The course and The course and conduct conduct of normal labor and of normal labor and delivery delivery Song Weiwei Song Weiwei OB&GY Department of OB&GY Department of Shengjing Hospital Shengjing Hospital
Dec 29, 2015
The course and conduct The course and conduct of normal labor and deliveryof normal labor and delivery
Song WeiweiSong WeiweiOB&GY Department of Shengjing OB&GY Department of Shengjing
HospitalHospital
Definition of laborDefinition of labor
Labor is strictly defined as regular Labor is strictly defined as regular
uterine contractions with resultant change of uterine contractions with resultant change of
cervical effacement and dilatation and cervical effacement and dilatation and
extrusion of the products conception.extrusion of the products conception.
Types of deliveryTypes of delivery
Premature delivery:Premature delivery:28w28w~36w~36w+6+6
Term delivery:37~41wTerm delivery:37~41w+6+6
Postterm delivery:>42w
Why and when the labor initiated?Why and when the labor initiated?
Mechanical theory Mechanical theory Endocrine regulating theoryEndocrine regulating theory
Neurohumone theoryNeurohumone theory
No exact course has been found that can initiate the onset of labor.
expulsive force birth canal fetal factors psychological factors(3 Ps: powers, passage and passenger)
Four factors that determineFour factors that determine a normal labora normal labor
Expulsive forceExpulsive force
----- uterine contraction
Characteristics of uterine contraction
rhythmicity
symmetry
polarity
retraction
----- uterine contraction
Characteristics of uterine contraction
rhythmicity
symmetry
polarity
retraction
Birth canal (passage)
bone canal
pelvis: size \shape\ inclination of pelvisinclination of pelvis
soft canal
vagina 、 cervix 、 low segment of uterine
cervical effacement :2~3cm before labor
cervical dilatation: closed to 10cm open
FetusFetus
LieLie- relationship between the long axis - relationship between the long axis of the fetus and that of the mother of the fetus and that of the mother (longitudinal, transverse or oblique).(longitudinal, transverse or oblique).
PresentationPresentation- the fetal part that lies - the fetal part that lies closest to the pelvic inlet (cephalic - closest to the pelvic inlet (cephalic - vertex, face; breech; shoulder).vertex, face; breech; shoulder).
PositionPosition- relationship of the fetal parts - relationship of the fetal parts to maternal parts.to maternal parts.
FetusFetus
Body weight of fetus Diameters of fetal skull
BPD:9.3cm Occipito frontal diameter : 11.3cm Occipito bregmatic diameter : 9.5cmOccipito mental diameter : 12.5cm
Fetal positionFetal anomality: hydrocephalus, conjoined twins.
Body weight of fetus Diameters of fetal skull
BPD:9.3cm Occipito frontal diameter : 11.3cm Occipito bregmatic diameter : 9.5cmOccipito mental diameter : 12.5cm
Fetal positionFetal anomality: hydrocephalus, conjoined twins.
What signs might the patient report What signs might the patient report to herald the onset of true labor?to herald the onset of true labor?
Bloody show:Bloody show: the release from the cervix of the the release from the cervix of the protective mucous plug intermixed with a small protective mucous plug intermixed with a small amount of blood as a result of cervical amount of blood as a result of cervical effacement.effacement.
Regular contractionsRegular contractions: contractions occurring at : contractions occurring at regular intervals (such as every five minute) regular intervals (such as every five minute) suggest true labor. The contractions are felt in suggest true labor. The contractions are felt in the lower abdomen and back, and are noted to the lower abdomen and back, and are noted to increase in intensity over time. increase in intensity over time.
Rupture of membranes (ROM)Rupture of membranes (ROM) : a gush of clear : a gush of clear fluid (break your water) is felt coming from the fluid (break your water) is felt coming from the vagina. The fluid may otherwise leak slowly but vagina. The fluid may otherwise leak slowly but steadily out of the vagina.steadily out of the vagina.
What is a Bishop score?What is a Bishop score?-----evaluate the condition of cervix-----evaluate the condition of cervix This system is used to grade the cervix in terms of
readiness for delivery. Each factor is given a score of 0 to 3. the factors graded are dilation, effacement, station, consistency and position.
Station refers to the level of descent of the presenting part (usually the head) of the fetus. The preferred method is in relationship to the ischial spines. Above the spines one uses -5 to -1 cm (-5 being most superior). Zero station is at the level of the ischial spines. Similarly, +1 to +5 cm describes the presenting part below the level of the ischial spines (+5 being at the introitus).
A cervix that is ready (ripe) for delivery is considered favorable. A score of 5 or greater strongly suggests an advancing cervix.
What are the stages of labor?What are the stages of labor?
Stage 1: onset of labor ~ full dilation of the cervix. Stage 1: onset of labor ~ full dilation of the cervix.
latent phaselatent phase: in which early cervical effacement : in which early cervical effacement and dilation occur:0~3cm.and dilation occur:0~3cm.
active phaseactive phase: cervical dilation becomes more : cervical dilation becomes more rapid (approximately 3 to 4 cm to full dilation of rapid (approximately 3 to 4 cm to full dilation of 10cm).10cm).
Stage 2 : complete cervical dilation~ delivery of Stage 2 : complete cervical dilation~ delivery of the infant. the infant.
Stage 3: after delivery of the infant ~ delivery of Stage 3: after delivery of the infant ~ delivery of the placenta.the placenta.
Duration of the laborDuration of the labor
I stage II stage III stage
Nullipara 9-15 hr 1-2 hr 15-30min
Multipara 7-9 hr 0.5-1 hr 5-15 min
Mechanisms of laborMechanisms of labor
The special labor mechanisms is due to The special labor mechanisms is due to asymmetry of the shape of both the asymmetry of the shape of both the fetal head and maternal pelvis.fetal head and maternal pelvis.
Changes in the position of the fetal head Changes in the position of the fetal head are required for the average size fetus are required for the average size fetus to accomplish passage through the to accomplish passage through the birth canal. birth canal.
The rotations are accomplished by the The rotations are accomplished by the propulsive force of uterine activity.propulsive force of uterine activity.
Cardinal movements of laborCardinal movements of labor
engagementengagement
descentdescent
1. flexion1. flexion
2. internal rotation2. internal rotation
3. extension3. extension
4. external rotation4. external rotation
expulsionexpulsion
movements movements of the headof the head
EngagementEngagement
It is the descent of the largest It is the descent of the largest
transverse diameter of fetal head transverse diameter of fetal head
(BPD) to a level below the plane of (BPD) to a level below the plane of
the pelvic inlet.the pelvic inlet.
Then the head is engaged. Then the head is engaged.
Flexion (IFlexion (I movement of the head) movement of the head)
- placement of the fetal chin on the thorax - placement of the fetal chin on the thorax
(fetus takes a chin-to-chest posture)(fetus takes a chin-to-chest posture)
Internal rotation (IIInternal rotation (II movement) movement)
- the occiput rotates toward the mother’s - the occiput rotates toward the mother’s
pubic symphysis.pubic symphysis.
Extension - III Extension - III movement movement
Begins at the level of maternal vulvaBegins at the level of maternal vulva
The fetal head is delivered by extension The fetal head is delivered by extension
from the flexed to the extended position from the flexed to the extended position
rotating around the symphysis pubis ( the rotating around the symphysis pubis ( the
occiput arches toward the fetal back).occiput arches toward the fetal back).
External rotation - IV External rotation - IV movement movement
After delivery of the head the forces After delivery of the head the forces exerted on the head by the maternal exerted on the head by the maternal pelvic musculature are relived and pelvic musculature are relived and the fetus resumes its normal face-the fetus resumes its normal face-forward position.forward position.
Its face begins to „look” at one of Its face begins to „look” at one of mother’s leg.mother’s leg.
ExpulsionExpulsion
Delivery of the shoulders - first the Delivery of the shoulders - first the
anterior one (under the symphysis anterior one (under the symphysis
pubis) and then the posterior one. pubis) and then the posterior one.
The rest of the body is usually quickly The rest of the body is usually quickly
delivered.delivered.
How are uterine contractions How are uterine contractions monitored?monitored?
Uterine contractions may be monitored by an internal or external pressure monitor (tocometer). Internal monitoring with an intrauterine pressure catheter (IUPC) confirms the adequacy of contractions. The unit of measure for the IUCP is called the Montevideo unit.
Uterine contraction can also be evaluated by the palpation of abdomen.
How is fetal heart rate monitored?How is fetal heart rate monitored?
Intermittent Doppler ultrasound or (rarely) fetal stethoscope
Continuous electronic monitoring via an external monitor or internally via a fetal scalp electrode
What are the types of episiotomy What are the types of episiotomy and their indication?and their indication? Sometimes episiotomy is considered
necessary to facilitate delivery of the fetus or to avoid a spontaneous tear or tears during a forceps delivery. It is an incision in either the midline or in the mediolateral position of the perineum.
EpisiotomyEpisiotomy
A lateral incision of perineum before A lateral incision of perineum before delivery of the headdelivery of the head
Why?Why?– to enlarge the area of the outlet to enlarge the area of the outlet easier easier
delivery of the head delivery of the head prevention of prevention of intraventricular hemorrhageintraventricular hemorrhage
– prevention of lacerationsprevention of lacerations– prevention of late complications - relaxation of prevention of late complications - relaxation of
pelvic muscles and urine incontinencepelvic muscles and urine incontinence
EpisiotomyEpisiotomy
Prophylactic - nulliparas, some Prophylactic - nulliparas, some
multiparas multiparas
MandatoryMandatory
– in instrumental delivery, like forceps or in instrumental delivery, like forceps or
vacuum extractorvacuum extractor
– in abnormal presentations, like breechin abnormal presentations, like breech
– in preterm deliveriesin preterm deliveries
How is pain controlled?How is pain controlled?
The most common form of pain control by far is the epidural. This allows a woman to receive analgesia while maintaining enough sensation to push during the delivery. Alternatively, narcotic analgesics are sometimes used. Spinal anesthetics are sometimes used, delivered into the same area as an epidural but in a single dose. Local blocks, such as a pudendal block, may be given for perineal anesthesia. A local is also given before repair of a tear or episiotomy.
What is VBAC?What is VBAC?
VBAC stands for vaginal birth after cesarean. This is a trial of labor for a patient who has previously undergone a C-section with a low transverse uterine incision. The patient should have had no more than two prior sections, an adequate pelvis, and no history of other uterine incision or rupture. VBAC is contraindicated in patients who have had a prior classical cesarean section due to the increased risk of uterine rupture.