Cervical lesion proportion measure using a digital 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. CLP was measured for each image by observers counting the total number of squares containing at least one type of FGS associated lesion. For assessment of inter- and intra-observer reliability, three different observers measured 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 FGS associated lesions of the cervix. In the future, grading of cervical pathology by CLP may provide insight into the natural course of schistosome egg-induced pathology of the cervix and may have a role in assessing praziquantel treatment efficacy against FGS. Trial Registration: ClinicalTrials.gov, trial number NCT04115072; trial URL https://ichgcp.net/clinical-trials-registry/NCT04115072?term=Female+genital+schistosomiasis+AND+Madagascar&draw=2&rank=1.

Conflict of interest statement

The authors have declared that no competing interests exist.

Figures

Fig 1. Digital image showing female genital schistosomiasis associated pathognomonic lesions of the cervix (picture A) and the same lesions being digitally marked by QubiFier to determine the cervical lesion proportion (picture B).

The left picture (A) shows an area, which contains homogenous yellow sandy patches appearing as yellow colored area (indicated by white dashed line). The differently colored arrows indicate the other pathognomonic lesion types: a grainy sandy patch (white arrow), clustered grainy sandy patches or rice-grain shaped sandy patches (green arrow) and a rubbery papule colored in beige with an uneven surface (yellow arrow). Abnormal blood vessel (rounded, uneven-calibered, corkscrew or convoluted) are indicated by the blue arrow. The right picture (B) shows squares of the grid marked digitally containing any types of pathognomonic lesions. The red arrow shows the proportion of the cervix covered by any type of pathognomonic lesions.

Fig 2. Flowchart displaying the different testing procedures in the FGS digital gridded imaging technique study in which 70 images of the cervical portio were reviewed for cervical lesion proportions (CLP) and rubbery papule counts (RPC), respectively.

Fig 3. Distribution of cervical lesion proportions (%) for the 60 digital images as rated by the three observers and ranked in accordance with the respective individual mean values.

Fig 4. Three cases representing different levels of female genital schistosomiasis (FGS) associated pathology in accordance with the cervical lesion proportion (CLP) categories: low (1 to 15%), intermediary (16 to 30%), and high (>30%).

Fig 5

A box-and-whisker-plot of cervical lesion proportions (%) for each observer (A, B, and C) rating the 60 digital images. The bold horizontal line indicates the median, the upper and the lower line of the box the interquartile range.

Fig 6

A box-and-whisker plot of median rubbery papule counts (n) and interquartile range for each observer (A, B, and C) rating the 60 digital images.

Fig 7. Distribution of rubbery papule count (n) for the 60 digital images as rated by the three observers and ranked in accordance with the respective individual mean values.