Introduction
Microdissection testicular sperm extraction (micro-TESE) is increasingly being recognised as the surgical sperm retrieval (SSR) technique of choice in non-obstructive azoospermia (NOA). We reviewed our experience of this technique, assessing factors predictive of successful retrieval.

Methods
Interrogation of our database of 101 micro-TESE cases (2013-2016). Factors considered included FSH levels, histopathology and impact of previous SSR. Outcomes included SSR rate, fertilisation rate, embryo quality, pregnancy and live births.

Results
SSR was achieved in 59% (60/101) of cases, with a 35% retrieval rate in Sertoli cell-only (SCO), 88% in maturational arrest (MA) and 95% in hypospermatogenesis (HS). In cases with mixed testicular histology (SCO with another sub-type), the success rate was 100% (5/5).
FSH levels were 22.5 (successful SSR) and 28.4 (unsuccessful group) mIU/mL (P=0.18).
Micro-TESE was successful in 63% (5/8) of previous failed SSR cases, and 60% (3/5) of micro-TESEs performed with radical orchiectomy for NOA in testicular cancer (onco-TESE). Of the 40 cases which progressed to ICSI; 39/40 (98%) achieved fertilisation and 36/40 (90%) progressed to embryo transfer. 21/40 (53%) had blastocysts, 9/40 (23%) developed clinical pregnancy and 7/40 (18%) had live births (8 children).

Conclusion
Micro-TESE is an invaluable SSR technique in NOA, and should be considered even if conventional SSR has failed. SSR rates vary depending on histopathology, but are not affected by the presence of concurrent tumour. FSH is not predictive of success. While embryo transfer rates are high, live birth rates, also influenced by female factors, are reduced compared to ICSI in obstructive cases.