60-yrs-old male with a poor stream of urine, post-void residual urine is 400ml, b/l hydronephrosis and prostate weighing 70 g. His urea is 120 and creates 3.5. Ideal "next immediate" step :

Catheterization is mandatory for acute urinary retention. Spontaneous voiding may return, but a catheter should be left indwelling for 3 days while detrusor tone returns."- CSDT 13/e This is a case of bladder outlet obstruction most likely due to BHP (can also be due to ca). So the immediate next step is to drain the bladder a transurethral Foley catheter. If this fails suprapubic drainage can be done. Ref : Bailey and Love 25/e p1316