It has been seen that about globally 30% of women are affected by bacterial vaginosis (BV) making it the most prevalent form of vaginal infection.1 Bacterial vaginosis frequently recurs despite full successful treatment. The effect of bacterial vaginosis has been seen with increased postoperative infections after gynaecological surgeries but not so much after obstetric surgeries.2 It is primarily a polymicrobial phenomenon and many adverse outcomes associated with it.3 It increases the chances of acquiring other sexually transmitted infections especially human immunodeficiency virus type-1 (HIV-1) infection.3 In the obstetric population it is seen to be associated with increased chances of preterm birth.3 Therefore there are no recommendations for routine antenatal screening and treatment of bacterial vaginosis. Need of the hour is to develop innovative preventive as well as management approaches so that burden of bacterial vaginosis is reduced in terms of its prevalence, recurrence and several adverse associations.3 Novel point-of-care (POC) tests have the potential to fill the underlying unmet need for rapid and accurate detection of bacterial vaginosis (BV).

The vaginal secretions pH in bacterial vaginosis is seen to be greater than 4.5 (4.7 to 5.7).4 This higher pH is due to the alteration of normal vaginal bacterial flora, which in turn is because of fall in number of hydrogen peroxide-producing lactobacilli. On microscopical examination of the vaginal secretions there are scarce leukocytes in addition to plenty of clue cells which are pathognomic of bacterial vaginosis. Hence presence of clue cells is used as laboratory confirmatory test for BV. The presence of clue cells indicates laboratory-confirmed bacterial vaginosis. This study was done to analyze the correlation between vaginal pH with clue cells and to establish its sensitivity and specificity as a point-of-care test for bacterial vaginosis.

The study was carried out in the Outpatient Department (OPD) of Obstetrics & Gynecology along with the laboratory of Department of Microbiology, J.K. Hospital Bhopal from October 2022 to March 2023. Institutional Ethics Committee of LN Medical College and JK Hospital approved the study for ethical considerations [ LNMC&RC/Dean/2022/Ethics/012]. The Declaration of Helsinki Principles were followed during conduction of entire study. 96 women who came to OPD with complaints of discharge per vaginum participated in the study after due written and informed consent. Women who were menstruating, antenatal women, women with cervical cancer and women who were on antibiotic treatment for vaginal discharge were excluded from the study. Clear documentation was done for participant’s demographic details, complaints, clinical findings and treatment history. Women were asked not to pass urine before the test was applied to avoid contamination and it was ensured that no antibiotic treatment was taken before the sample to prevent false results. Vaginal pH kit used included a pH screening strip, a sterilized cotton swab and a color chart to determine pH (Fig.1). After due consent, the swab was inserted into the vagina followed by rubbing all sides of the swab’s tip on the pH screening strip for 10 seconds. After 30 seconds, the color on the screening strip was compared with the pH-determining color chart provided in the kit. pH more than 4.5 according to the color chart was diagnosed as bacterial vaginosis. Another swab was used to make a slide which was sent to the microbiology laboratory for visualization of clue cells and was taken as the confirmatory test for bacterial vaginosis. Data thus obtained was analyzed. Vaginal Ph kit was used as a POC Test for Bacterial Vaginosis in the study and its Sensitivity, specificity, Positive predictive value (PPV) and Negative Predictive Value (NPV) were calculated.

Out of 96 cases, the majority belonged to the age group 26 to 35 years and upper socioeconomic status as shown in Table 1 and Table 2.

Table 1: Age distribution

Table 2: Socioeconomic distribution.

Out of 96 cases included in the study, only four women had vaginal pH less than 4.5 and the rest all had a pH more than 4.5 which contributed that 95.83% of women in the study had bacterial vaginosis. (Table 3)

Table 3:  Vaginal pH detected by Vaginal pH detection Kit

Irrespective of the pH denoted in the vaginal swab, all cases were subjected to laboratory estimation for the clue cells visualization which is taken as a laboratory confirmatory test for Bacterial vaginosis. It was seen that out of 92 women with pH more than 4.5, 66 (71.7%) had the presence of clue cells as well hence confirmed cases of bacterial vaginosis. The rest of the 26 women turned out to be false positives as clue cells were absent on microscopic evaluation. Out of four women with pH below 4.5, only two women had clue cells in the laboratory test and other two women had negative result for clue cells thus contributing to be the true negatives. (Table 4)

Table 4: Correlation of Vaginal pH detection kit and Clue cells presence on Laboratory evaluation

All the data on statistical analysis showed that the Vaginal pH detection kit as a point of care test for bacterial vaginosis was found to have a Sensitivity of 97.06% and Specificity of 7.14% (95% CI) along with Positive Predictive Value (PPV) 71.74% and Negative Predictive Value (NPV) 50.0%.

Screening tests are not actually diagnostic, but they just identify individuals who have a higher predilection towards a disease being tested. This makes early management feasible and therefore resulting in decreased morbidity and mortality. Ideal Screening test needs to be extremely sensitive, cost effective, easy to administer along with minimal discomfort. These tests ideally should be easily accessible as well as minimally invasive. Utilization of screening tests in a point of care (POC) setting helps reduce the burden on diagnostic tests and consequentially on the health system too. Although it is widely accepted that these POC tests need to be benchmarked against the agreed gold standard test.5

Laboratory diagnosis is considered the gold standard for diagnosis of Bacterial vaginosis.6 despite that fact, it is seen that many times due to the non-availability of facilities for clinical examination or competent staff in the low resource field scenario, there is a huge possibility of misidentification of cases. The prevalence of bacterial vaginosis differs widely from country to country irrespective of similar geographical and ethical considerations and it has been estimated to be in the wide range of 8% to 75% depending on the diagnostic strategy.7 Based on Gram staining laboratory test showing clue cells which is the gold standard for BV, the prevalence was found to be only 35%, hence it is evident that syndromic management algorithm over diagnoses and over treats bacterial vaginosis.8

Waiting for laboratory confirmation of diagnosis we have two options--empirically give treatment which drains resources as well as may lead to antibiotic resistance. The other option is to treat only after laboratory confirmation which in the Indian scenario is not in the best interest of women due to high loss to follow up for re-visits. Hence there is a need for point-of-care tests to balance out just the use of treatment modalities as well as giving more directed treatment and making it easily accessible on the same visit.

The results of our study are similar to observations made by Posner et al, wherein pH plus amine (whiff) test was evaluated using the Fem Exams card, a rapid test developed for BV diagnosis.8 It was found to be an easy to implement screening test in low resource settings.

In a study by Hemlatha et al conducted in India in 2013, they found that Vaginal pH above 4.5 as detected by the pH strips and pH Glove had a sensitivity of 72% and 79% and specificity of 60% and 53%, respectively for screening of BV.9 Hence, they concluded for detecting women affected with BV, the determination of vaginal pH is relatively sensitive but less specific. It was observed that when the whiff test was performed along with the pH test, the specificity improved but at the cost of reduced sensitivity. On an outpatient basis it was thus noted that both the pH strip and pH glove are equally suitable for screening POC tests for BV.

In another study done in Rhode Island, the most sensitive of all the criteria was found to be vaginal pH (sensitivity 89%) and a positive amine odor was the individual criteria with the highest specificity (93%.).10 The sensitivity of 97.06% for vaginal Ph was seen in our study too.

In a review done by Lin YP et al, the value of vaginal pH was evaluated in Common Vaginitis diagnosis and treatment. They noted that the sensitivity of using only a pH test to diagnose vaginitis was 66% however, using a pH test combined with clinical symptoms to screen for BV can increased the sensitivity to 81.3%.11

A study done on 100 women in 2021 in India by Prasad N showed that 78% of syndromically screened RTIs/STI cases had laboratory evidence of infection as well. Whereas a positive predictability of 92% with 75% sensitivity and 79% specificity was found when screening was carried out by a combined approach, i.e., syndromic approach and Vaginal pH estimation both.12

Evidence clearly suggests that vaginal pH tests can serve as a tool for the clinical detection of BV.11 It is a very convenient tool for women to use by themselves to monitor their vaginal health, especially while experiencing vaginitis symptoms, though the sensitivity is limited. Reasons for falsely elevated vaginal pH can be when semen and mucus are found along with vaginal secretions. Good detection rates can be ideally achieved by exclusion of women who have had coitus in the previous two days as well as women with Candidal infection. However, women with mixed vaginal infections could not be excluded clinically, which is a limitation for our study. It is also to be understood that a limitation of sample size as seen in our study could be countered in the future by evaluating vaginal pH detection kits in multicentric studies.

The benefits of using a vaginal pH detection kit as a point-of-care (POC) screening test include immediate results which can allow for immediate diagnosis and treatment during an outpatient department visit. Also, this test can accurately identify most cases of bacterial vaginosis and hence has a high sensitivity of 97.06% thereby reducing the risk of false negatives. The most significant benefit is that healthcare providers can prescribe directed treatment rather than using empirical treatments which are a drain on healthcare resources. This can lead to better patient outcomes and reduce the risk of antibiotic resistance in the long run. However, it's imperative to note that while a high vaginal pH is indicative of BV, it's not definitive.

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