Dynamics of the intrauterine fluid-wall interface

Intrauterine fluid movements, which are responsible for embryo transport to a successful implantation site at the fundus, may be induced by myometrial contractions. Myometrial contractions in nonpregnant uteri were studied fr om in vivo measurements of intrauterine pressures with fluid-filled cathete rs and by visual observations of high-speed replaying of ultrasound images of the uterus. Transvaginal ultrasound (TVUS) images of sagittal cross sect ions of the nonpregnant uterus were scanned with an intravaginal ultrasound probe. Images at consecutive times (2 s apart) were digitized and processe d by employing modem techniques of image processing. The sets of images wer e compared to evaluate time variation of the fluid-wall interface with resp ect to amplitude, frequencies, and wavelength of myometrial contractions. A nalysis of TVUS images from 11 volunteers during the proliferative phase re vealed that myometrial contractions are fairly symmetric and are propagated from the cervix towards the fundus at a frequency of about 0.01-0.09 Hz, T he wavelength, amplitude, and velocity of the fluid-wall interface during a typical contractive wave were found to be 10-30 mm, 0.05-0.2 mm, and 0.5-1 .9 mm/s, respectively. Additional data acquisition from a large number of n ormal subjects is needed to build a data base to predict normal characteris tics of myometrial contractions in a nonpregnant uterus, in order to better understand their role in the preimplantation process. (C) 1999 Biomedical Engineering society. [S0090-6464(99)02003-2].