Examining the safety of menstrual cups among rural primary school girls in western Kenya: observational studies nested in a randomised controlled feasibility study

Objective Examine the safety of menstrual cups against sanitary pads and usual practice in Kenyan schoolgirls. Design Observational studies nested in a cluster randomised controlled feasibility study. Setting 30 primary schools in a health and demographic surveillance system in rural western Kenya. Participants Menstruating primary schoolgirls aged 14–16 years participating in a menstrual feasibility study. Interventions Insertable menstrual cup, monthly sanitary pads or ‘usual practice’ (controls). Outcome measures Staphylococcus aureus vaginal colonization, Escherichia coli growth on sampled used cups, toxic shock syndrome or other adverse health outcomes. Results Among 604 eligible girls tested, no adverse event or TSS was detected over a median 10.9 months follow-up. S. aureus prevalence was 10.8%, with no significant difference over intervention time or between groups. Of 65  S.aureus positives at first test, 49 girls were retested and 10 (20.4%) remained positive. Of these, two (20%) sample isolates tested positive for toxic shock syndrome toxin-1; both girls were provided pads and were clinically healthy. Seven per cent of cups required replacements for loss, damage, dropping in a latrine or a poor fit. Of 30 used cups processed for E. coli growth, 13 (37.1%, 95% CI 21.1% to 53.1%) had growth. E. coli growth was greatest in newer compared with established users (53%vs22.2%, p=0.12). Conclusions Among this feasibility sample, no evidence emerged to indicate menstrual cups are hazardous or cause health harms among rural Kenyan schoolgirls, but large-scale trials and post-marketing surveillance should continue to evaluate cup safety.