Comparison of renal artery Doppler parameters of monochorionic diamniotic twin pregnancies with and without twin?to?twin transfusion syndrome

Monochorionic diamniotic (MCDA) twin pregnancies are considered high?risk for several reasons, especially the risk of  win?to?twin transfusion syndrome (TTTS). Renal artery Doppler (RAD) is reported as a useful tool for predicting oligohydramnios in singleton pregnancies. We aimed to compare the RAD indices between MCDA twins with and without TTTS.

In this case–control study, all pregnant women aged 18–38 years, with gestational age ? 18 weeks, who were referred to two Prenatal Clinics, Alzahra and Beheshti Educational Hospitals,  ffiliated to Isfahan University of Medical Sciences, Isfahan, Iran, October 2020–March 2022 were enrolled; the women with MCDA twin pregnancies complicated by TTTS (case group, n = 12) and without TTTS (control group, n = 24). For each twin, biometric analysis, fetal weight, and Doppler study of fetal arteries, including RAD, middle cerebral artery (MCA), umbilical artery, and ductus venosus were performed. Peak systolic velocity, Pulsatility index (PI), resistance index (RI), and systole/diastole (S/D) were measured for all arteries.

The donors of the case grouphad a lower mean MCA S/D (4.48 ± 1.89) than the control group (6.48 ± 1.97) (P = 0.01) and higher mean umbilical parameters, including PI, RI, and S/D (P < 0.05). The recipients of the case group had a lower mean renal PI than the control (P = 0.008) and lower mean MCA PI, RI, and S/D (P < 0.05). The donor group had a higher mean umbilical RI and S/D than the recipient twin, while the mean fetal weight of the recipient group was higher (P < 0.05).

Comparing the RAD parameters between the twins with and without TTTS in the present study did not identify significant results, which rejected the primary hypothesis. Among all RAD parameters, the only significant difference observed in the present study was the lower RAD PI in RT, which cannot suggest this measurement as a valuable tool for the prediction of TTTS in MCDA twins. Therefore, the results of the present study failed to show the additional value of RAD, compared with the conventional Doppler examination of fetal arteries. Further studies arerequired to prove this conclusion.