OF THE FIRST STAGEFIRST STAGE

1.1. Regular uterine contraction.Regular uterine contraction. From the onset of labor, it occur every 5-From the onset of labor, it occur every 5-

6 minutes and last about 30 seconds. 6 minutes and last about 30 seconds. With the progression of labor, the uterine With the progression of labor, the uterine

contractions increase progressively in contractions increase progressively in intensity. At the same time, frequency intensity. At the same time, frequency increases to every 2-3 min, and the increases to every 2-3 min, and the duration increases to 50-60 seconds. duration increases to 50-60 seconds.

When the cervix is nearly fully dilated, When the cervix is nearly fully dilated, the contractions last to 1min or even the contractions last to 1min or even longer, and rest for only 1-2 min.longer, and rest for only 1-2 min.

2. Dilatation of cervix2. Dilatation of cervix

Dilatation of the cervix is determined Dilatation of the cervix is determined by vaginal examination. by vaginal examination.

If progress is slow, evaluation for uterine If progress is slow, evaluation for uterine dysfunction, fetal malposition, or cephaldysfunction, fetal malposition, or cephalopelvic disproportion should be undertaopelvic disproportion should be undertaken.ken.

3. Descent of fetal head3. Descent of fetal head

Determined by vaginal examination. Determined by vaginal examination. The level of the lowest presenting fetal pThe level of the lowest presenting fetal p

art in the birth canal is described in relatart in the birth canal is described in relationship to the ischial spines.ionship to the ischial spines.

4. Rupture of membranes4. Rupture of membranes

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

MANAGEMENT OF THE FIRST MANAGEMENT OF THE FIRST STAGE OF LABORSTAGE OF LABOR

On admission the general condition of tOn admission the general condition of the patient is assessed, her pulse rate anhe patient is assessed, her pulse rate and blood pressure are recorded, and her d blood pressure are recorded, and her urine is tested for protein.urine is tested for protein.

By abdominal examination the presentaBy abdominal examination the presentation and position ot the fetus, and the retion and position ot the fetus, and the relation of the presenting part to the brim lation of the presenting part to the brim of the pelvis, are determined. of the pelvis, are determined.

Abdominal examination will also show the Abdominal examination will also show the frequency and strength of the uterine frequency and strength of the uterine contractions. The fetal heart rate is contractions. The fetal heart rate is counted for a full minute, and any counted for a full minute, and any abnormality of rate or rhythm is noted. abnormality of rate or rhythm is noted.

A vaginal examination will show the A vaginal examination will show the degree of dilatation of the cervix, whether degree of dilatation of the cervix, whether the membrane are intact or ruptured, and the membrane are intact or ruptured, and the level and position of the presenting the level and position of the presenting part. part.

PartogramPartogram

Once the labor has become established, Once the labor has become established, all events during labor are noted on a paall events during labor are noted on a partogram—a most useful graphical recorrtogram—a most useful graphical record of the course of labor. d of the course of labor.

Routine observations of the mother’s pulse rRoutine observations of the mother’s pulse rate and blood pressure, with an assessment of ate and blood pressure, with an assessment of the strength of the uterine contractions are enthe strength of the uterine contractions are entered on it. Records of the findings at successitered on it. Records of the findings at successive vaginal examinations are plotted on a grapve vaginal examinations are plotted on a graph, showing the dilatation of the cervix and the h, showing the dilatation of the cervix and the descent of the fetal head in centimeters againsdescent of the fetal head in centimeters against the time in hours. t the time in hours.

The curve obtained is compared with an average norThe curve obtained is compared with an average normal curve for primigravidae or multigravidae as may bmal curve for primigravidae or multigravidae as may be appropriate. If the patient’s progress is normal her e appropriate. If the patient’s progress is normal her curve will correspond with the normal curve, or “lie tcurve will correspond with the normal curve, or “lie to the left” of it. o the left” of it.

If for any reason labor is not progressing normally dilaIf for any reason labor is not progressing normally dilatation of the cervix will become slower or may cease, tation of the cervix will become slower or may cease, and the patient’s partogram will be “to the right” and the patient’s partogram will be “to the right” of the normal curve.of the normal curve.

Certain steps should be taken in the clinical managemCertain steps should be taken in the clinical management of the patient during the first stage of labor.ent of the patient during the first stage of labor.

Uterine ActivityUterine Activity Uterine contractions should be monitored every 30 miUterine contractions should be monitored every 30 mi

nutes by palpation for their frequency, duration, and inutes by palpation for their frequency, duration, and intensity. With the palm of the hand resting lightly on tntensity. With the palm of the hand resting lightly on the uterus, the time of contraction onset is determined.he uterus, the time of contraction onset is determined. Its intensity is gauged from the degree of firmness the Its intensity is gauged from the degree of firmness the uterus achieves. uterus achieves.

For high-risk pregnancies, uterine contractions shoFor high-risk pregnancies, uterine contractions should be monitored continuously along with the fetal uld be monitored continuously along with the fetal heart rateheart rate. This can be achieved electronically using e. This can be achieved electronically using either an external tocodynamometer or an internal preither an external tocodynamometer or an internal pressure catheter in the amniotic cavity. ssure catheter in the amniotic cavity.

Fetal MonitoringFetal Monitoring The fetal heart rate should be evaluated by eitThe fetal heart rate should be evaluated by eit

her auscultation with a DeLee stethoscope, by her auscultation with a DeLee stethoscope, by external monitoring with Doppler equipment, external monitoring with Doppler equipment, or by internal monitoring with a fetal scalp eleor by internal monitoring with a fetal scalp electrode. ctrode.

In patients with no significant obstetric risk facIn patients with no significant obstetric risk factors, the fetal heart rate should be auscultated tors, the fetal heart rate should be auscultated or the electronic monitor tracing evaluated evor the electronic monitor tracing evaluated every 1-2h in the latent phase of labor, and at leaery 1-2h in the latent phase of labor, and at least every 15-30 minutes in the active phase of tst every 15-30 minutes in the active phase of the first stage of labor and at least every 15 minhe first stage of labor and at least every 15 minutes in the second stage of labor. utes in the second stage of labor.

DILATION OF CERVIX AND DILATION OF CERVIX AND DESCENT OF FETAL HEADDESCENT OF FETAL HEAD

Measurement of progressMeasurement of progress During the first stage, the progress of During the first stage, the progress of

labor may be measured in terms of labor may be measured in terms of cervical effacement, cervical cervical effacement, cervical dilatation, and descent of the fetal dilatation, and descent of the fetal head. head.

PhasesPhases

The first stage of labor consists of two The first stage of labor consists of two phases: a latent phase, during which cphases: a latent phase, during which cervical effacement and early dilatatioervical effacement and early dilatation(to 3cm) occur, and an active phase, n(to 3cm) occur, and an active phase, during which more rapid cervical dilatduring which more rapid cervical dilatation occurs, the cervix dilate from 3cation occurs, the cervix dilate from 3cm to 10cm.m to 10cm.

And the active phase has 3 And the active phase has 3 component parts component parts

acceleration phase the cervix dilates acceleration phase the cervix dilates from 3-4cm, normally takes 1h and 30 from 3-4cm, normally takes 1h and 30 min.min.

maximum acceleration phase the maximum acceleration phase the cervix dilates from 4-9cm, normally cervix dilates from 4-9cm, normally takes 2h.takes 2h.

deceleration phase the cervix dilates deceleration phase the cervix dilates from 9-10cm, normally takes 30 min.from 9-10cm, normally takes 30 min.

LengthLength The length of the first stage may vary in relatioThe length of the first stage may vary in relatio

n to parity; primiparous patients generally expn to parity; primiparous patients generally experience a longer first stage than do multiparouerience a longer first stage than do multiparous patients. s patients.

Because the latent phase may overlap consideBecause the latent phase may overlap considerably with the preparatory phase of labor, its drably with the preparatory phase of labor, its duration is highly variable. uration is highly variable.

It may also be influenced by other factors, sucIt may also be influenced by other factors, such as sedation and stress. h as sedation and stress.

This phase normally takes 8h, and the maxiThis phase normally takes 8h, and the maximum is 16 h in primiparous patients.mum is 16 h in primiparous patients.

The active phase begins when the cervix The active phase begins when the cervix is 3 cm dilated in the presence of regularis 3 cm dilated in the presence of regularly occurring uterine contractions. The mily occurring uterine contractions. The minimal dilatation during the active phase nimal dilatation during the active phase of the first stage is nearly the same for prof the first stage is nearly the same for primiparous and multiparous women: 1 animiparous and multiparous women: 1 and 1.2cm/hour, respectively. d 1.2cm/hour, respectively.

This phase normally takes 4h, and the This phase normally takes 4h, and the maximum is 8 h.maximum is 8 h.

Descent of fetal headDescent of fetal head The level—or The level—or stationstation—of the presenting fetal —of the presenting fetal

part in the birth canal is described in relationspart in the birth canal is described in relationship to the ischial spines. hip to the ischial spines.

When the lowermost portion of the presenting When the lowermost portion of the presenting fetal part is at the level of the spines, it is desigfetal part is at the level of the spines, it is designated as being at zero (0) station.nated as being at zero (0) station.

As the presenting fetal part descends from the As the presenting fetal part descends from the inlet inlet towardtoward the ischial spines, when it is 3,2an the ischial spines, when it is 3,2and 1 cm above the ischial spines, the designatiod 1 cm above the ischial spines, the designation is –3, –2, –1. When it is 1, 2,3 and 4cm blow tn is –3, –2, –1. When it is 1, 2,3 and 4cm blow the spines, as the presenting fetal part descendhe spines, as the presenting fetal part descends, it is then +1, +2, +3, +4.s, it is then +1, +2, +3, +4.

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

Rupture of membranesRupture of membranes

Rupture of membranes usually occurs wRupture of membranes usually occurs when the cervix is nearly fully dilated. hen the cervix is nearly fully dilated.

Once the membrane is ruptured, the fetOnce the membrane is ruptured, the fetal heart should be monitored, and the cal heart should be monitored, and the color and amount of Amnionic Fluid shouolor and amount of Amnionic Fluid should be noted. ld be noted.

And the time of rupture should be recorAnd the time of rupture should be recorded. ded.

Blood PressureBlood Pressure

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

Maternal Position.Maternal Position.

If the head is engaged there is no need for the If the head is engaged there is no need for the patient to remain in bed during early labor. If spatient to remain in bed during early labor. If she is up and about, the weight of the liquor anhe is up and about, the weight of the liquor and fetus helps to dilate the cervix, and pressure d fetus helps to dilate the cervix, and pressure on the lower segment stimulates the uterus to on the lower segment stimulates the uterus to contract. contract.

If she is lying in bed, the lateral recumbent If she is lying in bed, the lateral recumbent position should be encouraged position should be encouraged to ensure perto ensure perfusion of the uteroplacental unit.fusion of the uteroplacental unit.

There may be a frequent desire to pass water There may be a frequent desire to pass water during the first stage. If the bladder becomes fduring the first stage. If the bladder becomes full and the patient cannot empty it a soft cathull and the patient cannot empty it a soft catheter should be passed, as a full bladder has an eter should be passed, as a full bladder has an inhibiting effect on the uterine contractions.inhibiting effect on the uterine contractions.

Although it is common practice to give an eneAlthough it is common practice to give an enema and to clip or shave the vulval hair, there is ma and to clip or shave the vulval hair, there is little to show that either of these practices is nlittle to show that either of these practices is necessary, and many women dislike them. ecessary, and many women dislike them.

Vaginal ExaminationVaginal Examination

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

AmniotomyAmniotomy

The artificial rupture of fetal membranes may The artificial rupture of fetal membranes may provide information on the volume of amniotiprovide information on the volume of amniotic fluid and the presence or absence of meconic fluid and the presence or absence of meconium. In addition, rupture of the membranes maum. In addition, rupture of the membranes may cause an increase in uterine contractility.y cause an increase in uterine contractility.

Amniotomy incurs risks of chorioamnionitiAmniotomy incurs risks of chorioamnionitis if labor is prolonged and of umbilical cord s if labor is prolonged and of umbilical cord compression or cord prolapse if the presentcompression or cord prolapse if the presenting part is not engaged.ing part is not engaged.

CHAPTER 6 CLINICAL MANIFESTATION CHAPTER 6 CLINICAL MANIFESTATION AND MANAGEMENT OF SECOND STAGE AND MANAGEMENT OF SECOND STAGE

OF LABOROF LABOR

This stage begins when cervical This stage begins when cervical dilatation is complete and ends with dilatation is complete and ends with fetal delivery.fetal delivery.

CLINICAL MANIFESTATIONCLINICAL MANIFESTATION With full cervical dilatation, which signifies With full cervical dilatation, which signifies

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

With each contraction, the peWith each contraction, the perineum bulges increasingly. Trineum bulges increasingly. The vulvovaginal opening is dilhe vulvovaginal opening is dilated by the fetal head, and thated by the fetal head, and the fetal head is seen at the vule fetal head is seen at the vulva at the height of each contrva at the height of each contraction. Between the contractiaction. Between the contractions the elastic tone of the perons the elastic tone of the perineal muscles push the head ineal muscles push the head back , and this is called back , and this is called head head visible on vulval gappingvisible on vulval gapping. .

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

Six movements of the baby enable it to aSix movements of the baby enable it to adapt to the maternal pelvis: descent, fledapt to the maternal pelvis: descent, flexion, internal rotation, extension, externxion, internal rotation, extension, external rotation, and expulsion.al rotation, and expulsion.

The second stage generally takes from The second stage generally takes from 1 to 2 hours in primigravid women and 1 to 2 hours in primigravid women and from 5 to 60 minutes in multigravid wfrom 5 to 60 minutes in multigravid women.omen.

MANAGEMENT OF THE SECOND MANAGEMENT OF THE SECOND STAGESTAGE

Fetal MonitoringFetal Monitoring During the second stage, the fetal During the second stage, the fetal

heart rate should be monitored heart rate should be monitored continuously or evaluated every 5-10 continuously or evaluated every 5-10 minutes. Fetal heart rate minutes. Fetal heart rate decelerations (head compression or decelerations (head compression or cord compression) with recovery cord compression) with recovery following the uterine contraction may following the uterine contraction may occur normally during this stage. occur normally during this stage.

Bearing DownBearing Down

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

Vaginal ExaminationVaginal Examination

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

Delivery of the FetusDelivery of the Fetus

When delivery is imminent, the patient iWhen delivery is imminent, the patient is usually placed in the lithotomy positios usually placed in the lithotomy position, and the skin over the lower abdomen, n, and the skin over the lower abdomen, vulva, anus, and upper thighs is cleansevulva, anus, and upper thighs is cleansed with an antiseptic solution. d with an antiseptic solution.

The The modified Ritgen maneuvermodified Ritgen maneuver The midwife must control the head to preThe midwife must control the head to pre

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

Once the head is deOnce the head is delivered, the airway ilivered, the airway is cleared of blood as cleared of blood and amniotic fluid und amniotic fluid using a bulb suction sing a bulb suction device. The oral cavdevice. The oral cavity is cleared initiallity is cleared initially and then the narey and then the nares are cleared. A secs are cleared. A second towel is used tond towel is used to wipe secretions fro wipe secretions from the face and heom the face and head.ad.

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

CHAPTER 7 CLINICAL MANIFESCHAPTER 7 CLINICAL MANIFESTATION AND MANAGEMENT OF TATION AND MANAGEMENT OF

THIRD STAGE OF LABORTHIRD STAGE OF LABOR

clinical manifestation: : placental separation

ManagementManagement

the care of the newbornthe care of the newborn assist the delivery of placenta to exam the placenta and fetal membranesto exam the placenta and fetal membranes to check the to check the soft birth canal to prevent PPH to prevent PPH to observe the to observe the general state of health manual removal of placentamanual removal of placenta