Indocyanine green (ICG)-GUIDED lymphatic sparing laparoscopic varicocelectomy in children and adolescents. Is intratesticular injection of the dye safe? A mid-term follow-up study

Background: Laparoscopic Palomo varicocelectomy using indocyanine green (ICG) fluorescent lymphography (FL) is standardized technique to perform lymphatic sparing and avoid post-operative hydrocele. No data regarding the safety of intratesticular injection of ICG are currently available. Objective: The study aimed to assess the safety and efficacy of this procedure at mid-term follow-up. Study design: Seventy-two patients (median age 14.5 years) undergoing laparoscopic Palomo varicocelectomy using ICG-FL from January 2019 to July 2022, were enrolled. Operative indication was high-grade varicocele in all patients, associated symptoms in 30/72 (41.7 %) and left testicular hypotrophy in 42/72 (58.3 %). Follow-up included clinical examination at 1, 6, 12 months and scrotal Doppler ultrasonography (US) at 12 months postoperatively to assess varicocele persistence, hydrocele, and injections-related complications. Results: Lymphatic sparing was achieved using ICG-FL in all cases. No intra-operative complications or adverse reactions secondary to ICG occurred. The median follow-up was 22.8 months (range 11-49). Self-limited scrotal hematoma at the injection site occurred in 1/72 (1.4 %). Intratesticular hypoechoic millimetric area was detected at the injection site in 3/72 (4.2 %) on US. This finding disappeared after 1-year observation in 2/3 cases (66.7 %) (Figure). Persistent grade II varicocele was observed in 4/72 (5.5 %), not requiring re-intervention. No hydrocele occurred and 14/22 (63.6 %) with pre-operative hypotrophy showed catch-up growth. Discussion: ICG-FL was clinically safe, with no allergy or systemic adverse reactions to the dye reported in this series. No injury directly related to the injection of the dye was clinically observed, except for self-limiting scrotal hematoma in one patient. A millimetric hypoechoic and avascular area in the body of the left testicle at the injection site was found on scrotal US at 1-year follow-up in 3 patients of our series. This finding does not seem to be clinically relevant as patients were asymptomatic and serum tumor markers were normal in all cases. Furthermore, the hypoechoic area with calcifications resolved 1 year later in 2/3 patients. The absence of evolution of this finding seems to exclude the heteroplastic nature. We hypothesized that this finding may be linked to elevated volume and/or pressure of intratesticular injection. Future prospective study with larger series and longer follow-up is needed to assess long-term testicular outcomes. Conclusion: Laparoscopic Palomo varicocelectomy using ICG-FL reported excellent outcomes with low incidence of varicocele persistence and no post-operative hydrocele. These preliminary data also confirmed safety of intratesticular injection of ICG at mid-term follow-up, without specific risks for both testis and patient.