Benign prostatic enlargement.

Benign enlargement of the prostate occurs in nearly all men as they grow older, but only one in ten is likely to need a sur geon.1 Surgical relief is required for obstruction to the outflow of the bladder. The obstruction may be due to hypertrophy of the muscle at the bladder neck, or to the for mation of benign adenoma in the prostate, or (as is usual) a combination of both processes (Fig. 1, a-f). If there is resis tance to the free emptying of the bladder the pressure rises inside it and like the myocardium in response to valvular stenosis it undergoes hypertrophy. Unfortunately, though the hypertrophy of the bladder detrusor may restore flow to something near normal, hypertrophy is accompanied by trabeculation and sacculation?herniation of the mucosa between bands of muscle. When these herniations no longer empty out, the residual urine inside the diverticula may become infected (Fig. 2). As the process continues, the detru sor fails (just as the myocardium fails) and no longer pushes its contents past the obstructed outflow. The residual urine in the bladder may then become infected, and stones may be formed (Fig. 3). At the same time the ureterovesical valve may give way and allow reflux up the ureter, or the bulk of the adenoma may compress the intramural ureter. In either event the ureter develops dilatation and the kidney becomes hydronephrotic. This in turn leads to loss of renal concentrat ing and acidifying power, and ultimately to diminished glomerular filtration and uraemia. To correct the trouble the obstructing muscle and adenoma have to be removed from the neck of the bladder. Pills, freez ing, and injections have all been tried in vain, and are (so far) neither so safe nor so reliable as surgical excision. The opera tion can be done either by an open or a transurethral approach, each with advantages and disadvantages. Open