Endosonographic monitoring of transurethral cryoprostatectomy

Cryoprostatectomy, the use of subzero temperatures to ablate prostate tissue gained favour in the 1960s because of its speed and lack of haemodynamic effects. It fell from use because the freezing process could not be monitored and this led to a high incidence of local complications. We have performed transrectal real time ultrasound in 12 patients undergoing cryoprostatectomy. In all the freezing process was easily visualized as an advancing hyperechoic 'iceball' with distal acoustic shadowing. Monitoring allowed maximum prostate ablation without breaching the prostatic capsule. There were no significant complications and all but one patient gained symptomatic relief. Ultrasound at 1 month showed a heterogeneous echo pattern with very little cavity formation but by 3 months a significant cavity was seen. This study demonstrates that it is possible to monitor the freezing process during transurethral cryoprostatectomy. This, theoretically, should significantly reduce the local complications encountered in previous studies.