Strengths of this study included the consistent entry criteria, the use of histologic and microbiologic markers for upper genital tract disease, and the large number of women studied. Weaknesses included the lack of a purely unaffected control group (i.e., a group of women without clinical symptoms of PID) and the lack of a laparoscopic diagnosis for PID. Women with objective evidence of PID were compared with women in the same cohort who had no evidence of the disorder, all of whom had signs and symptoms consistent with PID. This made it unlikely that women would be selected in a biased fashion (i.e., by both douching patterns and outcome) for this study because the outcome was actual upper genital tract disease. Furthermore, in the previous report by Wolner-Hanssen et al, both control subjects such as those used in the current study and asymptomatic “external” control subjects gave similar results. Therefore, the authors think it unlikely that their results, comparing clinically similar women, are spurious. The authors also regarded laparoscopic data as not compulsory because the histologic finding of endometritis has been well correlated with salpingitis in previous studies.
Another weakness was the fact that for many of the significant findings, the lower bounds of the confidence intervals included, or came close to including, 1. This may well reflect small sample sizes within stratified comparisons. Finally, by necessity, this study relied on reported douching behavior. The focus on douching within the previous month may have minimized, but probably not eliminated, all the problems with exposure classification based on recall
This large study of predominantly black women with symptoms of PID showed a relation between douching and endometritis or UGTI, particularly for women who had douched more frequently and more recently. These data add to the growing literature suggesting that douching might relate to PID.