Pregnancy and perinatal outcomes of early vs late selective termination in dichorionic twin pregnancy: systematic review and meta-analysis

Perinatal outcomes of selective termination in dichorionic twin pregnancies: a retrospective study from a single center

OBJECTIVE

Selective termination (ST) is an appropriate procedure for managing discordant fetal anomalies in dichorionic diamniotic (DCDA) twin pregnancies. The aim of this study was to investigate the perinatal outcomes of ST at different gestational ages in DCDA twin pregnancies.

METHODS

This retrospective study was conducted on DCDA twin pregnancies with STs at West China Second University Hospital between January 2012 and December 2022. According to the gestational age at which ST was performed, the patients were assigned to four groups: Group 1 (13 to 17 + 6 weeks), Group 2 (18 to 23 + 6 weeks), Group 3 (24 to 27 + 6 weeks), and Group 4 (≥ 28 weeks).

RESULTS

We identified 230 patients for this study. The overall rates of miscarriage, preterm delivery at < 32 weeks, and term delivery were 1.3%, 10.5%, and 50%, respectively, while the rates of live birth and neonatal survival were 98.7% and 98.2%, respectively. The rate of term birth was highest (70.6%) and the birth weight was heaviest (2931 ± 535 g) in Group 1 (p = 0.000). In the presence of a fetus subjected to feticide, the mean delivery age was earlier than that in the non-presenting group (p = 0.017); accordingly, the mean birth weight in the feticide group was lower (2366 ± 628 g) than that in the non-presenting group (2590 ± 634 g) (p = 0.011). When we examined the relative relationship between reduction weeks and delivery weeks of twins by correlation analysis, we observed that with regard to maternal prognosis, two pregnancies involved preterm premature rupture of membranes (PPROM) at 7 days and 3 days after the procedure. Intrauterine infection occurred in two patients in Group 4, but there were no maternal deaths or maternal coagulatory abnormalities.

CONCLUSIONS

Optimal perinatal outcomes were obtained by ST of DCDA pregnancies before 18 weeks, regardless of whether or not the reduced fetus was the presenting twin. However, if legally possible, late (i.e., after 28 weeks) procedures can be a safe alternative for patients diagnosed after the 18th week of gestation. Overall, we herein noted a negative correlation between the procedure week and the delivery week in this study. Moreover, ST of the non-presenting twin was associated with a heavier birth weight and later gestational age at delivery.

Diagnostic accuracy of cell-free fetal DNA in maternal blood in detecting chromosomal anomalies in twin pregnancy: systematic review and meta-analysis

OBJECTIVE

To report the diagnostic accuracy of cell-free fetal DNA (cfDNA) in maternal blood in detecting fetal chromosomal anomalies in twin pregnancy.

METHODS

PubMed, MEDLINE, EMBASE and Cochrane databases were searched from inception to November 2023. The inclusion criteria were twin pregnancy undergoing cfDNA screening for trisomies 21, 18 and 13, monosomy X and/or other sex-chromosome aneuploidies (SCA). The index test was cfDNA screening. The reference standard was pre- or postnatal karyotyping (in the case of a positive cfDNA result) or neonatal phenotypic assessment (in case of a negative cfDNA result). The quality of included studies was assessed using the revised quality assessment of diagnostic accuracy studies (QUADAS-2) tool. Summary estimates of diagnostic accuracy were computed using a bivariate random-effects model.

RESULTS

Thirty-five studies were included in the systematic review and meta-analysis. cfDNA had a high accuracy in detecting trisomy 21 in twin pregnancy, with a sensitivity of 98.8% (95% CI, 96.5-100%) and specificity of 100% (95% CI, 99.9-100%). Sensitivity and specificity were 94.9% (95% CI, 75.9-99.1%) and 100% (95% CI, 99.9-100%), respectively, for trisomy 18 and 84.6% (95% CI, 54.6-98.1%) and 100% (95% CI, 99.9-100%), respectively, for trisomy 13. We could not compute the diagnostic accuracy of cfDNA in detecting monosomy X, owing to an absence of positive cases, while cfDNA had a sensitivity of 100% (95% CI, 71.5-100%) and specificity of 99.8% (95% CI, 99.7-99.9%) for other SCA. The accuracy of cfDNA in detecting the common trisomies was similar in dichorionic and monochorionic twin pregnancies.

CONCLUSIONS

cfDNA has high diagnostic accuracy in detecting trisomies 21 and 18 in twin pregnancy, irrespective of chorionicity. Estimation of diagnostic accuracy for trisomy 13 and other SCA was limited by the small number of affected cases and the difficulty associated with detecting false-negative cases of other SCA, and thus requires confirmation in larger studies. © 2024 International Society of Ultrasound in Obstetrics and Gynecology.

Counselling in Fetal Medicine: Uncomplicated Twin Pregnancies

Twin pregnancies account for 3% of all pregnancies and they are burdened by higher morbidity and mortality compared to singletons. The role of ultrasound in the screening, diagnosis and management of possible complications of twin pregnancies has been widely investigated in the current literature. However, despite the progress that have been made in the last decades regarding treatment and evidence-based management of complications, twin pregnancies remain at higher risk of adverse outcomes, requiring therefore dedicated surveillance. Thorough counselling regarding the risks and prenatal care should be offered to all future parents of twin pregnancies. This review aims to summarize the current evidence regarding the management of uncomplicated dichorionic and monochorionic pregnancies.

Outcomes of twin pregnancies complicated by prelabor rupture of membranes before 26 weeks of gestation: systematic review and meta-analysis

OBJECTIVE

To investigate the rate of obstetric and perinatal outcomes of premature rupture of membranes (PROM) occurring before 26 weeks in twin pregnancies.

DATA SOURCE

Medline, Embase, Cinahl and Web of Science databases were searched electronically up to January 2024.

STUDY ELIGIBILITY CRITERIA

The selection criteria included both prospective and retrospective studies of twin pregnancies with PROM before 26 weeks of gestation. Case reports, case series with fewer than 5 cases, review articles, letters to the editor and editorials were excluded. Studies including both singletons and twin pregnancies were also excluded.

STUDY APPRAISAL AND SYNTHESIS METHOD

We used meta-analyses of proportions to combine data and assess the pooled proportions. We used a random-effect model to perform the pooled data analyses. The study was registered with the PROSPERO database (CRD 42022368057). Quality assessment of the included studies was performed usingthe Newcastle-Ottawa Scale for cohort studies.

RESULTS

Eight studies including 227 twin pregnancies were included in the analysis. The pooled proportion of termination of pregnancy (TOP) was 4.6 % (95 % CI 1.5-13.4), while the rate of selective TOP (sTOP) was 24.5 % (95 % CI 7.1-57.7). After the exclusion of cases of TOP, the overall rate of spontaneous miscarriage or fetal demise was 20.9 % (95 % CI 11.1-35.8), whereas the live birth rate of at least one twin was 71.6 % (95 % CI 61.2-80.1) of the ongoing pregnancies. The mean gestational age at delivery was 26.5 (95 % CI 25.1-28.0) weeks and the mean latency between PROM and delivery was 5.4 weeks (95 % CI 4.8-5.9) in all cases including those with fetal deaths. Neonatal outcomes showed that the overall neonatal mortality was 26.4 % (95 % CI 16.7-39.2). When focusing only on pregnancies undergoing sTOP, the observed livebirth rate was 87.7 %. The gestational age at rupture of membranes in these cases was 16.8 (95 % CI 14.9-18.6) weeks and the latency between PROM and delivery was significantly longer (19.9 (95 % CI 18.0-21.7) weeks) than that observed in unterminated pregnancies, with a mean gestational age at delivery nearly in the range of term (36.9 weeks).

CONCLUSIONS

PROM in twins before 26 weeks is associated with overall high rates of adverse obstetric and neonatal outcomes, and it represents a clinical challenge for both counseling and management. Larger prospective studies unified objective protocols in terms of antenatal surveillance and management are needed.

Counselling in Fetal Medicine: Complications of Monochorionic Diamniotic Twin Pregnancies

Twin pregnancies are at increased risk of morbidity and mortality compared to singletons. Among all twins, monochorionic pregnancies are at higher risk of specific and non-specific complications compared to dichorionic pregnancies. Therefore, it is of great importance to properly counsel future parents with monochorionic pregnancies regarding the risks of adverse outcomes and the modalities of monitoring and intervention of the potential complications. Conditions related to the monochorionicity include twin-to-twin transfusion syndrome (TTTS), twin reversed arterial perfusion sequence (TRAP), and twin anemia polycythemia syndrome (TAPS); other complications include selective fetal growth restriction (sFGR) and congenital anomalies. This review aims to summarize the information available in the current literature regarding the complications in monochorionic diamniotic twin pregnancies, including outcomes and guideline recommendations about the clinical surveillance, management, and timing of interventions of these conditions that should be included in counselling in routine clinical practice.

Late selective termination in dichorionic twins: comparing late second and third trimester procedures

RESEARCH QUESTION

Do perinatal outcomes of selective termination performed in the late second versus third trimester differ and what risk factors are associated with subsequent preterm birth?

DESIGN

This is a retrospective cohort study of late selective terminations performed in dichorionic twins between 2009 and 2021. Perinatal outcomes were compared between two groups: group A, late second trimester (20.2 to 24.2 weeks, n = 26), and group B, third trimester (≥28.2 weeks, n = 55) selective terminations. Univariate and multivariate analyses were conducted to identify factors associated with post-procedure preterm birth.

RESULTS

In total, 81 dichorionic twin pregnancies were included. There were no pregnancy losses but 16% (13/81) of cases experienced complications. Group A had a higher median birthweight centile (36.5th versus 15th centile, P = 0.002) and lower rates of intrauterine growth restriction (IUGR) and Caesarean delivery (11.5% versus 32.7%, P = 0.04; and 26.9% versus 61.8%, P = 0.003) than group B. Preterm birth rates were similar (46.2% versus 63.6%, P = 0.15). Multiple regression revealed that reduction of the presenting twin and cervical length ≤35 mm were independently associated with post-procedure preterm birth (odds ratio [OR] 8.7, P = 0.001, 95% confidence interval [CI] 2.5-29.8; OR 3.8, P = 0.015, 95% CI 1.3-11).

CONCLUSIONS

Late second trimester selective termination is associated with a higher birthweight centile and lower rates of IUGR and Caesarean delivery, compared with third trimester selective termination. Cervical length 35 mm or less and reduction of the presenting twin are independent risk factors for post-procedural preterm birth. These findings may help determine the optimal time to perform a late selective termination.

Perinatal outcomes between immediate vs deferred selective termination in dichorionic twin pregnancies with fetal congenital anomalies: a French multicenter study

BACKGROUND

Because selective termination for discordant dichorionic twin anomalies carries a risk of pregnancy loss, deferring the procedure until the third trimester can be considered in settings where it is legal.

OBJECTIVE

To determine whether perinatal outcomes were more favorable following deferred rather than immediate selective termination.

STUDY DESIGN

A French multicenter retrospective study from 2012 to 2023 on dichorionic twin pregnancies with selective termination for fetal conditions, which were diagnosed before 24 weeks gestation. Pregnancies with additional risk factors for late miscarriage were excluded. We defined 2 groups according to the intention to perform selective termination within 2 weeks after the diagnosis of the severe fetal anomaly was established (immediate selective termination) or to wait until the third trimester (deferred selective termination). The primary outcome was perinatal survival at 28 days of life. Secondary outcomes were pregnancy losses before 24 weeks gestation and preterm delivery.

RESULTS

Of 390 pregnancies, 258 were in the immediate selective termination group and 132 in the deferred selective termination group. Baseline characteristics were similar in both groups. Overall survival of the healthy co-twin was 93.8% (242/258) in the immediate selective termination group vs 100% (132/132) in the deferred selective termination group (P<.01). Preterm birth <37 weeks gestation was lower in the immediate than in the deferred selective termination group (66.7% vs 20.2%; P<.01); preterm birth <28 weeks gestation and <32 weeks gestation did not differ significantly (respectively 1.7% vs 0.8%; P=.66 and 8.26% vs 11.4%; P=.36). In the deferred selective termination group, an emergency procedure was performed in 11.3% (15/132) because of threatened preterm labor, of which 3.7% (5/132) for imminent delivery.

CONCLUSION

Overall survival after selective termination was high regardless of the gestational age at which the procedure was performed. Postponing selective termination until the third trimester seems to improve survival, whereas immediate selective termination reduces the risk of preterm delivery. Furthermore, deferred selective termination requires an expert center capable of performing the selective termination procedure on an emergency basis if required.

Clinical value of high-intensity focused ultrasound in fetal reduction

Complex twin reduction surgery is a common but challenging procedure that aims to reduce the risks and complications of multiple pregnancies. The search for safer and more effective methods has led to the development of high-intensity focused ultrasound (HIFU) technology in the field of fetal reduction. This technology utilizes high-energy sound waves to focus precisely on specific areas, achieving non-invasive therapeutic effects. This paper discusses the principles and features of HIFU technology, as well as its application in complex twin reduction surgery. The paper aims to elucidate the important role of this technology in improving surgical outcomes and reducing risks, explore the current limitations of the modality, and propose directions for future development. Through these investigations, it is hoped to improve overall understanding of HIFU, and thereby promote the application of this technology in the field of fetal reduction.

Perinatal outcome and timing of selective fetal reduction in dichorionic diamniotic twin pregnancies: a single-center retrospective study

Objective

The study aimed to evaluate the pregnancy outcomes of dichorionic diamniotic twin pregnancies that were reduced to singletons at different gestational ages.

Study design

This was a retrospective cohort study of twin pregnancies that underwent fetal reduction to singletons in a single tertiary referral center between 2011 and 2020. A total of 433 cases were included. The cohort was divided into five groups according to gestational age at surgery: Group A: <16 weeks (125 cases); Group B: 16-19+6 weeks (80 cases); Group C: 20-23+6 weeks (74 cases); Group D: 24-26+6 weeks (48 cases); and Group E: ≥27 weeks (106 cases). Outcome data were obtained by reviewing the electronic medical records or interviews.

Results

Selective reduction was technically successful. The clinical characteristics of the population were not different. The overall live birth rate and the survival rate were 96.5 and 95.4%, respectively. Although the rate of spontaneous miscarriage was comparable, gestational age at delivery significantly differed among groups (p < 0.001). Additionally, there was a trend that gestational age at delivery decreased with the increasing gestational age at surgery in Groups A, B, C, and D, whereas gestational age at delivery in Group E was later than that in Group D. In Groups A, B, C, and D, the rates of preterm birth at <32 weeks and <34 weeks increased with the increasing gestational age at surgery, while the rates in Group E were significantly lower than that in Group D. Regression analysis showed that timing of reduction may be an independent factor after adjusting for maternal age, parity, pre-pregnancy BMI, ART, and cervical length.

Conclusion

Selective reduction performed by experienced hands for a dizygotic abnormal twin is safe and effective. Gestational age at surgery (<26+6 weeks) was inversely correlated with gestational age at delivery and positively with the rate of preterm birth. Reduction after 27 weeks, where legal, can be performed with a good outcome for the retained fetus.

Clinical outcomes of vanishing twin syndrome and selective fetal reduction after double embryos transferred in IVF pregnancy: A propensity score matching study

OBJECTIVE

The purpose of this study was to analyze the influence of early vanishing twin syndrome (VTS) and selective fetal reduction (SEFR) on surviving singleton births in in-vitro fertilization (IVF) pregnancy.

METHODS

We collected patients who conceived through IVF and delivered singletons over the past six years. The VT group (n = 194) and SEFR group (n = 144) had underwent double embryos transferred (DET) and only one fetus was born, due to the subsequent one birth reduction. The SET group had one embryo transferred (SET) and gave birth to singleton. Using the propensity score matching (PSM) method to reduce confounding, the VT group and SEFR group were matched and compared with 570 and 576 singleton controls, respectively (SET-I/II group). Obstetric complications and neonatal outcomes were compared. In addition, quantity and quality of transferred embryos of VT (n = 194) and singleton groups (born with singleton after DET and matched with VT group by PSM, n = 554) were compared.

RESULTS

Compared with the SET-I group, VT group had increased incidence of severe obstetric complications, including severe preeclampsia (p = 0.031), oligohydramnios (p = 0.038) and polyhydramnios (p = 0.015). VT group was more likely to show more frequent small for gestational age (SGA) (p = 0.046) and very small for gestational age (VSGA) (p = 0.031). Newborns in the SEFR group had a significantly lower birth weight (p = 0.005) and were more likely to manifest as low birthweight (LBW) (p = 0.009) and very low birthweight (VLBW, birth weight < 1500 g) (p = 0.012), and the incidence of very large for gestational age (VLGA) was lower (p = 0.030), compared with the control group. There were more developmental abnormalities in newborns of VTS, for decreased incidence of SGA (OR 0.156, 95% CI 0.036-0.669), VSGA (OR 0.057, 95% CI 0.006-0.553) and VLGA (OR 0.415, 95% CI 0.212-0.815) in SEFR group. The good quality embryo rate was higher in VT group (72.7% vs. 63.3%, p = 0.001) compared with the singleton group.

CONCLUSIONS

DET with subsequent VTS/SEFR carried a higher rate of adverse clinical outcomes, and the VTS group had worse perinatal outcome compared with SEFR. Therefore, we recommend SET in ART.