The urethra (UPP, MUPP, instability, LPP)

Urethral function can be assessed using many different techniques and this is very important when applied to women with neurological abnormalities. Urethral pressure profilometry, although not diagnostic for urethral sphincter incompetence, can be used to detect strictures and the ostia leading to urethral diverticula. Urethral instability may be recorded using urethral pressure catheters. The significance of this finding is uncertain but it has been suggested that women with urethral instability and detrusor instability are less responsive to therapy with anticholinergic drugs than those with a stable urethra. Micturition pressure profilometry is useful for determining obstruction during voiding and enables the site of obstruction to be determined. Leak point pressures (LPP) can be classified as detrusor or abdominal. Detrusor LPP are useful in patients with neurological disease. Abdominal LPP are subdivided according to the method used to increase intra-abdominal pressure either the Valsalva manoeuvre or coughing. The technique used to obtain an LPP can alter the measurement obtained and a standardized technique is essential for consistent results. LPP correlate with the urinary incontinence of women with genuine stress incontinence undergoing a pad test but is of no value if the woman does not leak! Tests of urethral function during bladder filling, stress and voiding phases help in assessing lower urinary tract dysfunction in neurourology.