Ultrasonographically measured umbilical cord cross‐sectional area – reproducibility of the method

A prospective cross‐sectional study was developed in order to determine the reproducibility of the measurement of the umbilical cord cross‐sectional area (UCCSA) during normal pregnancies (patients with known dates of LMP and an ultrasound examination before the 20th week, without any pathologic condition), measured by different and trained examiners. The measurements of the umbilical cord cross‐sectional area were obtained in a plane adjacent to the insertion of the cord abdomen, as proposed by Raio et al. 1999, after the different examiners were trained by the author. The inclusion criteria were: (1) singleton pregnancy; (2) gestation age >20 weeks; (3) intact membranes (4) normal umbilical Doppler flow velocimetry. The exclusion criteria, in the presence of any of those were: (1) congenital and/or chromosomal abnormalities; (2) pregnancy complications (any type); (3) inadequate size for gestational age with when the examination was performed, i.e. the weight below the 10th percentile or above the 90th; (4) abnormal AFI for the gestational age. The patients were examined and included only once. During the period of the study (February 2000–May 2001), 545 patients were examined, after meeting the inclusion criteria determined for the present study. The age of the patients ranged from 15 to 42 years (mean = 26.7 ± 4.8), 242 patients (44.4%) had two gestations, 135 patients (28.1%) were at their first gestation, 129 patients (23.7%) were at their third gestation and 39 patients had four or more gestations (3.8%). The ultrasound machine used was the Synergy Multi Sync M 500. The statistical program used was the statistical package for social sciences (SPSS). The first examiner collected 22% of the data, the second examiner collected 45% of the data, the third examiner collected 24% of the data and the fourth one collected 9% of the data. According to the analysis of variance (anova), we performed, comparing the data obtained by the different examiners, no significance was found and this fact was also showed by the comparison of the data among them and verifying that the data had a dispersion inside tolerable limits. The anova showed the following data (example for 3 weeks): At 25 weeks, the F‐test showed a value of 0.930 and a P‐value of 0.454; at 32 weeks the values were 0.106 for the F‐test and 0.956 for the P‐value and for week 38 the values were 0.102 (F‐test) and 0.904 (P‐value). We conclude that the measurement of the UCCSA as proposed by Raio et al. 1999 is reproductible and can be adopted as a new obstetric ultrasound parameter.