Discharge pad weight predicts continence of women after obstetric fistula repair
Introduction: After repair of an obstetric vesicovaginal fistula (VVF), women may continue to experience incontinence from unsuccessful repair or other causes. However, it is difficult to predict which women will have residual incontinence and need close follow-up. The 1-hour pad weight is recommended as a non-invasive test of continence by the International Continence Society1, but this has not been previously used as a screening test for continence in a repaired fistula population.
Objective: To determine if a 1-hour pad weight at discharge can predict continence status during the first 90 days after VVF repair.
Methods: We analyzed data from a prospective cohort study of women who had VVF fistula repair at the Fistula Care Centre in Lilongwe, Malawi between January 2012 and December 2014. Data on demographics, physical exam findings, and post-operative pad weight were collected during surgical admission, and data on residual incontinence status was collected during 1-month and/or 3-month follow-up visits. 1-hour pad weights performed on day 14 post-operative that were ≥1.5 grams were considered positive, whereas pad weights <1.5 grams were considered negative. Women were considered to be continent if they had Grade 1 continence (“no incontinence”) during their follow-up visit and to have residual incontinence if they had Grade 2-5 continence. Differences in the baseline and surgical characteristics between women with no incontinence or residual incontinence were calculated using Wilcoxon-Mann-Whitney tests and Pearson’s χ2 tests. Sensitivity, specificity, positive and negative predictive values, and risk ratios were calculated to assess the utility of using discharge pad weight to predict continence at follow-up.
Results: Four hundred and thirty-four women had both VVF repair and a 1-hour pad weight performed prior to discharge. Of the 336 who completed follow-up within 90 days of repair, 136 (40.5%) had a positive pad weight and 200 (59.5%) had a negative pad weight. Women with residual incontinence were older (p=0.024), had larger fistulas (p<0.001), and were more likely to have had a positive discharge pad weight (p<0.001). The 1-hour pad weight had a high negative predictive value (93.5%).
Conclusions: A negative 1-hour pad weight at discharge may help to predict women who will remain continent within 90 days of VVF repair. The addition of the 1-hour pad weight may help to identify women in need of close follow-up in settings where resources are limited and follow-up after fistula repair is difficult.