Diagnostic ultrasound criteria was the display of an image of bright two or three parallel lines arranged in successive segments, circling the fetal10 neck. Used ultrasound equipment brand Medison Sonoet, model 5000, 3.5 MHz, with biconvex transducer electronic and thermal paper printer camera brand Sony. The standard of comparison was direct viewing of the presence or absence of circular cord during vaginal delivery or cesarean section. Statistical analysis to evaluate discordance between the use and the gold standard was the test of McNemar square Xi. For the evaluation of the association between circular cord and scores of Apgar score at birth, exact test of Fisher, as well as to evaluate the association with pregnancy resolution via are used. For the evaluation of the diagnostic test was carried out calculations of sensitivity and specificity, with their confidence intervals of 95%, in addition to the positive and negative predictive values, as well as test accuracy and likelihood ratio. A P value of equal to or less than 0.05 was considered significant. RESULTS General characteristics of the 57 patients studied were the following: the average age of the patients was 25.5 years, 36.8% of patients was primigesta (n = 21), 17.5% secundigesta (n = 10), 46.6% had three or more pregnancies (n = 26). All patients were enrolled at term, in effective labor and uncomplicated, placenta Placentae, membranes intact. The resolution of the birth was vaginal in 80% of patients (n = 47) and by caesarean section in 20% (n = 10). The cesarean section indication was fetal distress acute in 50% of cases (n = 5), cephalopelvic disproportion in 30% (n = 3), and the remaining 20%, one was by prolonged second stage and another by dystocia of contraction. Of the babies born by vaginal delivery, 7 had circular lace, and of those born by caesarean section, 10 had circular cord. The analysis with Fisher’s exact test showed a statistically significant association between circular cord and cesarean section (p = 0, 000468).