[Contribution of modeling to the analysis of mictional modifications caused by TVT: study of free uroflows].

AIM OF STUDY: Using modeling to analyze the free uroflows after TVT, procedure, to search for a unique mechanical hypothesis which could explain the changes in the voiding pattern induced by the tape and the success of the procedure.

POPULATION AND

METHODS

In this retrospective study 50 women who underwent a TVT, procedure for cure of SUI were included. They had physical examination and urodynamic tests before and after (1, 6, 12 and 24 months) surgery. Preoperatively, a lateral urethrocystography (X-rays at restraint and at strain) allowed to measure the urethra mobility. The analysis of the free uroflow curves was qualitative (superimposition of the curves) and quantitative (VBN method). Modeling allowed to test the hypotheses of an induced obstruction (compressive or constrictive), and to search for an abnormality of the nervous control.

RESULTS

A change in the voiding pattern which was compatible with a urethral obstruction was observed in 34 (68%) patients. The hypothesis of a compressive obstruction (counter-pressure between 10 and 35 cm H2O) which could explain restoration of continence was proposed for these 34 patients (with a counter-pressure variable from one voiding to the other for 12 patients). The hypothesis of a constrictive obstruction which could not explain restoration of continence and implied a reduction of the cross-section of the urethra of about 60% was proposed for 27 patients.

CONCLUSION

The results of the modelized analysis are consistent with the hypothesis of the occurrence at strain of a counter-pressure on the dynamic kinking due to the TVT. This counter-pressure achieves continence; during voiding, this effect can be unmasked if the woman strains with the result of a lower flow rate and/or dysuria.