EP564 Sentinel lymph node biopsy using indigocyanine green fluorescence in uterine cancer

Introduction/Background Professional societies recommend sentinel lymph node biopsy using indigocyanine green (ICG-SLNB) as a staging strategy in endometrial cancer. According to a meta-analysis, ICG as a tracer injected into the cervix yields higher detection rates than other tracers or injection sites. Compared to standard systematic lymphonodectomy (LND), ICG-SLNB has lower morbidity, allows detection of lymph nodes (LN) in atypical locations and allows microstaging of LN. Methodology This retrospective analysis included 40 uterine cancer patients having ICG-SLNB, using conventional laparoscopy or robotic surgery from 2012–2019. ICG was injected into the cervix (1 ml subepithelial, 1 ml stromal). Two optical systems were used: Karl Storz Opal-1 NIR/ICG (n=10) and Novadaq Pinpoint (n=30). Pathological ultrastaging was done at 2 mm intervals with cytokeratin staining. Technical failures, detected SLN and locations were assessed. Technical failures were defined as no LN staining or only unilateral pelvic staining. We also compared sites of LN metastasis using ICG-SLNB to 16 endometrial cancer patients having metastatic LN assessed by SLNB. Results Five technical failures occurred (12.5%). Median number of sentinel LN found using Pinpoint was 10 (range 2–45) and using Opal-1 was 2 (range 1–5), which was significantly less (p Conclusion The imaging device impacts both detection and technical failure rates. 4% of SLN were in atypical locations, however none were metastatic. The pattern of nodal spread was similar in both ICG-SLN and systematic LND. Disclosure Nothing to disclose.