Twin Pregnancy Xiongyu Obstetric & Gynecology Hospital, Fudan Universtity

case 1  Shi ××, , 26 years old  chief complaint ： gravida 1 para 0, 27 weeks of gestation, found dyspnea one week and prostration three days.  Present history ： last menstrual period (LMP):12,June,2011. estimated date of conception(EDC):19, March,2012. Urine chorionic gonadotrophin(HCG) was positive at thirty-seven days of gestation and the morning sickness was severe. One sac was found through altrasound in the first trimester. Regular prenatal examination was not perform. Twin pregnancy was found at 25 weeks of gestation. Dyspnea one week and prostration three days.  Physical examination ： T:36.8°C, P 98 counts per minute ， R 18 counts per minute ， BP 100/65mmHg ，

Ultrasound results ：  Fetus A: BPD(biparietal diameter)-HC(head circumference)- AC(abdominal circumference)-FL(femur length): , estimated weight 1454g, AFV(amniotic fluid volume):26cm, bladder was visible, no abnormal doppers.  Fetus B: BPD-HC-AC-FL: , estimated weight 832g, AFV:1cm, bladder was visible, no abnormal doppers.  AFI: , 461. no twin peak, amniotic separation was found.

Question 1:diagnosis  gravida 1 para 0, 27 weeks of gestation,twin pregnancy  monochorionic diamniotic twins(MC/DA)  TTTS(stage 1)

Question 2:management  An amnioreduction of 6.2 L was performed in the recipient sac.  Tocolytics (magnesium sulfate ） were administered.  Follow up: ultrasound weekly

ten days later  Ultrasound surveillance ：  anuria and virtually no amniotic fluid in the donor twin, polyuria and excess amniotic fluid in the recipient, and abnormal umbilical venous and ductus venosus flows in both twins.

Question 3:diagnosis  gravida 1 para 0, 29 weeks of gestation,twin pregnancy  monochorionic diamniotic twins (MC/DA)  TTTS(stage 3)

Question 4:management  Termination: Cesarean section  One hours later, premature donor and recipient twin boys were delivered, weighing 895 and 1450 g, with haemoglobin levels of 16.4 and 22.9 g/dl, all associated with severe TTTS. In addition, in this case the neonatal criteria of TTTS were valid (a difference of >25% in birth weight, and >5 g/dl Hb). Both infants required mechanical ventilation and administration of surfactant due to respiratory distress syndrome. The donor twin developed acute renal failure and necrotising enterocolitis which required surgery. The recipient developed the polycythaemiae hyperviscosity syndrome which required a partial exchange transfusion. Both children are alive.  Check the placenta after delivery: one placenta, two layer of membrane partition that separated twin fetuses

case 2  Chen ××, , 28 years old  chief complaint ： gravida 2 para 0, 32 weeks of gestation, found discordance weight of twins one day.  Present history ： last menstrual period (LMP):10,september,2010. estimated date of conception(EDC):17, June,2011. Urine chorionic gonadotrophin(HCG) was positive at thirty-five days of gestation and the morning sickness was severe. Two sac was found through altrasound in the first trimester. Twin peak and amniotic separation was record at 13 weeks of gestation. No abnormal results through the regular prenatal examination. Discordance weight of twins was found today.  Physical examination ： T:36.8°C, P 88 counts per minute ， R 18 counts per minute ， BP 105/65mmHg ，

Ultrasound results ：  Fetus A: BPD(biparietal diameter)-HC(head circumference)- AC(abdominal circumference)-FL(femur length): , estimated weight 2050g, AFV(amniotic fluid volume):7cm, bladder was visible, no abnormal doppers.  Fetus B: BPD-HC-AC-FL: , estimated weight 1477g, AFV:2cm, bladder was visible, no abnormal doppers.  AFI: , 121.

Question 1:diagnosis  gravida 2 para 0, 32 weeks of gestation,twin pregnancy  dichorionic diamniotic twins (DC/DA)  One fetus sIUGR

Question 2:management  Follow up:  ultrasound every two weeks  NST (non-stress test) every day

three weeks later  NST: the small fetus display no react.

Question 3:management  Cesarean section,  indication: fetal distress  One hours later, large boy and small girl were delivered, weighing 2550 and 2000g. Both children are alive and well.  Check the placenta after delivery: two placenta, one small, one normal.

Incidence  twins ： 1:100 。  triplets ： 1:10,000 。  quadruplets ： 1:1,000,000 。  quintuplets ： 1:100,000,000 。

Classification  Dizygotic twins ： 2/3  influenced remarkably by race, heredity, maternal age, parity, and, especially, fertility treatment  monozygotic twins ： 1/3  1:250  independent of race, heredity, age, and parity

Dizygotic twins  two ovum ， two sperm 。  different gene ： 1.appearance:different or alike 2.gender ： same or different  placenta ： 1.two placenta 2.fuse to one placenta,twin peak,no communicated blood vessel  Diamnionic/dichorionic (DA/DC)

Placenta and membrane of dizygotic twin

Monozygotic twin  one ovum ， one sperm 。  same gene ： 1.appearance: same 2.gender ： same

classification of monozygotic twin 1.dichorionic diamniotic twins:18-36% ， 0 to 4 days postfertilization 2.monochorionic diamniotic twins:65%, 4 to 8 days postfertilization 3.monochorionic monoamniotic twins: <1% ， 9 to 13 days postfertilization 4.monochorionic monoamniotic conjoined twins: rare, >13 days postfertilization

dichorionic diamniotic twins: 18 ～ 36% monochorionic diamniotic twins: 65% monochorionic monoamniotic twins: <1% Placenta and membrane of monozygotic twin

Conjoined twin

Determination of Chorionicity

Sonographic Evaluation （ prenatal)--- dichorionic diamniotic twins  first trimester （ before 8 weeks ）： two sacs  after 14 weeks ： opposite gender （ dizygotic ）  weeks ： 1.two separate placentas 2.dividing membrane: ≧ 2 mm 3.one fused placenta,twin peak

Sonographic Evaluation （ prenatal)--- monochorionic diamniotic twins  first trimester （ before 8 weeks ）： one sac  after 14 weeks ： same gender  weeks ： one placenta ， none twin peak  divided amnion

Sonographic Evaluation （ prenatal)  monochorionic monoamniotic twins  no divided amnion

Determination of Chorionicity (postnatal)  Gender 1.Same: monochorionic diamniotic or dichorionic diamniotic 2.Opposite: dichorionic diamniotic  Placenta:  two placentas ： dichorionic diamniotic  one placenta: number of membrane partition that separated twin fetuses 1.0 ： monochorionic monoamniotic 2.2 ： monochorionic diamniotic 3.3 or 4 ： dichorionic diamniotic

Twin-Twin Transfusion Syndrome ) TTTS (Twin-Twin Transfusion Syndrome )  anastomoses in monochorionic diamniotic placenta ： arterio-arterial,venous –venous,arterio-venous  Only arterio-venous anastomoses will result to TTTS.

Twin-Twin Transfusion Syndrome (TTTS)  blood is transfused from a donor twin to its recipient sibling  the donor becomes anemic and its growth may be restricted  the recipient becomes polycythemic and may develop circulatory overload manifest as hydrops  donor twin is pale, and its recipient sibling is plethoric

Quintero staging system but urine still visible sonographically within the donor twin's bladder  Stage I: polyhydramnios(>8cm) in recipient / aligodramnios(<2cm) in donor, but urine still visible sonographically within the donor twin's bladder II–criteria of stage I, but urine is not visible within the donor's bladder  Stage II: II–criteria of stage I, but urine is not visible within the donor's bladder criteria of stage II and abnormal Doppler studies of the umbilical artery, ductus venosus, or umbilical vein. Such as umbilical artery and lower  Stage III: criteria of stage II and abnormal Doppler studies of the umbilical artery, ductus venosus, or umbilical vein. Such as AEDF in donor, higher RI of umbilical artery and lower RI of middle cerebral artery in recipient. ascites or frank hydrops in either twin  Stage IV: ascites or frank hydrops in either twin demise of either fetus  Stage V: demise of either fetus

Prenatal diagnosis （ ultrasound ） --- monochorionic diamniotic  same-sex gender hydramnios defined if the largest vertical pocket is > 8 cm in one twin and oligohydramnios defined if the largest vertical pocket is 8 cm in one twin and oligohydramnios defined if the largest vertical pocket is < 2 cm in the other twin significant growth discordance  advanced stage ： significant growth discordance,one larger,the other smaller （ distinguish ： one IUGR in twins ， one normal, the other smaller ）

Postnatal diagnosis  monochorionic diamniotic: 1.number of placenta, chorionic membrane, amniotic membrane 2.same-sex gender  Examination in neonate ： 1.discordance 1.discordance in hemoglobin:≥5g/l 2.discordance 2.discordance in red blood cell: ≥ Discordance in 3.Discordance in body weight : ≥15-20%

management weeks bladder, abnormal Dopplers.  Stage I: follow up,ultrasound weekly,including amniotic fluid volum, bladder, abnormal Dopplers.  Stage II-IV ： 1.amnioreduction （ recipient ） 2.laser ablation of vascular anastomoses, 3.selective feticide (donor) 4.septostomy (intentional creation of a communication in the dividing amnionic membrane). 5.abortion (both fetus)

management--- after 28weeks  Stage I: follow up, ultrasound weekly （ amniotic fluid volum ）, amnioreduction necessary  Stage II-IV ： Cesarean section

Outcome  No interventional therapy : nervous system integrity of survival fetus ＜ 5% ；  Outcome of interventional therapy ： 1.minimally invasive approaches (amnioreduction and/or microseptostomy therapy): survival rate of one fetus is 60%, survival rate of both is %, however nervous system abnormalities is 25-60% ； 2.laser ： survival rate of one fetus is 85% ， survival rate of both is 70% ， nervous system abnormalities is 7-15% ；

Discordant Twins (one IUGR)  Distinguish with TTTS  One small ， the other normal.  One oligohydramnios ， the other normal volum of amniotic fluid.

Discordant Twins (one IUGR) （ MC/DA ）  10-20% IUGR fetus will die and result in the bad outcome of nervous system in 20% survival fetus  Treatment Protocols （ before 26 weeks ）： 1.Expect treatment, close ongoing surveillance, terminate in time if abnormal ultrasonic apperance: 10-20% small fetus will die, then accompany to 50% death of large fetus. 2.Termination of pregnancy ： abortion 3.Laser ： 2/3 small fetus will die ， but large fetus all survive. 4.RFA or bipolar coagulation: selective to terminate the IUGR fetus 。

Discordant Twins (one IUGR) （ DC/DA ）  Before 28 weeks: follow up, ultrasound weekly.  After 28 weeks: intensive care, terminate in time if abnormal apperance.

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