topics in high risk ob advanced maternal age, twins, vbac, preterm labor
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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 - PowerPoint PPT PresentationTRANSCRIPT
Topics in High Risk OB
Advanced maternal age, Twins, VBAC, Preterm laborSusan 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
labor
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 yrs
2006 – 1 in 12
Non-invasive prenatal testingQuad screenIntegrated screenCell-free DNA testing
Invasive Prenatal testing = Amniocentesis
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 Alpha-fetoprotein hCG Estriol 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 area 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 www.sequenom.com
Who gets Cell-free DNA test? Age over 35 years Personal or family history of chromosomal abnormalities
Fetal ultrasound suggestive of aneuploidy
Positive screening test
Prevention of stillbirth Unclear etiology Studies do not support placental insuffiency as
cause 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.
Twins
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
MorulaDays 1-3
BlastocystDays 4-8
ImplantedBlastocystDays 8-13
Formed Embyonic discDays 13-15
Dichorionic/Diamniotic
Monochorionic/Diamniotic
Monochorionic/Monoamniotic
Conjoined twins
US identification of twin chorionicity 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 gestations Preterm labor Small birth weight and IUGR Gestational diabetes Preeclampsia, Acute fatty liver of pregnancy DVT/PE 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 twins1 in 10,000 pregnancies Twin-to-Twin transfusion is less common but
possible 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
advantages 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
increased
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 pregnancy
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
weeks Risks associated with preterm birth follow the child into early
childhood 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 labor 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
placement
Bibliography ACOG Practice Bulletin #77 – Screening for Fetal Chromosomal
Abnormalities Reddy et. al. Maternal age and the risk of stillbirth throughout
pregnancy in the United States. Am J Obstet Gyn. 195: 764-770. (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