[Cesarean uterine scar evaluation by the grey-level histogram]

To evaluate the Cesarean uterine scar by the grey-level histogram (GLH) in women with a previous Cesarean section, performed either during labor or before labor (elective Cesarean).

A prospective study was conducted with 40 women between 11 and 14 weeks of gestation, who were allocated to three groups: 15 pregnant women with a previous elective Cesarean (group A); 9 with a previous Cesarean section performed during labor (group B); and 16 with a single previous vaginal delivery (group C). The pregnant women were examined by transvaginal ultrasound, to obtain an image corresponding to the 'shadow' formed by the uterine scar in groups A and B. In group C GLH was accomplished in the region of the uterine isthmus. After capture of the image, the region-of-interest (ROI) was delimited and the option 'histogram' was activated, to automatically obtain graphic representation. The mean, median and standard deviation (SD) were calculated. for each group under study Mean values of the control group histograms were used as the normality parameter for comparison with the other groups. To compare averages of the three groups, the ANOVA test was used. A (p) value of < 0.05 was considered statistically significant.

GLH in group A varied from 7.0 to 40.5 (mean: 24.9 and DP: 11.2), in group B from 23,1 to 47.2 (mean: 34,. and DP: 9.6) and in group C from 21.6 to 58.8 (mean: 40.3 and DP: 11.3).

There was a significant difference of GLH in the region of the uterine scar of previous Cesareans, when it was elective and when performed during labor, suggesting a larger tissue change in the elective Cesarean.