Measurement of the speed of sound in follicular fluid.
BACKGROUND
Measurement of ovarian follicles by ultrasound is common practice in fertility treatment. However, the effect of the speed of sound is not taken into account. We present results from a study aimed at measuring this.


METHODS
The speed of sound was measured in samples of follicular fluid aspirated from patients undergoing fertility treatment. The transmitted and received pulses from a single element ultrasound transducer were recorded using a digital oscilloscope for a pulse passed through a sample of the fluid. The distance over which the pulse travelled was known from calibration with pure water. Variation with temperature was investigated in the range 25-45 degrees C. Dependence on ultrasound frequency, patient and time from aspiration were also investigated.


RESULTS
The speed of sound in follicular fluid was found to be 1550+/-3 m/s at 37.3 degrees C using 5.0 MHz ultrasound. The speed varied from 1528+/-3 m/s at 24.8 degrees C to 1561+/-3 m/s at 44.8 degrees C. Variation with patient, time and frequency were not detected.


CONCLUSIONS
The speed of sound in follicular fluid at body temperature is 1550 m/s. This small difference from the speed assumed by the ultrasound machine corresponds to the systematic bias in volume measurement evident in previously published results.
Gooding
M J
MJ
Medical Vision Laboratory, Department of Engineering Science, University of Oxford, Parks Road, Oxford OX1 3PJ, UK. gooding@robots.ox.ac.uk
Barber
D
D
Kennedy
S H
SH
Noble
J A
JA
D001707:Biopsy, Needle; D002138:Calibration; D005260:Female; D005307:Fertilization in Vitro; D015571:Follicular Fluid / Q000000981:diagnostic imaging*; D006801:Humans; D066298:In Vitro Techniques; D007247:Infertility, Female / Q000000981:diagnostic imaging*; D012016:Reference Values; D013696:Temperature; D014463:Ultrasonography / Q000379:methods / Q000592:standards*