Surgery beyond the visible light spectrum: theoretical and applied methods for localization of the male urethra during transanal total mesorectal excision.

The risk of urethral injury during transanal total mesorectal excision (taTME) is delineated, and potential risk factors for iatrogenic transection are reviewed. A variety of applied and theoretical techniques can be used by surgeons to diminish the risk of injury in males undergoing this operation. Many of the approaches utilize non-optic media and wavelengths beyond the visible light spectrum which can enhance the surgeon's frame of reference. The aim of the present study was to assess the techniques and theoretical approaches to urethral localization during taTME. Future directions in surgical imaging are also discussed, including the use of organic dyes, quantum dots, and carbon nanotubes; collectively, technology that could someday provide surgeons with an ability to identify anatomic structures prone to injury.