What prenatal diagnosis should be offered in multiple pregnancy?

Clinical practice guidelines for the antenatal management of dichorionic diamniotic twin pregnancies: a systematic review

OBJECTIVE

This review aimed to identify guidelines with recommendations applicable to the antenatal management of dichorionic diamniotic twin pregnancies within high-income countries, appraise their methodological quality, and discuss the similarities and variability across guidelines.

METHOD

A systematic literature review of electronic databases was performed. Manual searches of guideline repositories and websites of professional organisations were performed to identify additional guidelines. The protocol for this systematic review was registered on PROSPERO (CRD42021248586, 25 June 2021). AGREE II and AGREE-REX tools were applied to assess the quality of eligible guidelines. A narrative and thematic synthesis described and compared the guidelines and their recommendations.

RESULTS

Twenty-four guidelines were included, from which 483 recommendations were identified across 4 international organisations and 12 countries. Guidelines addressed eight themes and recommendations were classified accordingly: chorionicity and dating (103 recommendations), fetal growth (105 recommendations), termination of pregnancy (12 recommendations), fetal death (13 recommendations), fetal anomalies (65 recommendations), antenatal care (65 recommendations), preterm labour (56 recommendations) and birth (54 recommendations). Guidelines showed significant variability in recommendations, with conflicting recommendations regarding non-invasive preterm testing, definitions surrounding selective fetal growth restriction, screening for preterm labour and the timing of birth. Guidelines lacked a focus on standard antenatal management of DCDA twins, management of discordant fetal anomaly and single fetal demise.

CONCLUSIONS

Specific guidance for dichorionic diamniotic twins is overall indistinct and access to guidance regarding the antenatal management of these pregnancies is currently difficult. Management of discordant fetal anomaly or single fetal demise needs greater consideration.

Relationship of intertwin crown-rump length discrepancy to chorionicity, fetal demise and birth-weight discordance

OBJECTIVES

To study the frequency and clinical significance of crown-rump length (CRL) discrepancy at 11-14 weeks of gestation in twin pregnancies from an unselected population.

METHODS

This was a retrospective analysis of all twin pregnancies that underwent a routine 11-14-week scan at a large teaching hospital. Fetal loss was defined as fetal demise of one or both twins after 14 weeks.

RESULTS

A total of 507 twin pregnancies were studied; 382 (75.3%) were dichorionic and 125 (24.7%) were monochorionic twins. The discrepancy in CRL was expressed as a percentage of the CRL of the larger twin. The 95(th) and 99(th) centile for CRL discrepancy in twins was 12.2% and 19.3%, respectively. The discrepancy in CRLs in monochorionic and dichorionic twins was not significantly different (Mann-Whitney U = 22,406, P = 0.302). In 39 twin pairs, there was subsequent intrauterine death of one or both twins. Fetal loss was more common in monochorionic twins (24/125) than in dichorionic twins (15/382) (chi-square = 30.9, P < 0.001). In monochorionic twins, the discrepancy in CRLs in the 24 cases with subsequent loss was significantly greater than in the 101 twin pairs with no subsequent loss (Mann-Whitney U = 896, P = 0.048). The discrepancy in CRLs in 15 dichorionic twins with subsequent loss was not different from that in the 367 twins with no loss (Mann-Whitney U = 2116.5, P = 0.129). The CRL discrepancy was significantly correlated with birth-weight discordance in twins (Spearman's rho = 0.128, P = 0.006). However, this was due to a significant correlation in dichorionic twins (Spearman's rho = 0.127, P = 0.016) but not in monochorionic twins (Spearman's rho = 0.145, P = 0.14).

CONCLUSIONS

Fetal loss is significantly associated with discrepancy in CRL at the 11-14-week scan in monochorionic twins and discordance in birth weights is significantly associated with discrepancy in CRL in dichorionic twins. However, intertwin CRL discrepancy is of limited value in screening for these adverse events.