Resolution of selective fetal growth restriction after laser surgery for twin-to-twin transfusion syndrome can be predicted by predisease growth discordance

Objective: To determine if the resolution of fetal growth discordance after laser surgery in pregnancies with twin-to-twin transfusion syndrome (TTTS) and coexisting selective fetal growth restriction (sFGR) can be predicted by estimated fetal weight (EFW) discordance recorded prior to the development of TTTS (pre-TTTS).

Methods: This was a single-center, retrospective analysis of prospectively collected data on monochorionic twins with concurrent TTTS and sFGR that underwent laser surgery and had available growth ultrasound records from a pre-TTTS ultrasound evaluation. Maternal demographics, pregnancy characteristics and birth outcomes were compared between three outcome groups: double twin survival with resolved sFGR determined by birth weight discordance (BWD) < 20%; double twin survival with ongoing sFGR determined by BWD ≥ 20%; and single or double fetal demise after laser surgery. One-way analysis of variance or the Kruskal-Wallis test was used for continuous variables. The chi-square test or Fisher's exact test was used for categorical variables. A multivariate logistic regression model was constructed based on univariate associations.

Results: Ninety-seven patients with TTTS and concurrent sFGR underwent same- or next-day laser surgery after a TTTS staging ultrasound at a median gestational age of 19.4 (interquartile range (IQR), 18.0-22.3) weeks, with a median EFW discordance of 28.8% (IQR, 22.9-34.0%). At delivery, 34 (35.1%) patients had resolved sFGR with a median BWD of 7.7% (IQR, 3.5-13.0%), 34 (35.1%) had ongoing sFGR with a median BWD of 30.6% (IQR, 24.4-43.9%) and 29 (29.9%) had a single or double fetal demise. Although some characteristics available at the time of TTTS diagnosis, such as the donor umbilical artery end-diastolic velocity (P = 0.0087) and donor umbilical artery pulsatility index (P = 0.0061), also correlated with growth outcome, multivariate logistic regression analysis identified EFW discordance at the pre-TTTS ultrasound as the primary determinant of the odds of resolved growth discordance at birth (P = 0.0063).

Conclusions: In patients undergoing laser surgery for TTTS with coexisting sFGR, a history of concordant growth at the pre-TTTS scan prior to the development of TTTS was associated with the resolution of fetal growth discordance at birth. These findings suggest that TTTS pathophysiology can contribute to growth discordance noted at the time of TTTS diagnosis. © 2024 International Society of Ultrasound in Obstetrics and Gynecology.