title: The obstructive effect of a urethral catheter.
abstract: OBJECTIVE
  The effect of a urethral catheter on pressure-flow relationships of the urethra has important implications for the practice to this question in the past in men with benign prostatic hyperplasia. We assessed the obstructive effect of an 8 Ch. urethral catheter in men who presented with lower urinary tract symptoms due to benign prostatic hyperplasia.
  
  
  METHODS
  During combined pressure-flow studies 59 men completed 2 voids of similar volume with and without a urethral catheter in situ. Maximum flow rate, detrusor pressure at maximum flow and the group of specific urethral resistance factor were measured and compared between these 2 voids.
  
  
  RESULTS
  There was no significant difference in maximum flow rate between voids (with catheter 9.1 ml. per second versus without catheter 8.6 ml. per second). Although detrusor pressure was significantly greater with the urethral catheter in situ (80 versus 67 cm. water), voids (with catheter 42.1 cm, water versus without catheter 36.6 cm water).
  
  
  CONCLUSIONS
  A 8 Ch. catheter does not appear to have a significant obstructive effect in the urethra. This finding has important implications for the practice and interpretation of pressure-flow studies.
authors.affiliation: Bristol Urological Institute, Southmead Hospital, United Kingdom.
authors.forename: J M
authors.initials: JM
authors.lastname: Reynard
authors.forename: C
authors.initials: C
authors.lastname: Lim
authors.forename: S
authors.initials: S
authors.lastname: Swami
authors.forename: P
authors.initials: P
authors.lastname: Abrams
mesh_terms: D000368:Aged; D006801:Humans; D008297:Male; D008875:Middle Aged; D011470:Prostatic Hyperplasia / Q000150:complications; D014521:Urethra / Q000503:physiopathology*; D014546:Urinary Catheterization / Q000295:instrumentation*; D014555:Urination Disorders / Q000209:etiology / Q000503:physiopathology; D014563:Urodynamics