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Ultrasound examination is now considered as part of almost every clinic setting. The creation of an image from sound is achieved in three steps: producing a sound wave, receiving echoes, and interpreting those echoes. The four different modes of ultrasound used in medical imaging are: A-mode, B-mode, M-mode and Doppler mode. The Doppler frequency shift information can be displayed graphically in various ways that include color Doppler (directional Doppler), power Doppler, and spectral (pulsed) Doppler. The different modes of Doppler waves include: Continuous-wave Doppler (CW) and Pulsed-wave Doppler (PW). The blood flow measurements are performed by calculation of velocity, calculation of absolute flow and flow waveform analysis. Despite its impressive safety record of ultrasound to date, the intensity (or acoustic output) level of ultrasound used to scan the fetus in utero has increased almost eightfold over the level that was allowed in the early 1990s.
This chapter discusses the techniques, methodology, and procedures that are highly relevant to the current practice of assisted human reproduction and sperm banking. Cryopreservation of sperm cut down the necessity of obtaining fresh sperm for subsequent assisted reproductive technology (ART) cycles. Abundant evidence exists in literature indicating that frozen sperm are as good as fresh sperm in fertilizing oocytes and subsequent developments. The success of cryopreservation is affected by many factors including membrane permeability, amount of intracellular water, type of cryoprotectant, and the method of freezing and thawing. Four cryoprotectants that are most often used for cryopreservation of human spermatozoa are: glycerol, dimethylsulfoxide (DMSO), ethylene glycol, propanediol, egg yolk and buffering agents. The American Society for Reproductive Medicine (ASRM) practice committee recommends evaluations of potential sperm donors incorporating recent information about optimal screening and testing for sexually transmitted infections, genetic diseases, and psychological assessments.
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