The sensitivity, specificity and accuracy of liquid based cytology (LBC) in the diagnosis of vaginal candidiasis in Harare, Zimbabwe

Abstract

Background: The primary role of Liquid Based Cytology (LBC) is the detection of atypical epithelial cells of the cervix; however, it can play a marginal role in the diagnosis of infections of the vagina. A few studies have evaluated the performance of a conventional Pap smear for the diagnosis of Candidiasis. However, there is no published data on the performance of Liquid Based Cytology (LBC) (a superior sample preparation method) for the detection of vaginal Candida. Objective: To determine the sensitivity, specificity, NPV, PPV, and accuracy of LBC in the diagnosis of vaginal Candidiasis. Design: Cross sectional descriptive study. Setting: Cimas Medical Laboratories. Subjects: Women presenting with vaginal discharge. Materials and Methods: Fixed LBC slides were stained using the Papanicolaou stain and evaluated for the presence of Candida. A High Vaginal Swab (HVS) culture on Sabouraud Dextrose Agar (SDA) culture was used as the gold standard. A Cohen’s Kappa test was done to determine the level of agreement between LBC and HVS culture. Results: Of the 299 paired samples (LBC and HVS) evaluated for the presence of Candida, 29 LBC (9.7%) and 93 HVS (31.1%) were positive for Candida. The sensitivity, specificity, PPV, NPV and accuracy of the LBC was 25.8, 97.6, 82.8, 74.4 and 75.3% respectively. The LBC and HVS showed a fair agreement in detection of Candida (Kappa value = 0.307, p value < 0.05). Conclusions: 1. LBC is 26% sensitive and 75% accurate; therefore, it can assist but is not always reliable for diagnosing of vaginal Candidiasis. 2. The performance of LBC in the detection of vaginal Candidiasis is similar to that of conventional Pap smears.