<prompt> 60-yrs-old male with a poor stream of urine, post-void residual urine is 400ml, bl hydronephrosis and prostate weighing 70 g. His urea is 120 and creates 3.5. Ideal next immediate step :Catheterize with Foley catheterb1 PC NephrostomiesCT to rule out caMRI pelvis  <response>: 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 13e 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 25e p1316 