Radiographic Estimation of the Size of the Prostate

Because open prostatic surgery is not a completely lost art and because some urologists still perform both open prostatic surgery and transurethral prostatic resections, the size of the obstructing prostate becomes important. Many urologists state: “We resect all prostates up to 30 gm. or at most 40 gm. and do open surgery on the rest.” The problem is: How does one determine the size of the enlarged prostate? Symptoms are certainly no criteria. A patient may carry a residual urine of 300 to 400 c.c. or more; he may be voiding every half hour by day and six or eight times at night, or acute retention of urine may even develop. These could be the result of an occluding urethral stricture or a fibrous contracture of the bladder neck, in which the obstructing prostatic tissue may not be more than 10 gm. on resection. On the other hand, an adenomatous hyperplasia of the prostate weighing over 100 gm. may at times be responsible for few , if any, symptoms. Rectal examination is also frequently misleading. Recently a prostate which on rectal examination was estimated to weigh about 30 or 40 gm. actually weighed over 100 gm. by the end of a two-stage transurethral prostatic resection, whereas a prostate estimated to weigh at least 60 gm. was found, on suprapubic enucleation, to be a small nubbin of less than 20 gm. Rectal palpation, while indispensable, obviously can be misleading. This is owing to the difference in thickness of the prostatic capsule, variable amounts of edema and inflammation which may be present, and, most importantly, to the fact that the patient may have a large intravesical median lobe comprising one-half to two-thirds of the weight of the obstructing tissue which cannot be outlined by rectal palpation. On excretion urography we often note in the cystogram a defect near the pubic symphysis, which we interpret as a median lobe or “intravesical” prostatic enlargement (Fig. 1, A and B). Care must be taken not to confuse this appearance with that observed when urine containing concentrated contrast medium fails to mix with and diffuse into urine already in the bladder, as they may be somewhat similar radiographically. Sometimes the whole floor of the bladder is raised, and the ureters enter the bladder in the form of a “J.” This “fishhooking” of the distal ureter indicates probable extravesical or lateral lobe prostatic enlargement. Because the apex of the prostate is fixed, lateral lobe enlargement will gradually raise the floor of the bladder and trigone, causing a “J”-shaped deformity of the distal ureters (Fig. 2). Without this deformity of the distal ureters the “raised bladder floor” is of no clinical significance and does not indicate prostatic enlargement. Significant distortion can also be produced by the angling of the x-ray beam, which may erroneously suggest a “raised bladder floor” because of extravesical prostatic enlargement, but the distal ureters will not have the pathognomonic “J” shape. These routine clinical modalities all assist in deciding the operative procedure of choice, but none is completely accurate. A more exact method would be very helpful.