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Multiple Gestations
Cynthia S. Shellhaas, MD, MPHAssociate Professor – ClinicalObstetrics & [email protected]
Objectives
To understand the epidemiology of multiple gestations
To be able to list and describe the most common maternal complications of multiple gestations
To be able to list and describe the most common fetal complications of multiple gestations
To describe an ante-partum plan for specialized care for multiple gestations
To describe a delivery plan for multiple gestations
Objective
To understand the epidemiology of multiple gestations
Twin Birth Rate—United States: 1980-2006
Twin Birth Rate: Maternal Age and Ethnicity
Objective
To be able to list and describe the most common maternal complications of multiple gestations
Physiologic Changes in Multiple Gestation
Increase in plasma volume related to fetal number (96% in triplets/48% in singletons)
Increased TV, O2 consumption, respiratory alkalosis
Increased placental massincreases in HPL, HCG, AFP, progesterone, estradiol
Increased energy demands
Maternal Complications: Hypertension
2-3 X increase (Twins:Singletons) Presents earlier in gestation Presents w/greater severity (BP elevations,
eclampsia) Increase in HELLP variant Twins more likely than singletons with same
condition to have PTD, LBW, or C/S Incidence does not vary with zygosity Higher order gestations: atypical presentations
more likely
Maternal Complications: GDM
Increased incidence in multiples/Increased HPL 3-6% twins 22-29% triplets Each fetus increases the risk by a factor of 1.8
Decreased incidence after pregnancy reduction Unknown: Ideal calories, optimal weight gain, oral
hypoglycemic agents in PCO patients, best fetal surveillance, or ideal delivery time
Maternal Complications: Other
Acute fatty liver 1 in 10,000 singleton deliveries; 14% of cases occur in
twins; 7% of triplet pregnancies Placental abruption
8.2 X increase (twins:singletons) Pruritic Urticarial Papules & Pustules of Pregnancy
0.2% singletons, 3% twins, 14% triplets Pulmonary Embolism
Increased C/S, bedrest, AMA Post-partum hemorrhage (atony)
Physiologic Change - Quiz
Antepartum Management: Diet
• Increase caloric consumption by 300 kcal/day/fetus over singleton; 600 kcal/day over non-pregnant woman
• Anemia– Iron deficiency anemia 2.4-4X higher– Folate deficiency anemia 8X higher
• Nutritional supplements– Iron (60-100 mg/day)– Folic acid (1 mg/day)
Weight Gain
BMI < 18.5 kg/m2: Insufficient data BMI 18.5-24.9 kg/m2: 37-54 lbs BMI 25-29.9 kg/m2: 31-50 lbs BMI > 30.0 kg/m2: 25-42 lbs
Recommedations for Supplemental Folic Acid
Objective
To be able to list and describe the most common fetal complications of multiple gestations
Relationship between Zygosity & Chorionicity
Gross specimen: Dichorionic/diamniotic placenta
Ultrasound Assessment of Chorionicity
Twin Zygosity and Corresponding ComplicationsType Incidence IUGR PTD Placental
Vascular Anasomosis
Perinatal Mortality
Dizygotic 80 25 40 0 10-12
Monozygotic
20 40 50 ---- 15-18
Di/Di 6-7 30 40 0 18-20
Di/Mono 13-14 50 60 100 30-40
Mono/Mono < 1 40 60-70 80-90 58-60
Conjoined 0.002-0.008 ---- 70-80 100 70-90
Twin-Twin Transfusion Syndrome
Incidence: 10-15% of monochorionic/diamniotic twins Etiology: Artery-to-vein anastomoses Median GA at dx: 21 weeks Underlying cause of 16% of twin mortality
Twin-Twin Transfusion Syndrome
Williams’ Obstetrics, 22nd edition
Quintero Stages
1—Abnormal AFV levels; Donor has identifiable bladder 2—Collapsed bladder in oliguric donor 3—Abnormal doppler studies 4—Hydrops 5--Death
Monoamniotic Twins
Incidence: 1 in 10,000 pregnancies Twin-twin transfusion syndrome: 1% Monozygotic twins: 1-5% Increased fetal loss: 23%
Cord entanglement: 67%
Congenital anomalies: 26% NTD, abdominal wall, urinary malformations
Monochorionic/Monoamniotic Twins
Conjoined Twins
Ventral (87%) Parapagus (28%) Thoracopagus (19%) Omphalopagus (18%) Ischiopagus (11%) Cephalopagus (11%)
Dorsal (13%) Pygopagus (6%); craniopagus (5%); rachiopagus
(2%)
Ultrasound image: Conjoined Twins
Conjoined Twins
Conjoined Twins
Twin Reversed Arterial Perfusion (TRAP) Sequence Incidence: 1 in 35,000 deliveries
1% monochorionic gestations Abnormal zygote division at time of twinning
Arterial-arterial anastamoses Donor (“pump”) twin perfuses recipient (“acardiac”) twin “Pump” twin: Heart failure, PTD
Weekly surveillance
Gross specimen: TRAP Sequence
Division of a monozygote between the 4th & 8th day after fertilization creates which of the following?
A. Conjoined twins B. Diamnionic, dichorionic C. Diamnionic, monochorionic D. Monoamnionic, monochorionic
Monozygote Division
Morbidity/Mortality in Multiple Gestation
Twins Triplets Quadruplets
Avg BW 2,347 grams 1,687 grams 1,309 grams
Avg GA 35.3 wks 32.2 wks 29.9 wks
% IUGR 14-25 50-60 50-60
% NICU 25 75 100
Avg LOS 18 days 30 days 58 days
% HCP ----- 20 50
CP Risk 4X 17X -----
IM Risk 7X 20X -----
Objective
To describe an ante-partum plan for specialized care for multiple gestations
Antepartum Management: Fetal Growth
Similar rate of growth compared to singletons in 1st & 2nd trimesters; start to lag around 30-32 weeks’ Sub-optimal placentation Abnormal umbilical cord morphology/insertion Structural/genetic anomalies Monochorionicity
2006 Preterm Birth Rates: Twins vs. Singletons
Congenital Anomalies
MZ twins have a 2-3X increase compared to singletons/DZ twins Anencephaly Holoprosencephaly VATER association Extrophy of cloaca Sacrococcygeal teratoma Sirenomelia
Antepartum Management: Prenatal Diagnosis Dizygotic twins: independent & additive
aneuploidy risk The risk of having at least one affected fetus is
doubled Twin pregnancy in 33 year old has risk=35
year old with singleton Monozygotic twins: same risk as singletons
Prenatal Diagnosis
Ultrascreen MS-AFP Amniocentesis Chorionic villus sampling
Antepartum Management: Ultrasound
Assessment of chorionicity Level II Ultrasound Growth
Every 4-6 weeks if normal Evaluate interval growth every 10-14 days if
compromise Cervical length
Not before 16 weeks
What are these images?
Ultrasound images: Cervical Length
Antepartum Management: Fetal Surveillance Increased risk for IUFD compared to singletons Both NST & BPP effective in identification of
compromised twins/triplets Questions
Higher order gestations GA to initiate testing Frequency: Once or twice weekly ? Normally growing dichorionic twins
Twins Questions
Objective
To describe a delivery plan for multiple gestations
Timing of Delivery
Most twins deliver between 35-36 weeks’ gestation Lung maturity Growth velocity Perinatal mortality & morbidity Best delivery time: 37-38 weeks’ gestation
Twins: Intra-Partum Management
Twin A VertexTwin B Vertex
Twin A Non-Vertex
Twin A VertexTwin B Non-Vertex
Vaginal DeliveryCesarean Delivery
CesareanDelivery External
Cephalic Version
BreechExtraction
UnsuccessfulSuccessful
Vaginal DeliveryCesarean Delivery
External Cephalic Version
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