Preputial pedicle flap ICG blood flow assessment during proximal hypospadias repair: Development of a standardized protocol.

Introduction: Blood supply to preputial flap drives outcomes of hypospadias repair. Unfortunately, we only have surgeon's subjective assessment to evaluate flap perfusion which may not be accurate. Indocyanine green (ICG) has been used in a multitude of surgeries for perfusion assessment, however, no standardized protocol has been described for use of ICG in hypospadias repairs. The aim of this study is to develop a standardized protocol of ICG use in proximal hypospadias and establish perfusion patterns of preputial flaps.

Study Design: A pilot study was conducted using ICG in patients with proximal hypospadias undergoing first stage repair with a preputial flap. The Stryker SPY PHI system and novel quantification software, SPY-QP, were used for ICG imaging. An adaptive approach was taken to develop and implement a standardized protocol (Summary Figure). Per the protocol, ICG was administered at 3 time points which were felt to be critical for assessment of flap perfusion. Of the study patients who have undergone second stage repair, ICG was also used to reassess the flap prior to tubularization of the urethra.

Results: A total of 14 patients underwent first stage hypospadias repair with preputial flaps and intraoperative use of ICG. Median ICG uptake of the prepuce after degloving (dose 1) was 58.5% (IQR 43-76). ICG uptake decreased after flap harvest and mobilization (dose 2) with a median ICG uptake of 34% (IQR 26-46). ICG uptake remained stable after securing the flap in place and closing the skin (dose 3) with a median ICG uptake of 34% (IQR 25-48). ICG was able to delineate subtle findings in the preputial flaps not visible to the naked eye and in one case impacted intraoperative decision making. To date, 5 patients have undergone second stage repair. Flap assessment prior to tubularization of the urethra showed hypervascularity with a median ICG uptake of 159%.

Conclusions: A standardized protocol for ICG use in proximal hypospadias was successfully developed and implemented. ICG uptake in the preputial flap decreased with increasing manipulation and mobilization of the flap. ICG was able to detect changes to flap perfusion which were not able to be seen with the naked eye. Reliance on surgeon's subjective assessment of flap perfusion may be inadequate and ICG could provide a useful tool for surgeons to improve preputial flap outcomes. ICG may also enhance the learning experience for trainees and early career urologists in these complex surgeries.