Introduction
VaIN is the dysplasia of the vaginal squamous epithelium, mostly associated with persistent HR-HPV infection. VaIN is classified as low-grade squamous intraepithelial lesion (LSIL) including VaIN1 (mild dysplasia in the past classification) and high-grade intraepithelial lesion (HSIL) including VaIN2,3 (moderate and severe dysplasia respectively) according to the 2014 WHO classification of tumors of female reproductive organs [1]. The natural history of VaIN is similar to that of cervical intraepithelial neoplasia (CIN), but the incidence of VaIN is less than 1% of CIN. The annual morbidity of VaIN was about 0.2~2 per million [2], accounting for approximately 0.4% of all squamous neoplastic lesions of the lower genital tract [3]. The incidence of VaIN was severely underestimated due to missed diagnosis. It was reported that VaIN consumed 8.09%, 12.45% and 13.08% of squamous lesions of the lower genital tract from 2013 to 2015 in a hospital in China [4]. The yearly increasing detection rates of VaIN were attributable to the increased awareness of the condition in our peers.
The management for LSIL(VaIN1) is conservative because most LSIL(VaIN1) can regress spontaneously [5~7]. Otherwise, the rate of HSIL(VaIN2,3) progressing to cancer was about 2~12% [8~10]. Thus, HSIL(VaIN2,3) are usually treated aggressively. The treatment modalities for HSIL(VaIN2,3) generally include conservative observation, topical agents, laser ablation, excision and so on [3]. Because of the specialty of vaginal anatomy and sexual function, the excisional procedure is technically difficult and adversely affects the quality-of-life. Observation or topical agents for VaIN show uncertain effects or evident side effects. Thus, laser ablation has become a dominant choice for VaIN with the advantages of considerable efficacy, easy training for practitioners and few severe complications [11]. There was obvious fluctuation in the literature about the efficacy of laser ablation for VaIN with effective rate varying from 47% to 100% and relapse rate varying from 20% to 57% [8,12~18]. The samples of literature on laser ablation for VaIN were usually small, and the essays lacked detailed description of treatment modalities and standard follow-up schedule.
To achieve a standard method of CO2 laser ablation for the treatment of VaIN with stably high cure rate and low complication incidence, this study discussed the details of MTLA procedure and related high-risk factors.