Doppler Assessment of the Uterine Arteries for the Definition of Pubertal Onset in Girls

Abstract

Abstract Pelvic ultrasonography (US) is a quick, non-invasive and low-cost method, and doppler analysis facilitates assessment of flow impedance measurement in the uterine vascular tree. The pulsatility index (PI) reflects blood flow impedance in the vessel distal to the sampling point and has been suggested as a parameter to define pubertal development. In order to evaluate the PI and US measurements of uterus and ovaries in girls with different pubertal stages, we performed a cross-sectional study in girls with normal pubertal development. US and Doppler assessed PI of the uterine arteries (defined as the difference between the peak systolic flow and end-diastolic flow divided by the mean maximum flow velocity), endometrial thickness, uterine and ovarian volumes were evaluated. All the US exams were performed with the same equipment by the same radiologist. Clinical data such as the age of menarche, pubarche and thelarche were recorded. Statistical analyses were performed in SPSS, with ANOVA test, Spearman correlation and ROC curve with Youden. One hundred and sixty-nine girls aged 5-16 years (mean 11.3 ± 1.8) who performed two hundred and two pelvic US were included (Tanner 1=20%, Tanner 2=22%, Tanner 3=23%, Tanner 4=17%, Tanner 5=17%). Mean age of thelarche, pubarche and menarche were 11.1 ± 1.8, 10.2 ± 1.2 and 12.2 ± 1.1 years respectively. Prepubertal girls (Tanner 1) had mean PI significantly higher than girls in initial puberty (Tanner 2 and 3 grouped) and in late puberty (Tanner 4 and 5 grouped), respectively 6.5 ± 2.27 vs. 4.15 ± 1.55 vs. 2.82 ± 1.06, p<0.001 for all the comparisons. ROC curve analysis demonstrated that the PI is able to identify the onset of puberty with an area under the curve of 0.80 ± 0.04, P<0.001, and a cutoff point of IP=5.05 presented a sensitivity of 0.77 and a specificity of 0.80 to identify the onset of puberty. When we combined the cutoffs of IP <5.05 plus uterine volume >3.75 cm³, we found a sensitivity of 0.72 and specificity of 0.90 to detect puberty. We identified a strong negative correlation between PI and uterine volume (rs=-0.72, p<0.001) and a moderate negative correlation with endometrial thickness (rs=-0.68, p<0.001) and right (rs=-0.60, p<0.001) and left (rs=-0.59, p<0.001) ovarian volumes. In conclusion, we found a significant reduction of the PI during pubertal development, reflecting a progressive increase in blood flow to the uterus, which can be a valuable non-invasive and highly specific tool to confirm the onset of puberty.