Multiple GestationSupervised by:Prof. Salah RoshdyDone by:Yasser Abdulmohsen Alresiny426035045
OBJECTIVES:• Definition.• Incidence and epidemiology.• Clinical characteristics.• Classification.• Diagnosis.• Complications.• Abnormalities of the twinning process.• Management.
DEFINITION:• Any pregnancy which two or more embryos or fetuses present in the uterus at same time.• It is consider as a complication of pregnancy due to ; ▫ The mean gestational age of delivery of twins is approximately 36w. ▫ The perinatal mortality &morbidity increase.
Terminology vs. number Singletons one fetus Twins tow fetuses. Triplets three fetuses. Quadruplets four fetuses. Quintuplets five fetuses. sextuplets six fetuses. Septuplets seven fetuses.
Mean gestational age of deliveryNumber of babies Weeks of Gestation 1 40 weeks 2 36 weeks 3 33 weeks 4 29 ½ weeks
Incidence & epidemiology• The incidence of multiple pregnancy in US is approximately 3% (increase annually due to ART ).• Monozygotic twins ( approx. 4 in 1000 births ).• Triplet pregnancies ( approx. 1 in 8000 births ).• Multiple gestation increase morbidity & mortality for both the mother & the fetuses.• The perinatal mortality in the developed countries ▫ Twins = 5 – 10 % births. ▫ Triplets = 10 – 20 % births.
Clinical characteristics:Multiple gestation should be suspected when ; Uterine size is greater than expected for gestational age. Multiple FHRs are heard Multiple fetal parts are felt. hCG & serum alpha-fetoprotein levels are elevated for gestational age. If the pregnancy is a result of ART. Diagnosis is confirmed by US .
DDx of uterus that is greater thanexpected for gestational age:1- Polyhydramnios.2- Macrosomia.3- Placental abruption.4- Gestational trophoplastic disease.5- Uterine fibroid.6- Ovarian mass.
Classification Dizygotic (>70%) Monozygotic (<30%) Dichorionic/Diamniotic Dichorionic/Diamniotic Monochorionic/Monoamniotic (8%( (1%) Monochorionic/Diamniotic (20%)N.B. : Placentation in higher-order multiples ( triplets, quadruplets…( follows the sameprinciples, except monochorionic & dichorionic may coexist.
Important notes:1- Monozygotic twins having same sex & blood group.2- Process of formation of chorion is earlier than formation of amnion.3-Dizygotic twins must be dichorionic/diamniotic.4- There is no dichorionic/ monoamniotic.
A- Dizygotic twins (fraternal):Most common represents 2/3 of cases.Fertilization of more than one egg by more than one sperm.Non identical ,may be of different sex.Two chorion and two amnion.Placenta may be separate or fused. “each fetus is contained within a complete amniotic-chorionic membrane “
Cont The incidence of dizygotic twins is higher in ;1. Certain families .2. Race ;African Americans .3. Increases with maternal age, parity, weight and height .4. Ovulation induction.
B- Monzygotic twins:Constitutes 1/3 of twinsThese twins are multiple gestations resulting from cleavage of a single, fertilized ovum.The timing of cleavage determines the placentation of the pregnancy.Constant incidence .Not affected by heredity.Not related to induction of ovulation.
Time of Nature of membranes % Perinatalcleavage mortality0 - 72 hr diamniotic,dichorionic 8 8.9%4 – 8 days diamniotic,monochorionic 20 25%9-12days monoamniotic,monochorionic 1 50-60%>13 days Conjoined twin ---- -----
Placentation in Higher-Order Multiples ; The relationship of placentas among triplets, quadruplets, and higher-order multiple fetuses generally follows the same principles, except that monochorionic and dichorionic placentation may coexist, and placental anomalies are more frequently found in higher-order multiples.
Diagnosis:• History: ▫ Family hx of dizygotic twins. ▫ Use of fertility drugs. ▫ sensation of excessive fetal movements. ▫ Exaggerated symptoms of pregnancy (hyperemesis gravidarum ).• Examination: ▫ GPE ( weight gain, Pre-eclampsia signs ) ▫ Abdominal examination (excessive uterine fundal growth, and auscultation of fetal heart rates in separate quadrants of the uterus are suggestive but not diagnostic).• Sonographic examination ( diagnostic )
Ultrasound evaluation:• The diagnosis of multiple gestation requires a sonographic examination demonstrating two separate fetuses and heart activities.• The diagnosis can be made as early as 6 weeks of gestation.
DETERMINATION OF ZYGOSITY: Very important as most of the complications occur in monochorionic monozygotic twins. By ; Ultrasound : genders,numbar of placentas, Blood groups. HLA. DNA analysis.
• During pregnancy by US :• Very accurate in the first trimester, two sacs, presence of thick chorion between amniotic membrane .• Less accurate in the second trimester the chorion become thin and fuse with the amniotic membrane .• Different sex indicates dizygotic twins.• Separate placentas indicates dizygotic twins
After birth ;• By examination of the MEMBRANE, PLACENTA,SEX , BLOOD group .• Examination of the newborn DNA and HLA may be needed in few cases.
DETERMINATION OF ZYGOSITY:Findings Zygosity Freq.Different genders dizygotic 30%Two placentas,same gender dizygotic 27%different blood groupsOne placentas monozygotic 23%Two placentas,same gender HLA & DNA analysis 20%Same blood group
US different gender samedizygotic Monozygotic Number of twins twins 1 placenta 2 different same same Blood HLA & DNA group analysis different
Septum Placental type Twin type 1- None Monochorionic/Monoamniotic monozygotic 2- Amnion only Monochorionic/Diamniotic monozygotic3- Amnion & chorion Dichorionic/ diamniotic Dizygotic or monozygotic4- No common septum Dichorionic/ diamniotic dizigotic 1 2 3 4
Complications:• A - Maternal: ▫ Antepartum Anemia. Miscarriage. Preeclampsia ( 40% in twins & 60% in triplets ). Polyhydramnios ( 5 – 8%). PTL ( Twin account for 10% of all PTL & 25% of all preterm perinatal deaths ). Cervical incompetence. Hyperemesis gravidarum. ▫ Intrapartum CS. ▫ Postpartum postpartum uterine atony. b/c of post partum Hemorrhage. Over distended uterus postpartum endometritis
Conjoined Twins ; • Etiology : It result from cleavage of the embryo is incomplete because it happen very late (after 13 days, when the embryonic disc has completely formed). • • Incidence : once in 70,000 deliveries. • Classification: ▫ Thoracopagus (antreior) “most common”. ▫ Pygopagus (posterior) ▫ Craniopagus (cephalic) ▫ Ischiopagus (caudal) • Delivery by C.S.
Interplacental Vascular Anastomoses:• It occurs almost exclusively in monochorionic twins at a rate of 90% or more.• Type: ▫ Arterial_artarial(most common). ▫ Arterial_venous. ▫ Venous_venous.• Complications: ▫ Abortion. ▫ Hydramnios. ▫ Twin-twin transfusion syndrome (TTTS). ▫ Fetal malformations.
Twin-Twin Transfusion Syndrome ; • Definition: ▫ 15% of monochorionic twins have domensturable anastomosis. ▫ The presence of unbalanced anastomosis in the placenta (typically arterial-venous connections) leads to a syndrome in which one twin’s circulation perfuses the other Twin. • Complication: ▫ Donor : anemic HF, hypovolemia, hypotension, anemia, oligohydramnios, growth restriction. ( do intrauterine blood trans fusion). ▫ Recipient : hypervolemic HF , hypervolemia, hypertension, polyhydramnios, thrombosis, hyperviscosity,cardiomegaly, polycythemia, hydrops fetalis. ( do repeated amnioreduction). ▫ Both: risk of demise & PTL.
Management of TTTs ; If not treated death occurs in 80-100% of cases. If extreme prematurity prevents immediate delivery, Several interventions can be considered in view of the high mortality associated with expectant management.• Repeated amniocentesis from ( recipient) .• Intrauterine transfusion of the anemic (donor) twin is of no benefit in this condition.• Indomethacin.• Fetoscopy and laser ablation of communicating vessels.
Fetal Malformations: • Incidence: ▫ Twice as common in twins & 4 times more common in triplets than in singleton infants. ▫ Monozygotic > Dizygotic. • Etiology: ▫ Usually result from arterial-arterial anastomosis. ▫ Common deformations in twins include limb defects, plagiocephaly, facial asymmetry, and torticollis. ▫ Acardia and twin-reversed arterial perfusion (TRAP) “ rare but unique to multiple pregnancy”. • Amniocentesis: ▫ If U/S shows abnormality.
Umbilical Cord Abnormalities:• Absence of one umbilical artery occurs in about 3% to 4% of twins (30% of case absence of one artery associated with other congenital anomalies”renal agenesis” ).• Cord entanglement ( esp. in monochorionic monoamniotic twins ).
Discordant Twin Growth:• Definition: ▫ Discrepancy of more than 20% in the estimated fetal weights.• Causes: ▫ TTTS. ▫ Chromosomal or structural anomalies. ▫ Discordant viral infection. ▫ Interplacental Vascular Anastomoses.
Specific indication C/S in Twins ;1. monochorionic monoamniotic twins2. Conjoined twins3. Non vertex presentation of first twin4. Locked twins5. Twin-reversed arterial perfusion (TRAP)6. Placentation in Higher-Order Multiples7. Other obstrictic indication of C/S
Management: Antepartum • Adequate nutrition. ▫ Adequacy of maternal diet is assessed due to the increased need for overall calories, iron, vitamins, and folate . ▫ The Institute of Medicine (IOM) recommends women with twins gain a total of 16.0 to 20.5 kg during the pregnancy. • More frequent prenatal visits. • Periodic U/S assessment “ every 3-4 weeks from23weeks’ gestation “ to monitor the growth and detection of discordant growth or TTTS. • Fetal surveillance: ▫ Performance of NST is not indicated before 34 wks unless to confirm IUGR or discordant growth. ▫ ( avoid CST ) • Amniocentesis. ( If indicated )
In case of death of one fetus is managed based on the gestational age and condition of the surviving fetus.1- fetal surveillance weekly measured Until evidence2- maternal clotting profiles of fetal lung maturity in the surviving fetus is exhibitedDelivery should be considered if :1) Fetal lung maturity is demonstrated2) If compromise of the remaining fetus develops3) If evidence of disseminated intravascular coagulation in the mother is present.In the setting of TTTS, the death of one twin should prompt consideration of delivery, particularly after 28 weeks, given the high rates of embolic complications in the surviving twin.
Cont..Intrapartum• The route of delivery depends on: ▫ Presentation of the twins. ▫ Gestational age. ▫ Presence of maternal or fetal complications. ▫ Experience of obstetrician. ▫ Availability of anesthesia & neonatal intensive care.
Delivery: • Vertex/Vertex(43%): ▫ Vaginal delivery. (Successful in 70-80%of cases). ▫ Surveillance of twin B with real-time U/S. • Vertex/Nonvertex(38%): ▫ Vaginal delivery ( better ) (in absence of discordant growth). ▫ Either external cephalic version or podalic version with breech extraction may be attempted. ▫ CS. • Nonvertex Twin A(19%): ▫ CS .
Cont.postpartum• Active management of PPH:By giving oxytocin in the 3nd stage of labor just after delivery of both fetuses and placentas.
Multiple gestation with more thantwo fetuses Most frequent cause is iatrogenic from the use of ovulation induction agent. Prematurity increase as the number of fetuses increase . 1) Multifetal reduction may be offered: Reduce the risk to the mother & the remaining fetuses. Performed only in the setting of dichorionic /diamniotic gestation. 2) Selective termination: Termination of one or more fetuses with structural or chromosomal anomalies.