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Twins. Topic Conference LU VI Block 10 Tindoc.Tugano.Urquiza.Uy.Velasco.Ventigan.Ventura.Verdolaga . VillanuevaM.VillanuevaR.Visperas.Yabut.Yambot.YapB.YapJ. EV, 33 year old G2P1(0010), single. EV, 33 year old G2P1(0010), single. EV, 33 year old G2P1(0010), single.
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Twins Topic Conference LU VI Block 10 Tindoc.Tugano.Urquiza.Uy.Velasco.Ventigan.Ventura.Verdolaga. VillanuevaM.VillanuevaR.Visperas.Yabut.Yambot.YapB.YapJ
Prevalence of spontaneous twinning • 1 in 80 live births (1 in 40 babies) • 10-20/1000 live births in US, Europe • 40/1000 in Africa • 6/1000 in Asia
Etiology of multifetal gestation • Dizygotic – fertilization of 2 ova
Etiology of multifetal gestation • Monozygotic – division of single fertilized ovum
Factors that influence twinning • Race • 6/1000 livebirths in Asia • E.g. 4.3/1000 in Japan, 11.3/1000 in India, 12.3/1000 in England, Wales • Heredity • Maternal history more important • Mother’s who themselves are twins gave birth to twins at a 1/58 live births • Maternal Age and Parity • Taller, heavier more nutritionally provided women, 25-30% inc in twinning rate • Pituitary Gonadotropin • Inc dizygotic twinning rate w/in 1 mo. of stopping oral contraceptives, associated with sudden surge in gonadotropin • Assisted Reproductive Technology • Responsible for 17% of multiple births in the US
Maternal physiology • Cardiovascular • More hyperdynamic circulation than singleton pregnancy • Cardiac output increases by 20% more in twin gestation than in singleton • 15% from stroke volume: due to increase in preload • 3.5% from heart rate • GI and Hepatic Changes • Pregnancy nausea and vomiting 50% • Twice the risk for obstetric cholestasis • Twin pregnancy independent risk factor for acute fatty liver, 9-25% of all cases seen in twin pregnancies • Renal • No significant difference from singleton • Increased GFR, leads to decreased BUN, Crea and increased urine protein
Maternal physiology • Respiratory • No significant difference • Increase use of accessory muscles • Exaggerated abdominal distention • Loss of abdominal tone • Hematologic • RBC mass increases by 25% in both single and multifetal gestations • Inc. in plasma volume is 10-20% greater in twin pregnancy vs singleton • Other changes associated with singleton pregnancy occur in the same way • Fall in Hct 1st-2nd trimester • Granulocytosis with increase in immature WBCs • Hypercoagulability due to changes in coagulation and fibrinolytic cascades
Complications • Antepartum complications • preterm labor • gestational diabetes • Preeclampsia • preterm premature rupture of the membranes • intrauterine growth restriction • intrauterine fetaldemise • TTTS • 80% in multiple gestations vs 25% in singleton pregnancies
MATERnal complications • Preterm Delivery • 57% of twin gestations are preterm • Not all spontaneous • Higher risk for male-male twins • Ave. length of pregnancy 35 wks for twins vs 39 wks for singletons • Gestational DM • May be increased in multifetal gestation though not universally confirmed • Treated the same way in twin pregnancies
Maternal complications • Pregnancy HPN • Gestational HPN - RR 2.04 (95% CI 1.60 - 2.59) • Pre-eclampsia – RR 2.62 (95% CI 2.03 - 3.38), w/ earlier onset, greater severity • Gestational HPN and preeclampsia also associated with higher preterm delivery rates • Gestational HPN, <37 wks 51.1% vs 5.9% singleton • Preeclampsia, <37 wks 66.7% vs 19.6% singleton • pPROM • Occurs in 7-10% of twin pregnancies • Typically occurs in the presenting sac • Management same as in singleton pregnancies
Fetal complications • Fetal Growth Restriction • 10 times more likely in multiple gestations compared to singletons • Growth Discordance • >=20% difference in EFW • 5-15% of twins • Usu. birth weight difference of 15% for twins • 34% chance of growth restriction in at least one twin for monochorionic twins, 23% for dichorionic twins • Associated with 6 fold increase in risk for perinatal morbidity and mortality • Congenital anomalies • Studies suggest 2-3x increased risk in twins, with probably 10% of twins born w/ congenital anomalies
Fetal Complications • Spontaneous Pregnancy Loss • Around 14% of twin gestations spontaneously convert to singleton pregnancies before the 1st trimester – “Vanishing twin” • Remaining fetus a 3x inc risk for abortion • Est. that only 1/8 individuals conceived as a twin is born a twin • Intrauterine Fetal Demise • Overall survival rate of both twins is 93.7% • Death of one or both fetus at 11-15 wks 5% vs 2% in singletons • Subsequent risk of miscarriage of surviving fetus 24% • Chorionicity important • Monochorionic twin – death of one fetus inc risk of death of the other of 25% • Dichorionic twin – 5-10% risk
Fetal Complications • Twin-to-Twin Transfusion Syndrome (TTTS) • Almost exclusively confined to monochorionic twins, with 10-15% of these having a severe form • Around ¼ of all monochorionic twins have some features of the syndrome • Due to the presence of intertwinanastomosis: A-A, V-V, A-V • A-V and A-A occur in 70% of monochorionic twins • Classically due to A-V anastomoses carrying unidirectional blood flow from donor to recipient twin
Fetal complications • TTTS • Donor twin may become anemic and growth restricted • Recipient twin may become polycythemic, w/ circulatory overload and heart failure • Diagnosed by UTZ at 15-22 wks. • Diagnosed by presence of monochorionic twins with one oligohydramnios twin, other polyhydramnios twin • Most commonly treated with aggressive amniodrainage and laser photocoagulation of anastomoses • Survival rate of at least one twin with laser therapy higher (66%) vsamniodrainage (57%) • Acute twin-to-twin transfusion • Antepartum complication in the interval of cord clamping of 1st twin and delivery of the 2nd twin • 2nd twin left alone with 2 placentas, where its blood may be pumped into - death
DIAGnosis • Suggested by • Accelerated fundal growth • Multiple fetal parts • Auscultation of 2 FHTs • Sonography – the “sine qua non” of diagnosis • Chorionicity • Fetal viability/diagnosis of intrauterine death • Nuchal translucency thickness • Chromosomal abnormalities • Early TTTS diagnosis • Fetal structural abnormalities • IUGR, discordant growth • Fetal circulation • Placental localization, fetal position
Diagnosis • Chorionicity • Important – highest rate of death in twins occurs before 24 wks, most often due to TTTS • Chorionicity easier to determine at early gestation • What to look for • Separate placentas – diagnostic but usu. difficult • Intertwin membrane – from 2 amnions, 2 chorions, >2mm in dichorionic twins • Extraembryoniccoelimic space – 2 in dichorionic • Yolk sacs – 2 in dichorionic • Fetal sexes • Lambda/twin peak sign – diagnostic of dichorionic twins; triangular chorionic tissue from fused dichorionic placenta extending into the intertwin membrane
Labor management & delivery • The cornerstone of antepartum care is prevention of preterm labor and delivery • Main cause of high perinatal mortality and complications in twins • Labor and Delivery Problems • Hypotonic uterine inertia • Due to overdistended uterus • Oxytocin just as effective as in single births, dosage, time to delivery, complications same • Intrapartum bleeding • More common in twins due to abruptio or vasaprevia
Labor management & delivery • Route of Delivery • Vaginal delivery for mature vertex-vertex twins and <1500g vertex-vertex twins – same outcome as CS • CS indications for singleton pregnancy still apply • If the 1st twin is transverse or breech, CS in favored • Avoid “locked-twins” complication • CS for non-vertex second twin • No improvement in fetal outcome • Inc. maternal febrile morbidity • Best delivered by assisted breech delivery or breech extraction
Labor and Delivery • Presentation and Position • Most common combination is cephalic-cephalic, cephalic-breech, and cephalic-transverse • Presentations other than cephalic-cephalic are unstable
Vaginal delivery • Cephalic-cephalic: spontaneous or forceps assisted • Cephalic-noncephalic: vaginal delivery of the noncephalic twin can be done if the weight > 1500g • VBAC: same risk of uterine rupture as in singleton pregnancy
Cesarean section • Breech: CS if • Large fetus, and the aftercoming head is larger than the birth canal • Small fetus the extremities and trunk may deliver through an inadequately effaced and dilated cervix, but the head may become trapped above the cervix • The umbilical cord prolapses.
In this study there was no significant differencein perinatal mortality and neontala mortality in both the CS group and planned vaginal group.