英文醫(yī)學(xué)課件資料：Management of Twin Pregnancy

1、MMANAGEMENTANAGEMENT OFOF T TWINWIN P PREGNANCYREGNANCY Rania Okby-MD Rania Okby-MD The incidence of twin pregnancy has risen in the last decades. Twin births accounted for 3.3 % of all live births in 2009. In the United States, between 1980 and 2006, the rate of twin births climbed 101%. Suneet et

2、al J Obstet Gynecol. 2010 TWO MAJOR REASONS: 1.The use of assisted reproductive techniques (ART) 2.Older maternal age at childbirth Approximately 1% of infants born in the Unites states in 2006 were conceived with the use of ART. Up to 24% of successful IVF procedures result in multiple pregnancies.

3、 ART assisted births accounted for 18% of all multiple births. The management of twin NICE guidelines 2011 MULTIPLE PREGNANCIES ARE ASSOCIATED WITH HIGHER MATERNAL MORBIDITY : Miscarriage Anemia Hypertensive disorders Postpartum hemorrhage Cesarean section Anxiety and postpartum depression Maternal

4、mortality MULTIPLE PREGNANCIES ARE ALSO ASSOCIATED WITH HIGHER FETAL-NEONATAL MORBIDITY AND MORTALITY INCLUDING Stillbirth Malformation Preterm birth Intra uterine growth restriction (IUGR). Certain conditions are unique to twin pregnancies such as: Twintwin transfusion syndrome (TTTS) Twin anemiapo

5、lycythemia sequence (TAPS) Selective intrauterine growth restriction Twin reversed arterial perfusion sequence (TRAP). The management of multiple pregnancies differs from that of singleton pregnancies in light of the higher associated maternal and fetal-neonatal morbidity and mortality rates. Women

6、with multiple pregnancies need more monitoring and increased contact with healthcare professionals. In addition to the special attention indicated with respect to the psychosocial aspects of women carrying twins. Zygosity refers to the genetic identity of each twin in the pregnancy Chorionicity refe

7、rs to its placentation. Dizygotic twins occur from ovulation and fertilization of two oocytes, which almost always results in dichorionic placentation and usually with two separate placentas (dichorionic). Monozygotic twins result from ovulation and fertilization of one oocyte with subsequent divisi

8、on of the zygote (twinning); placentation may be dichorionic or monochorionic. THE TIMING OF ZYGOTIC DIVISION DETERMINES PLACENTATION IN MONOZYGOTIC TWINS Chorionicity, rather than zygosity, has a major impact on the outcome of twin pregnancies. Dube et al, Does chorionicity or zygosity predict adve

9、rse perinatal outcome in twins. Am J Obstet Gynecol. 2002 Monochorionic twins share one placenta, usually unequally. The imbalanced or abnormal placental sharing can cause complications including Twintwin transfusion syndrome (TTTS), Twin anemiapolycythemia sequence (TAPS), Selective intrauterine gr

10、owth restriction Twin reversed arterial perfusion sequence (TRAP). MONOCHORIONIC TWINS HAVE A HIGHER RISK OF STRUCTURAL ABNORMALITIES Cardiac defects, Neural tube and brain defects, Facial clefts, Gastrointestinal and abdominal wall defects. Chorionicity should be determined as early as possible in

11、twin pregnancy, because of the risks associated with monochorionicity. The optimal time to determine chorionicity is 10- 14 weeks. Two gestational sacs imply a dichorionic pregnancy Single gestational sac with two identified heartbeats implies a monochorionic pregnancy. The number of yolk sacs could

12、 help in diagnosing amnioncity; the presence of two yolk sacs in the extra- embryonic coeloma indicates diamniotic pregnancy, while a single yolk sac will in most cases indicate monoamniotic twins. Ultrasound examination of monochorionicity assessment at 14 weeks was compared to postnatal placental

13、histopathologic Sensitivity 89.8% Specificity 99.5% positive predictive value 97.8% Negative predictive value 97.5% Lee et al. Antenatal sonographic prediction of twin chorionicity Am J Obstet Gynecol. 2006 At the second trimester different parameters assist in determining chorionicity: Sex discorda

14、ncy Number of placentas Twin peak sign Inter-twin membrane Sex discordancy: identification of fetuses of different genders is a highly reliable means of confirming a dichorionic pregnancy. Number of placentas: the presence of two distinct and separate placentas indicates dichorionicity, whereas a si

15、ngle placenta likely indicates monochorionicity. Exceptions are cases where two placentas fuse into one placental mass. TWIN PEAK SIGN Represents a triangular projection of chorionic tissue from fused dichorionic placentas and extending between layers of the inter-twin membrane. The presence of twin

16、 peak sign, also called lambda sign indicates dichorionic twins. Inter-twin membrane: in dichorionic- diamniotic twins the membrane is thicker because it consists of 4 layers (2 layers of amnion and two of chorion) in monoamniotic- dichorionic twins it consists of only 2 layers. A membrane thicker t

17、han 2 mm indicates dichorionicity with a positive predictive value of 95% and monochorionicity with a positive predictive value of 90% when a membrane thickness is 2 mm. Winn et al. US criteria for the prenatal diagnosis of placental chorionicitry in twin pregnancy Am J Obstet Gynecol. 1989 MMATERNA

18、LATERNAL CONSEQUENCESCONSEQUENCES Multiple pregnancies are associated with higher maternal morbidity and mortality Women with multiple pregnancies have an increased risk for miscarriage, anemia, hypertensive disorders, postpartum hemorrhage, cesarean section and postpartum illness. MATERNAL MORTALIT

19、Y The overall maternal mortality in multiple births is 2.5-3 times the rate in singleton births. In Europe the maternal mortality rate was estimated at 14.9/100,000 live births for multiple pregnancies versus 5.2 for singleton births. Senat et al How does multiple pregnancy affect maternal mortality

20、 and morbidity? Clin Obstet Gynecol. 1998 The high fetal demand for iron in pregnancy is doubled in mothers of multiples. Anemia was found in 35.8% of mothers with twin pregnancy compared to 27% with singleton pregnancy. Chowdhury et al. Maternal complications in twin pregnancies. Mymensingh Med J.

21、20112011 Despite the higher incidence of anemia in multiple pregnancies the National Institute for Health and Clinical Excellence recommended to give women with multiples the same advice about diet and nutritional supplements as in routine antenatal care. HYPERTENSIVE DISORDERS Hypertension is the m

22、ajor maternal complication associated with multiple pregnancies. The frequency of hypertensive disorder in twin pregnancy varies markedly, from 12.9% to 25.9% The risk of developing severe hypertension is two to three times greater for a twin pregnancy than for a singleton pregnancy. Hypertensive di

23、sorders in twin versus singleton gestations. National Institute of Child Health and Human Development Network of Maternal-Fetal Medicine Units. ACOG 2000 Mothers carrying twins develop an earlier onset of hypertensive disease and have higher rates of adverse neonatal outcomes than do those with sing

24、leton pregnancies. GESTATIONAL DIABETES Gestational diabetes occurs as a result of the diabetogenic effects of hormones secreted by the placenta and act as antagonists to insulin such as HPL, oestrogen and progesterone. It would be expected that the incidence of gestational diabetes would be increas

25、ed with twin because the levels of these hormones are higher in multiple than singleton pregnancy. Nowadays, there are conflicting data as to whether gestational diabetes is more common in twin pregnancies. Diagnosis and management of gestational diabetes are similar to that in singleton pregnancy.

26、PRETERM BIRTH Several approaches are used to prevent preterm delivery including bed rest, cervical cerclage and the use of tocolysis. These management strategies expose the mother to higher rates of complications such as thromboembolism in the case of bed rest, infection with cerclage and risk for c

27、ardiovascular and pulmonary complications with tocolytic drugs. There is a substantial and steady rise in cesarean delivery rates for twin gestations in the United States from 1995 to 2008. The rate of cesarean section for breech presentation was already high but the relative increase in cesarean de

28、livery for twins in vertex presentation was dramatically higher, increasing more than 50% from 45.1% to 68.2%. Lee et al. Trends in Cesarean Delivery for Twin Births in the United States: 19952008. Obstet gynecol 2011 POSTPARTUM HEMORRHAGE After delivering twins the uterus may be atonic due to overd

29、istension. Brian et all (2010) found an odds ratio of 2.8 for PPH in multiple pregnancy The Epidemiology of Postpartum Hemorrhage in a Large, Nationwide Sample of Deliveries 2010 PPH poses the mother at a higher risk of acute renal failure, acute respiratory failure, coagulopathy, sepsis, blood tran

30、sfusion and hysterectomy. F FETALETAL- -NEONATALNEONATAL CONSEQUENCESCONSEQUENCES AneuploidyAneuploidy MalformationMalformation Embryonic and perinatal deathEmbryonic and perinatal death Preterm birth Preterm birth Fetal growth and discordancyFetal growth and discordancy TTTS A ANEUPLOIDYNEUPLOIDY T

31、win pregnancies are at higher risk than singleton pregnancies for aneuploidy. In dizygotic pregnancies the background risk for each twin is similar to singleton pregnancies, however the number of the fetuses results in a 2 fold increase in risk for aneuploidy compare to singletons. In monozygotic tw

32、ins the risk of both fetuses being effected is equivalent to that of singletons. Rodis et al (1990) found the probability of a 32 year old woman carrying twins of unknown zygosity having at least one child with Down syndrome ,similar to the risk of a 35 year old with a singleton pregnancy. The SOGC

33、consensus at 2000 statement declared “all women carrying twin pregnancies should be referred for counseling to a center for the consideration of invasive testing at age 32”. Nuchal translucency (NT) alone has shown to be an affective marker for aneuploidy in twin gestations. NT can be determined sep

34、arately for each twin. NT measurement combined with maternal age has been the method of choice for prenatal aneuploidy screening in twins Prenatal screening for and diagnosis of Aneuploidy in twin pregnancy. SOGC-CCMG guidelines 2007 . BIOCHEMICAL SCREENING: The routine use of second trimester serum

35、 screening for fetal trisomies is not recommended in twin pregnancy. Firstly, biochemical serum markers are elevated in twin pregnancy. They are approximately twice those found in singleton pregnancies and the distribution of these markers in the presence of Down syndrome is un reliable. Secondly, t

36、he interpretation of the markers relates to the entire pregnancy and not specifically to each twin The detection rate of Down syndrome is lower in twin pregnancy compare to singleton pregnancy and it differs with chorionicity The integrated test has a detection rate of 93% in MC and 78% in DC twins

37、compared to 95 % in singleton pregnancies, with a high false positive rate, about 10%. Madsen et al. A reassessment of biochemical marker distributions in trisomy 21-affected and unaffected twin pregnancies in the first trimester. Ultrasound Obstet Gynecol. 2011 AMNIOCENTESIS During amniocentesis bo

38、th amniotic sacs should be sampled using the one or two puncture technique. Patients should be made aware of the risk of sampling error. The risk of fetal loss with invasive prenatal diagnosis in twin pregnancy is higher than that observed for singleton pregnancies. A comparison of spontaneous loss

39、rate versus loss rate after amniocentesis indicates that the fetal losses are approximately 160% after the procedure, 1.1% vs 2.9%. Suneet et al J Obstet Gynecol. 2010 Oct MMALFORMATIONALFORMATION The incidence of structural anomalies is higher in monozygotic twins compared with dizygotic twins and

40、singletons. In dizygotic twins the rate per fetus is similar to that of singletons, while in monozygotic twins the rate is 2-3 times higher. RR is: 1.17 for dizygotic twins 1.25 for monozygotic twins. The most common structural abnormalities, are cardiac defects, neural tube and brain defects, facia

41、l clefts, gastrointestinal and abdominal wall defects. In addition to these structural malformations, there are three types of congenital anomalies unique to twin pregnancies Midline structural defects -twining process. Malformations caused by vascular events. Anomalies seen in these cases include m

42、icrocephaly, periventricular leukomalacia, hydrocephalus, intestinal atresia, renal dysplasia and limb amputation. Deformities caused by intrauterine crowding, such as foot deformities, hip dislocation and skull asymmetry. The NICE guidelines for the management of multiple pregnancies in the antenat

43、al period (2011) recommend an anomaly scan in all twin pregnancies, optimally performed between 18-22 weeks EMBRYONIC AND PERINATAL EMBRYONIC AND PERINATAL DEATHDEATH Multiple gestations account for approximately 3% of all live births, but contribute to a disproportionate 15% of the overall perinata

44、l mortality Vanishing twin-the spontaneous reduction of one sac, occurs before the 12th gestational week Rate of late fetal death of one or more fetuses in multiple pregnancies is also common,comprising1%- 5% of all multiple pregnancies. Infant mortality in twins is five times higher than singletons

45、; 37 versus 7 per 1000 live births It can be explained by the higher rate of prematurity, intrauterine growth restriction and malformations. Infant mortality among singletons and twins in the United States during 2 decades: effects of maternal age. Pediatrics 2002 Single fetal demise occurs in up to

46、 6.2% of all twin pregnancies. Hillman et al. Single twin demise: consequence for survivors. Semin Fetal Neonatal Med. 2010 Dec Embryo demise in the first trimester (vanishing twin) is not known to result in an adverse outcome for the co-twin. Intrauterine fetal death in the second and third trimest

47、er places the co-twin at increased risk for fetal morbidity and mortality. This can be explained by transient haemodynamic fluctuations between twins and transchorionic embolisation and coagulopathy when death occurs. The ischemia to the central nervous system caused by hemodynamic fluctuations resu

48、lts in specific malformation such as porencephaly, multicystic encephalomalacia, microcephaly and hydrancephaly. PRETERM BIRTH PRETERM BIRTH Prematurity remains the leading cause of neonatal morbidity and mortality. Twin births account for 3.3 % of live births but comprise 15% of all preterm births

49、Overall 52.2% of multiple births deliver before 37 weeks and 10.7% before 32 weeks. Births before 32 weeks represent only 1 to 2% of overall deliveries but account for 50% of all the long-term neurologic morbidity and 60% of the neonatal mortality. Am J Obstet Gynecol. 2010. Twins: prevalence, Probl

50、ems , and preterm births. suneet et al 2010 FETAL FIBRONECTIN Fetal fibronectin is used as a marker for preterm birth. fetal fibronectin testing in twins has a high negative predictive value and it may be useful in screening twins with symptoms of preterm labor, when fibronectin is negative the wome

51、n at a low risk for delivering within 2 weeks of testing. Singer, et al Accuracy of Fetal Fibronectin to Predict Preterm Birth in Twin Gestations With Symptoms of Labor. Obstetrics and Gynecology 2007 CERVICAL LENGTH In a systematic review and meta-analysis of 21 studies with a total of 3523 women i

52、t was found that transvaginal sonography for cervical length at 20-24 weeks gestation is a good predictor of spontaneous preterm birth in asymptomatic women with twin pregnancies. Conde-Agudelo et al Transvaginal sonographic cervical length for the prediction of spontaneous preterm birth in twin pre

53、gnancies: a systematic review and metaanalysis. Am J Obstet Gynecol 2010 However, the positive predictive value for preterm birth was low and there is no evidence that any intervention based on this information is effective for prevention of preterm birth. TOCOLYTIC DRUGS The use of tocolytic drugs

54、to prevent preterm birth in multiple pregnancies has different consequences for the mother than singletons. Increased risk of suffering from pulmonary edema, associated with the use of -agonists as tocolytics and calcium channel blocker. PROPHYLACTIC CERCLAGE: In a meta-analysis examining the effect

55、iveness of cerclage in preventing preterm birth cerclage does not prevent preterm birth in all women with short cervical length on transvaginal ultrasonography and paradoxically was associated with a significantly higher incidence of preterm birth in twins. Therefore, cerclage placement is not recom

56、mended for short cervix detected by transvaginally ultrasound in twin pregnancies. ADMINISTRATION OF PROGESTERONE In a randomized control trial including 653 women . There was no reduction of preterm birth or neonatal morbidity after treatment with progesterone. Lim AC et al. 17-hydroxyprogesterone

57、caproate for the prevention of adverse neonatal outcome in multiple pregnancies: a randomized controlled trial. Obstet Gynecol 2011 BED REST In Cochrane (2010) systematic review of hospitalization and bed rest for multiple pregnancies there was insufficient evidence to support a policy of routine ho

58、spitalization for bed rest . There was no reduction in the risk of preterm birth or perinatal death, although there was a suggestion that fetal growth may be improved. Nevertheless, in uncomplicated twin pregnancy bed rest is not recommended for routine clinical practice. FETAL GROWTH AND FETAL GROW

59、TH AND DISCORDANCYDISCORDANCY The growth rate of twins in the first and second trimesters is similar to that of singletons. In the third trimester, primarily after 31- 32 weeks, the growth rate is slower. For this reason the ACOG has recommended using growth charts derived from twin pregnancies Howe

60、ver, most twin growth curves are derived from small populations and do not consider chorionicty, gender or race. Therefore, the literature still suggests the use of growth curves of singletons in the follow up of twin pregnancies, which provide good predictors of adverse prenatal outcomes. Growth re