The current guidelines on the diagnosis and therapy of benign prostatic hyperplasia have resulted in a number of questions about the increasing variety of alternative treatment modalities. There are disputes about the different ideas of pressure-flow analysis, and about the general necessity for quantification of bladder outlet obstruction for treatment decisions. Over the past year, literature has confirmed again that obstruction can only be quantified with pressure-flow studies and this review aims to describe the advantages and disadvantages of such a procedure and to demonstrate the possible consequences.