Transurethral catheterization of the urinary bladder is commonly used as a diagnostic and therapeutic aid.
Figure 1: Indwelling transurethral catheter that was mutilated by a male dog. After the dog separated the funnel end of the
catheter by chewing, the remaining portion of the catheter disappeared into the urethral lumen. Also shown is a Swan-Ganz
catheter with deflated balloon.
However, it should not be considered a "routine procedure" since it is associated with several risks including iatrogenic
trauma to the urethral and bladder mucosa and iatrogenic bacterial urinary tract infections.
We have also encountered situations in male dogs where the entire catheter has been "lost" inside the lower urinary tract.
Retrieval of catheters "lost" in the patient is the subject of this Diagnote.
Diameters The diameters of the distal end of urethral catheters are often designed to be greater than the diameter of the body of the
catheter in order to accommodate the tips of syringes (so-called funnel end catheters). If a catheter has been advanced into
a male dog to a point where its distal end is adjacent to the tip of the penis, the funnel-end also prevents inadvertent ascending
migration of the distal end of the catheter beyond the distal end of the urethra.
In order to attach a syringe with a regular Leur-tip to a urinary catheter with a funnel end, it may be necessary to remove
a portion of the funnel-end with scissors. However, if the diameter of the distal end of the modified catheter becomes smaller
than the diameter of the urethra, there is a risk that the distal end of the catheter could disappear into the distal urethra.
Figure 2: Illustration of Swan-Ganz catheter after its balloon tip has been inserted into the lumen of the mutilated catheter.
We have also encountered this problem when male dogs with indwelling transurethral catheters have mutilated them by chewing
off the funnel tip (Figure 1).
To the rescue A simple technique that we use to "rescue" transurethral catheters "lost" in this fashion involves use of balloon-tipped
catheters (available from, Edwards Life Sciences, One Edwards Way, Irvine California 92614; or call 800-4-A-HEART). To retrieve
transurethral catheters approximately 8 to 12 French in diameter, we use 4 to 5 French Swan-Ganz flow directed balloon catheters.
The technique involves advancing the balloon tip of the Swan-Ganz catheter through the distal urethral lumen with the goal
of inserting it into the lumen of the distal end of the lost urinary catheter (Figure 2). After inserting the balloon tip
of the smaller diameter Swan-Ganz catheter for a short distance into the lumen of the larger diameter urethral catheter, the
ballon of the Swan-Ganz catheter is distended with a sufficient quantity of air to create a tight pressure seal with luminal
surface of the urethral catheter (Figure 3). Then, when the Swan-Ganz catheter is withdrawn from the patient, the urethral
catheter will be withdrawn with it.
Other techniques At times it may not be possible to advance the balloon tip of the Swan-Ganz catheter into the lumen of the "lost" transurethral
Figure 3: Swan-Ganz catheter following distension of balloon with air. If the balloon is distended following insertion of
the Swan-Ganz catheter into the lumen of the urinary catheter, a tight pressure seal will be formed (Figure 2).
In this situation, consider distending the balloon of the Swan-Ganz catheter after it has been advanced through the urethra
to a site a few centimeters beyond the distal end of the lost catheter.
The goal is to create enough pressure to cause the urethral catheter to move with the Swan-Ganz catheter when it is pulled
out of the urethra. However, in this application of the technique, care must be used not to create so much pressure in the
balloon that it also causes trauma to the urethral lumen.
Caution should also be used not to allow a Swan- Ganz catheter with distended balloon to remain in the urethral lumen for
prolonged periods. This could result in ischemic injury to the urethra.