Alterações fisiológicas mamárias durante a gravidez e lactação: aspectos ultrassonográficos e dopplerfluxométricos

Abstract

During pregnancy and lactation breasts undergo important changes that are not fully understood. Ultrasound and magnetic resonance are the most suitable methods to assess breast alterations during pregnancy and lactation, making a solid knowledge of anatomy and breast diseases essential. Moreover, there are few articles on breast imaging, relating anatomy and physiology during the pregnancy-postpartum cycle. The present study aimed to assess physiological breast changes using ultrasound and dopper flowmetry of internal mammary arteries (IMA) in normal pregnant and lactating women, compared to a group of non-pregnant women evaluated in the folicular phase of the menstrual cycle. This cross-sectional observational study was conducted between August 2013 and August 2016, with 165 women. The dependent variables were measures of skin, subcutaneous adipose tissue, fibroglandualr tissue, retromammary adipose tissue, duct diameter, as well as pulsatility (PI) and resistive indices (RI) of internal mammary arteries. The independent variables were the different assessment moments, represented by the five groups established. Statistical analysis involved calculating the means and standard deviations using two MANOVA models (Multivariate analysis of variance) to assess the group effect on the average values obtained. ANOVA univariate models were individually fit to the mean values. The Tukey-Kramer multiple comparisons test was applied to analyze intergroup differences and characteristics, at a 5% significance level. In the comparison between three groups of pregnant women, it was observed that fibroglandular tissue thickness and duct diameter showed a significant difference with gestational period (p< 0.001), from the first to the second and from the first to the third trimesters. Doppler fluxometry of the internal mammary arteries showed a difference between breasts and between gestational period, i.e. the right breast exhibited higher measures than the left and these values decreased throughout the pregnancy (p< 0.001). No differences were found when the groups of pregnant and lactating women were compared, but significant differences with a control group were observed in terms of skin (p = 0.001), fibroglandular tissue thickness, duct diameter and laser Doppler flow measurements of the IMA (all three with p < 0.001) and subcutaneous adipose tissue (p = 0.045). This study provides more specific information on the ultrasound characteristics of breasts and Doppler flowmetry aspects of internal mammary arteries during normal pregnancy and lactation, quantifying the values and characterizing the physiological changes of each period of the pregnancy-lactation cycle, which may serve as parameters for future studies.