An Analysis of Pregnancy Outcome in Dichorionic and Monochorionic Twins Given Special Antenatal and Intranatal Care: A Four-Year Survey

Objective

The present study aims to analyze perinatal outcomes in twins given special care during pregnancy and labor and to compare fetal and neonatal outcomes in dichorionic twins with monochorionic twins.

Study Design

Eighty eight (88) twin pregnancies booked for care at a tertiary care Fetal Medicine centre were included in this study. The maternal demographic variables, course of pregnancy, fetal problems, and specialized fetal therapeutic and diagnostic interventions were noted. The above parameters were compared in the sub-groups of dichorionic and monochorionic twin pregnancies and related to the perinatal outcome. Statistical analysis was done using the student’s t test and the two-tailed chi sqaure tests with Yate’s continuity correction. A p value <0.05 was considered as significant.

Results

Mean maternal age was 30.34 + 4.81 years (range 19–48). 81 % of the twins were DCDA, and 19 % were MCDA. The mean gestational age at delivery was 34.4 ± 3.5 weeks, and this was not significantly different in MCDA and DCDA groups. Serious fetal problems warranting intervention at the time of initial referral were significantly higher in MCDA twins although overall perinatal outcome in both groups were not different.

Conclusion

Specialized care during pregnancy and labor including active fetal surveillance and therapeutic intervention when indicated improves the perinatal outcome in twin pregnancies and ensured at least one healthy live birth in over 90 % cases, although with an increase in late prematurity.     

Monochorionic, diamniotic triplet pregnancy complicated by twin reversed arterial perfusion sequence. Postpartum autopsy of placenta and acardiac fetus

The twin reversed-arterial-perfusion sequence (TRAP) is a severe complication of monochorionic twin pregnancies characterized by the hemodynamic dependence of a "recipient" twin from a "pump" twin. The recipient twin exhibits lethal abnormalities including acardia and acephaly. The pump twin has a mortality rate of 50% as a result of high-output heart failure. We present a case of a 24-year-old female, gravida 2, para 2, with monochorionic diamniotic triplet pregnancy. The sonographic examination at 18 weeks' gestation revealed acardiac-acephalus fetus. Reversed arterial perfusion sequence was confirmed with Doppler sonography. Postpartum autopsy examination of placenta and acardiac fetus (acardius anceps) was detailed described.     

Dichorionic twins and monochorionic triplets after the transfer of two blastocysts

Purpose

To describe a unique case of MZ dichorionic twins and MZ monochorionic triplets in a quintuplet gestation after intracytoplasmatic sperm injection (ICSI) and blastocyst transfer.

Methods

Case report. A 24-year-old woman underwent ICSI and received two blastocysts transferred. A quintuplet gestation was established .Transvaginal ultrasonography was performed sequentially during early pregnancy.

Results

Three intrauterine gestational sacs were revealed at about 5th week. At the 7th week, five gestational sacs presenting heart beats were detected and a quintuplet pregnancy consisting of two monozygotic (MZ) dichorionic twins and three MZ monochorionic triplets was determined. At the 10th week, a single gestational sac with heart beats was detected. The prenatal course was uneventful. A healthy baby was born at 36th week.

Conclusion

Few other reports have described the occurrence of a quintuplet gestation after the transfer of two blastocysts generated by ICSI. Our case is unique in that the two blastocysts underwent two different splitting processes, which occurred possibly at a similar time giving rise to MZ dichorionic twins and MZ monochorionic triplets.     

The use of radiofrequency in the treatment of twin reversed arterial perfusion sequence: a case series and review of the literature

Objective

To evaluate the initial experience at our centre in the treatment of monochorionic twin pregnancies complicated by twin reversed arterial perfusion sequence (TRAP), using radiofrequency ablation (RFA) with expandable needles, and to review the existing literature on the subject.

Study design

Between July 2007 and October 2010, 11 monochorionic twin pregnancies complicated by TRAP were referred to our centre. Seven patients underwent intrafetal ablation of the acardiac twin with RFA using LeVeen™ expandable needle electrodes. Data on the procedures and the obstetric outcome were reviewed, and subsequently we performed a review of the literature on the use of RFA in TRAP.

Results

Median gestational age at the intervention was 17⁺³ weeks (range 14⁺¹–23⁺¹ weeks). Technical success was obtained in all cases. Preterm premature rupture of membranes (PPROMs) occurred in 4/7 (57%) patients. Intrauterine death of the pump twin occurred in one patient at 21⁺⁵ weeks, and one patient opted for termination of pregnancy because of PPROM at 21⁺⁴ weeks. Five fetuses were delivered alive at a median gestational age of 33⁺⁰ weeks (range 31⁺⁰–39⁺⁵ weeks). All five infants (71%) were alive and had a normal examination at 6 months of age. The review identified 6 studies, for a total of 78 pregnancies (either monochorionc twins or triplets with a monochorionic component). Including our data, overall neonatal survival was 75/88 (85%).

Conclusion

RFA appears to be a relatively safe and reliable technique in the treatment of TRAP sequence pregnancies. Further research is needed to define the best timing of the procedure.     

Gestational diabetes mellitus in twin pregnancies is not associated with adverse perinatal outcomes

Objective

To investigate the influence of gestational diabetes mellitus (GDM) on maternal and neonatal outcomes in twin pregnancies.

Methods

A retrospective population-based study was conducted, comparing maternal and neonatal outcome in women carrying twins with and without GDM. Deliveries occurred in a tertiary medical center between the years 1988 and 2010. Multivariable analysis was used to control for confounders.

Results

The study population included 4,428 twin pregnancies, of these 341 (7.7 %) were complicated with GDM. Twin pregnancies complicated with GDM had higher rates of fertility treatment, chronic hypertension, preeclampsia and cesarean deliveries (CD). Nevertheless, using a multivariable analysis, with CD as the outcome variable, controlling for confounders such as maternal age, fertility treatments and hypertensive disorders, GDM in twins was not found to be an independent risk factor for CD (adjusted OR = 1.8, 95 % CI 0.9?1.4; P = 0.18). Rates of low 5 min Apgar scores (<7) and perinatal mortality were lower among twins with GDM (2.9 % vs. 5.3 %, OR = 0.5, 95 % CI 0.3?0.8 0; P = 0.005 and 2.3 % vs. 4.4 %, OR = 0.5, 95 % CI 0.3–0.8; P = 0.005, respectively).

Conclusion

In our population, GDM in twin pregnancies was not associated with increased rates of adverse perinatal outcomes. In addition, GDM was not found to be an independent risk factor for CD in twin pregnancies.     

Perinatal outcome and neurological follow up of the cotwins in twin pregnancies complicated by single intrauterine death

Objective

To review the outcome of twin pregnancies complicated by single fetal intrauterine death (IUD) managed at our Centre and to evaluate the neurological follow up of the surviving cotwins.

Study design

Twenty-three twin pregnancies (10 dichorionic and 13 monochorionic diamniotic) complicated by IUD in the II or III trimester were seen at our Centre during the study period (2001–2006). All patients were managed conservatively unless non-reassuring signs of fetal well-being were present at ultrasound examination or CTG after 28 weeks, suggesting immediate delivery. Serial scans after the diagnosis of single death were performed and, in addition, eight monochorionic twin pregnancies underwent prenatal MRI in order to identify the presence of cerebral lesions in the survivors. Live born surviving cotwins underwent neurological follow up.

Results

In the monochorionic group one cotwin died in utero and one in the neonatal period with a perinatal survival rate of 83.4% (10/12) (excluding one case who opted for termination of pregnancy); in the dichorionic group perinatal survival rate was 100%. In all monochorionic cases there were no signs of ischemic brain lesions in the surviving cotwins at the diagnosis of single death and during ultrasonographic follow up. In monochorionic pregnancies prenatal MRI, when performed, was negative for signs of brain damage in the surviving cotwins. Gestational age at delivery was not statistically different between monochorionic and dichorionic pregnancies (36 (range, 28.4–40.2) vs. 34.6 (range, 28.2–41.3) weeks) (p = 0.6) and the rate of early preterm delivery before 32 weeks was 23.8% (5/21) and independent from chorionicity (18.2% vs. 30%, p = 0.5). Neurodevelopmental follow up was available for 18/20 live born survivors (85%) and was normal in all but one twin; this case was born from a dichorionic pregnancy with a suspicion of congenital infection.

Conclusions

Our data confirmed a trend to a higher risk of perinatal mortality of cotwins in monochorionic twin pregnancies compared to dichorionic ones. In our experience prenatal ultrasound and MRI were useful to exclude cerebral lesions in utero and subsequent neurological sequelae in surviving monochorionic cotwins, even if definitive conclusions, especially on MRI, are limited by the small number of cases in our study.     

Risk factors for postpartum hemorrhage requiring transfusion in cesarean deliveries for Japanese twins: comparison with those for singletons

Objective

The aim of this study was to identify the factors associated with the increased risk of postpartum hemorrhage requiring transfusion in Japanese twin pregnancies in comparison with those in Japanese singleton pregnancies.

Methods

We reviewed the obstetric records of all singleton and twin deliveries after 22?weeks’ gestation at the Japanese Red Cross Katsushika Maternity Hospital from 2003 through 2011. Potential risk factors for transfusion due to hemorrhage after cesarean delivery were selected according to previous studies of postpartum hemorrhage or transfusion or both after delivery: maternal age, parity, previous cesarean deliveries, history of infertility therapies such as in vitro fertilization, gestational age at delivery, neonatal birth weight, placenta previa, uterine myoma ≥6?cm, hypertensive disorders, placental abruption, emergency cesarean deliveries and general anesthesia.

Results

Using multiple logistic regression, the independent risk factors for postpartum hemorrhage requiring transfusion in singleton pregnancies were preterm delivery [odds ratio (OR) 2.40, 95?% confidence interval (CI) 1.2–4.6, p?<?0.01], placenta previa (OR 8.08, 95?% CI 3.9–16, p?<?0.01) and placental abruption (OR 12.8, 95?% CI 2.3–76, p?<?0.01). In twin pregnancies, however, the independent risk factors for postpartum hemorrhage requiring transfusion were gestational age at ≥41?weeks (OR 8.20, 95?% CI 1.3–40, p?<?0.01) and hypertensive disorders (OR 5.45, 95?% CI 2.2–14, p?<?0.01).

Conclusions

The factors associated with postpartum hemorrhage requiring transfusion in cesarean deliveries of twins seemed to be different from those in singleton cesarean deliveries.     

Radiofrequency ablation for selective reduction in complex monochorionic multiple pregnancies: A case series

Objective

To determine the safety and efficacy of radiofrequency ablation (RFA) for selective fetal reduction in complex monochorionic multiple pregnancies.

Delayed Interval Delivery of the Second Twin: Obstetric Management,Neonatal Outcomes,and 2-Year Follow-Up

Objectives

To evaluate the obstetric management and neonatal outcomes in twin pregnancies with delayed delivery of the second twin, including follow-up.

Methods

This study is a review of four cases of delayed delivery of the second twin in our hospital from 2009 to 2012. The obstetric management of the cases from the expulsion of the first twin to the delivery of the second twin is analyzed. The neonatal outcomes including follow-up for 2 years were reviewed.

Results

The first twins were delivered between 15 and 25 weeks (average 21 weeks) and the second twins were delivered between 25 and 31 weeks (average 27 weeks). One first twin (25 %) survived, while three (75 %) second twins survived. Two out of the three second twins delivered after 28 weeks were in satisfactory condition.

Conclusions

The delayed delivery of the second twins which occurred in the third trimester is associated with favorable outcome, however, the risks should not be ignored.     

Transcervical fetoscopic diagnosis of structural defects in four first-trimester monochorionic twin intrauterine deaths

OBJECTIVE: While chromosomal abnormalities are often the cause of early failed pregnancies, other mechanisms could be involved in monochorionic twin intrauterine deaths, that might be screened for careful morphological analysis. METHODS: Transcervical fetoscopy prior to instrumental evacuation of the uterus was performed in four first-trimester monochorionic twin intrauterine deaths. RESULTS: We present fetoscopic and cytogenetic findings in four cases of monochorionic twin intrauterine deaths. In the first, generalized abnormal embryonic development observed in both twins was a manifestation of trisomy 20. The second (thoracophagus) and third (acardius) pair of twins had anomalies peculiar to multiple gestations. The fourth pair of twins was remarkable because of the concordance for the observed limb-reduction defects. CONCLUSION: Malformations of first-trimester monochorionic twin intrauterine deaths might cover a wide spectrum of etiologies from abnormal chromosomes and single gene defects to rare duplication anomalies. Their detection by careful morphological analysis and the identification of a specific mechanism provides valuable information for genetic counseling and prenatal investigation in a future pregnancy.     

Successful Rescue Cerclage in a Monochorionic Diamniotic Twin Pregnancy at 20 Weeks: Case Report and Overview of Literature

Background

In twin pregnancies, elective cerclage placement based on obstetrical history or ultrasound findings has been shown to be ineffective and even harmful. There are currently no guidelines for the use of rescue cervical cerclage in twin pregnancies.

Human papillomavirus in amniotic fluid

Background

There is evidence to suggest that human papillomavirus (HPV) can cross the placenta resulting in in-utero transmission. The goal of this study was to determine if HPV can be detected in amniotic fluid from women with intact amniotic membranes.

Methods

Residual amniotic fluid and cultured cell pellets from amniocentesis performed for prenatal diagnosis were used. PGMY09/11 L1 consensus primers and GP5+/GP6+ primers were used in a nested polymerase chain reaction assay for HPV.

Results

There were 146 paired samples from 142 women representing 139 singleton pregnancies, 2 twin pregnancies, and 1 triplet pregnancy. The women were 78% Caucasian, 5% African American, 14% Asian, and 2% Hispanic. The average age was 35.2 years with a range of 23–55 years. All samples were β-globin positive. HPV was not detected in any of the paired samples.

Conclusion

Given the age range, race, and ethnicity of the study population, one would anticipate some evidence of HPV if it could easily cross the placenta, but there was none.     

Acardiac twins: pathophysiology, diagnosis, outcome and treatment. Six cases and review of the literature

Twin gestation is often a hazardous pregnancy and especially the monochorionic twin pregnancy significantly contributes to fetal morbidity and mortality. Among the serious complications with twins, the twin-twin transfusion syndrome complicates 5-35% of monozygotic twin pregnancies with monochorionic placentation. Acardiac twinning, earlier known as chorioangiopagus parasiticus, is the most extreme manifestation of this condition. An acardiac twin is a rare complication of multifetal pregnancy, in the literature reported at an incidence of 1% of monochorionic twin pregnancies, i.e. 1 of 35,000 pregnancies. In the following paper we review the literature on the subject and report 6 cases, 5 twins and 1 triplet, that were diagnosed at our department during the period of 1993-1997 and treated conservatively. Only 1 child survived.     

Guideline No. 440: Management of Monochorionic Twin Pregnancies

ObjectiveThis guideline reviews the evidence-based management of normal and complicated monochorionic twin pregnancies.Target PopulationWomen with monochorionic twin or higher order multiple pregnancies.Benefits, Harms, and CostsImplementation of these recommendations should improve the management of both complicated and uncomplicated monochorionic (and higher order multiple) twin pregnancies. They will help users monitor monochorionic twin pregnancies appropriately and identify and manage monochorionic twin complications optimally in a timely manner, thereby reducing perinatal morbidity and mortality.These recommendations entail more frequent ultrasound monitoring of monochorionic twins compared to dichorionic twins.EvidencePublished literature was retrieved through searches of PubMed and the Cochrane Library using appropriate MeSH headings (Twins, Monozygotic; Ultrasonography, Prenatal; Placenta; Fetofetal Transfusion; Fetal Death; Fetal Growth Retardation). Results were restricted to systematic reviews, randomized controlled clinical trials, and observational studies. There were no date limits, but results were limited to English or French language materials.Validation MethodsThe content and recommendations were drafted and agreed upon by the principal authors. The Board of the SOGC approved the final draft for publication. The authors rated the quality of evidence and strength of recommendations using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach. See online Appendix A (Tables A1 for definitions and A2 for interpretations of strong and conditional [weak] recommendations).Intended AudienceMaternal-fetal medicine specialists, obstetricians, radiologists, sonographers, family physicians, nurses, midwives, residents, and other health care providers who care for women with monochorionic twin or higher order multiple pregnancies.Tweetable AbstractCanadian (SOGC) guidelines for the diagnosis, ultrasound surveillance and management of monochorionic twin pregnancy complications, including TTTS, TAPS, sFGR (sIUGR), acardiac (TRAP), monoamniotic twins and intrauterine death of one MC twin.SUMMARY STATEMENTS

• 1.Morbidity and mortality in twin pregnancies are most commonly related to: (1) chorionicity, (2) prematurity, (3) fetal growth restriction, and (4) congenital anomalies (high).
• 2.Virtually all monochorionic placentas have vascular anastomoses between the two placental cord insertions (high).
• 3.Besides prematurity and growth discordance, the vast majority of twin complications arise in monochorionic twin pregnancies (high).
• 4.Twin–twin transfusion syndrome affects approximately 10%–15% of monochorionic twin pregnancies (high).
• 5.The diagnosis of twin–twin transfusion syndrome is based on ultrasound findings of significant discordance in both amniotic fluid volume and bladder size (high). Cardiac dysfunction in the recipient twin or growth discordance often co-exist, but are not essential criteria for the diagnosis (high).
• 6.Fetoscopic laser ablation of the placental vascular anastomoses is the best treatment for twin-twin transfusion syndrome presenting before 28-30 weeks gestation, rather than amnioreduction or septostomy (high).
• 7.The Solomon laser technique decreases the risk of twin–twin transfusion syndrome recurrence and twin anaemia-polycythaemia sequence (high).
• 8.Twin anaemia-polycythaemia sequence occurs spontaneously in 4%–5% of monochorionic twin pregnancies (moderate). It typically develops later in pregnancy than twin–twin transfusion syndrome (usually >24–26 weeks gestation) (moderate). Twin anaemia-polycythaemia sequence may co-exist with twin–twin transfusion syndrome and has been reported in up to 13% of cases of TTTS in which the fetoscopic laser ablation procedure was incomplete (high).
• 9.Ultrasound features of twin anaemia-polycythaemia sequence are increasingly discordant middle cerebral artery peak systolic velocities, suggestive of anaemia in one fetus and polycythaemia in the other, often without significant amniotic fluid discordance (high). Other signs may include differential placental echogenicities and a “starry sky” liver in the recipient twin (moderate).
• 10.Selective fetal growth restriction in monochorionic twin pregnancies has been defined as an estimated fetal weight (EFW) of one twin below the 3^rd percentile, or at least 2 of the following four variables: (1) EFW <10^th percentile, (2) abdominal circumference <10^th percentile, (3) EFW discordance ≥25%, or (4) umbilical artery pulsatility index of the smaller twin >95^th percentile (high).
• 11.In monochorionic twins, estimated fetal weight discordance >25% and abnormal umbilical artery Doppler waveforms are independent risk factors for an adverse perinatal outcome. (high).
• 12.The ultrasonographic features of twin reversed arterial sequence are an amorphous, usually edematous, acardiac twin, which is retrogradely perfused via a placental artery-to-artery anastomosis by its healthy “pump” co-twin (high).
• 13.A large acardiac twin (e.g., an acardiac:“pump” twin abdominal circumference ratio ≥50%) may put its “pump” co-twin at risk of high-output cardiac failure (high). The overall risk of intrauterine death of the “pump” twin is approximately 30% before 18 weeks gestation (high).
• 14.If one of a monochorionic twin pair dies, the surviving co-twin may be at risk of neurological morbidity and intrauterine death (high). Imaging may not detect changes in the co-twin’s brain for several weeks after the death of its sibling (moderate).
• 15.Ultrasound features of monoamniotic twins include the absence of a dividing amniotic membrane, a single placenta, close proximity of placental cord roots, concordant sex and, commonly, cord entanglement (high).
• 16.Only 2%–4% of monoamniotic twins will develop twin–twin transfusion syndrome (high).
• 17.Structural anomalies, particularly cardiac, are more common in monochorionic twins than in dichorionic twins or singletons (high).
• 18.Conjoined twins are extremely rare and the organs/structures that are shared will determine the potential for surgical intervention and survival (high).

RECOMMENDATIONS

• 1.In spontaneously conceived pregnancies, we recommend using the larger of the two crown–rump lengths to estimate gestational age (conditional, moderate).
• 2.Viability, gestational age, chorionicity and amnionicity should be assessed between 11⁰ and 13⁶ weeks gestation in all multiple pregnancies (strong, high).
• 3.If chorionicity cannot be confidently established sonographically, pregnancies should be monitored as if they were monochorionic (conditional, moderate).
• 4.Twins should be labelled on antenatal ultrasound according to their lateral (right/left) or vertical (top/bottom) orientation, rather than their proximity to the cervix, and, ideally, that labelling should be maintained across all subsequent ultrasound examinations (strong, moderate).
• 5.A detailed anatomy scan should be performed at approximately 18–20 weeks gestation for all monochorionic twins (strong, high). Where the expertise is available, an early anatomy ultrasound can be performed at 12–14 weeks gestation (conditional, moderate).
• 6.In all twin pregnancies, cervical length should be assessed, either transabdominally or transvaginally, at the time of the anatomical ultrasound scan and, ideally, once more at around 23–24 weeks gestation (strong, moderate).
• 7.All monochorionic pregnancies should undergo ultrasound surveillance every 2 weeks from 16 weeks gestation until delivery to detect twin–twin transfusion syndrome, twin anaemia-polycythaemia sequence and selective fetal growth restriction (strong, high).
• 8.Ultrasound assessment of all monochorionic twins from 16 weeks onwards should include measurement of growth (fetal biometry), fetal bladder filling, and the single deepest pocket of amniotic fluid on both sides of the membrane, as well as umbilical and middle cerebral artery peak systolic velocity Doppler studies for each fetus (strong, high).
• 9.Monochorionic twins without complications should be delivered between 36 and 37 weeks gestation. Unless there are other obstetric contraindications, vaginal delivery is appropriate (strong, high).
• 10.If twin–twin transfusion syndrome or significant selective fetal growth restriction is suspected, the ductus venosus should be assessed (strong, high). Cardiac structure and function should be assessed in the recipient twin whenever twin–twin transfusion syndrome is suspected (strong, high).
• 11.For cases of twin–twin transfusion syndrome, urgent consultation with or referral to one of the fetal therapy laser centres in Canada is recommended, as fetoscopic laser ablation of placental vascular anastomoses is the best therapy for twin–twin transfusion syndrome (strong, high).
• 12.Ultrasonography should be performed weekly for 4 weeks after fetoscopic placental laser and then every 2 weeks following clinical resolution, with ongoing antenatal care shared or co-ordinated with the regional maternal–fetal medicine centre (strong, high). Assessment should include amniotic fluid volume in both sacs, bladder sizes, Doppler waveforms (middle cerebral artery peak systolic velocity, umbilical artery pulsatility index and ductus venosus), and intra-cranial anatomies, as well as measurement of cervical length and documentation of any chorio-amnion separation (strong, high).
• 13.Fetal intracranial anatomy should be carefully re-evaluated after an interval of at least 4 weeks following a laser procedure (strong, moderate).
• 14.Whenever monochorionic twin complications are encountered, including twin anaemia-polycythaemia sequence, selective fetal growth restriction, twin reversed arterial perfusion sequence, monoamnioticity, discordance for an anomaly, or a single intrauterine death, referral to, or at least consultation with, the regional maternal–fetal medicine program or fetal therapy centre is recommended (strong, high), so that all management options can be explored. The optimal management of twin anaemia-polycythaemia sequence has yet to be determined. (conditional, moderate).
• 15.When selective fetal growth restriction is suspected, fetal surveillance should be intensified and the pregnancy managed by referral to, or at very least with input from, a regional maternal–fetal medicine centre with expertise in this condition (strong, moderate).
• 16.In selective fetal growth restriction, timing of delivery should take into account gestational age, evidence of haemodynamic compromise as assessed by umbilical and middle cerebral artery and ductus venosus Doppler studies, and biophysical wellbeing (strong, moderate).
• 17.Whenever the death of one monochorionic twin is diagnosed early in pregnancy, colour Doppler ultrasonography should be used to exclude twin reversed arterial perfusion sequence, by confirming the absence of blood flow in the suspected demised twin (strong, high).
• 18.In twin reversed arterial perfusion sequence, especially with a large acardiac twin, occlusion of the circulation to the acardiac twin, either by laser, radio frequency ablation of the intra-fetal vessels or bipolar cautery should be considered (conditional, moderate).
• 19.After the spontaneous death of one monochorionic twin, surveillance for fetal anaemia by middle cerebral artery peak systolic velocity measurement should be instituted rapidly, as anaemia correlates with the risk of a hypotensive neurological injury (strong, high). The surviving twin may benefit from intrauterine transfusion (conditional, moderate). Fetal neurosonography and, ideally, MRI should be used to identify any potential cerebral injury; however, ultrasonographic evidence of injury may take 3-4 weeks to develop after the death of the co-twin (strong, high).
• 20.Care should be taken not to misdiagnose monochorionic-diamniotic pregnancies as monoamniotic, when one twin has anhydramnios (e.g., the donor in twin–twin transfusion syndrome) (conditional, moderate).
• 21.Monoamniotic twins are at high risk of cardiac abnormalities and should undergo a detailed anatomical ultrasound with particular emphasis on fetal cardiac evaluation (strong, high).
• 22.Monoamniotic twins should be monitored closely from viability onwards (either as out-patients or in-patients) and should undergo an elective caesarean delivery at approximately 33 weeks gestation (conditional, moderate).
• 23.Aneuploidy screening can be offered in monochorionic pregnancies as either combined prenatal serum screening (i.e., first-trimester screening or integrated prenatal screening, as available provincially) or cell-free fetal DNA analysis of maternal blood (conditional, moderate).
• 24.Invasive prenatal testing (chorionic villus sampling or amniocentesis) should be offered in the presence of a structural anomaly or abnormal genetic screening (strong, high). Amniocentesis from both sacs should be considered for discordant anomalies because of the rare possibility of heterokaryotypic anomalies in monochorionic twins (strong, high).
• 25.If indicated for discordance for an anomaly, selective termination of pregnancy in monochorionic twins must always be performed by a vascular occlusion method and never by intravascular fetal injection (strong, high).

     

The management of acardiac twins: a conservative approach

OBJECTIVE: Optimal management of acardiac twin pregnancies is controversial. Data suggest a 50% mortality rate in the "pump" twin when the pregnancy is managed expectantly. Because of increased antenatal diagnosis, outcomes in expectantly managed cases may be better than reported. Our objective was to determine the outcome of expectantly managed acardiac twin pregnancies. STUDY DESIGN: All cases of antenatally diagnosed acardiac twins delivered in our community between 1994 and 2001 were ascertained. All were managed expectantly. Perinatal outcome of pump twins was the primary outcome variable. RESULTS: Ten cases were identified. Nine women were delivered of healthy pump twins. There was one neonatal death. The mean gestational age at delivery was 34.2 weeks. The mean weights of the pump and acardiac twins were 2279 g and 1372 g, respectively. CONCLUSION: Neonatal mortality of pump twins in antenatally diagnosed acardiac twin pregnancies may be considerably less than reported. Expectant management with close antepartum surveillance deserves consideration.     

Earliest ultrasound findings and description of splicing mutations in Meckel–Gruber syndrome

Objective

To describe early ultrasound findings in Meckel–Gruber syndrome (MKS) in first and second trimester of three families, detailed ultrasound findings have been documented in addition to pathoanatomical findings and results of DNA studies. A splice site mutation in the MKS4 gene could be detected. Clinical management accounting risk assessment for future pregnancies is discussed and early ultrasound markers in MKS are described.

Methods

All cases were examined in a tertiary center for prenatal diagnosis by ultrasound. Necroscopy confirmed the clinical diagnosis. Fetal DNA analysis was accomplished in a reference center for MKS. In addition, ultrasound findings in early pregnancy of two further cases are described.

Results

Three couples presented with pregnancies complicated by MKS. The earliest diagnosis was suspected in 11?+?6?weeks of gestation and was confirmed in 13?+?0?weeks by ultrasound revealing a large occipital encephalocele and polycystic kidneys. Another case with recurrent MKS in two consecutive pregnancies was diagnosed in 20?weeks and 14?weeks of gestation, respectively. Here a close molecular genetic follow-up was performed leading to the detection of two mutations in the MKS4 gene in both fetuses. The third case was diagnosed in 15?weeks of gestation. Ultrasound findings in all pregnancies were doubtless and autopsies confirmed the diagnosis.

Conclusion

Detection of MKS is already possible in the first trimester. Knowledge of the underlying genetic defect helps counseling the couples with recurrence of MKS and chorionic villi sampling in the first trimester of pregnancy can be offered.     

Emergency cervical cerclage after miscarriage of the first fetus in dichorionic twin pregnancies: obstetric and neonatal outcomes of delayed delivery interval

Purpose

To study the effectiveness of emergency cervical cerclage in order to delay the delivery interval after miscarriage of the first fetus in dichorionic twin pregnancies.

Methods

Dichorionic twin pregnancies after miscarriage of the first fetus (<24?weeks) were exclusively included in the present analysis. Prolongation of delivery interval was managed with additional emergency cervical cerclage in the already initiated tocolytic therapy. Obstetric outcomes (cervical dilatation, gestational age at delivery of the first twin, interval between miscarriage and delivery of the second fetus) and neonatal outcomes [neonatal birth weight, Apgar score in the first and fifth minute, admission to Neonatal Intensive Care Unit (NICU)] of the second twin were analyzed.

Results

Five cases of dichorionic twin pregnancies were included in our study. Cervical dilatation (mean?±?SD) at admission time was 3.7?±?1.4?cm. The gestational week at delivery of the first twin was 20.6?±?2.6. The median delivery interval was 72?days and the maximum 121?days. Mean gestational age at delivery of the second twin was 28.8?±?7.2?weeks and mean birth weight 1,772.5?±?742?g. The rate of live birth was 80?%, while NICU admission was demanded in 75?% of the live births. All neonates discharged from NICU remained alive after 1?month of life.

Conclusion

The present study demonstrated beneficial effect concerning obstetric and neonatal outcomes of the second twin after performing emergency cervical cerclage to postpone the delivery interval in premature dichorionic twin pregnancies.     

Twin reversed arterial perfusion sequence: two different heartbeats in one umbilical cord - rare finding in monochorionic twin pregnancy

The development of twin-twin transfusion syndrome complicates 5-35% of twin pregnancies with monochorionic placentation. Acardiac twinning is the most extreme manifestation of pathological vascular anastomoses between twins. An acardiac twin is a rare complication of multifetal pregnancy, reported in the literature with an incidence of 1% in monochorionic twin pregnancies, i.e. 1/35 000 pregnancies, and more than 400 cases have been described. We review the literature on this subject and report a special case of twin reversed arterial perfusion (TRAP) sequence in a twin pregnancy with the rare finding of a functional univentricular circulation pump in the acranius, its antenatal ultrasound diagnosis and postnatal findings. Remarkably, prenatally we could demonstrate two different arterial pulsations in the umbilical cord of the acranius. Etiological hypotheses of the TRAP sequence and new implications for risk-adapted therapeutic options are discussed.