(480) Selective Fetal Growth Restriction in Monochorionic Twins: Natural History and a Call for Classification Modification

To evaluate the natural history of selective fetal growth restriction (sFGR) in monochorionic (MC) twins according to  Gratacós classification including progression/improvement/stability of umbilical artery (UA) Dopplers and development of superimposed twin-to-twin transfusion syndrome (TTTS) or twin anemia polycythemia syndrome (TAPS).

Study Design:

PubMed, Scopus, and Web of Science were searched systematically from inception until February 2022. Articles investigating sFGR progression and outcomes according to UA dopplers end diastolic flow (EDF) (Gratacós classification) were included. Type I includes sFGR with positive EDF, type II with persistently absent (AEDF), and type III with intermittent absent/reversed (IAREDF). Pregnancies in which the diagnosis of TTTS or TAPS was made before that of sFGR were not included in the analysis. The random-effect model was used to pool the odds ratios (OR) and the corresponding 95% confidence intervals (CIs). Heterogeneity was assessed using I² value.

Results:

Total of 18 studies encompassing 1362 sFGR twins were included in the analysis. The incidence of stability, deterioration, improvement of UA Dopplers in type I were 63% (95% CI 26, 89), 18% (95% CI 7- 40), and 9% (95% CI 0.0-100), respectively, in type II were 50% (95% CI 18, 81), 54% (95% CI 23, 82) , and 31% (95% CI 9, 67), respectively, and in type III were 53% (95% CI 2, 99), 22% (95% CI 9, 43), and 21% (95% CI 6, 54), respectively. Risk of development of superimposed TTTS was comparable between type I (7%) and type III (9%). Risk of development of superimposed  TAPS were highest in type I (12%) and comparable between type II (2%) and III (1%).

Conclusion:

Our study presents the natural history of sFGR according to UA Dopplers EDF patterns at diagnosis. Type I sFGR most commonly remained stable, type II most commonly had worsening UA Dopplers, and type III most commonly remained stable. The current data provide vital counseling points and support the need for modifications of the current sFGR classification system to include the progression of UA Dopplers.