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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
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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 • 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 diabetesand 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 testing • Quad screen • Integrated screen • Cell-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.
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 Morula Days 1-3 Dichorionic/Diamniotic Blastocyst Days 4-8 Monochorionic/Diamniotic Implanted Blastocyst Days 8-13 Monochorionic/ Monoamniotic Formed Embyonic disc Days 13-15 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!
Risks Unique to Mono/Mono twins • 1 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