ULTRASOUND ASSESSMENT OF CERVICAL DYNAMICS DURING THE FIRST STAGE OF LABOR

Objective: Assessment of cervical dynamics during the first stage of l abor by a combination of ultrasound cervimetry and intrauterine tocogr aphy. Methods: Sixty-two parturients were divided into four groups: nu lliparous women in spontaneous (n = 9) or oxytocin-induced labor (n = 26), parous women in spontaneous (n = 11) or oxytocin-induced labor (n = 16). Intrauterine pressure and cervical dilatation were continuousl y recorded and assessed by off-line computer analysis. Results: All wo men with spontaneous labor showed cervical responses to uterine contra ctions at the beginning of the recording. The first cervical response to a uterine contraction occurred at a significantly smaller dilatatio n in parous than in nulliparous women with induced labor (2.9 and 3.6 cm, respectively). Also, acceleration of-cervical dilatation occurred at less dilatation in parous than in nulliparous women (3.4 cm and 4.8 cm, respectively), and myometrial work per cm of cervical dilatation was less in parous than in nulliparous parturients. Conclusions: The r esults indicate significant differences between cervical dilatation pa tterns in nulliparous and parous women, which may be due to structural cervical changes caused by labor and parturition. The labor patterns found were different from those originally described by Friedman (Frie dman EA. Graphic analysis of labor. Am J Obstet Gynecol 1954; 68: 1568 -1575),as no deceleration phases were detected. Ultrasound cervimetry is a valuable technique for the study of cervical dynamics during labo r.