Urology & Stone Disease
Every urology & stone disease calculator on CalcEngines — unit converters, derived indices and interpretive tools, each with its formula, a worked example and the reference intervals it is judged against.
8 calculators in this section
- Bladder Outlet Obstruction Index CalculatorThe Abrams–Griffiths number from a pressure-flow study — detrusor pressure at maximum flow minus twice the maximum flow rate — with the bladder contractility index from the same two numbers. These are the only two figures in this category that measure obstruction rather than infer it.
- Hydronephrosis Grade InterpreterAn SFU grade and a UTD category read side by side on the same kidney, with the anteroposterior renal pelvic diameter thresholds for the gestational or postnatal timing entered. The two systems do not map onto one another, and this page is built to show where they part company.
- International Prostate Symptom Score CalculatorThe seven-item IPSS, scored 0 to 35, with the quality-of-life item reported beside the total rather than added to it, and the voiding and storage subscores. This is the prostate symptom score, not the prognostic scoring system.
- Kidney Stone Volume and Burden CalculatorStone burden from three CT diameters, by all three published ellipsoid formulas at once. A stone is reported by its longest diameter and behaves like a volume, so a 10 mm stone is eight times the burden of a 5 mm one rather than twice.
- Post-Void Residual and Bladder Emptying CalculatorBladder voiding efficiency — the voided volume as a share of everything the bladder held — from a voided volume and a residual. A residual of 100 mL means one thing after a 500 mL void and another after a 120 mL one, which is the whole reason this fraction exists.
- Prostate Volume from Ultrasound CalculatorGland volume from the three dimensions on an ultrasound report, with both published coefficients shown — the prolate ellipsoid π/6 and the bullet 5π/24 — because they disagree by a quarter and the published bias runs in opposite directions in small and large glands.
- Stone Composition from Hounsfield Units InterpreterWhat a CT attenuation value is consistent with, and why it cannot be more than that. The published ranges for uric acid, cystine, struvite and the calcium stones overlap so widely that one series found a 700–1,000 HU threshold misclassified 68 per cent of calcium oxalate monohydrate stones.
- Ureteric Stone Spontaneous Passage InterpreterThe published proportions of ureteric stones that passed spontaneously, by size and by location, read straight off the EAU's own figures — 49 to 52 per cent in the upper ureter against 68 to 83 per cent in the distal, and 89 per cent for a distal stone under 5 mm.