[Can genital infections alter the results of preterm birth predictive tests?].

Purpose: To determine if the presence of infectious agents in vaginal or cervical content can alter the results of the insulin-like growth factor binding protein-1 (phIGFBP-1) test and the measurement of cervical length (CC) by transvaginal ultrasonography.

Methods: A total of 107 pregnant women with a history of spontaneous preterm birth were submitted to the phIGFBP-1 test and to measurement of CC by transvaginal ultrasonography every 3 weeks, between 24 and 34 weeks of gestation. Genital infections were determined immediately before testing. The patients were distributed into four groups (GA, GB, GC, and GD) and the correlation between genital infection and changes in the tests was determined within each group based on the odds ratio (OR) and the Pearson correlation coefficient.

Results: In each group, over 50% of the patients had genital infections (GA 10/17; GB 28/42; GC 15/24; GD 35/53), with bacterial vaginosis being the main alteration of the vaginal flora. Positive results for phIGFBP-1(GA 10/10; GB 18/28; GC 15/15; GD 19/35) and CC ≤ 20 mm (GA 10/10; GB 20/28; GC 10/15; GD 20/35) were obtained more frequently in patients with genital infection in all groups. Nonetheless, when applying the Pearson correlation coefficient we detected a poor correlation between genital infection and positivity for markers.

Conclusion: The presence of changes in the vaginal flora and of other genital infections does not significantly alter the results of phIGFBP-1 and the measurement of cervical length when compared to cases without infection. However, more studies with larger samples are necessary to confirm these results.