I read, with interest, the article titled, “Use of the Learning Curve-Cumulative Summation test for quantitative and individualized assessment of competency of a surgical procedure in obstetrics and gynecology: fetoscopic laser ablation as a model.” Papanna et al should be congratulated for attempting to apply a standardized methodology of assessment of competency for the laser procedure used for the treatment of the twin-twin transfusion syndrome (TTTS).

However, I find it highly unusual that the outcome used to assess proficiency for this procedure was limited to a clinical one, namely, the survival of at least 1 twin. Surely, a multitude of factors that may or may not be related to surgeon competency may affect a clinical outcome, regardless of which clinical outcome is chosen. The surgical goal of laser treatment for TTTS is to occlude all vascular communications. Thus, surgical success should be defined, at least in part, as the number of cases without residual patent vascular communications. This can be documented using injection studies of the placenta after delivery of 2 live twins using methodology described previously. Placental injection studies are possible in approximately 60% of the total laser treated TTTS population.

It is standard procedure for surgeons in other disciplines to submit tissue for pathologic evaluation. Similarly, it should be standard protocol for fetal surgeons to have the placenta submitted for injection studies and gross and microscopic assessment. Placental injection studies should be a part of any assessment of surgeon proficiency for laser surgery treatment of TTTS.