William Jg Finch

Objectives: To determine the optimal method for assessing stone volume, and thus stone burden, by comparing the accuracy of scalene, oblate, and prolate ellipsoid volume equations with three‐dimensional (3 D )‐reconstructed stone volume. Kidney stone volume may be helpful in predicting treatment outcome for renal stones. While the precise measurement of stone volume by 3 D reconstruction can be accomplished using modern computer tomography ( CT ) scanning software, this technique is not available in all hospitals or with routine acute colic scanning protocols. Therefore, maximum diameters as measured by either X ‐ray or CT are used in the calculation of stone volume based on a scalene ellipsoid formula, as recommended by the E uropean A ssociation of U rology. Methods: In all, 100 stones with both X ‐ray and CT (1–2‐mm slices) were reviewed. Complete and partial staghorn stones were excluded. Stone volume was calculated using software designed to measure tissue density of a certain range within a specified region of interest. Correlation coefficients among all measured outcomes were compared. Stone volumes were analysed to determine the average ‘shape’ of the stones. Results: The maximum stone diameter on X ‐ray was 3–25 mm and on CT was 3–36 mm, with a reasonable correlation ( r = 0.77). Smaller stones (15 mm towards scalene ellipsoids. There was no difference in stone shape by location within the kidney. Conclusions: As the average shape of renal stones changes with diameter, no single equation for estimating stone volume can be recommended. As the maximum diameter increases, calculated stone volume becomes less accurate, suggesting that larger stones have more asymmetric shapes. We recommend that research looking at stone clearance rates should use 3 D ‐reconstructed stone volumes when available, followed by prolate, oblate, or scalene ellipsoid formulas depending on the maximum stone diameter.

INTRODUCTION: Conventional consent forms often contain incomplete information regarding risks associated with invasive procedures. BAUS has introduced procedure-specific consent forms (PSCF) documenting the risks associated with urological procedures. We compared patients' understanding of the risks and benefits of TURP after the consenting process with either conventional documentation or PSCF. PATIENTS AND METHODS: One hundred patients were randomised to be consented with either a conventional or PSCF. After 3 h, their understanding was assessed with a questionnaire asking patients to document the indication and likelihood of symptomatic improvement, estimate frequency of complications and the risk of future re-operation. Data were compared by Mann–Whitney test. RESULTS: Fifty patients were randomised to each group. There was no significant difference in mean age, grade of doctor obtaining consent or time interval from consent to questionnaire. Both groups accurately predicted the chance of improved symptoms (median, 80%). There was no significant difference in patients' median estimation of risk of complications such as incontinence, erectile dysfunction, or retrograde ejaculation. Patients consented with the PSCF predicted the risk of re-operation more accurately (median answer, 10% versus 30%; P = 0.007, Mann–Whitney test). CONCLUSIONS: Recall of data was sub-optimal in both groups. For most data points there was no significant difference in estimation of risks between groups. Those consented with a procedure-specific consent form predicted risk of re-operation at 10 years more accurately. Procedure-specific consent forms offer an advantage over conventional consent in this study. We feel that the provision of a written structured framework allows better informed consent for TURP.