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ObjectiveTo determine from urodynamic data what causes an increased postvoid residual urine volume (PVR) in men with bladder outlet obstruction (BOO), urethral resistance or bladder failure, and to determine how to predict bladder contractility from the PVR.Patients and methodsWe analysed retrospectively the pressure-flow studies (PFS) of 90 men with BOO. Nine patients could not void and the remaining 81 were divided into three groups, i.e. A (30 men, PVR < 100 mL), B (30 men, PVR 100–450 mL) and C (21 men, PVR > 450 mL). The division was made according to a receiver operating characteristic curve, showing that using a threshold PVR of 450 mL had the best sensitivity and specificity for detecting the start of bladder failure.ResultsThe filling phase showed an increase in bladder capacity with the increase in PVR and a significantly lower incidence of detrusor overactivity in group C. The voiding phase showed a significant decrease in voided volume and maximum urinary flow rate (Qmax) as the PVR increased, while the urethral resistance factor (URF) increased from group A to B to C. The detrusor pressure at Qmax (PdetQmax) and opening pressure were significantly higher in group B, which had the highest bladder contractility index (BCI) and longest duration of contraction. Group C had the lowest BCI and the lowest PdetQmax.ConclusionsIn men with BOO, PVR results from increasing outlet resistance at the start and up to a PVR of 450 mL, where the bladder reaches its maximum compensation. At volumes of >450 mL, both the outlet resistance and bladder failure are working together, leading to detrusor decompensation.

Stomach seems to be an ideal source of material for bladder augmentation or replacement. The high capacity, low pressure reservoir provided by gastric tissue is probably due to the nature of the involuntary contractions, which occur only late in filling with a low amplitude. Also, the gastric neobladder is evacuated mainly by contraction of its musculature, supplemented with abdominal straining at the end of voiding.

ObjectiveTo define the different urodynamic patterns in female bladder outlet obstruction (BOO) and to assess whether urodynamics alone can be relied on for the diagnosis.Patients and methodsThis prospective study included 60 clinically obstructed women and 27 with stress urinary incontinence as a control group. All patients had pressure-flow studies and were divided into four groups. Group A (control group, 27 patients) and group B (22) had a maximum urinary flow rate (Qmax) of >15 mL/s and a detrusor pressure at Qmax (PdetQmax) of <30 or >30 cm H2O, respectively. Group C (20 patients) and group D (18) had a Qmax of <15 mL/s and a PdetQmax of >30 or <30 cm H2O, respectively.ResultsThe mean Qmax for groups A, B, C, and D were 21.8, 21.9, 10.8 and 9.9 mL/s, respectively, while the mean PdetQmax was 20.8, 40.4, 48.7, and 18.7 cm H2O, respectively. The residual urine volume was <100 mL in groups A and B but >100 mL in groups C and D. When compared with group A, groups B–D had a significant difference in vesical pressure, groups B and C had a significant difference in PdetQmax, while Qmax, the maximum voided volume and residual urine volume were significantly different in groups C and D. Group A was obviously unobstructed, group B might have early obstruction, group C had compensated obstruction, while group D can be considered to have late de-compensated obstruction.ConclusionsBOO in females has three different urodynamic patterns, i.e. early, compensated and late obstruction. However, urodynamics should be combined with the clinical presentation and residual urine volume for an accurate diagnosis.

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