The Use of Indocyanine Green (ICG) in the Detection of Endometriosis-Related Fibrosis and Inflammatory Changes

Abstract

<h3>Study Objective</h3> Indocyanine green (ICG), a dye that fluoresces in areas of increased vascularity, has been shown to aid in the identification of endometriosis in otherwise normal-appearing or ambiguous 'clear' lesions. Fibrosis and inflammation involve vascular processes known to play a significant role in the natural history and pathogenesis of endometriosis. The aim of this study is to determine if ICG can detect fibrosis or inflammatory changes seen on histopathology, and to determine if such histopathologic evidence of fibrosis is associated with endometriosis. <h3>Design</h3> Retrospective chart review. <h3>Setting</h3> A community-based hospital. <h3>Patients or Participants</h3> Women ranging from ages 18-50 undergoing minimally invasive surgery using ICG for the diagnosis and treatment of suspected endometriosis between July 2014 to February 2022. <h3>Interventions</h3> Robotic-assisted resection of areas visualized using ICG fluorescence. <h3>Measurements and Main Results</h3> Of the 64 patients in this study, a total of 211 peritoneal biopsies from the pelvis were examined on pathology for presence of fibrosis and endometriosis. The use of ICG fluorescence demonstrated a sensitivity of 97.4% in detecting fibrosis and inflammatory changes with a negative predictive value (NPV) of 86.7%. A Chi-square statistical test was performed to calculate a significance value of 5.07 (p=0.024). Based on the chi-square result, the presence of fibrosis detected using ICG fluorescence is significantly associated with the histopathological diagnosis of endometriosis. <h3>Conclusion</h3> ICG fluorescence demonstrates high sensitivity and NPV in detecting fibrosis and inflammatory change which is also significantly associated with histopathological evidence of endometriosis. These findings support the growing literature that propose that fibrosis and inflammatory changes are inherently related to the natural history and pathogenesis of endometriosis. These findings may suggest that the presence of fibrosis in the absence of glands and stroma on histopathology does not definitively rule out a diagnosis of endometriosis. More studies are needed to further elucidate the role of ICG in detecting changes related to the pathogenesis of endometriosis.