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