Dependence of ultrasound decorrelation on urine scatter particle concentration for a non-invasive diagnosis of bladder outlet obstruction

AIMS

To develop a non-invasive method to diagnose Bladder Outlet Obstruction (BOO) based on decorrelation of subsequently acquired UltraSound (US) data of urinary flow, we studied the influence of scatter particle concentration on the decorrelation process in urethra models using both aqueous solutions of scattering particles and urine samples.

METHODS

A tissue mimicking urethra model made from PolyVinyl Alcohol (PVA) solution was infused with seven aqueous solutions containing different particle concentrations at a constant flow rate value of 10 ml/sec. The average correlation coefficients between subsequent US images were calculated and plotted as a function of particle concentration. This procedure was also applied to stepwise diluted urine samples from nine healthy volunteers. An inversely exponential curve was fitted to the experimental data to estimate the scatter particle concentration in the urine samples.

RESULTS

The average correlation values between subsequent US images increased with the particle concentration. The morning urine samples contained an appropriate number of scattering particles to make clinical application of the decorrelation method possible. The fitted correlation curves made an estimation of urine particle concentration possible.

CONCLUSION

The results of this study show that morning urine is suitable for US decorrelation without correcting for differences in particle concentration.

Urodynamics for clinically suspected obstruction after anti-incontinence surgery in women

PURPOSE

We determined the usefulness of urodynamics in patients with obstruction secondary to anti-incontinence surgery.

MATERIALS AND METHODS

We retrospectively reviewed the records of all procedures performed from January 2001 to June 2011 to relieve obstruction due to anti-incontinence surgery. Patients were excluded from study if they underwent prior procedures to relieve obstruction, followup data were missing or a neurological disorder was present. Patients were grouped into categories before intervention, including urodynamics diagnostic of obstruction vs nondiagnostic urodynamics vs no urodynamics testing. We also separated patients with predominantly storage symptoms and those with incomplete emptying.

RESULTS

A total of 71 women were included in analysis. Of 54 women who presented with increased post-void residual urine volume 33 (61%) were diagnosed with obstruction on urodynamics, urodynamics was not diagnostic in 4 (7.4%) and 17 (32%) did not undergo urodynamics preoperatively. All 18 patients with predominantly storage symptoms underwent urodynamics. In patients with incomplete emptying there was no difference between the groups in storage or voiding symptom improvement, overall cure or success according to whether diagnostic urodynamics were or were not done. Of patients with storage symptoms who underwent urodynamics those without evidence of detrusor overactivity had significantly greater storage symptom improvement than those with detrusor overactivity (85.7% vs 53.8%, p = 0.02).

CONCLUSIONS

When voiding symptoms or urinary retention is the primary indication for intervention after anti-incontinence surgery, urodynamic findings are not predictive of outcomes after intervention to relieve obstruction. If storage symptoms are the main indication for intervention, urodynamics may be valuable for patient counseling.