mechanismsandmanagementoflabor生产的机制和.ppt

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1、MechanismsandManagemMechanismsandManagementofLaborentofLabor生产的机制和管生产的机制和管理理Definition of Laborn nLabor is the physiologic process by which the fetus is Labor is the physiologic process by which the fetus is expelled from the uterus to the outside worldexpelled from the uterus to the outside worldn

2、nCould also be described as the transition from Could also be described as the transition from“contracturescontractures”to to“contractionscontractions”n nBottom line defination:Contractions with cervical Bottom line defination:Contractions with cervical change.The diagnosis is a clinical one.change.

3、The diagnosis is a clinical one.Gabbe:Obstetrics Normal and Problem pregnancies 4 Gabbe:Obstetrics Normal and Problem pregnancies 4thth edition editionLabor PhysiologyThe regulation of uterine activity can be divided into 4 The regulation of uterine activity can be divided into 4 physiologic phasesp

4、hysiologic phasesPhase 0:uterus is quiet due to progesterone,relaxin,Phase 0:uterus is quiet due to progesterone,relaxin,prostacyclin Iprostacyclin I2 2(PGI(PGI2 2),parathyroid hormone),parathyroid hormonePhase 1:before term Phase 1:before term“activationactivation”phase-uterus is more phase-uterus

5、is more responsive to estrogen and more receptors for oxytocin and responsive to estrogen and more receptors for oxytocin and prostaglandinsprostaglandinsPhase 2:uterus more stimulated because of increase in gap Phase 2:uterus more stimulated because of increase in gap junctions so that it can be st

6、imulated by oxytocins and junctions so that it can be stimulated by oxytocins and prostaglandins(PGEprostaglandins(PGE2 2 and PGF and PGF2 alpha2 alpha)Phase 3:involution of the uterus(mediated by oxytocin)Phase 3:involution of the uterus(mediated by oxytocin)Gabbe:Obstetrics Normal and Problem preg

7、nancies 4Gabbe:Obstetrics Normal and Problem pregnancies 4thth edition editionLabor MechanicsFor a successful vaginal delivery,the fetus must negotiate the maternal pelvis.Three factors:the power,the passage,and the passenger.Labor Mechanicsn nThe passengerEstimating fetal size:ultrasound,leopolds,w

8、hat does Estimating fetal size:ultrasound,leopolds,what does mom think?mom think?How big is too big?Definition of macrosomia is How big is too big?Definition of macrosomia is diabetics:4500g non-diabetics:5000gdiabetics:4500g non-diabetics:5000gLabor Mechanicsn nPowerPowerAssessing amplitude,duratio

9、n,and intensity of ctxAssessing amplitude,duration,and intensity of ctxinternal IUPC vs external tocointernal IUPC vs external tocoWhatWhat s adequate contractions?(ultimately it is a clinical dx)s adequate contractions?(ultimately it is a clinical dx)3-5 ctx in 10 min3-5 ctx in 10 min7 ctx in 15 mi

10、n7 ctx in 15 min250 MVU250 MVU s the average strength of ctx in mm Hg multiplied by s the average strength of ctx in mm Hg multiplied by the number of contractions in 10 minutes.No real data support the number of contractions in 10 minutes.No real data support an absolute number of ctx or MVUan abso

11、lute number of ctx or MVU s to be adequateadequacy is s to be adequateadequacy is still a clinical determination.still a clinical determination.If ctx are adequate either the cervix will dilate or the caput will If ctx are adequate either the cervix will dilate or the caput will become worse.become

12、worse.Labor Mechanicsn nThe most precise way of determining uterine The most precise way of determining uterine contractions are adequate is with internal contractions are adequate is with internal monitoring by IUPCmonitoring by IUPCn nExternal monitoring measures the change in External monitoring

13、measures the change in shape of the abdominal wall relative to shape of the abdominal wall relative to contractions thus is qualitative rather than contractions thus is qualitative rather than quantitative.Does allow for accurate correlation quantitative.Does allow for accurate correlation between f

14、etal heart rate and contraction pattern between fetal heart rate and contraction pattern.Labor MechanicsThe Passenger The passenger is the fetus.Fetal size can influence labor The passenger is the fetus.Fetal size can influence labor Can be assessed by Leopold Can be assessed by Leopold s,US or both

15、.(Moms,US or both.(Mom s s opinion counts,too!)opinion counts,too!)ACOG definition of Macrosomia is defined as 4500 gACOG definition of Macrosomia is defined as 4500 gLabor Mechanicsn nThe passengerThe passengerFetal lie:Fetal position relative to the maternal spine.Fetal lie:Fetal position relative

16、 to the maternal spine.longitudinal,oblique,transverselongitudinal,oblique,transversePresentation:refers to the fetal part that is above the pelvic inlet.(eg a fetus can have a logitudinal Presentation:refers to the fetal part that is above the pelvic inlet.(eg a fetus can have a logitudinal lie but

17、 be breech or cephalic)lie but be breech or cephalic)Attitude:refers to position of fetal head relative to the fetal spineAttitude:refers to position of fetal head relative to the fetal spinePosition:referes to the relationship of a nominated site of the presenting part to a denomintating Position:r

18、eferes to the relationship of a nominated site of the presenting part to a denomintating location in the internal pelvis.Eg.Occiput/sacrum ROA,RSAlocation in the internal pelvis.Eg.Occiput/sacrum ROA,RSAStation:a measure of descent of the presenting part.Station:a measure of descent of the presentin

19、g part.Abnormalilty of any of these variables can influence whether or not to proceed with a vaginal delivery.Abnormalilty of any of these variables can influence whether or not to proceed with a vaginal delivery.Fetal presentation:Fetal part directly over the pelvic Fetal presentation:Fetal part di

20、rectly over the pelvic inlet;inlet;eg breech,cephalic,compound,funiceg breech,cephalic,compound,funicLabor Mechanicsn nThe passengerMalpresentation is any presentation that is not cephalic with occiput leading.(about 5%)Multifetal pregnancies increase the risk of malpresetnation The cephalic present

21、ation can be classified by The cephalic presentation can be classified by boney landmarks of the skull;eg occiput,boney landmarks of the skull;eg occiput,mentum,browmentum,browpassengerpassengerpasengerpasengerA:Right occiput anterior(ROA);B:Left occiput anterior(LOA);C:Occiput A:Right occiput anter

22、ior(ROA);B:Left occiput anterior(LOA);C:Occiput anterior(OA).anterior(OA).*Posterior fontanel.This is the smaller of the two fontanels and is at the*Posterior fontanel.This is the smaller of the two fontanels and is at the intersection of the three sutures:the sagittal suture and two lambdoid suture

23、s.intersection of the three sutures:the sagittal suture and two lambdoid sutures.*Anterior fontanel.This large fontanel is at the intersection of four sutures:the*Anterior fontanel.This large fontanel is at the intersection of four sutures:the sagittal,frontal,and two coronal sutures.sagittal,fronta

24、l,and two coronal sutures.From UpToDFrom UpToD n nOcciput posterior From UpToD From UpToDOcciput transverse From UpToD From UpToDLabor Mechanicsn nThe passengerStation:measure of descent of the presenting part Station:measure of descent of the presenting part through the birth canal relative to isch

25、ial spinesthrough the birth canal relative to ischial spines this is the relationship between the leading bony part of fetal this is the relationship between the leading bony part of fetal presenting part(skull bone NOT scalp)and the maternal ischial spines.presenting part(skull bone NOT scalp)and t

26、he maternal ischial spines.Must take into account molding and caput succedaneum(not doing so Must take into account molding and caput succedaneum(not doing so is a common error)is a common error)Often described as-3 to+3Often described as-3 to+3Newer scale is-5 to+5Newer scale is-5 to+5Nucleus medic

27、al art.Nucleus medical art.NNLabor Mechanicsn nThe PassageThe Passage The passage consists of the bony pelvis(sacrum,ilium,ischium,pubis)The passage consists of the bony pelvis(sacrum,ilium,ischium,pubis)and the resistance provided by the soft tissues.and the resistance provided by the soft tissues.

28、Bony pelvis is divided into the greater(false)and lesser(true)pelvis by Bony pelvis is divided into the greater(false)and lesser(true)pelvis by the pelvic brim which is demarcated by the sacral promontory.the pelvic brim which is demarcated by the sacral promontory.The diagonal conjugate is the dist

29、ance from the sacral promontory to The diagonal conjugate is the distance from the sacral promontory to the inferior margin of the symphysis pubis as assessed on the inferior margin of the symphysis pubis as assessed on examination(see next slide)examination(see next slide)Clinical pelvimetry is the

30、 only way to assess the dimensions of the Clinical pelvimetry is the only way to assess the dimensions of the pelvis in labor.pelvis in labor.To figure out the true conjugate,measure the diagonal To figure out the true conjugate,measure the diagonal conjugate and subtract 1.5 2cm.The limiting factor

31、 is conjugate and subtract 1.5 2cm.The limiting factor is the interspinous diameter.the interspinous diameter.Bony pelvismost favorable is gynecoid and antropoidBony pelvismost favorable is gynecoid and antropoid From UpToD From UpToD A little bit about cervical ripeningA little bit about cervical r

32、ipeningn nWhen induction is attempted against an unripe cervix the likelihood When induction is attempted against an unripe cervix the likelihood of succcess is reduced.of succcess is reduced.Bishops score:dilatation,effacement,position,consistency,station.Bishops score:dilatation,effacement,positio

33、n,consistency,station.Total score is up to 13.Total score is up to 13.BishopBishop s=8 chances of successful induction are the same as s=8 chances of successful induction are the same as spontaneous laborspontaneous laborBishopBishop s=6 s=6 “favorable cervixfavorable cervix”(A)Cervix is uneffaced a

34、nd minimally dilated.(B)Cervix is almost completely(A)Cervix is uneffaced and minimally dilated.(B)Cervix is almost completely effaced and dilated.effaced and dilated.From UpToDFrom UpToDMethods of cervical ripeningMethods of cervical ripeningNon Pharmacologic methods:Non Pharmacologic methods:membr

35、ane stripping digital separation of chorionic and amniotic membranes from membrane stripping digital separation of chorionic and amniotic membranes from the cervix.Releases endogenous prostaglandins from the decidua and adjacent the cervix.Releases endogenous prostaglandins from the decidua and adja

36、cent membranes.membranes.May also cause May also cause“Ferguson reflexFerguson reflex”stimulating release of oxytocin from the pituitary.stimulating release of oxytocin from the pituitary.Foley bulbFoley bulbAmniotomy needs favorable cervix,but if cervix is favorable amniotomy by itself Amniotomy ne

37、eds favorable cervix,but if cervix is favorable amniotomy by itself can get labor started(better still when combined with Pitocin)can get labor started(better still when combined with Pitocin)risks:risks:cord prolapse,prolonged ROM,fetal injury,rupture cord prolapse,prolonged ROM,fetal injury,ruptur

38、e of vasa previa with fetal hemorrhage,fetal malposition and of vasa previa with fetal hemorrhage,fetal malposition and asynclitismasynclitismBenefits:FSE placement,can determine if MSF or blood,high success Benefits:FSE placement,can determine if MSF or blood,high success in inducing laborin induci

39、ng laborMethods of cervical ripeningMethods of cervical ripeningn nPharmacologic methodsPharmacologic methods Dinoprostone(Prepadil and Cervadil)PGE Dinoprostone(Prepadil and Cervadil)PGE2 2,oxytocin,oxytocin,misoprostyl(cytotec)PGEmisoprostyl(cytotec)PGE1 1 The uterus has precursors of the prostagl

40、andin of the 2 The uterus has precursors of the prostaglandin of the 2 series.series.PGEPGE2 2 :important for cervical maturation:important for cervical maturation PGF PGF 2 2 alpha.:causes myometrial alpha.:causes myometrial contractions contractions Stages of LaborStages of Laborn nFirst stage:Ons

41、et of labor to full dilatationFirst stage:Onset of labor to full dilatationlatent phase-onset of labor until cervix starts to make latent phase-onset of labor until cervix starts to make change.change.active phase-greater rate of cervical changeactive phase-greater rate of cervical change 1.2 cm/h f

42、or nulliparous 1.2 cm/h for nulliparous 1.5 cm/h for multiparous 1.5 cm/h for multiparousSecond stage:full dilation to deliverySecond stage:full dilation to deliveryLength of Pushing:nullip:2h without epidural,3 h Length of Pushing:nullip:2h without epidural,3 h with epiduralwith epiduralmultip:1 h

43、without epidural,multip:1 h without epidural,2 h with epidural 2 h with epiduralThird stage:delivery of placenta-can take up to 30 minutesThird stage:delivery of placenta-can take up to 30 minutesCardinal movements of laborEngagement:Engagement:passage of the widest diameter of the presenting part t

44、o passage of the widest diameter of the presenting part to a level below the plane of the pelvic inlet.In cephalic fetus,the a level below the plane of the pelvic inlet.In cephalic fetus,the largest diameter is the biparietal diameter(9.5 cm);in a breech largest diameter is the biparietal diameter(9

45、.5 cm);in a breech fetus the widest diameter is the bitrochanteric diameter.The fetus the widest diameter is the bitrochanteric diameter.The presenting part is engaged if you can feel presenting part both presenting part is engaged if you can feel presenting part both abdominally and vaginally.abdom

46、inally and vaginally.Descent:Descent:downward passage of the presenting part downward passage of the presenting partFlexion:Flexion:occurs passively d/t boney maternal pelvis occurs passively d/t boney maternal pelvisInternal rotation:refers to rotation of presenting part from its original Internal

47、rotation:refers to rotation of presenting part from its original position(usually transverse)to the AP positionposition(usually transverse)to the AP positionExtension:Extension:Occurs once the fetus has descended to the introitus Occurs once the fetus has descended to the introitusExternal rotationE

48、xternal rotation(aka restitution)return of the fetal head to the correct (aka restitution)return of the fetal head to the correct anatomic position in relation to the fetal torso.anatomic position in relation to the fetal torso.Expulsion:Expulsion:delivery of the rest of the fetus.delivery of the re

49、st of the fetus.Management of Normal Labor and DeliveryManagement of Normal Labor and Deliveryn nAll women need adequate surveillance throughout labor All women need adequate surveillance throughout labor and delivery.and delivery.n nOkay to let women walk(doesnOkay to let women walk(doesn t shorten

50、 course of labor,the t shorten course of labor,the need for augmentation,the use of analgesia,or the rate of C/S)need for augmentation,the use of analgesia,or the rate of C/S)n nRecord FHTRecord FHT s q 30 minutes(minimum)s q 30 minutes(minimum)n nDuring second stage,FHTDuring second stage,FHT s sho