Fetal Renal Artery Doppler Changes in Monochorionic Diamniotic Twins Treated by Fetoscopic Lazer Coagulation

OBJECTIVES: To evaluate changes in fetal renal artery Doppler (RAD) indices before and after fetoscopic laser coagulation (FLC) in monochorionic diamniotic (MCDA) twin pregnancies with twin-to-twin transfusion syndrome (TTTS), and to assess their potential role in predicting procedural success and TTTS diagnosis. METHODS: This prospective single-center before-and-after cohort study included MCDA twin pregnancies treated with FLC for TTTS between 16 and 26 weeks' gestation. Fetal RAD pulsatility index (PI), resistance index (RI), and peak systolic velocity (PSV), along with umbilical and middle cerebral artery Doppler parameters, were measured preoperatively and at 24-48 hours and 10-15 days post-procedure. Only successful FLC procedures without early complications were analyzed. RESULTS: Thirty-one pregnancies were analyzed. In donor fetuses, RAD PI decreased significantly following FLC at 24-48 hours compared with preoperative values (mean ± SD: 1.80 ± 0.26 versus 1.69 ± 0.22; p < .001), with a further significant reduction at 10-15 days post-procedure (1.45 ± 0.26; p = .001). Donor RAD PSV increased significantly after FLC (15.76 ± 3.25 versus 17.28 ± 3.19; p < .001), with continued elevation at follow-up (p < .001). Recipient fetuses also demonstrated a significant reduction in RAD PI at 24-48 hours (p < .001), though no significant change was observed between post-procedural time points. Preoperatively, RAD PSV differed significantly between donor and recipient fetuses (p < .05). CONCLUSIONS: Fetal RAD parameters, particularly donor RAD PI, demonstrate significant changes following FLC and may reflect restoration of systemic circulation in TTTS. These findings support the potential role of RAD measurements in TTTS assessment and prognostication, warranting further prospective validation.