Perinatal outcome, placental pathology, and severity of discordance in monochorionic and dichorionic twins

OBJECTIVE: To evaluate differences in pregnancy outcomes and placental findings among severely discordant monochorionic and dichorionic twins. METHODS: We studied retrospectively a cohort of 382 twin pregnancies with gestational ages that ranged from 24 to 40 weeks. Pregnancies were classified as dichorionic or monochorionic by histologic examination of placentas. Infants were subdivided into concordant (less than 5% difference in birth weight), mildly discordant (5-25% difference), and severely discordant groups (more than 25% difference), and their clinical characteristics and findings at placental examination were analyzed and compared. RESULTS: Severe discordance occurred significantly more often in monochorionic than in dichorionic twins and was associated with significantly more deliveries before 36 weeks and more newborns remaining more than 10 days in the neonatal intensive care unit. Severely discordant monochorionic and dichorionic twins had significantly worse perinatal mortality and morbidity than mildly discordant and concordant twins. The weight of the placenta of the smaller fetus in severely discordant dichorionic twins with separate placentas and the total placental weight in severely discordant monochorionic twins were significantly smaller than the weights of the placentas in their concordant and mildly discordant counterparts. The umbilical cords of the smaller fetuses in both dichorionic and monochorionic pregnancies exhibited significantly more velamentous insertions and single umbilical arteries than in concordant or mildly discordant twins of similar chorionicity. CONCLUSION: Severe discordance is more frequent and has greater morbidity in monochorionic than dichorionic twins. The most frequent findings in the placentas of severely discordant twins were small placental weight and umbilical cord abnormalities.     

Discordant lower urinary tract obstruction in early twin gestations: management and outcome

OBJECTIVE: To report our experience with the management of twin pregnancies discordant for lower urinary tract obstruction. METHODS: Cases of twin pregnancies discordant for lower urinary tract obstruction were identified from our fetal medicine database. Information on ultrasonographic findings, antenatal course, pregnancy complications, and perinatal outcome was obtained by reviewing medical records or contacting the referring obstetricians. RESULTS: Five twin pregnancies discordant for lower urinary tract obstruction were diagnosed between 11 and 15 weeks of gestation. There were 3 dichorionic and 2 monochorionic pregnancies (1 diamniotic and 1 monoamniotic). The dichorionic pregnancies were managed conservatively, resulting in a pregnancy loss of both twins in 1 case, a single fetal death at 29 weeks in 1 case, and an early neonatal death due to lung hypoplasia of the affected twin in 1 case. On the other hand, both monochorionic twin pregnancies were managed with serial vesicocenteses. In both cases, the prenatal course was complicated, 1 by premature rupture of the membranes and the other by cord entanglement, requiring delivery at 29 and 31 weeks, respectively. Among the 4 continuing pregnancies with complete perinatal outcome, none of the affected twins survived, and the structurally normal twins were delivered between 29 and 36 weeks and discharged from the hospital in good condition. CONCLUSION: Twin pregnancies discordant for lower urinary tract obstruction are at high risk of perinatal death and premature delivery. Prenatal intervention seems not to be associated with an improved perinatal outcome of the affected twin, but it may be beneficial in selected cases to attain viability of the unaffected twin.     

Growth pattern of twins of different chorionicity evaluated by sonographic biometry

OBJECTIVE: To determine differences between growth patterns of monochorionic and dichorionic twins, and of concordant and discordant twins of both chorionicities. METHODS: We studied 70 cases of concordant twins (24 monochorionic, 46 dichorionic) and 45 cases of discordant twins (25 monochorionic, 20 dichorionic). In each case, growth was measured longitudinally by ultrasound biometry and the growth pattern was depicted. RESULTS: There were no differences in incremental growth between concordant monochorionic and dichorionic twins. The growth curve of concordant twins of both chorionicities was almost the same as that of a singleton until 34 weeks' gestation. However, in the discordant twins, the growth of the larger twin matched the growth curve of a singleton or concordant twin, but the growth of the smaller twin gradually decreased to the range of growth restriction. The growth curves for monochorionic discordant twins appeared to be representative of two groups, one of which had onset of discordancy before 24 weeks.CONCLUSION: It is clinically important to determine chorionicity early in twin pregnancies, to calculate the percentage of discordancy between the fetuses, and to examine longitudinal fetal growth curves in each chorionicity.     

Obstetric complications of twin pregnancies

Advances in assisted reproductive technology and increases in the proportion of maternities in older women have both contributed to the steep increase in the incidence of twin pregnancies since the 1980s. Maternal and perinatal complications are higher in twins than in singleton pregnancies. A significant proportion of perinatal mortality and morbidity among twins is due to the high incidence of preterm delivery and the added complication of twin-to-twin transfusion syndrome (TTTS) in monochorionic twins. Monochorionic twins also have a much higher rate of perinatal mortality than dichorionic twins, the greatest risk being before fetal viability (<24 weeks gestation). Early diagnosis of twins and their chorionicity, close fetal surveillance, particularly of monochorionic twins, and prompt therapeutic intervention in TTS are necessary to reduce perinatal mortality. Intrapartum management in the hospital setting with anaesthetic and neonatal facilities, as well as critical assessment of mode of delivery, have led to better outcomes. Ultrasonography is a valuable tool in the management of twin pregnancy. This chapter briefly summarises these topics, with a particular focus on recent literature.     

Umbilical cord complications in twin pregnancies

OBJECTIVES: The postpartum umbilical cord examination can provide a lot of significant information concerning discordant twin growth or reasons of intrauterine death of one or all the fetuses. The aim of this study was the postpartum assessment of umbilical cords in twin pregnancies. MATERIAL AND METHODS: The examination material consisted placentas coming from 110 twin pregnancies. The analysis concerned the assessment of placenta types, the umbilical cords attachment place and also the twins birth weight. RESULTS: Basing on the studies of placentas coming from 110 twin pregnancies 76 (69.0%) dichorionic and 34 (31.0%) monochorionic placentas were found. Among dichorionic, 40 (53%) separated and 36 (47%) fused placentas were observed. Among monochorionic 31 (91%) diamniotic and 3 (9.0%) monoamniotic placentas were present. Abnormal umbilical insertion to placenta was most frequently observed in monochorionic pregnancies: in diamniotic--marginal insertion in 21.2%, velamentous insertion in 15.9%, and in monoamniotic--equally 33.3%. In dichorionic pregnancies, for fused placentas--marginal in 8.7%, velamentous in 9.1%, and for separated--5.6% and 3.1%. CONCLUSIONS: The abnormal umbilical cord insertions to the placenta was most frequently found in monochorionic pregnancies. Among pairs of twin born with body weight discordance, the abnormal umbilical cord insertion was more frequently found in the case of the smaller newborn.     

双胎妊娠的孕期胎儿监护

因绒毛膜性不同,单绒双胎较双绒双胎胎儿的特殊并发症较多,围产儿预后较差。如何减少双胎妊娠母胎并发症,除了加强规范产前检查与健康指导,应在孕早期尽早超声监测明确绒毛膜性。孕早中期超声测量胎儿颈项透明层厚度以及系统超声筛查胎儿结构畸形,及早发现胎儿异常尤其是单绒双胎一些特有的特殊并发症,进行个体化超声动态监测、胎儿脐血流及胎心电子监护等了解胎儿宫内安危,及时发现异常及时干预,必要时终止妊娠,以降低出生缺陷,改善围产儿预后,保障母儿安全。     

Management of twin pregnancies discordant for anencephaly

Objective To examine options of management and outcome of twin pregnancies discordant for anencephaly.
Design Retrospective study.
Setting Research Centre for Fetal Medicine.
Population Twenty-four twin pregnancies discordant for anencephaly.
Methods A computer search was made of our database for twin pregnancies discordant for anencephaly. The data were reviewed for gestation at presentation, chorionicity, management and pregnancy outcome.
Main outcome measures Pregnancy outcome in relation to chorionicity and management.
Results There were 13 dichorionic and 11 monochorionic twin pregnancies discordant for anencephaly. In the dichorionic group five pregnancies had selective fetocide at 17 to 21 weeks; one pregnancy resulted in spontaneous abortion but in the others a healthy infant was born at a median gestation of 37 weeks. The other eight dichorionic pregnancies were managed expectantly, but three developed polyhydramios at 26 to 30 weeks; in one case amniodrainage was performed and in another selective fetocide was carried out. In this group the median gestation at delivery was 35 weeks. All 11 monochorionic pregnancies were managed expectantly and in three there was intrauterine death of both fetuses. In the other eight cases the normal twin was liveborn at a median gestation of 34 weeks; in four of these pregnancies polyhydramnios developed and two were managed by amniodrainage.
Conclusions In monochorionic pregnancies, expectant management is associated with a high rate of intrauterine lethality of the normal twin. In dichorionic pregnancies selective fetocide in the second trimester prevents the development of polyhydramnios and is associated with a lower risk of preterm delivery but can cause miscarriage.     

Perinatal mortality in twin pregnancies: a 3-year analysis in Seine Saint-Denis (France).

OBJECTIVES: Our purpose was to evaluate perinatal mortality in twins and to investigate factors associated with this mortality. STUDY DESIGN: A prospective study on the perinatal mortality was performed in the department of Seine-Saint-Denis. Out of all the perinatal deaths, we have retrospectively isolated those arising from twin pregnancies. RESULTS: There were 54 twin pregnancies complicated with perinatal death. The perinatal mortality rate in twin pregnancy was 78.0 per 1000 twin babies delivered. Out of 86 twin deaths, 38 (44.2%) were born before 28 weeks gestation and out of 82 twin perinatal deaths, 37 (45.1%) weighed less than 1000 g. Chorionicity was recorded in 44 twin pairs: 21 (47.7%) were dichorionic and 23 (52.3%) monochorionic. Finally, out of 48 twin sets there were four (8.3%) monoamniotic pregnancies. CONCLUSIONS: The present data show that extreme prematurity represents nearly half of perinatal mortality in twins. This study indicates also a significant proportion of monochorionic placentation among twin pregnancies with poor outcome.     

Fetal umbilical artery flow velocity-time waveforms in twin pregnancies

Summary. The umbilical artery flow velocity-time waveforms were studied in 76 twin pregnancies. The ratio of peak systolic (A) to least diastolic (El) velocity was calculated for each fetus as an index of umbilical placental flow resistance. Seventy-one sets of twins were studied within 14 days before delivery. In 65 cases both twins were alive at the time of study. In 32 pregnancies both fetuses were of birthweight appropriate for gestational age (AGA) and had A/B ratios within the normal singleton range. In 33 pregnancies one or both of the liveborn infants were small for gestational age (SGA) and in 78% of these at least one fetus had an elevated A/B ratio. Discordancy in birthweight and A/B ratio was associated with growth retardation. Clinically manifest twin-to-twin transfusions occurred in five of the ten pregnancies resulting in an SGA infant (eight with discordant weight) associated with a normal and concordant A/B ratio. Two twin-to-twin transfusions were associated with perinatal death. The placentas were examined in 61 patients. In 43 dichorionic pairs the A/B ratio was elevated in 12 of the 18 where there was at least one SGA infant. There was a greater incidence of growth retardation in the monochorionic pairs (12 of 18). Only seven of these were identified by an elevated A/B ratio. In 10 of these 18 pairs vascular anastomoses were demonstrated on placental inspection and in a further two there was evidence of twin-to-twin transfusion by haemoglobin discrepancy. Twin pregnancy may result in the birth of a small-for-dates infant because of intrauterine growth retardation or twin-to-twin transfusion. An abnormally elevated A/B ratio identifies growth retardation. In twin-to-twin transfusion the A/B ratio of the two fetuses is similar (crossed circulation) yet difference in size may be seen on ultrasound measurement.     

Detecting fetal growth restriction or discordant growth in twin gestations stratified by placental chorionicity

OBJECTIVE: To use recommendations made by the Evidence-Based Medicine Working Group to determine the accuracy of sonographically estimated fetal weight to diagnose fetal growth restriction (FGR) (estimated or actual birth weight < 10% for gestational age [GA]) or discordancy in dichorionic and monochiorionic twin gestations. STUDY DESIGN: The inclusion criteria for this retrospective analysis were nonanomalous twins, reliable GA and sonographic estimate of fetal weight within 21 days of live births of both fetuses beyond 26 weeks. For likelihood ratio (LR) and odds ratio (OR), 95% confidence intervals (CIs) were calculated. RESULTS: Over 52 months, 126 twin gestations met the inclusion criteria; 29% were monochorionic and 71% dichorionic. The incidence of FGR in 1 of monochorionic twin fetuses (46%) was twice as high as in dichorionic (26%; OR 2.01; 95% CI 1.00, 4.03), but the rates of discordance > or = 20% were similar (21% vs. 18%, respectively; OR 1.26; 95% CI 0.64, 2.47). The LR (95% CI) of detecting discordant growth > or = 20% was 6.1 (2.5, 15.1) for dichorionic twins and 6.0 (1.8, 20.0) for monochorionic. The LR of identifying FGR in twin A and B in dichorionic twins was 6.3 (2.0, 19.7) and 8.7 (2.9, 26.9), respectively; the corresponding LR for monochorionic twins was 14.5 (1.9, 112.3) and 18.7 (2.6, 135.1). To determine the number of twins required for a tight confidence interval around an LR of 10, post hoc sample size calculations indicated: (1) regardless of chorionicity, attaining LR > 10 is not feasible; (2) in dichorionic twins, detection of FGR with twin A or B is not possible; and (3) about 500 monochorionic pregnancies are necessary to ensure that estimated fetal weight can accurately identify FGR. CONCLUSION: Using guidelines proposed by the Evidence-Based Medicine Working Group, at present it may not befeasible to identify aberrant growth in twins.     

Antepartum management of twin gestation: ultrasound

1. The use of ultrasound may improve perinatal outcome in twin pregnancy. 2. Singleton growth curves for FL, BPD, and AC may be used to assess fetal growth prior to 28 weeks gestation. 3. After 28 weeks gestation, specific twin growth curves should be used. However, increased morbidity may be seen when fetal weight falls from the normal singleton predictive curves. 4. Amnionicity and chorionicity frequently can be determined. This should be attempted early in the second trimester so that appropriate monitoring can be offered for the monoamnionic and monochorionic gestations. 5. Serial assessment of fetal growth should be performed. In the authors' institutions, growth scans are performed in twins every 2 weeks after 24 weeks gestation. 6. Evidence on ultrasound examination of discordant growth suggests either fetal growth retardation or TTS. In the presence of a dichorionic placentation, growth retardation of one twin is the usual diagnosis. If placentation is monochorionic, it is difficult to differentiate between growth retardation and TTS. The presence of polyhydramnios, a stuck twin, or fetal hydrops are suggestive of TTS. 7. The value and safety of cordocentesis and the management of twin pregnancy and diagnosis of TTS have not been established. 8. Doppler ultrasound may be useful in the assessment of the IUGR twin fetus. The use of Doppler in the identification of TTS is not yet clear.     

Clinical evaluation of the risk of twin-to-twin transfusion syndrome using the relative power contribution of fetal heart rate fluctuations

OBJECTIVES: In twin pregnancies, it has been suggested that fluctuations of the two fetal heart rates should be considered as two variates that affect each other. We therefore investigated whether the relative power contribution (RPC) of heart rate fluctuation between twins reflects the clinical severity of twin-to-twin transfusion syndrome. STUDY DESIGN: Sixty-three cases of twin pregnancy including 43 monochorionic twins and 20 dichorionic twins were studied. Thirteen monochorionic twins with polyhydramnios in one twin were regarded as twin-to-twin transfusion syndrome (TTTS). Of the 13 TTTS cases, 8 cases with polyhydramnios in one twin and oligohydramnios in the other were deemed to be a 'stuck' twin. The RPC of the very low frequency domain (VL; 0.0125-0.0625 Hz) of fetal heart rate fluctuation in the twin fetuses of monochorionic and dichorionic pregnancies was obtained within a week of delivery. The relationship between the value of the RPC and the outcome of these twins was examined. RESULTS: For both monochorionic and dichorionic twins the RPC of twin fetuses was significantly higher in TTTS twins than in twins without TTTS. In particular, in pregnancies that resulted in fetal death, early neonatal death, or hydrops of one of the twins, this twin had a higher RPC than the other twin. No significant difference was observed in the RPC value between twins of either monochorionic or dichorionic pregnancies that did not develop TTTS. Serial changes in RPC values were followed in 7 cases of TTTS. The RPC value rose rapidly just before delivery in three cases with resultant poor outcome. CONCLUSION: A rapid change in the RPC of twin fetuses measured using the VL frequency domain of fetal heart rate fluctuations may predict poor outcome in twin pregnancies.     

Perinatal outcomes of twin pregnancies discordant for major fetal anomalies

OBJECTIVE: The aim of this study was to determine perinatal outcomes of twin pregnancies discordant for a major fetal anomaly and to compare with twins without anomaly. METHODS: All twin pregnancies admitted or referred to the maternal-fetal unit were prospectively entered into a computer database. Chorionicity, fetal anomaly, mean gestational age at delivery, birth weight and perinatal survival rate were reviewed. MAIN OUTCOME MEASURES: Mean gestational age at delivery, birth weight and perinatal survival rate of twins with and without anomaly. RESULTS: There were 48 cases of monochorionic diamniotic (MCDA), 2 cases of monochorionic monoamniotic (MCMA) and 217 twins with dichorionic (DC) placentation. Out of 267 twin pregnancies, there were 17 (6.3%) twins with fetal anomaly. Twins discordant for a major fetal anomaly were diagnosed in 13 cases (4.8%). We observed 3 cases with MCDA and 10 cases with DC placentation and the incidence of discordance for a major fetal anomaly as 4.6% (10/217) in DC and 6.0% (3/50) in MC twin pregnancies. We identified 8 cases (62%) with craniospinal, 2 (15%) with gastrointestinal, 2 (15%) with urinary system, and 1 case (8%) with both craniospinal and gastrointestinal anomalies. There were significant differences between the normal co-twin of the major anomaly group (n = 13) and twins without anomaly group (n = 235) in mean gestational age at delivery (32 vs. 34 weeks; p = 0.029), mean birth weight (1,640 vs. 2,030 g; p = 0.022) and perinatal survival rate (69.2 vs. 91.1%; p = 0.018), respectively. CONCLUSION: The presence of a fetus with a major anomaly in a twin gestation increases the risk of preterm delivery, low birth weight and perinatal mortality of the normal co-twin.     

Multiple pregnancy at 11+0 - 13+6 weeks

Chorionicity, rather than zygosity, is the main factor determining pregnancy outcome. In monochorionic twins the rates of miscarriage, perinatal death, preterm delivery, fetal growth restriction and fetal abnormalities are much higher than in dichorionic twins. High mortality confined to monochorionic pregnancies is the consequence of severe early-onset TTTS. Death of a monochorionic fetus is associated with a high chance of sudden death or severe neurological damage in the co-twin. Sonographic examination provides reliable distinction between dichorionic and monochorionic pregnancies. Reduction of the excess fetal loss in twins, can only be achieved through early identification of monochorionic pregnancies by ultrasound examination at 11+0 - 13+6 weeks, close surveillance and appropriate treatment in those that develop severe TTTS. In multiple pregnancies, compared to singletons, prenatal diagnosis of chromosomal abnormalities is complicated because, firstly, the techniques of invasive testing may provide uncertain results or may be associated with higher risks of miscarriage and, secondly, the fetuses may be discordant for an abnormality.     

The hidden mortality of monochorionic twin pregnancies

In an ultrasound screening study at 10 to 14 weeks of gestation for measurement of fetal nuchal translucency thickness there were 102 monochorionic and 365 dichorionic twin pregnancies. In the monochorionic compared with the dichorionic pregnancies there was a higher rate of fetal loss before 24 weeks of gestation (12.2% versus 1.8%), perinatal mortality (2.8% versus 1.6%), prevalence of delivery before 32 weeks (9.2% versus 5.5%), and prevalence of birthweight below the 5th centile in both twins (7.5% versus 1.7%). However, the proportion of pregnancies with a birthweight discordancy of more than 25% was similar in the two groups (11.3% versus 12.1%).     

Screening for trisomy 21 in twin pregnancies in the first trimester: an update of the impact of chorionicity on maternal serum markers

OBJECTIVE: To examine the distribution of first-trimester biochemical markers of aneuploidy in twin pregnancies, and to assess whether there are differences in the distributions between monochorionic and dichorionic twins. METHODS: Maternal serum-free beta-hCG and PAPP-A were measured between 11 + 0 and 13 + 6 weeks as part of a routine first-trimester screening program in conjunction with fetal nuchal translucency (NT) performed at two sites. Data from twin pregnancies were extracted from the fetal databases along with information on the chorionicty. The individual marker concentrations were expressed as weight corrected, ethnicity corrected, smoking corrected and IVF corrected MoM using data from singleton pregnancies as the reference. The overall medians were compared to those in singleton pregnancies and between monochorionic and dichorionic twins. RESULTS: Data was available from 1914 sets of twins. Of these, 1214 had information with respect to chorionicity, with 1024 being dichorionic and 190 being monochorionic. The overall median weight corrected, ethnicity corrected, smoking corrected and IVF corrected MoM amongst twin pregnancies were 2.023 for free beta-hCG (sd log(10) MoM = 0.2611 and 2.121 for PAPP-A (sd log(10) MoM = 0.2255) -- both medians were significantly greater than the medians in singleton pregnancies (1.00 MoM). In the case of monochorionic and dichorionic twins the median weight corrected, ethnicity corrected, smoking corrected and IVF corrected, free beta-hCG MoM's were not significantly different (1.983 v 2.041), however for PAPP-A the median weight corrected, ethnicity corrected, smoking corrected and IVF corrected MoM in monochorionic twins was significantly lower than in dichorionic twins (1.756 v 2.250) whilst the sd log(10) MoM's were not significantly different (0.2185 v 0.2167). CONCLUSION: Screening in twin pregnancies requires adjustment of the calculated MoM to account for the presence of two fetuses. In general, for free beta-hCG, this should be by dividing the observed corrected MoM by 2.023. For PAPP-A two different factors are required - 2.192 in dichorionic twins and 1.788 in monochorionic twins.     

Fetal umbilical artery flow velocity-time waveforms in twin pregnancies

The umbilical artery flow velocity-time waveforms were studied in 76 twin pregnancies. The ratio of peak systolic (A) to least diastolic (B) velocity was calculated for each fetus as an index of umbilical placental flow resistance. Seventy-one sets of twins were studied within 14 days before delivery. In 65 cases both twins were alive at the time of study. In 32 pregnancies both fetuses were of birthweight appropriate for gestational age (AGA) and had A/B ratios within the normal singleton range. In 33 pregnancies one or both of the liveborn infants were small for gestational age (SGA) and in 78% of these at least one fetus had an elevated A/B ratio. Discordancy in birthweight and A/B ratio was associated with growth retardation. Clinically manifest twin-to-twin transfusions occurred in five of the ten pregnancies resulting in an SGA infant (eight with discordant weight) associated with a normal and concordant A/B ratio. Two twin-to-twin transfusions were associated with perinatal death. The placentas were examined in 61 patients. In 43 dichorionic pairs the A/B ratio was elevated in 12 of the 18 where there was at least one SGA infant. There was a greater incidence of growth retardation in the monochorionic pairs (12 of 18). Only seven of these were identified by an elevated A/B ratio. In 10 of these 18 pairs vascular anastomoses were demonstrated on placental inspection and in a further two there was evidence of twin-to-twin transfusion by haemoglobin discrepancy.(ABSTRACT TRUNCATED AT 250 WORDS)     

Twin pregnancy outcome and chorionicity

BACKGROUND: Based on research of relatively poor quality, it is generally believed that dichorionic twins have lower perinatal mortality than monochorionic twins. We assessed the relationship between the pattern of perinatal loss in twin pregnancy and chorionicity. METHODS: A cohort study of 238 consecutive sets of twin pregnancies registered in our antenatal service over a 2-year period (1996-98) had chorionicity determined by ultrasound at 12-16 weeks' gestation. Follow up included scanning at 20 weeks' gestation for anomaly, and at 2-3-weekly intervals from 24 weeks' gestation onwards for growth and well being. Hazard ratios were computed for comparing the risk of death according to chorionicity. The perinatal loss patterns were analyzed according to gestational age at demize and that at delivery using survival analysis. RESULTS: Overall, 17/238 (7.1%) twin pregnancies suffered mortality: 14/190 (7.3%) amongst the dichorionic and 3/48 (6.2%) amongst the monochorionic twins. The hazard ratio for mortality was 0.89 (95% confidence interval 0.27-2.97, p = 0.85), considering gestational age at demize as the outcome. For gestational age at delivery as the outcome, the hazard ratio for mortality was 0.93 (95% confidence interval 0.27-3.15, p = 0.91). Survival analysis showed that amongst the dichorionic twins the hazard of death continued to rise throughout gestation. In contrast, the hazard of death for the monochorionic twins rose gradually to a maximum at 28 weeks' gestation and was then constant. CONCLUSION: Chorionicity did not affect the overall fetal loss rate amongst the twin pregnancies in our setting. There were differences in patterns of loss according to chorionicity, which require further investigation.     

Fetoscopic surgery in triplet pregnancies: a multicenter case series

OBJECTIVE: The purpose of this study was to evaluate the feasibility of fetoscopic surgery in complicated monochorionic and dichorionic triplet pregnancies. STUDY DESIGN: This was a case series of fetoscopic surgery in 12 cases of monochorionic (n = 5) or dichorionic (n = 7) triamniotic triplets complicated by severe feto-fetal transfusion (n = 8), twin reversed arterial perfusion sequence (n = 3), or discordant for an anomaly (n = 1). Six underwent cord occlusion, and 6 had laser coagulation of the vascular anastomoses. RESULTS: All procedures were successfully completed, and the outcome was comparable to that reported for similar procedures in twins. Eighty-three percent of fetuses survived, and 13% had long-term problems. CONCLUSION: Fetoscopic surgery may be considered as a therapeutic option in complicated triplet pregnancies, with results similar to those found in twins.     

Congenital cytomegalovirus infection among twin pairs

Objective: The purpose of this study was to describe the fetal/neonatal cytomegalovirus (CMV) status according to chorionicity and outcome in twin pregnancies diagnosed with CMV.

Methods: An opportunistic diagnosis of CMV infection was performed in a tertiary referral center. All cases diagnosed in twin pregnancies (2006–2011) were included. Prenatal diagnosis was performed by CMV-DNA in the amniotic fluid (AF) of both fetuses only on the evidence of sonographic findings in either one or both twins. Neonatal screening was selectively assessed in symptomatic newborns, preterm, and infants born to HIV-infected mothers. Congenital infection was considered in the presence of CMV-DNA in AF, fetal tissues or newborn urine within the first 2 weeks of life, and symptomatic disease with clinical findings at birth or autopsy.

Results: A total of six twin pregnancies with congenital CMV infection were diagnosed, five dichorionic and one monochorionic diamniotic. Only one sibling was infected among dichorionic pregnancies, two diagnosed prenatally, and three after birth. In the monochorionic pregnancy, the diagnosis was performed prenatally and the two fetuses were infected and severely damaged.

Conclusions: Congenital CMV infection in twins might be related, among other factors, to chorionicity, and in DC twins a non-concordant infection can be expected.