Normal Labor and Delivery

Normal Labor and Delivery

Obs&Gyn Department of 1st Clinical Hospital Wuhan University

Associate Professor Ming lei

OutlineDefinition

12Four factors for labor3Mechanism of labor

OutlineDiagnosis of threatened labor and labor4Labor stages5Clinical course andmanagement of 2nd stages6Clinical course andmanagement of 1st stages78Clinical course andmanagement of 3rd stages

Delivery is the process by which the mature or nearly mature (fetus ,umbilical cord,membranes and placenta) are expelled from the maternal body after 28 weeks

The last few hours of human pregnancy are characterized by uterine contraction that effect dilatation of the cervix and force the fetus through the birth canal. Much energy is expended during this time, hence the use of term labor to describe this processMyometrium is unresponsive during pregnancy. After the prolonged period of quiescence, a transitional phase is requires during which myometrial unresponsiveness is suspend and cervix is softened and effaced

Cause of onset of labor: Precise mechanism in initiation of labor is not defined Endocrine Mechanical theory Neurological factor

LMP :last menstrual period 56EDC :expected date of confinement

OutlineNormal Labor and delivery

Expulsive Force uterine contractionA rhythmic tightening in labor of the upper uterine musculature that contracts the size of the uterus and pushes the fetus toward the birth canalMajor force

RhythmSymmetryPolarityRetractionintermissionduration

durationuterine ContractionfeatureFour characteristics

Retraction is a phenomenon of the uterus in labor in which the muscle fibres are permanently shortened. Unlike any other muscles of the bodyContraction is a temporary reduction in length of the fibres, which attain their full length during relaxation

The effects of retraction in normal labor are:Formation of lower uterine segment and dilatation and effacement of the cervixMaintain the advancement of the presenting part made by the uterine contractions and help ultimate expulsion of the fetusTo reduce the surface area of the uterus favoring separation of placentaEffective haemostasis after the separation of the placenta

Birth canal

Pelvis anatomical marksSacral promontory

Ischial spine (L,R)

Symphysis pubis

Birth canalBony canalPelvic inlet planeSuperior straitPelvic outlet planeInferior straitMidpelvis outletleast pelvic dimension plane

pelvic axis: A hypothetical line curving through the midpoint of the pelvic planes

4 diameters of the pelvic inletAnteroposterior: 11cmTransverse: 13cm Two obliques: 12.75cmPelvic inlet planePosteriorly by the promontory and alae of the sacrum, laterallyby the linea terminalis

Anteriorly by the horizontal Rami of the pubic bones and symphysis pubis

4 types in shape gynecoid (50%), anthropoid, android, platypelloid. Most are intermediate type.4 diameters anteroposterior(AP), transverse, and 2 obliquesObstetrical conjugate the shortest distance between promontory and symphysis pubis. Estimated by substracting 1.5 to 2 cm from the diagonal conjugate.True conjugate the A-P diameter of the pelvic inlet

DC:distance from the lower margin of symphysis to promontory of the sacrumOC:From result according to the height and inclination of the symphysis pubis,OC can be measured by substracting 1.5-2cm, it should be 10cm or more

Anteroposterior diameter through the level of the ischial spines >11.5cm

Interspinous diameter is 10cm or somewhat more

mid plane of pelvisThe midpelvis at the level ofIschial spines is of particular importance following engagement of the fetal head in obstructed labor

pelvic outlet planeConsists of two approximately triangular areas not in the same plane but having a common base, Which is a line drawn between the two ischial tuberosities

Birth canalSoft canalSoft tissue part canal

Soft part of birth canal Formation of uterine lower segmentCervix effacement and dilatation

Isthmus: between anatomical internal OS and histological internal OSPhysiological retraction ring :develops at the junction of the upper and lower uterine segment. As labor progresses, a boundary ridge on the inner uterine surface is marked between the thinning of the lower segment and the concomitant thickening of the upperPathological retraction ring: also called Bandl ring, develops from the physiological ring when the thinning of the lower uterine segment is extreme, as in obstructed labor, the ring is very prominent, forming it.

cervical effacement and dilatation

2Four factors for laborFetal sizeFetal lieFetal attitudeFetal stationFetal presentationFetal position

FetusFetal lie Relation of long axis of fetus to that of the mother. Longitudinal (99%), transverse or oblique

Fetal presentation Fetal part that directly overlies pelvic inletCephalic , breech , or shoulder

Fetal position The relation of a chosen portion of the presenting part of the fetus to the right or left side of the maternal birth canal. For more accurately anterior, transverse, posterior

LOA (left occipito-anterior)ROA (right occipito-anterior)

Denominator:bony fixed point on presenting partocciput

LOT(left occipito-transverse)ROT(right occipito-transverse)

LOP(left occipito-posterior)ROP(right occipito-posterior)

The fetus is in the occiput or vertex presentation in approximately 95% of all labor

In majority of cases, the vertex enters the pelvis with the sagittal suture in the transverse pelvic diameter or the oblique lines

The fetus enters the pelvis in the left occiput transverse(LOT) or LOA position in 40%;in the ROT or ROA in 20%; in OP position in 20%

1 stepLeopolds maneuvers Run hands down maternal abdomen on either side of fetus to determine fetal lie, identifying small parts and fetal spine

Using the thumb and fingers of one hand, the lower portion of the maternal abdomen is grasped just above the symphysis pubis to determine the presentation

With the tips of the fingers of each hand, exerts deep pressure in the direction of the axis of the pelvic inlet to determine if the head or breech descended into the pelvis

Gently palpate the fundus with the tip of the fingers of both hand in order to define which fetal pole is present in the fundus and appropriate size.

2 step3 step

The mother should be supineand comfortable position withher abdomen bared

2.During the first three maneuversthe examiner stands at the sideof the bed that is most convenientand faces the patient

3.The examiner reverses thisposition and face the feet for the last maneuver

1 stepGently palpate the fundus with the tip of the fingers of both hand in order to define which fetal pole is present in the fundus and appropriate size.

Run hands down maternal abdomen on either side of fetus to determine fetal lie, identifying small parts and fetal spine

2 step

3 stepUsing the thumb and fingers of one hand, the lower portion of the maternal abdomen is grasped just above the symphysis pubis to determine the presentation

With the tips of the fingers of each hand, exerts deep pressure in the direction of the axis of the pelvic inlet to determine if the head or breech descended into the pelvis

bregmaAdultfetusSuture: it permits gliding movement of one bone over the other during moulding of the head while the head passes through the pelvis;During Internal examination in labor, palpation of sagittal suture give anidea of the manner of engagement of the head

post fontanelle(lambda) Bregma(Ant fontanelle)BPD(parietal bones diameter)frontal bonesOccipital boneSagittal sutureThe bones of the vault are not joined thus changes in the shape of the fetal head during labor can occur due to molding

fontanelle:wide gap in suture line

OutlineDefinition

1Occiput presentation()1. The ability of the fetus to successfully negotiate the pelvis during labor involves changes in position of its head during its passage in labor

2. The mechanisms of labor, also known as the cardinal movements, are described in relation to a vertex presentation, as is the case in 95% of all pregnancies

3. In reality, the mechanism of labor consists of a combination movements that are ongoing simultaneously

4. For purposes of instruction, the various movements often are described as though they occurred separately and independently the cardinal movements are described as 7 discrete sequences, as discussed below

OutlineDefinition

1Occiput presentation()7. expulsion

Mechanism of labor()Occiput presentation31. Engagement Passage of widest diameter of presenting part to level below the plane of the pelvic inletOccurs earlier in primigravidae, usually before the onset of labor while in multiparae, the same may occur in late 1st stage with rupture of the membrane

ischial spines

Mechanism of laborOcciput presentation323. Descent &FlexionDownward passage of presenting part through the pelvisOccurs passively as the head descends due to the shape of the bony pelvis and resistance of pelvic floor soft tissues resulting in passive flexion of the fetal occiput. The chin is brought into contact with the fetal thorax, and the presenting diameter changes from occipitofrontal (12cm) to suboccipitobregmatic (9.5 cm) which is the smallest diameter of fetal head for optimal passage through the pelvis

Occipitofrontal Diameter 12cmSuboccipitobregmatic Diameter 9.5cm

Occipito frontal diameter 12cmOccipito subregmatic diameter 9.5cmOccipito mental diameter 13cm

LOTROT

Mechanism of labor()Occiput presentation34. Internal rotationAs the head descends, the presenting part, usually in the transverse position, is rotated about 45to anteroposterior (AP) position under the symphysis. Internal rotation brings the AP diameter of the head in line with the AP diameter of the pelvic outlet

Mechanism of labor()Occiput presentation35. Extension 1) With further descent and fullflexion of the head, the baseof the occiput comes in contactwith the inferior margin of thepubic symphysis

2) Upward resistance from thepelvic floor and the downwardforces from the uterine contractions cause the occiput to extend and rotate around the symphysis

Forces Concerned in LaborPositive forces * Uterine contractions * Abdominal pressure by rectus muscles * Fundal pressure * Forceps delivery and vacuum extractionResistance * The uterine cervix * The muscles of the pelvic floor

Mechanism of labor()Occiput presentation36. External Rotation When the fetus' head is free of resistance, it untwists about 45left or right, returning to its original anatomic position in relation to the body

Mechanism of laborOcciput presentation37. Expulsion After the fetus' head is delivered, further descent brings the anterior shoulder to the level of the pubic symphysis

The anterior shoulder is then rotated under the symphysis, followed by the posterior shoulder and the rest of the fetus

Mechanism of labor()Occiput presentation3Mechanism of labor for left occiput anterior position

FalselaborDiagnosis of threatened labor As the fetal presenting part descends into the pelvic inlet, the fundal height decreases. Theprimigravida feels comfort of the upper abdomen, eats more, and respires briskly.

Braxon Hicks contractions,during the last 4-8weeks of pregnancy irregular,generally painless uterine contractions occur with slowly increasing frequencylighteningshowCervical effacement, the mucus plug within the cervical canal may be released .And a small amount of blood creating by the ruptured capillary and the mucous in the cervix are mixed together and are discharged , this is called show

Diagnosis of in laborRegular uterine contractioncervical effacementcervical dilatationdescent

False labor vs. True labor

Stage of laborTOTAL STAGE

2nd stageexpulsion of the fetus

1st stage cervical dilatation

3rd stageexpulsion of the placenta primipara 11-12 hours 1-2hours5-15mins

Three stages of laborThe first stage begins when uterine contractions of sufficient frequency, intensity and duration are attained to bring about effacement and progressive dilatation of the cervix and ends when the cervix is fully dilated

The second stage begins when dilatation of the cervix is complete, and ends with delivery of the fetus

The third stage begins immediately after delivery of the fetus, and ends with the delivery of the placenta and fetal membranes

The fourth stage is the stage of observation for 2 hours after expulsion of the placenta

The first stage is divided into a relatively flat latent phase and a rapidly progressive active phase. In active phase, there are 3 identifiable component parts: an acceleration phase, a linear phase of maximum slope, and a deceleration phase

Clinical course and management of 1st stagesClinical manifestationsAdd Your TextRegular contraction1 cervical effacement and dilatation2fetodescent3Rupture of membranes 4

2Clinical manifestations1. At the beginning of the first stage of labor, it is weak

2. intermission lasts a little longer about 5-6mins; duration is about 30s

3. As labor progresses, the intermission lasts 2-3mins; duration is 50-60s

4. intensity increases when the cervix is fully dilated, intermission only last one min or more longer; duration can last more than one min

Uterine contraction1

intensityduration intermission durationIntensity: describes the degree of uterine systole, it gradually increases with the advancement of labor until it becomes maximum in the second stage during delivery of the baby

Duration: In the 1st stage,the contraction last for about 30s initially but Gradually increase in duration with the progress of labor. Thus in the 2nd stage, the contractions last longer than in the 1st stage

2

Clinical manifestations

Cervical changes and descent2-3Cervical effacement: the obliteration of the cervix is the shortening of the cervical canal from a length of about 2cm to a mere circular orifice with almost paper-thin edgesCompared with the body of the uterus, the lower segment and the cervix are regions of lesser resistance, these structures are subjected to distention. As the uterinecontraction cause pressure on the membranes, the hydrostatic action of the aminionic sac in turn dilates the cervical canal. In absence of intact membranes, the pressure of the presenting part against the cervix and lower uterine segment is effective. It wont retard cervical dilatation

2

Clinical manifestations

LATENT PHASE

It begins with theregular contractionsafter in labor ends when the cervix dilates to 2cm.8-16h; 1cm/2-3hACTIVE PHASE

It refers the cervix dilated from 2cm to complete dilatation.4-8h;

Cervical changes and descent2-3

The first stage is divided into a relatively flat latent phase and a rapidly progressive active phase. In active phase, there are 3 identifiable component parts: an acceleration phase, a linear phase of maximum slope, and a deceleration phase

2Clinical manifestationsThe fetal membrane is always ruptured when the cervix is completely dilated and the amnionic fluid runs out , this is called rupture of membranesWhen the membrane rupture before the onset of labor, it is called premature rupture

4Rupture of membrane

management of 1st stages education, eating, voiding

1position(sitting, reclining, recumbent)2 monitoring of the fetal heart rate3dilation of cervix and frequencyseverity of uterus contractions

54

Management principles of 1st stageNon-interference with watchful expectancy so as to prepare the patient for natural birth

To monitor carefully the progress of labor, maternal conditions and fetal behavior so as to detect any intrapartum complicating early

Actual management of 1st stageGeneral: antiseptic dressing, encouragement and assurance constant supervision

Bowel: an enema with soap or glycerine suppository is traditionally given in early stage. Reduce infection rate and increase the progress of the laborRest and ambulation:

Diet: food is withheld during active labor; water,fluid juice can be given

Bladder care: full bladder often inhibits uterine contraction and may lead to infection, so encourage the patient to pass urine by herself or catheterisation to be done to her with strict aseptic precautions

Actual management of 1st stageRelief of pain: analgesia in labor can be used on primigravida. The analgesic drugs should not be given if delivery is anticipated within two hoursMaternal condition: routine check up includesto record per 2 hours about P,BP, T, cervical dilatation and fetal presentation descent by anal or vaginal examinationto note the urine outputI.V fluid, drugsElectronic fetal monitoring, auscultation ,dopplerMonitor the uterus contraction(intensity,duration,frequency)

Clinical course and management of 2nd stagesClinical manifestationsAdd Your TextMore intensive contraction with defecation1Head visible on vulval gapping2Crowning of head3

Head visible on vulval gappingCrowning of headCrowning refers to when the widest part of the baby's head (or their crown) is emerging. At this point, the baby's crown, part of their forehead and the back of the baby's head can be clearly seen.

Crowning refers to when the widest part of the baby's head (or their crown) is emerging. At this point, the baby's crown, part of their forehead (nearly to their eyebrows) and the back of the baby's head can be clearly seen. As the baby's head crowns, the woman's perineum is stretched to its maximum, being nearly paper-thin. There is usually an intense burning (or stinging sensation) for a few seconds as this occurs, generally easing as the perineum numbs. The burning can trigger panic for some women, causing them to cry out, or scream.

management of 2nd stages fetal heart rate

1 maternal conditions2Pushing3Head visible on vulval gappingCrowning of head 8

Laceration or Episiotomy

Delivery of fetus

Deal with umbilical cord

aiding in fetal descent through birth canal59674

Management principles of 2nd stageTo assist in the natural expulsion of the fetus slowly and steadilyTo prevent perineal injuries

Actual management of 2nd stageGeneral: constant supervision is mandatory and the FHR is recorded at every 5minsvaginal examination is done at the beginning of the 2nd stage not only to comfirm its onset but to detect any accidental cord prolapse. The position and the station of the head are once more to be reviewed and the progressive descent of the head is ensuredPreparation for delivery: position the accoucheur scrubs up, put on the sterile gown, mask and gloves and stands on the right side of the tableToileting the external genitaliaTo catheterise the bladder

Actual management of 2nd stageConduction of delivery: Episiotomy is done selectively, usually as a routine in ChinaSlowly delivery of the head in between the contractions is to be regulatedThe mucus and blood in the mouth and pharynx are to be wiped with sterile gauze piece on a little finger or electrical sucker

Prevention of perineal lacerationDelivery by early extension is to be avoidedSpontaneous forcible delivery of the head is to be avoidedTo deliver the head in between contractionsTo perform timely episiotomy(

Actual management of 2nd stageImmediate care of the newborn air passage should be cleared of mucus and liquor by gentle suction apgar rating at 1min and at 5mins is to be recorded clamping and ligature of the cordbaby is wrapped with a dry warm towel, the identification tape is tied both on the wrist of the baby and the mom

Clinical course and management of 3rd stagesClinical manifestationsAdd Your Textthe uterus decreases in size

1delivery of placenta(spontaneously, manually2inspection of the birth canal3evaluated for lacerations

4

Management principles of 3rd stageTo ensure strict vigilance and to follow the management guidelines strictly in practice so as to prevent the complications

Actual management of 3rd stageExpectant management(traditional)Active management Control cord traction Fundal pressure Oxytocin iv drop Manual removal

Actual management of 3rd stageExamination of the placenta membranes and cordVulva, vagina and perineum are inspected

Placental Separation

begins immediately after delivery of fetus, involve separation & expulsion of placentaDiminution in Ut size PL implantation site area PL accommodate to reduced area thickness because of limited PL elasiticity forced to buckleResulting tension weakest layer of decidua (D. spongiosa) cleavage take place at that siteAs separation proceed hematoma forms between separtating PL & remaining Decidua result of separation

Placental Separation

begins immediately after delivery of fetus, involve separation & expulsion of placenta

Diminution in Ut size PL implantation site area PL accommodate to reduced area thickness because of limited PL elasiticity forced to buckle

-Resulting tension weakest layer of decidua (D. spongiosa) cleavage take place at that site

-As separation proceed hematoma forms between separtating PL & remaining Decidua result of separation

Placental Extrusionsome case abdominal pr PL be expelled women in recumbent position frequently cannot expel placenta spontaneously artificial means generally required compress & elevate fundus while exerting minimal traction on umbilical cord

Mechanisms of Placental Extrusion

(1) Schultze mechanism(central separation) PL separation occurs 1st at central areas retroplacental hematoma push placenta toward uterine cavity(2) Duncan mechanism(marginal separation) placental separation occurs first at periphery blood collects between membranes & uterine wall escapes from vaginaMaternal surface first to appear at vulva

1Signs of placental separation A sudden gush of blood from vagina

The uterus becomes globular and firmer.This sign is the earliest to appear23The uterus rises in the abdomen because the placenta, having separated, passes down into the lower uterine segment and vagina, where its bulk pushes the uterus upwardThe umbilical cord lengthens out of the vagina,indicating that the placenta has descended

manual placental removal

succenturiateplacenta

Mechanism of control of bleedingAfter placental separation,innumerable torn sinuses which have free circulation of blood from uterine and ovarian vessels have to be obliterated. The occlusion is effected by complete retraction where by the arterioles, as they pass tortuously through the interlacing intermediate layer of the myometrium, are literally clampedThrombosis occurs to occlude the torn sinusesApposition of the wall of the uterus following expulsion of the placenta also contributes to minimize blood loss

Perineum ,Cervical,Vaginal laceration First degree tear :involves only skin and a minor part of the perineal body

Perineum ,Cervical,Vaginal laceration

Second degree tear :involves perineal body and vaginal wall


Third degree tear :involves the anal sphincter and anal canal

The fourth stage General condition of the patient and behavior of the uterus are to be carefully watchedpostpartum uterine hemorrhage ,1% uterus palpation through the abdominal wall is repeatsthe amount of blood on pads are monitoredpulse and BP are monitored use of drug : oxytocin

QuestionsDefinitionDelivery; physiological retraction ring ; Obstetrical conjugate; fetal lie; fetal positionBraxon Hicks contractions; crowning of headThe first stage; the second stage; the third stage

essaysMechanism of normal laborIdentify false labor or true laborTalk about the signs of placental separationDescribe two mechanisms of Placental ExtrusionWhat is the most common fetal position at onset of labor?What is active phase?What are you going to do after the 3rd stages?

What is the correct order of the cardinal movements of labor? A). Flexion, descent, engagement, internal rotation, extension, external rotationB). Descent, engagement, flexion, internal rotation, external rotation, extensionC). Engagement, flexion, descent, external rotation, extension, internal rotationD). Engagement, flexion, decent, internal rotation, extension, external rotation

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Normal Labor and Delivery