What is the typical amount of sperm retrieved from a microtesticular sperm extraction (microtese)?

Typical Sperm Retrieval from Microdissection Testicular Sperm Extraction (Micro-TESE)

Micro-TESE typically yields successful sperm retrieval in approximately 46-50% of men with non-obstructive azoospermia (NOA), with the amount of sperm retrieved being minimal and limited to small isolated foci within the testicular tissue. 1, 2

Understanding Micro-TESE

Micro-TESE is considered the gold standard surgical procedure for sperm retrieval in men with NOA, offering several advantages over conventional techniques:

• Micro-TESE involves wide opening of the tunica albuginea to examine multiple regions of testicular tissue, which are oriented in a centrifugal pattern parallel to the intratesticular blood supply 1
• The procedure allows for extensive search of nearly all areas of the testis with limited risk of devascularization 1
• Operative microscopy is used to identify seminiferous tubules that are more likely to harbor sperm, which increases retrieval success while minimizing the amount of tissue sampled 1

Sperm Retrieval Success Rates

The success of micro-TESE varies based on several factors:

• Meta-analyses show micro-TESE results in successful sperm extraction approximately 1.5 times more often than conventional non-microsurgical testicular sperm extraction 1
• Overall sperm retrieval rates range from 18.4% to 70.8%, with most studies reporting around 46-50% success 2, 3
• The amount of sperm retrieved is typically minimal - just enough for intracytoplasmic sperm injection (ICSI) rather than quantifiable in traditional semen analysis terms 2
• Sperm are usually found in small, isolated foci within the testicular tissue 1

Factors Affecting Retrieval Success

Several factors may influence the likelihood of successful sperm retrieval:

• Testicular histology is a significant predictor - hypospermatogenesis has better outcomes compared to maturation arrest or Sertoli cell-only syndrome 1
• Genetic factors play a role - complete AZFa and AZFb Y-chromosome microdeletions predict poor prognosis for sperm retrieval 1
• Microscopic distinction between enlarged and collapsed seminiferous tubules is visible in about 35.7% of cases, with sperm typically retrieved from the enlarged tubules 3
• Even after failed first attempts, second micro-TESE procedures can yield sperm in approximately 18.4% of cases 4

Clinical Outcomes with Retrieved Sperm

When sperm are successfully retrieved through micro-TESE:

• Normal fertilization rates of approximately 64% can be achieved with ICSI 3, 2
• Embryo cleavage rates of about 75% are reported 3
• Clinical pregnancy rates per ICSI cycle range from 28.6% to 39% 3, 2
• Live birth rates of approximately 24% are reported in couples who had embryo transfer 2

Potential Complications and Considerations

Important considerations regarding micro-TESE include:

• Conventional TESE has been associated with decreased postoperative testosterone levels, while micro-TESE has less effect on testosterone levels 1
• Despite this advantage, testosterone deficiency requiring replacement therapy remains a risk even after micro-TESE 1
• Short-term postoperative complication rates are generally low at approximately 3% 2
• Lower complication rates (including hematoma and fibrosis) have been observed with micro-TESE compared to conventional TESE 1

Important Clinical Pearls

• For men with NOA, micro-TESE is the recommended approach for surgical sperm retrieval due to higher success rates and lower complication risk 1
• Sperm retrieval and cryopreservation may be done prior to assisted reproductive technology procedures, as there are generally no substantial differences in ICSI success rates between fresh and cryopreserved sperm 1
• Some centers perform simultaneous sperm retrieval with ART because the numbers of sperm obtained may be limited and sperm may not survive cryopreservation 1
• The procedure should be performed by experienced microsurgeons to maximize chances of successful retrieval 5, 2