Cervical length versus vaginal PH in the second trimester as preterm birth predictor
Abstract
Objective: To evaluate diagnostic value of vaginal pH and cervical length measurement in the second trimester of pregnancy as a preterm labor (PTL) predictor.
Methods: During a prospective cohort study 438 uncomplicated singleton pregnant women between 18 and 24 weeks of gestation were assessed regarding vaginal PH and cervical length. Vaginal pH was measured using Ph-indicator strips and cervical length was determined using transvaginal ultrasound. The cut-off values for vaginal PH and cervical length were defined as 5 and <30 mm respectively.
Results: Vaginal pH of 5 and above was found in 162/438 women (37%) while cervical length <30mm was found in 38/438 (8.7%). The incidence of PTL < 37 weeks was 87/438 (19.9%) while the incidence of early (PTL <34 weeks) was 51/438 (11.6%). Predictive value of higher vaginal PH was significantly more (31%) than vaginal PH<5 (13%) in predicting PTL. As a result, alkaline vaginal PH significantly increases the odds of preterm labor (OR=3.06). Shortened cervical length is better predictor of PTL than higher vaginal PH with positive predictive value of 71% and negative predictive value of 85%. Cervical length less than 30 mm nearly 14-fold increases odds of preterm birth (OR=13.9).
Conclusion: Compared to alkaline vaginal PH, shortened cervical length has better value to predict PTL overall. Â However, regarding early or late PTL, vaginal PH is more accurate to predict late PTL, while cervical length measurement is more appropriate to predict early PTL (<34 weeks).
Note: Manuscript has been published in local journal (in Iran) in Persian (Farsi) language in different form, but the authors re-analyzed the data and re-wrote it in English to publish it in an international journal.
doi: http://dx.doi.org/10.12669/pjms.312.6310
How to cite this:Foroozanfard F, Tabasi Z, Mesdaghinia E, Sehat M, Mahdian M. Cervical length versus vaginal PH in the second trimester as preterm birth predictor. Pak J Med Sci 2015;31(2):374-378. Â doi: http://dx.doi.org/10.12669/pjms.312.6310
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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