Ultrasonic assessment of variations in thickness of subcutaneous fat during the normal menstrual cycle

Abstract

Objective: To verify the occurrence of natural variations in thigh and abdominal subcutaneous fat thickness related to the phases of the menstrual cycle, to assess the value of ultrasonography as a reliable method for monitoring subcutaneous fat thickness changes and to evaluate their amplitudes. Methods: This study included 10 women (19–39 years) who menstruated regularly. None had used oral contraceptives or slimming products during the 3 months prior to the study. At cycle day 2 (CD2), CD6, CD14, CD22, CD27 and CD30 days (CD0: beginning of menstruation), the subjects were submitted to: (1) measurement of weight and thigh perimeters, (2) measurements of thigh and abdomen subcutaneous fatty tissue thickness on B-mode images acquired at 10 MHz. A protocol was designed to guarantee a reproducible repositioning during the whole time course of the study and ultrasound examinations (US) were always performed by the same trained person to avoid inter-examiner variability. Results: Subcutaneous fat thicknesses decreased during the first half of the cycle and reached their lowest values at day 22 (−2.0% for the thighs; −3.3% for the abdominal region). Both thigh and abdomen subcutaneous fat reached their maximum thicknesses during menstruation with respective increases of +2.2 and +4.0%. The observed cyclic amplitude variations in the subcutaneous adipose tissue thickness accounted for 7.3% for the abdominal region and 4.1% for the thighs. Conclusion: Variations in adipose tissue thickness during the menstrual cycle could be quantified and monitored by US. The thickness of the thigh and abdominal hypodermis was more important during menstruation and decreased in mid-cycle with a minimum occurring 1 week after ovulation.