B8.017 The Labor Process at Term: Normal Labor and Potential Complications Flashcards
general facts about term in pregnancy
38-42 weeks of pregnancy
weeks of pregnancy are dates from the 1st day of the patient’s LMP
normal pregnancy lasts 40 weeks
how many pregnancies end in normal labor and delivery
over 2/3
stages of labor
1st stage: cervical
2nd stage: expulsion
3rd stage: placental
describe the events of the cervical stage of labor
begins with the onset of labor
ends when the cervix is fully dilated
follows a characteristic course in a normal labor
gets shorter with subsequent pregnancies
acceleration phase of cervical dilation
4-5 cm range
cervix is thinned and progresses more quickly through active phase
events of the expulsion stage
begins at full cervical dilatation
ends with delivery of the baby
aided by use of abdominal muscles in a valsalva-like maneuver to bring pressure to bear on the uterine fundus
“pushing” can double the expulsive force
events of the placental stage
begins with the delivery of the baby
ends with delivery of the placenta
relies on involution of the uterus through continued contractions to affect separation of the placenta
signs of placental separation
increased bleeding per vagina in the majority of cases
lengthening of the umbilical cord
change in uterine shape to a globular configuration
cephalad displacement of the uterus as the placenta descends in the birth canal
possible outcomes with placental delivery
- successful delivery of the placenta
- avulsion of the umbilical cord
- inversion of the uterus
result of uterus inversion with placenta delivery
pronounced vagal response
patient hemorrhages and rather than HR increasing, it drops
cardinal movements of labor from the fetal aspect
- engagement
- descent
- flexion
- internal rotation
- extension
- external rotation
- expulsion
engagement
presenting part (head) has reached the ischial spines on vaginal exam
internal rotation
face turns toward sacrum
flexion
chin to chest
extension
head begins to push through cervix
neck extended against pubic symphisis
external rotation
face sideways again after coming out of vaginal canal
labor complications
dystocia
emergencies:
-cord prolapse
-shoulder dystocia
dystocia
difficult labor or childbirth
protracted labor/descent
slow labor
arrested labor/descent
stopped labor
protracted labor
<1.2 cm/h nulligravida
<1.5 cm/h
multipara
protracted descent
<1.0 cm/h nulligravida
<2.0 cm/h
multipara
arrested labor
> 2 hr
arrested descent
> 1 hr
causes for dystocia
the 3 p’s
power
passenger
passage
passage
birth canal = true pelvis
issues assessed with clinical pelvimetry
pelvic inlet
sacral contour
bony prominences
pelvic outlet
gynecoid pelvis
predominant female pelvis shape
anthropoid pelvis
long A/P
android pelvis
predominant male pelvis shape
heart shape
platypelloid pelvis
short A/P
long in lateral direction
frequency of pelvic types
gynecoid > android > anthropoid > platypelloid
complications with android pelvis
head wedged in
descent stops due to narrowing of canal
arrest of descent
complications with anthropoid pelvis
cant extend head all the way
persistent occiput posterior
complications with platypelloid pelvis
head stuck in transverse position
episiotomy
enlarges the vaginal outlet to facilitate delivery
prophylactic episiotomy controversial and has lost favor
types of episiotomy
midline
mediolateral
advantages of midline episiotomy
less pain
ease of repair
less blood loss
disadvantages of episiotomy
greater risk of extension into anal spinchter and/or rectum
umbilical cord prolapse
when the umbilical cord descends in advance of the presenting fetal part
funic umbilical cord
4%
when the membranes are intact, and the cord can be felt in the bag of waters
occult prolapse
11%
when the cord is lying beside the presenting part
overt prolapse
45% cord protruding through the cervix into the vagina
39% cord escaping from vagina
risk factors for cord prolapse
low birth weight preterm birth breech presentation multiple gestation malpresentation hydramnios obstetrical interventions
cord prolapse mortality
stable mortality rate: 36-162 per 1,000 cases
most deaths result from complications of prematurity rather than poor recognition or inadequate treatment
cord prolapse management
recognize
call for help
relieve
remove
recognition of cord prolapse
care provider should elevate the presenting part to prevent compression of the cord
relief of cord prolapse
place patient in trendelenburg position of knee-chest position
manual elevation of the presenting part of the fetus above the pelvic inlet
monitor the fetus as the maneuvers are carried out
removal of cord prolapse
if cervix is fully dilated, and there is no evidence of fetal distress, consider assisted vaginal delivery
if not fully dilated, emergency C section
shoulder dystocia
after delivery of the fetal head, further expulsion of the infant is prevented by impaction of the fetal shoulders within the maternal pelvis
epidemiology of shoulder dystocia
0.15-1.7% of all vaginal deliveries
severe asphyxia in 143 per 1,000 births with shoulder dystocia compared with 14 per 1,000 overall
mortality = 21-290 in 1,000
risk factors for shoulder dystocia
fetal macrosomia materal diabetes maternal obesity post term gestation prior history of either macrosomia or shoulder dystocia operative vaginal delivery
clinical findings that suggest possible shoulder dystocia
prolonged 1st stage of labor, especially the decelerative phase
protracted 2nd stage
fetal head draws back after delivery, with the chin tight to perineum
maneuvers to alleviate a shoulder dystocia
knees to chest suprapubic pressure (not fundal pressure tho) deliver the posterior arm corkscrew maneuvers fracture the fetal clavicle
maternal complications of shoulder dystocia
11% rate of postpartum hemorrhage
3.8% rate of fourth degree lacerations
neonatal complications of shoulder dystocia
fractures- clavicle and/or humerus
brachial plexus injuries- reported anywhere from 4-40% of deliveries complicated by shoulder dystocia
