Validation of cervical lesion proportion measure using a gridded imaging technique to assess cervical pathology in women with genital schistosomiasis

Abstract

Female genital schistosomiasis (FGS) is characterized by a pattern of lesions which manifest at the cervix and the vagina, such as homogeneous and grainy sandy patches, rubbery papules in addition to neovascularization. A tool for quantification of the lesions is needed to improve FGS research and control programs. Hitherto, no tools are available to quantify clinical pathology at the cervix in a standardized and reproducible manner. This study aimed to develop and validate a cervical lesion proportion (CLP) measure for quantification of cervical pathology in FGS. A digital imaging technique was applied in which a grid containing 424 identical squares was positioned on high resolution digital images from the cervix of 70 women with FGS. A CLP was made for each image by counting the total number of squares containing at least one type of pathognomonic lesions. For validation of inter- and intra-observer reliability, three different observers estimated CLP independently. In addition, a rubbery papule count (RPC) was determined in a similar manner. The intraclass correlation coefficient was 0.94 (excellent) for the CLP inter-rater reliability and 0.90 (good) for intra-rater reliability and the coefficients for the RPC were 0.88 and 0.80 (good), respectively. The CLP facilitated a reliable and reproducible quantification of the surface of the cervix affected by FGS pathognomonic lesions. Grading of cervical pathology by CLP can provide insight into the natural course of schistosome egg-induced pathology of the cervix. Moreover, CLP provides a measure for the efficacy of treatment.Author summaryFemale genital schistosomiasis (FGS) is characterized by development of egg-induced chronic inflammatory lesions of the cervix and the vagina. FGS causes various symptoms such vaginal discharge, dyspareunia and post-coital bleeding, and the disease is further associated with reproductive complications such as ectopic pregnancy and infertility. Moreover, FGS is today considered as a major risk factor for transmission of HIV in Sub-Saharan Africa. General prevention directed against Schistosoma infection and use of praziquantel as anthelmintic drug therapy are cornerstones in the FGS control strategy. In that overall context, we have developed an important new digital image tool for quantitative assessment of FGS evoked cervical lesions, which enables evaluation of treatment outcome at individual as well as community level. The tool will also provide new information in understanding the natural history of FGS including development of clinical pathology.