Transrectal ultrasound-guided biopsy of the prostate: what you see is not what you get

A prospective trial involving 282 patients, beginning in December 1993, was undertaken to assess the correlation between our sonographic impression of prostatic malignancy and the histological findings of a random six quadrant biopsy in addition to histology of any sonographically evident focal peripheral zone (PZ) abnormality. The sonographic criteria used to suggest malignancy were: (i) presence of hypo-echoic PZ nodule; (ii) inhomogeneity of PZ; and (iii) loss of zonal architecture (ZA). The sonographic appearance was graded as either definitely benign, indeterminate, or definitely malignant. These impressions were then compared with the histology results. Eighty-two patients had histologically proven malignancy. Ultrasound showed the correct extent and site of malignancy in 42 patients. A further 26 patients had the extent of their malignancy either over- or under-estimated or had the malignancy placed in an incorrect site. Fourteen patients with histologically proven carcinoma had sonographically normal PZs. These findings highlight the shortcomings of ultrasound as a diagnostic tool in prostate cancer and show that six quadrant random biopsy of the prostate is far superior to unifocal biopsy of sonographically evident masses in the detection of prostate cancer.