The investigators hypothesize that sperm production varies with time in men with no sperm in semen (non-obstructive azoospermia, NOA) and that the semen protein, TEX101, is able to monitor these changes. The investigators further hypothesize that TEX101 levels may be used to predict the optimum time for microsurgical testicular sperm extraction (mTESE) to provide the highest successful rates of sperm retrieval.
This is a non-randomized pilot study. All men with NOA, who may or may not consider having mTESE, will be approached to enter this study.
Recruited men will have a semen test performed at the initial visit (time 0) to measure semen TEX101 levels using an ELISA assay.
For men who are not considering a mTESE to retrieve sperm, the TEX101 semen levels will be measured monthly for three months to determine the variability of semen TEX101.
For men who are considering a mTESE in an attempt to retrieve sperm, the mTESE procedure to retrieve sperm will be booked. If the level of TEX101 is detectable at time 0, then the men will have semen testing monthly. If the TEX101 is persistently detectable then the men will have surgery at the time originally scheduled. If the TEX101 drops on any subsequent test to be undetectable, then the semen testing for TEX101 will continue monthly for a maximum of 3 additional months. If the TEX101 remains undetectable for all tests, the men will have the mTESE at the end of the additional 3 months. If the TEX101 is detectable on a subsequent test, then the men will undergo an immediate mTESE (< 2 weeks).
If the initial TEX101 is undetectable, then the men will have monthly semen testing for TEX101 for a maximum of 3 additional tests. If the TEX101 remains persistently undetectable, then a mTESE will be performed as originally booked. If the TEX101 is detected on a subsequent test, then an immediate mTESE (< 2 weeks) is performed.