141: Accuracy of digital measurement of the cervical portio length

Abstract

RICHARD BURWICK, GENE LEE, JENNIFER BENEDICT, MARGARET POURTEMOUR, MICHAEL G. ROSS, Harbor-UCLA Med. Ctr. (LABioMed), Dept. of Ob/Gyn, Torrance, California OBJECTIVE: To evaluate the accuracy of clinician-performed cervical length measurements using digital exams, as compared to an objective measure using the Cervilenz device in women presenting with symptoms of preterm labor. STUDY DESIGN: Informed consent for cervical exams was obtained from women presenting in preterm labor between 24-34 weeks gestation, as part of a prospective trial of factors predictive for preterm delivery. Exclusion criteria included cervical dilation 3cm, ruptured membranes, multiple gestation, vaginal bleeding, or intercourse within the prior 24 hours. Cervical length was measured initially by digital exam, estimated to the nearest 0.1 cm. A second examiner, blinded to the results of the digital exam, measured the cervical portio length (at 3:00 or 9:00) utilizing the Cervilenz measuring device. RESULTS: Digital measures of cervical length varied widely, and did not correlate significantly with the objective Cervilenz measures (r 0.23, p 0.10). Digital measures tended to be less than Cervilenz measurements, with a mean absolute difference of 0.88 cm (range 0.20-2.10cm, p 0.0005). The mean absolute difference between digital exam and Cervilenz measurements trended to be even greater among women with cervices described as “soft” versus “medium” or “firm” (1.08 vs. 0.76cm, p 0.07), and in women with long ( 3.5cm) versus short ( 2.5cm) cervices (1.29 vs. 0.76cm, p 0.09), but these did not reach statistical significance. The mean absolute difference between the two measures did not change in the presence or absence of uterine contractions (0.84 vs. 0.92cm, p 0.36). CONCLUSION: Using the objective Cervilenz measure as the standard, these results illustrate the relative inaccuracy of digital exams for cervical length assessment in preterm labor patients. We propose that if cervical length assessments are used for clinical decisions regarding preterm hospitalization or tocolysis, they be performed by an objective measure.