engleski

Fetal fibronectin and sonocervicometria in prediction of preterm birth

The aim of the study was to assess reability of new markers of preterm delivery for the group of pregnancies known as traditionally ririsky of preterm delivery. A group of 50 pregnant women having traditional risk factors of preterm delivery wae included into prospective study of fetal fibronectine taken from the cervical swab, and ultrasound measurements of cervical length for the periods of 24, 28 and 32 gestation weeks. All the three measurements were done in 40 pregnancies. The length of cervix was categorized either as short (< 25 mm) or normal (> 25 mm). Fibronectine concentration was evaluated for the same pregnancies and the same gestation age, and was categorized either as positive (> 50 ng/mL) or negative (< 50 ng/mL). From the total of 40 pregnant women who had their investigations completed, 8 (20 %) of them had preterm delivery (< 37 weeks). Sensitivity of positive fibronectine test was found to be low (50%) for 24 and 28 gestation weeks, with an increasing tendency (87, 5%) for 32 gestation weeks. High specificity (93, 7%) was detected throughout all gestation weeks studied. Positive predictive value of this marker increases as gestation weeks grow (from 66, 7% to 77, 7%). Negative predictive value was found to be high (88, 2% for two first measurements vs. 96, 7% for 32 gestation week measurement). Relative risk of preterm delivery of this merker increases with gestation age: from 8 to 14 time in the 32nd gestation week. Sensitivity of sonocervocometry was found to be high through entire period of gestation (75- 100%), however specificity was found to be decreasing as gestation weeks grow (87, 5% for 24 and 28 gestation weeks vs. 75% for 32 weeks of gestation). Relative risk was also found to be decreasing (6, 8 and 4 times9 due to false positive findings. Pozitive predictive value was relatively low (60%, 66, 7% and 50%), whereas negative predictive value, as was the case with fetal fibronectine, was found to be very high (93, 3-100%). Negative predictive value of fetal fibronectine concentraton and "long" cervical length may help us to reliably exclude the pregnancies with no risk of preterm delivery in a group of pregnancies otherwise known as traditionally risk of preterm delivery. Positive predictive value of both markers is a bit weaker. Sonocervicometry is an easy-to-do and cost benefit technique, and is therefore convenient for routine clinical use. Determination of fetal fibronectine values should be a matter of choice of each obstetrician.

Fetal fibronectin; sonocervicometria; preterm birth; risc factors

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