Multifetal gestation

Introduction

etiology Dizygotic (Fraternal) twins: not strict sense true twins Monozygotic (identical) twins: not identical d/t not equal sharing of protoplasmic materials

Genesis of Monozygotic & Dizygotic Twins

Placenta &Membranes in Twin pregnancy

Superfetation : interval mense cycle between 2 fertilization but not improved in human Superfecundation: 2 ovum in same mense cycle but not at same coitus

Frequency monozygote: constant (1/250) but increase d/t zygote splitting by ART (assisted reproductive technology) <<race, heredity, age, parity>> Dizygote: especially fertility treatment

Vanishing Twin: 20-60 % in twin conceptions Special increase in MC twins but singleton del 36% in twins, 53% in triple, 65% quadruplet before 12wks preg DDX d/t maternal serum AFP ↑ Amniocentesis >> CVS

Factors that influencing twinnig Race : nigeria Heredity : dizygosity(mother>father) Maternal age & parity : 37age Nutritional factor: higher folate intake Pituitary gonadotropin : within 1Mo stop OC Infertility Therapy: clomiphene citrate ART: 1% in birth but 17% in twins Reducing multifetal gestation but increase survival rate

Sex ratio with mutiple fetus Male decrease in multiple gestation 51.6% in singleton 50.9% in twins 49.5% in triplets 46.5% in quadruplets MCMA twin 70% female, conjoined twins 75% female→ female mortality & dividing tendency

Determine Chorionicity

Sonographic evaluation Twin-peak sign (lamda sign)

Sonographic evaluation T-sign

Sonographic evaluation Easiest & most accurate procedure by evaluation of dividing membrane More than 96% accuracy More sensitvity & specificity in 1st trimester >> 2nd trimester

Placenta Exam & infant sex Careful visual exam in delivery zygosity & chorionicity promptly in 2/3 ABO blood typing in Cord blood if same gender DNA finger printing : definite method Twins of opposite sex: always dizygosity but rarely monozygotic twins

Unique complications in Twins Monoamnionic twins : 1% in monozygotic twin : High fetal death rate d/t PTL, TTP, cord entanglement, congenital anormaly : 10% fetal demise if live until 20wks : Diamnionic twins→monoamnionic twins d/t dividing memb rupture

Mx: After Diagnosis, not promptly del → daily 1hr FHR monitoring in 26-28wks → betamethasone d/t lung maturation → C/S rec at 34wks

Abnormal twinning Conjoined twins

Classification: parapagus (m/c)

Dx: sono in Mid pregnancy Determine to continue preg If organ not share, surgical separation Termination by C/S rec

Vascular anastomoses between fetuses

Acardiac twins Twin reversed arterial perfusion(TRAP) sequence Rare(1/35,000) but serious complication in MC twins Donor: heart failure Recipient: lack of structure (acardiac) Arcardiac acephalus, arcardiac myelacephalus, arcardiac amorphus

Acardiac twins

Prognosis : donor(pump) twin : 50-75% death d/t cardiomegaly & high output heart failure Tx: RF ablation: 90% survival rate closed observation: 90%

Twin-Twin Transfusion syndrome(TTTS) Incidence : ¼ more in MC twin Donor : pale, anemic, growth restriction Recipient: plethoric, polycythemic →servere hyperbilirubinemia, hydrop with heart failure d/t circulatory overload

Pathophysiology With AV anasotomosis, uncompensated unidirectional blood flow in 2nd trimester → imbalance in blood volumes Donor: Oligo, pul hypoplasia Recipient: severe hydroamnios, PROM, heart failure  poly-oli syndrome, stuck twin

Fetal brain damage Cerebral palsy, microencephaly, proencephaly, muticystic encephalo-malasia  severe complications Neurologic damage: ischemic necrosis Donor: hypotension,anemia→ ischemia Recipient: BP unstable, severe hypotension episode → ischemia

Dx: monochorionicity Same genser sex hydroamnios(LP>8cm)Oligo(LP<2cm) umbilical cord size discordant hydro in recipient c cardiac dysfuction abnormal doppler in umbilicus,ductus venosus Significant growth discordant

Staging system Stage Ⅰ: discordant AF vol , but urine(+) in donor bladder Stage Ⅱ: urine(-) in donor bladder Stage Ⅲ: abnormal doppler study Stage Ⅳ:ascites hydrops in either twin Stage Ⅴ: fetal demise

Tx: poor prognosis amnioreduction septostomy laser ablation selective feticide

감사합니다.