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 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 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. 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 Morula Days 1-3
Dichorionic/Diamniotic Blastocyst Days 4-8 Monochorionic/Diamniotic Implanted Blastocyst Days 8-13 Formed
Embyonic disc Days 13-15 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 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 3 rd 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 VBACs and required RLTCS Wording was revised in 2010 to try to promote more VBACs 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 patients 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 STDs, UTIs, 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
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