Patients with nondraining catheters can present with incontinent leakage around the catheter or with abdominal distention and pain as a result of acute urinary retention. Although acute retention is direct evidence for obstruction, pericatheter leakage as a result of catheter blockage must be differentiated from either decreased urethral tone or spontaneous detrusor contractions. This can be accomplished by flushing the catheter with sterile water. Obstruction is suggested if the catheter does not easily flush or if there is no return of the irrigant.
Obstruction of the catheter by blood clots often creates a situation in which the catheter is easily flushed, but little or no irrigant is returned. If this occurs, the catheter can be replaced with a triple-lumen catheter so that the bladder can be easily irrigated. If, after clearing the bladder of all clots, evidence of continued bleeding is present, urologic consultation is recommended for possible cystoscopy. Some physicians advocate the use of single-lumen catheters to lavage the bladder, as its larger lumen may aid in the evacuation of larger clots.
Obstruction in long-term indwelling catheters can be caused by encrustation of the areas of the catheter exposed to urine. Ammonium magnesium phosphate (struvite), calcium phosphate, Tamm-Horsfall protein, and bacteria can all be components of encrustation. 3 Proteus mirabilis and other urea-splitting organisms contribute to obstruction by promoting struvite crystal formation. Routine catheter changes continue to be the mainstay of prevention, although multiple bladder irrigation solutions are currently in use to extend catheter-change intervals.
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