1、1 Normal Labor Chen Danqing Womens hospital,School of medicine,Zhejiang University2ObjectiveDefinition of labor.Determinate Factors of LaborAnatomical considerations:nThe female pelvis.nThe fetal skull.The stages of labor.The mechanism of labor(vertex,LOA).Management of normal labor.3Definitions：Lab
2、or is the process by which contractions of the gravid uterus expel the fetus and the other products of conception after 28 weeks from the last menstrual period.Term Delivery：A term delivery occurs between 37 and 42 weeks from the last menstrual period.4Premature labor：Preterm labor is that occurring
3、 before 37 weeks of gestational age.Postdate pregnancy：Postdate pregnancy occurs after 42 weeks.5 Not sure:1、Cervix ripend and lower uterine segment development theory；2、；3、；4、；5、Immunologic theory；The Etiology of LaborMaturation of fetus and change of uterus function is necessary.6The progress and
4、final outcome of labor are influenced by 4 factors.(1)the powers(2)the passage(3)the passenger(4)the psycheFour Determinate Factors of Labor7The Expulsive Forces(The powers)The power that expulse the fetus and the other products of conception is called the expulsive forces,which include uterine cont
5、raction intra-abdominal pressure levator ani muscles contractions.8Uterine Contractions Have three unique characteristics:Rhythm:。Symmetry and polarity Retraction9Periods of relaxation between contractions are essential to the welfare of the fetus.RhythmIncrease in frequency and duration宫缩宫缩间歇期间歇期宫缩
6、宫缩极极期期进行退行10Characteristic of normal uterine action11Symmetry and Polarity The intensity of the upper segment of the uterus is the most strong 12Retraction:The myometrium of the upper uterine segment does not relax to its original length after contractions;rather,it becomes relative fixed at a short
7、er length.13The Intra-abdominal pressureCreated by contraction of the abdominal muscles simultaneously with forced respiratory efforts with glottis closed.It is a necessary auxiliary to uterine contractions in second stage of labor。After the placenta has separated,its spontaneous expulsion is aided
8、by the mother increasing intra-abdominal pressure。14腹肌子宫收缩力膈肌肛提肌15 Form a V-shaped sling that tends to rotate the occipital anteriorly(internal rotation)。Help the fetus extension and delivery。Help the expulsion of the placenta。Levator ani muscles contractions16Passage The passage of the fetus delive
9、ry,including:the bony pelvis and soft tissues of pelvis骶骶 骨骨Os sacrum髂髂 骨骨 os ilium 耻骨联合耻骨联合Symphysis publis骶骶 尾尾 关关 节节Sacro-iliac jiont尾尾 骨骨Os coccyx坐骨结节坐骨结节Os ischium17The Bony Pelvis(the true pelvis)Pelvic inlet plane Pelvic midplane Pelvic outlet planeThree pelvic plane:18Pelvic inlet plane Have
10、 three diameters:(1)Anteroposterior diameter or The true conjugate:average 11cm.(2)Transverse diameter:average 13cm.(3)Inclined diameter:average 12.75cm19The true conjugateThe transverse diameterThe inclined diameter2021Three anteroposterior diameters of the pelvic inlet22The smallest plane of the p
11、elvis,particular importance in obstructed labor.Anteroposterior diameter of mid pelvis：average 11.5cm.Transverse diameter of mid pelvis：alse be called interspinous diameter,average 10cm.Pelvic midplane23AnteroposteriorAnteroposterior diameter of diameter of mid pelvismid pelvisTransverse diameter Tr
12、ansverse diameter of mid pelvisof mid pelvis24Transverse diameter of the midpelvis25Four diameters:Anteroposterior:diameter of outlet：11.5cm。Transverse outlet：the distance between the inner edges of the ischial tuberosities。9cm Anterior sagittal diameter：6cm。Posterior sagittal diameter：8.5cm。Pelvic
13、outlet plane2641、T Transverse outlet2、Anterior sagittal diameter3、Posterior sagittal diameter4、Anteroposterior diameter of outlet 2728Pelvic axis and inclination of pelvicPelvic axis：The axis of the pelvis refers to the curve of the birth canal as described by a line drawn through the center of each
14、 of the four planesInclination of pelvic:The angle of the pelvic inlet plane with ground level when women stand.always 60 degree。29 Pelvic axis Inclination of pelvic 3031The soft part of the birth canal Formation of lower uterine segment、cervix、vagina、soft tissue in the floor of pelvis.32The lower u
15、terine segment Developed from the isthmus of the uterus of nonpregnant women.Physiologic retraction ring:The actively contracting upper segment becomes thicker as labor advances,the lower uterine segment is relatively thin compared with the upper segment,between them a physiologic retraction ring ap
16、pear.3334Changes of cervixEffacement of cervixdilatation of cervixThe upper segment contracts,retracts,and expels the fetus;in response to the force of the contractions of the upper segment,the ripened lower uterine segment and cervix dilate and thereby form a greatly expanded、thinned-out muscular a
17、nd fibromuscular tube through which the fetus can be extruded.3536分娩过程中宫颈的变化分娩过程中宫颈的变化primigravidamultiparaEffacement of cervixdilatation of cervix37A crook canal formed by the vagina、tissue of pelvic floor and perineum as the fetal descending.38FPassenger39Size of the fetus head Very important for
18、delivery。The vault is composed of 2 frontal bones,2 temporal bone,2 parietal bones,and one occipital bone.They are slightly separated from one another at the margins of abutment and by wider spaces,the anterior and posterior fontanelles.40Four diameter of fetus head：Biparietal diameter：The greatest
19、transverse diameter of the head,which extends from one parietal bone to other.Average 9.3cm.Occipito-frontal diameter：Which follows a line extending from a point just above the root of the nose prominent portion of the occipital bone.Average 11.3cm.41Suboccipito-bregmatic diameter.Which follows a li
20、ne drawn from the middle of the large fontanel to the undersurface of the occipital bone just where it joins the neck.Average 9.5cmOccipito-mental diameter：From the chin to the most prominent portion of the occiput.Average 13.3cm42Suboccipito-bregmaticoccipito-frontalOccipito-mental diameter43Fetal
21、SkullVault.Face.Base.44Position of the fetus Fetal position of a particular presentation refers to the relationship of an arbitrary reference point on the fetus to a specific point in the right or left side of the maternal pelvis.45Psychologic Factors A high level of anxiety during pregnancy has bee
22、n associated with decreased uterine activity and with longer and dysfunctional labor。46include these cardinal movements of labor:engagement descentflexioninternal rotationextensionexternal rotation,and expulsion.Mechanism of labor in occiput presentation47Engagement The mechanism by which the bipari
23、etal diameter,the greatest transverse diameter of the fetal head in occiput presentations,passes through the pelvic inlet is defined engagement.48Descent Descent continues progressively until the fetus is delivered;the other movements are superimposed on it.49FlexionIn flexion,the chin is brought in
24、to more intimate contact with the fetal thorax,and the appreciably shorter suboccipitobregmatic diameter(9.5cm)is substituted for the longer occipitofrontal diameter(11.3cm).50Internal rotation Internal rotation is a turning of the fetus occiput gradually moves from its original position anteriorly
25、toward the symphysis pubis about 45 degrees.Its always finished in the end of the first stage of labor.51ExtentionExtention brings the base of occiput into direct contact with the inferior margin of the symphysis pubis.52Restitution:The fetus head rotates to the position it occupied at engagement af
26、ter it deliveried,following this the shoulders descend in a path similar to that traced by the head.External rotation：The anterior shoulder rotates internally about 45 degrees to come under the pubic arch for delivery.The head continutly rotates left about 45 degrees to its position at birth.53Flowi
27、ng these maneuvers,the body,legs,and feet are deliveried.54Mechanism of Labor55Diagnosis of laborThreatened laborFalse labor:1.Contractions occur at irregular intervals.;2.Intervals remain long;3.Intensity remains unchanged;4.Discomfort is chiefly in lower abdomen;5.Cervix does not dilate;6.Discomfo
28、rt is usually relieved by sedation.56Lightenting The settling of the fetal head into the brim of the pelvis.Bloody Show 57In laborOnset of labor is spontaneous uterine contraction with progressive dilation of the cervix uterine contraction interval 30 intensity is middle or heavy58Total Stage of Lab
29、or and Treatment The total stage of labor begins with the regular uterine contractions and ends when delivery of the placenta complete.Normal labor is a continuous process which has been divided into three stages for purposes of study.59First stage of labornThe first stage begins with the onset of l
30、abor and ends when 60Second stage of labor Third stage of laborFrom the birth of the infant to delivery of the placenta 515min,61Total stage of labor：24hFirst stage of labor（cervical dilation stage）Second stage of labor（fetus expulsive stage）Third stage of labor（placenta expulsive stage）515min 30min
31、62Clinical course and treatment in first stageChart of labor stage 1,Contraction and dilation of cervix63 Acceleration phase:cervical dilation from 3cm to 4cm.1.5h；Maximum acceleration phase:cervical dilation from 4cm to 9cm，2h;Deceleration phase:cervical dilation from 9cm to 10cm，30min。64The decent
32、 of the fetal head is measured to assess the progress of labor The level of the presenting fetal part in the birth canal is described in relationship to the ischial spines,which are halfway between the pelvic inlet and the pelvic outlet.65Management:Blood pressure、cervical dilation、fetus descending、
33、uterine contraction；When the membranes ruptured,please check the fetal heat rate,fluid colour and amount at onceFetal heart rate 120160bpm latent stage 12h fetal heat rate active stage 15-30 minute Need for subsequent vaginal examinations to identify the status of the cervix and the station and posi
34、tion of presenting part will vary considerably.66Management of second stage of laborManifestation Uterine contraction may last 1.5 minutes and recur at times after a resting phase of no more than a minute.The woman typically begins to bear down The perineum begins to bulge and the overlying skin bec
35、omes tense and glistening.67 Head visible on vulva gapping Crowning of headBetween uterine contractions the presenting part tends to recede slightly,but“crowing”occurs when the head is visible at the vaginal introitus and not receding in between contractions.68Management of the second stageFetal hea
36、rt rate:should be auscultated at least every 510min.Maternal expulsive efforts.Preparation for delivery69Management of third stage of labor.Clinical course After delivery of the infant,the height of the uterine fundus and its consistency are ascertained.Uterine contraction reappear after stopping fo
37、r few minutes.Placental separation70Apgar score of neonate71Signs of placental separation：a.the uterus becomes globular and firmer.b.The umbilical cord lengthened outside the vagina c.A fresh show of blood from vaginad.the uterus fundus rises up.72Pay attention to:Examine the placenta to ensure complete removal.Examine the soft part of the birth canal.Prevention of excessive postpartum bleeding.Uterine contraction、bladder distension73
