Introduction and hypothesis: This study explored whether the optimal pessary type and size can be predicted using the specific pelvic organ prolapse quantification system (POP-Q) measurements in women with pelvic organ prolapse in a fitting trial.

Methods: We conducted a prospective study in women who had undergone pessary fitting. A total of 78 patients with stage II, III or IV symptomatic pelvic organ prolapse completed a detailed history. Data were analysed using nonparametric tests, continuity correction chi-squared tests and multivariate logistic regression.

Results: Differences in total vaginal length (TVL; p < 0.01) and vaginal introitus width/TVL ratio (p = 0.012) were observed between patients with and without a history of hysterectomy. Patients with a history of hysterectomy and patients with a larger vaginal introitus had more success with the Gellhorn pessary than with the ring pessary with support (p = 0.005 and p = 0.01, respectively). Factors determining the size of the ring pessary with support were the genital hiatus (GH) width (p = 0.044), TVL (p = 0.011), vaginal introitus width (p < 0.001), and vaginal introitus width/TVL ratio (p = 0.025). Factors determining the size of the Gellhorn pessary were the GH width (p = 0.025), GH width/TVL ratio (p = 0.013), vaginal introitus width (p = 0.003), vaginal introitus width/TVL ratio (p = 0.001), stage of apical prolapse (p = 0.006) and stage of posterior prolapse (p = 0.003).

Conclusions: Patients with a history of hysterectomy or with a larger vaginal introitus were more likely to achieve success with the Gellhorn pessary. The GH width and the vaginal introitus width influenced the size of both pessaries chosen. The TVL was predictive of the optimal size of the ring pessary with support but was not predictive of the optimal size of the Gellhorn pessary. Finally, the size of the Gellhorn pessary was associated with POP stage.