Labor & Delivery Flashcards
At what gestational age can you do an ECV? Benefits/risks?
37w
- most likely to have spontaneously verted by then
- lower risk of spontaneous reversion
- increased risk of failure, but also lower risk of pre-term birth compared to version at 35-36w
What is the risk of ECV in patients with a h/o c-section?
Same success rate (50-80%) - some studies say higher success, some say lower success rates
No cases of uterine rupture reported
What are the risks of ECV?
Placental abruption Umbilical cord prolapse Rupture of membranes Stillbirth Feto-maternal hemorrhage (all <1%)
What are the success rates of ECV?
Range from 16% to 100%. Pooled success rate of 58%.
What increases the likelihood of ECV success?
- Normal or increased amniotic fluid
- Normal BMI
- Multiparity
- Non-anterior placenta
- High station
- Tocolysis (25% increase in success)
- Regional anesthesia (87% vs 57% success)
Incidence of OP position
5-12%. ROP most common (60% of OP)
What is the natural history of OP position? (what happens with expectant management)
80-90% spontaneously rotate to OA; 50-80% rotate still if OP at the start of the second stage
What factors are associated with OP position?
Anthropoid pelvis (narrower, deeper AP diameter) Nulliparous Possibly also associated: BMI>30 AMA macrosomia anterior placenta
What pelvic shape is most associated with OT position?
Platypelloid (small AP diameter)
What are the morbidities of OP position?
Labor dystocia (prolonged, longer 1st stage, need for augmentation)
Longer second stage, appx 45 minutes
Association with c/s, 4-10x with persistent OP position in 2nd stage.
Increased risk of atony, PPH
Increased risk of operative delivery and failure of operative delivery
Increase risk of OASIS injury
How good are vaginal exams in determining OP and OA position?
Accurately predict OA 80-85% of the time
Predict OP 50-60% of the time
Does the peanut ball work to change fetal position?
No evidence to support maternal positioning to encourage rotation
When is it recommended to attempt to rotate the fetal head?
During the second stage of labor. NOT prior to complete cervical dilation. Due to risk of cord prolapse or cervical lacerations.
Number needed to treat for manual rotation?
4! 4 rotations needed to prevent one c-section (by a large retrospective study)
By the data, how often is manual rotation successful?
90%
What is the primary benefit of successful rotation?
Decreased c-section, decreased operative vaginal delivery/oasis injuries
Arrest of descent
Fetal vertex w/o descent in 1 hour despite adequate maternal expulsive efforts
Prolonged second stage
nulliparous women > 3 hours with epidural or > 2 hours without; multiparous women > 2 hours with epidural or > 1 hour without.
Stillbirth definition
Fetal death at 20w or greater or 350g (50%ile at 20w) if GA is unknown
Excludes pre-viable pprom and pre-viable termination
Risk factors for stillbirth
Non-hispanic Black race
Multiple gestation (14/000 compared to 5/1000; triplet and higher order, 30/1000)
Prior stillbirth
Male sex (6/1000)
Young maternal age (<15) or advanced maternal age
Medical co-morbidities - DM, cHTN, SLE, renal, obesity, tobacco
Anti-phospolipid antibody
Etiologies of stillbirth
5-10% Abruption
10% umbilical cord events (stricture, entrapment, vasa previa)
6-13% abnormal karyotype
10-20% infection (GBS, E Coli; listeria, syphilis; CMV, Parvovirus, Zika)
How do you evaluate stillbirth?
placental pathology MOST HELPFUL fetal autopsy amniocentesis / genetic testing APLA testing less useful, KB and infectious testing
What is the induction regimen for IOL in 2nd trimester stillbirth?
400-600mcg vaginal misoprostol q3-6hrs
Can do this with hx cesarean
What is the recurrence risk of stillbirth?
2.5%
What is the antepartum surveillance for hx of stillbirth?
NST at 32w or 1-2wk prior to GA of stillbirth (if stillbirth <32w, individual plan)
third trimester growth ultrasound
What is the timing of delivery for a patient with hx of stillbirth?
May warrant early term delivery at 37-38w
What is the FHT sig associated with uterine rupture?
Fetal bradycardia (only stat sig finding compared to VBAC without rupture)
What are risk factors associated with uterine rupture?
IOL / prostaglandin use
What is the incidence of uterine rupture?
1x LTCS: 0.5-0.9% 2x LTCS: 0.9-3.7% Classical incision: 1-12% Low vertical: likely the same as LTCS Unknown prior incision - similar rates of rupture with low transverse
What are positive factors associated with VBAC?
spontaneous labor
prior vaginal delivery
What factors are negatively associated with VBAC?
prior arrest of labor increased BMI** increased maternal age higher birth weight GA >40w labor induction
What is the risk of rupture w/ and without prostaglandins?
without prostaglandins: 0.7-1.1%
with prostaglandins: 1.4-2.3%
difficult to interpret / mixed data
What is the recurrence risk of uterine rupture?
6% (lower uterine segment scar)
up to 32% if upper uterine segment
What is the delivery plan for women with h/o uterine rupture?
Consider rLTCS at 36-37w
Can you use prostaglandin inductions in IUFDs for h/o C-S?
ok to use prostaglandins in women with hx of CS unless vertical incision
What’s the max daily dose of labetalol IV?
300mg
What’s the max daily dose of PO nifedipine?
180mg
What’s the max daily dose of hydral IV/IM?
20mg
What is the 1st line treatment of eclampsia?
magnesium sulfate 4-6g loading dose over 30 min > 2g/hr
IM magnesium 5g and 5g followed by 5mg q4h
What’s the diagnostic criteria for HELLP?
LDH >600
LFTs 2x normal
Plt <100K
What percent of HELLP patients will not have high blood pressures?
15%
What are high risk factors for which patients should be on bASA?
h/o pre-eclampsia multifetal gestation cHTN T1DM T2M renal disease autoimmune disease
When should you start bASA for pre-eclampsia prevention?
max benefit if <16w
ok to start between 12 and 28 weeks
don’t start >28w due to lack of benefit
When should you treat cHTN in pregnancy?
persistent BPs >160/110
or lower but w/ comorbidities or renal disease
What is goal BP for treatment of cHTN in pregnancy?
120-160/80-110
Which women with cHTN need fetal surveillance?
- on meds
- other co-morbid conditions
- IUGR
- superimposed preE
What percent of cHTN will develop pre-E?
20-50%
if end-organ damage present with cHTN, up to 75%
What are consequences of Rh alloimmunization?
Hemolytic anemia of the newborn - high output cardiac failure, hydrops, stillbirth
What percent of alloimmunization is caused by feto-maternal hemorrhage?
1-2%
What is the critical titer for Anti-D?
1:16
What is the prevalence of Intrahepatic cholestasis of pregnancy?
0.2-6% of pregnancies
What are risk factors for cholestasis of pregnancy?
Multiple gestation
HCV positive
IVF
Advanced maternal age
What are the adverse outcomes of cholestasis of pregnancy?
Pre-term birth
meconium stained fluid
IUFD
Higher with bile acids at/above 40umol/L
Granulomatous infantile septis
acute rash
fever
abscesses in placenta
due to listeria
Definition of contraction stress test
3 contractions in 10 minutes
positive test is decels with >50% of contractions
What did the WOMAN trial show in terms of benefits of TXA in PPH?
Reduction in maternal mortality, 1.9% to 1.5% if given within 3 hours
IV or PO
How much contrast is excreted into breast milk?
<1% of contrast administered is excreted
<1% of this is absorbed into infant GI tract
How much gadolinium is excreted into breast milk?
<0.04%
<1% of this is absorbed by infant GI tract
What are the benefits of median vs mediolateral episiotomy?
Mediolateral - lower risk of extension into anal sphincter
Median - lower risk of postpartum pain or dyspareunia
What is the NNT for primary cesarean section in macrosomia in diabetic mothers
440 cesarean deliveries to prevent 1 shoulder dystocia
EFW 4500 + DM
What percentage of fetuses enter the pelvis in OP position?
20%
Tachysystole definition
> 5 contractions in 10 minutes averaged over 30 minutes
Which nerve roots transmit somatic pelvic pain in labor?
Pudendal
S2-S4
What does acetylcholinesterase on amniocentesis mean?
acetylcholinesterase + elevated AFP = Neural tube defect
What is the dose of rhogam after CVS?
125-300mcg
Fetal loss rate after amniocentesis in 2nd trimester
1:200 - 1:300
