Changes in the size of breast lesions during menstrual cycle observed by ultrasound: an initial study.

Purpose: We aimed to evaluate changes in size of breast lesions during menstrual phases. Material and methods: In this prospective study, 46 women aged 18-35 years old who were referred to our radiology clinic for breast sonography and had cystic or solid breast lesions larger than 5 mm were enrolled to the study. Breast ultrasound (US) was performed at two different times; one within 5 days before and one within 5 days after menstrual bleeding. Anteroposterior and transverse length of the lesions were measured. Results: In total, 145 breast lesions were detected by US. Of these lesions, 6 were visualized in premenstrual phase but were not observed in postmenstrual phase. 6 lesions different were not visualized in premenstrual, but were detected in postmenstrual phase. One hundred and twenty-three lesions were visualized by US both in luteal and follicular phases. Conclusions: Timing of breast US might cause false results and unnecessary further investigations. Therefore, we suggest that breast US in women should be performed in follicular phase of the menstrual cycle.