Normal Labour and Delivery Flashcards
what should you ask a woman when she presents to L&D
contractions
vaginal bleeding
leakage of fluid
fetal movement
what physical exam should you do on L&D
determine fetal lie (longitudinal, transverse)
determine fetal presentation (breech or cephalic)
in what % of pregnancies to membranes rupture before onset of labour
10%–> “premature rupture of membranes” (PROM)
define prolonged PROM…why do we care?
prolonged PROM is rupture 18 hours before onset of labour
greater risk of infection to both mother and fetus
what aspects of history suggest rupture of membranes
gush of, or leaking of, fluid from the vagina
how do you confirm ROM
pool, nitrazine or fern tests
what is the pool test
for ROM
collection of fluid found in the vagina on examination of the vaginal vault on sterile speculum exam
what is the nitrazine test
for ROM
vagina is normally acidic–> amniotic fluid is alkaline
when amniotic fluid comes in contact with nitrazine paper, paper turns blue
what is the fern test
for ROM
the estrogens in the amniotic fluid cause crystallization of the salts in the amniotic fluid when it dries
under low microscopic power, crystals resemble blades of a fern
DO NOT sample directly from cervix (cervical fluids also fern)
how do you confirm for sure if there was ROM if the other tests are equivocal
inject dilute indigo carmine dye into the amniotic sac to look for leakage of fluid from the cervix onto a tampon
list the 5 components of the cervical exam
dilation effacement fetal station cervical position consistency of the cervix
what is the Bishop score
determined by the 5 aspects of the cervical exam
Bishop score above 8 is consistent with a cervix favorable for both spontaneous labour and induced labour
what part of the cervix is assessed for dilation
internal os
define effacement of the cervix
subjective
how much length is left of the cervix and how thinned out it is
commonly reported by percent or by cervical length
typical cervix is 3-5 cm in length –> if cervix feels about 2 cm, then it is about 50% effaced
100% effacement occurs when cervix is as thin as the adjoining lower uterine segment
define fetal station
relation of the fetal head to the ischial spines
zero station is at the spines
define Bishop score 0 with respect to:
- cervix dilation
- cervical effacement
- station
- cervical consistency
- cervical position
- closed
- 0-30%
- -3
- firm
- posterior
define Bishop score 1 with respect to:
- cervix length
- cervical effacement
- station
- cervical consistency
- cervical position
- 1-2 cm dilated
- 40-50% effaced
- -2
- medium
- mid
define Bishop score 2 with respect to:
- cervix length
- cervical effacement
- station
- cervical consistency
- cervical position
- 3-4 cm dilated
- 60-70% effaced
- -1, 0 station
- soft
- anterior
define Bishop score 3 with respect to:
- cervix length
- cervical effacement
- station
- cervical consistency
- cervical position
- more than 5 cm dilated
- more than 80% effaced
- +1 station or more
reference point for fetal face presentations
chin
reference point for fetal breech presentations
fetal sacrum
shape of anterior fontanelle
diamond
shape of posterior fontanelle
triangle
define labour
regular contractions that cause cervical change in either effacement or dilation
define prodromal labour
“false labour”
irregular contractions that vary in duration, intensity and intervals and yield little to no cervical change
define induction of labour
attempt to begin labour in non labouring patient
define augmentation of labour
intervening to increase the already present contractions
what agents do you use to induce labour
prostaglandins
oxytocin
mechanical dilation of the cervix
and/or artificial ROM
what are the indications for induction of labour
post dates preeclampsia diabetes mellitus non reassuring fetal testing IUGR
what should you do to help prepare the cervix for induction
prostaglandins–> i.e PGE2 pessary (Cervidil) or PGE1 (misoprostol)
contraindications for the use of prostaglandins to ripen the cervix in induction
asthma or glaucoma in mom
prior cesarean delivery
non reassuring NST
what do you have to watch for when rupturing membranes with the amniotic hook
prolapse of the umbilical cord
how do you augment labour
with rupture of membranes or with oxytocin
how could you measure strength of contractions
with intrauterine pressure catheter (IUPC)
normal range for fetal HR
110-160
what does fetal tachy suggest
infection
hypoxia
anemia
what low fetal heart rate might we be worried about
decel longer than 2 min with rate below 90
describe an approach to NSTs
- baseline
- variations from baseline (variability) –> absent (less than 3 bpm), minimal (3-5), moderate (above 6) or marked (above 25)
- accelerations of at least 15 beats per min over baseline that last at least 15 seconds (2 in 20 min)
- decelerations
list the 3 types of decelerations
early
late
variable
define early deceleration and what causes it
begin and end approx same time as contractions
due to increased vagal tone secondary to head compression during contraction
define variable deceleration and what causes it
can occur at any time
tend to drop more quickly (be sharper) than early or late decels
due to umbilical cord compression
define late decelerations and what causes them
begin at the peak of a contraction and slowly return to baseline after contraction finished
due to uteroplacental insufficiency and are most worrisome
may degrade into bradys as labour progresses, especially with stronger contractions
when might you use a fetal scalp electrode
if having repeat decels or if difficult to get reading with doppler
what is the baseline intrauterine pressure
10-15 mmHg
how much does intrauterine pressure change during contractions
increase 20-30 mmHg in early labour and 40-60 mmHg in later labour
what values are reassuring and non reassuring for a fetal scalp pH
reassuring above 7.25
indeterminate 7.2-7.25
nonreassuring below 7.2
can be indicative of hypoxia and acidemia
name the cardinal movements of labour
engagement
descent
flexion
internal rotation
extension
external rotation (restitution/resolution)
cardinal movements of labour definition:
engagement
fetal presenting part enters pelvis
cardinal movements of labour definition:
descent
presenting part into pelvis
cardinal movements of labour definition:
flexion
allows the smallest diameter to present to the pelvis… ideally chin to chest movement
cardinal movements of labour definition:
internal rotation
with descent into pelvis, fetal head goes from OT position to OA (ideally) via internal rotation
disruption or absence of this movement can lead to a feturs maintained in OT or malrotation to OP
cardinal movements of labour definition:
extension
as vertex passes beneath and beyond the pubic symphysis, it will extend to deliver
cardinal movements of labour definition:
restitution/resolution
once the head delivers, will undergo external rotation and shoulders may be delivered
how many stages are there in labour and delivery
3 stages
when does stage 1 of labour begin
with onset of labour and lasts until dilation and effacement complete
when does stage 2 of labour begin and end
full dilation to delivery of infant
stage 3 of labour
delivery of infant to delivery of placenta
length of average first stage of labour
10-12 hours–nulliparous
6-8 hours–multiparous
define latent phase of stage 1 labour
onset of labour until 3-4 cm dilated
slow cervical change
define active phase of stage 1 labour
from 3-4 cm dilated until 9 cm dilation
faster cervical change –at least 1 cm /hour of dilation in nulliparous and 1.2 cm/hour in multiparous
what are the 3 Ps that determine the transit time during active labour
powers–> strength and frequency of uterine contractions
passenger–> fetus size and position
pelvis–> pelvic size and position
define cephalopelvic disproportion
CPD
if infant too large for pelvis
if rate of cervical change is less than 1 cm/hour, should assess 3 Ps to determine if vaginal delivery is viable
what is an adequate strength of uterine contraction
200 montevideo units
define active phase arrest
no change in either cervical dilation or station for 2 hours in setting of adequate montevideo units during active phase of labour–> common indication for section
some women, if you give them up to 4 more hours, will go on to deliver vaginally however
define prolonged second stage of labour
longer than 2hours in nulliparous woman (3 hours if have epidural) and longer than 1 hour in multiparous woman (2 hours if epidural)
why does epidural make second stage last longer
can cause reduced urge to push, sensation and strong motor block (less ability to push)
can allow for passive descent in this case
signs of non reassuring fetal status in second stage?
late decels
bradys
loss of variability
what do you do with nonreassuring fetal status in second stage?
place mom on face mask O2
turn mom onto left to decrease IVC compression and increase uterine perfusion
discontinue oxytocin until tracing normal again
what do you do in the setting of hypertonus (single contraction longer than 2 min) or tachysystole (more than 5 contractions in 10 min)?
diagnose by palpation or exam with tocometer
can give dose of terbutaline to help relax uterus
what do you do with your hands during delivery of the head
one hand supports perineum and one keeps the head in flexion
what is the first thing you do once the head is delivered
check for nuchal cord –> if present, reduce over the head
what do you do once the head is delivery and nuchal cord checked?
direct downward pressure to allow delivery of anterior shoulder then direct upward pressure to allow delivery of the posterior shoulder
define episiotomy
incision made in the perineum to facilitate delivery
indications for episiotomy
need to hasten delivery
impending on ongoing shoulder dystocia
relative contraindication for episiotomy
assessment than there will be large perineal laceration
what are the two types of operative vaginal delivery
forceps
vaccuum
conditions necessary for safe use of forceps (same as for vacuum)
full cervical dilation
ruptured membranes
engaged head at at least +2 station
absolute knowledge of fetal position
no evidence of CPD
adequate anesthesia
empty bladder
EXPERIENCED OPERATOR
possible complications from forceps
bruising on face and head
lacerations to fetal head, cervix or vagina and perineum
facial nerve palsy
rarely–skull fracture and/or intracranial damage
complications from vacuum delivery
scalp laceration
cephalohematoma
rare–subgleal hemorrhage (neonatal emergency)
when does placental separation occur
within 5-10 min of delivery of infant but up to 30 min is usually within normal limits
why is oxytocin indicated during stage 3
strengthens uterine contractions and thus decreases placental delivery time and blood loss
3 signs of placental separation
cord lengthening
gush of blood
uterine fundal rebound as placenta detaches
why do we apply suprapubic pressure during stage 3
to prevent uterine involution or prolapse
when do you make the diagnosis of retained placenta
if not delivered after 30 min
common in preterm deliveries but can also be sign of placenta accreta
define placenta accreta
invaded into or beyond the endometrial stroma
how do you manage retained placenta
manual extraction where hand is placed in intrauterine cavity and fingers used to shear the placenta from the surface of the uterus
if not able to completely extract manually, curretage is performed to ensure no products are retained
define first degree laceration
mucosa or skin is involved
define second degree laceration
extends into perineal body but not involving anal sphincter
define third degree tear
extend into or completely through the anal sphincter
define fourth degree tear
occurs if anal mucosa itself is entered
watch out for “buttonhole” fourth degree lacs (sphincter still intact)
what is the most common indication for primary cesarean delivery
failure to progress in labour
can be caused from any of the three Ps
other than failure to progress, what are other indications for primary cesarean delivery
breech presentation
transverse lie
shoulder presentation
placenta previa
placental abruption
fetal intolerance of labour
non reassuring fetal status
cord prolapse
prolonged second stage
failed operative vaginal delivery
active herpes lesions
most common overall–previous cesarean delivery
what is required to attempt a VBAC?
in house OB
anesthesiologist
surgical team
informed patient consent
Keer (low transverse) or Kronig (low vertical) incision without any extensions into the cervix or upper uterine segment
what is the greatest risk during a trial of labour after cesarean (TOLAC)
rupture of prior uterine scar (0.5-1% risk)
induction of labour has a higher risk for uterine rupture
list factors that increase the chance of success of TOLAC
prior vaginal birth
prior VBAC
non recurring indication for prior C/S (i.e herpes, previa, breech)
presents in labour at more than 3cm dilated and more than 75% effaced
what are factors that decrease success of TOLAC
prior C/S for CPD
induction of labour
what are factors that increase the risk of uterine rupture
more than one prior C/S
prior classical C/S
induction of labour
- -use of prostaglandins
- -use of high amounts of oxytocin
time from last cesarean less than 18 mo
uterine infection at time of last C/S
what factors decrease the risk of uterine rupture with TOLAC
prior vaginal birth
list common signs of uterine rupture in the setting of TOLAC
abdo pain
FHR decels or brady
sudden decrease of pressure in IUPC
maternal sensation of “pop”
what types of agents can be used in the first stage of labour to manage pain
narcotics or sedatives
i.e fentanyl, Nubain, Stadol
early in labour, IM morphone sulfate is commonly used to achieve patient pain relief and rest
why should sedating meds not be used close to the time of expected delivery
cross the placenta and may result in a depressed infant
can also cause maternal resp depression and increased risk of aspiration
describe the route of the pudendal nerve
travels just posterior to the ischial spine at its juncture with the sacrospinous ligament
when is a pudendal block often done
in case of operative vaginal delivery with either forceps or vaccuum
may be combined with local infiltration of the perineum to ensure adequate analgesia
when is local anesthetic used
for an episiotomy is they do not otherwise have anesthetic or for repairs of tears
maternal/fetal indications for cesarean
CPD
failed induction
maternal indications for cesarean section
maternal diseases–> active genital herpes, untreated HIV, cervical cancer
prior uterine surgery–> classical cesarean or full thickness myomectomy
prior uterine rupture
obstruction to birth canal–> fibroids, ovarian tumours
fetal indications for cesarean section
non reassuring fetal testing–> brady, absence of variability, scalp pH of less than 7.2
cord prolapse
fetal malpresentation–> breech, transverse lie, brow
multiple gestation–> non vertex first twin, higher order multiples
fetal anomalies–> hydrocephalus, osteogenesis imperfecta
placental indications for cesarean section
placenta previa
vasa previa
abruptio placentae
how is an epidural performed
epidural catheter is placed in the L3-L4 interspace when the patient requires analgesia –> usually not done until labour is in active phase
once catheter placed, initial bolus of anesthetic is given and then a continuous infusion is started
epidural does not commonly remove all sensation and can actually be detrimental to the ability to push in the second stage –> however, if need C/S, can usually just bolus the epidural and this is usually enough
how does a spinal differ from an epidural
similar regions anesthetized but spinal is given in a one time dose directly into the spinal canal leading to more rapid onset of anesthesia
used more commonly for C/S than vaginal
what is a common complication of epidurals and spinals
maternal hypotension secondary to decreased SVR, which can lead to decreased placental perfusion and fetal brady
more serious can be maternal resp depression if anesthetic reaches high enough level to affect the diaphragmatic innervation
spinal headache due to loss of CSF is post partum complication seen in less than 1% of people
what are the two major concerns about general anesthesia for C/S
risk of maternal aspiration
risk of hypoxia to mother and fetus during induction
list common reasons for a C/S that may require general anesthesia
abruption
fetal brady
umbilical cord prolapse
uterine rupture
hemorrhage from placenta previa
