Topics in High Risk OB Advanced maternal age, Twins, VBAC

Topics in High Risk OB
Advanced maternal age, Twins, VBAC,
Preterm labor
Susan Wing Lipinski, M.D.
October 16, 2013
Learning Objectives
 To become familiar with non-invasive options for prenatal
testing and the appropriate indications for use
 To become familiar with different types of twin gestations and
the unique risks associated with each
 To understand the risk and benefits associated with a trial of
labor after Cesarean section
 To become familiar with preventative treatments for preterm
Advanced Maternal Age
Age 35 years or older at anticipated date of delivery
Increased risk of miscarriage
Increased risk of trisomies – 13, 18, 21 especially
Increased risk of gestational diabetes and preeclampsia
Increased risk of stillbirth
Number of women delaying childbirth is increasing
 1970 – 1 in 100 first pregnancies to mothers over age 35
 2006 – 1 in 12
Non-invasive prenatal
Quad screen
Integrated screen
Cell-free DNA testing
Invasive Prenatal testing =
Quad screen
 Developed from AFP testing into triple marker screen and
now quadruple marker screening
 First option available to those under age 35 yrs – introduced
in 1984
 SCREENING test – not diagnostic
 Estimates risk of trisomy 13, 18,21; abdominal wall defects;
neural tube defects; indirect information about placenta and
risk of preeclampsia.
 Blood draw between 15-20 weeks
Inhibin -A
Integrated screen
 Takes the Quad screen (2nd trimester screening) and
combines with first trimester US of nuchal thickness and first
trimester biochemical markers
 Done at 11-13 weeks
 Detection rate for Down Syndrome 94-96%
 Biochemical markers tested
 Free B-hCG
 PAPP-A (pregnancy associated plasma protein A)
Cell-free DNA testing
Newest option available
Only validated in high risk patient populations
Can be done as early as 10 weeks up until 32 weeks
Several tests available – Materniti21 most widely used in this
 Highly accurate at identifying the following:
 Trisomy 13, 18, 21
 Sex chromosome aneuploidies (XXY, X0, XYY, XXX)
 Identifying gender – important for families with X-lined diseases
Taken from Se
Taken from
Who gets Cell-free DNA test?
 Age over 35 years
 Personal or family history of
chromosomal abnormalities
 Fetal ultrasound suggestive of
 Positive screening test
Prevention of stillbirth
 Unclear etiology
 Studies do not support placental insuffiency as
 Studies do show benefits of NST testing
 OR of stillbirth compared to age 25-29 yrs
 35-39 yrs OR is 1.8 – 2.2
 40+ yrs OR is 1.8-3.3
 When to test?
 Start 36-38 weeks then test weekly till delivery
 Some benefit to twice weekly testing for those over age 40 yrs
 Some benefit to delivery at 39 weeks in those over 40 yrs.
Monozygotic vs. Dizygotic
 Dizygotic are always Dichorionic/Diamniotic
 Monozygotic can be any type of chorionicity/amnionicity
 Dichorionic/Diamniotic twins
 85% dizygotic
 15% monozygotic
Embryologic development
monozygotic twins
Days 1-3
Days 4-8
Days 8-13
Embyonic disc
Days 13-15
Conjoined twins
US identification of twin
 Best determined in first trimester
 Absolutely necessary to know in order to determine
appropriate follow up!
 Twin peak sign -
“Heaping up” of villi into intermembrane space
Risks associated with all twin
Preterm labor
Small birth weight and IUGR
Gestational diabetes
Preeclampsia, Acute fatty liver of pregnancy
Cerebral palsy – 4 times that of a singleton pregnancy!
Increased risk of admission to NICU
Since 1980 there has been a 65% increase in twins and
500% increase in triplets and higher-order births!
Risks unique to Mono/Di Twins
 Twin-to-Twin transfusion syndrome (TTTS) – 10-15% of
Mono/di twins
 Twin anemia-polycythemia sequence (TAPS) – variant of
TTTS with normal amniotic fluid volumes
 Twin reversed arterial perfusion sequence (TRAP) –
acardiac twin uses co-twin for perfusion. 1% of mono/di
 Selective intrauterine growth restriction
 Early identification of all of these results in the best outcome
– this is the area where intrauterine surgery is taking off!
Twin-to-Twin Transfusion
Risks Unique to Mono/Mono twins
 1 in 10,000 pregnancies
 Twin-to-Twin transfusion is less common but
 Cord entanglement
 Begins in first trimester
 Results in up to 23% mortality in utero
Monitoring of twin pregnancies
 All twin gestations need growth US every 4 weeks through
out pregnancy
 Monochorionic should have q2 week US from 16-28 to
screen for TTTS and its variants
 NST screening should be done in 3rd trimester on all twins
 Monochorionic/Monoamniotic twins should be referred to
tertiary care center for hospitalized monitoring in 3rd trimester
Trial of Labor after Cesarean
section – the VBAC controversy
Why all the fuss?
30.8% of deliveries in Iowa were C/sections last year
<20% of women have a VBAC
Serious potential risks with BOTH Cesarean delivery and VBAC
ACOG practice bulletin in 2004 used the following wording
“immediate availability of Cesarean section.”
 This was interpreted to mean immediate surgical availability and
therefore, in-house surgeon and anesthesia
 As a result, many smaller hospitals discontinued VBAC’s and
required RLTCS
 Wording was revised in 2010 to try to promote more VBAC’s
What the evidence shows  Most maternal morbidity during a trial of labor occurs when
repeat LTCS becomes necessary
 Overall risks for maternal complications in repeat LTCS or
VBAC are very low
 For those with successful VBAC there are significant health
 Minimal difference in neonatal morbidity between elective
repeat LTCS and trial of labor
 Probability of successful VBAC is 60-80%
 Risks for VBAC after 2 Cesarean deliveries is only minimally
What do we do with this info?
 Counsel patients about the true risks
 There are VERY few absolute contraindications
 Decisions should be on case-by-case basis
 Start the conversations about VBAC/RLTCS early in
 Support a patient’s right to choose her delivery route
 Respect for patient autonomy argues that even if a hospital
does not “offer VBAC” you cannot force a woman to have a
Cesarean delivery
Preterm labor
 Delivery between 20 0/7 weeks to 36 6/7 weeks
 In 2010 12% of infants were born before 37 completed
 Risks associated with preterm birth follow the child into early
 Greatest predictor is history of a prior preterm birth
Options for prevention
 Progesterone supplementation from 16-36 weeks
Vaginal – Progesterone suppositories 100-200 mg nightly
IM injection – Makena and compounded 17 HP weekly
No proven benefit in twin gestation
Should be offered to EVERYONE with history of spontaneous
preterm birth
 Cerclage
 Controversial
 No proven benefit in twin gestation
Following up a history of Preterm
 Start with counselling at first OB visit
 Look for preventable causes such as STD’s, UTI’s, smoking,
substance abuse, low body weight (BMI<19)
 Offer Progesterone therapy
 Ultrasound for cervical length q 2 weeks from 16-23 weeks
 If cervical length 25-29 mm then move to weekly US
 If cervical length <25 mm then refer for possible cerclage
 ACOG Practice Bulletin #77 – Screening for Fetal Chromosomal
 Reddy et. al. Maternal age and the risk of stillbirth throughout
pregnancy in the United States. Am J Obstet Gyn. 195: 764770. (2006)
 Bahtiyar et. al. Stillbirth at term in women of advanced
maternal age in the United States: when could the antenatal
testing be initiated? Am J. Perinatology. 25(5): 301-304. (2008)
 ACOG Practice Bulletin #56 – Multiple Gestation: Complicated
twin, triplet, and high-order multifetal pregnancy
 Uptodate – Monoamniotic twin pregnancy
 Uptodate – Twin pregnancy: Prenatal issues
 ACOG Practice Bulletin #115 – Vaginal birth after previous
Cesarean Delivery
 ACOG Practice Bulletin #130 – Prediction and Prevention of
Preterm birth

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