Diseases of the male adnexa normally change the physical properties – shape, elasticity, consistency – of the posterior urethra and of the bladder neck. In order to demonstrate their influence on urodynamics experimental studies were undertaken: elastic models, straight tubes of equal diameter throughout their length, were used. Model I was a straight elastic tube of PVC material, three other models had unelastic segments of the same square area as the undeformed elastic parts. These segments were either circular (model II) or of the lunate (model III) or of the T-bar-type (model IV). Perfusion was performed under equal conditions. The experiments showed firstly that unelastic segments in an elastic system reduce the flow rate and secondly, that flow depends on cross section versus circumference, which is expressed by the so-called hydraulic diameter (Dh = 4F/U); Dh = hydraulic diameter, F = square area, U = wetted perimeter of the tube). The results support the clinical experience that size and volume of the prostate are by far not the only factors which determine the flow in the posterior urethra. They explain why changes of the physical properties of the wall of the posterior urethra and of the bladder neck alone can decrease the flow rate considerably. Elasticity, consistency and shape, frequently altered by diseases of the male adnexa are therefore at least as important regarding loss of friction as the factors mentioned above.

Keywords:
Urodynamics, Bladder neck obstruction, Elastic models urethra
This content is only available via PDF.
© 1978 S. Karger AG, Basel
1978
Copyright / Drug Dosage / Disclaimer
Copyright: All rights reserved. No part of this publication may be translated into other languages, reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying, recording, microcopying, or by any information storage and retrieval system, without permission in writing from the publisher.
Drug Dosage: The authors and the publisher have exerted every effort to ensure that drug selection and dosage set forth in this text are in accord with current recommendations and practice at the time of publication. However, in view of ongoing research, changes in government regulations, and the constant flow of information relating to drug therapy and drug reactions, the reader is urged to check the package insert for each drug for any changes in indications and dosage and for added warnings and precautions. This is particularly important when the recommended agent is a new and/or infrequently employed drug.
Disclaimer: The statements, opinions and data contained in this publication are solely those of the individual authors and contributors and not of the publishers and the editor(s). The appearance of advertisements or/and product references in the publication is not a warranty, endorsement, or approval of the products or services advertised or of their effectiveness, quality or safety. The publisher and the editor(s) disclaim responsibility for any injury to persons or property resulting from any ideas, methods, instructions or products referred to in the content or advertisements.
You do not currently have access to this content.