RESUMEN
UNLABELLED: BACGROUND: preterm birth is a major obstetric problem that contributes to 70% of perinatal mortality. OBJECTIVE: to determine the sensitivity, specificity and predictive values of fetal fibronectin and cervical length as predictors of preterm birth in the HGR No. 36, Puebla. MATERIAL AND METHODS: observational, prospective. comparative study. Pregnant women were included between 24 and 33 weeks amenorrhea and diagnosis of preterm labor. Quik Chek Kit was used to detect fibronectin using qualitative methods, and then subjected to measurement of cervical length with endovaginal ultrasound. Patients with a positive result or both proceeded to start treatment. To calculate sensitivity, specificity and predictive values were used odds ratios and Fisher exact test for statistical analysis. RESULTS: of 66 patients 34% reported positive fibronectin with a sensitivity and PPV of 92% and 77% compared with the assessment of 27% of patients with short cervical length at 55% and 88% respectively. 28% had two positive marker (fibronectin/cervical length), the sensitivity, specificity and positive and negative predictive values increased significantly (86%, 100%, 93%, 100%). The average time between birth positive test was observed at 21 days. Risk factors for preterm delivery were found: patients under 25 years (P:0.0009), primigravida (P:0.0057), genitourinary infection (P:0.0001). CONCLUSION: the double marker fibronectin / cervical length is useful for determining patients at risk of preterm delivery because of its high specificity and NPV, ideal for easy handling and low cost.