The artificial urinary sphincter (AUS) is the gold standard for males with urinary incontinence. It is generally a safe procedure with a high degree of satisfaction. However, there is a lifelong risk of infection and erosion. AUS cuffs are commonly placed around the bulbar urethral area. There is always a risk of trauma and erosion of cuffs with catheterization or endoscopy. At this time there is little guidance as to which size catheters or scopes can pass through each AUS cuff sizes safely. The goal of this study was to determine which size of catheters/scopes can pass through different cuff sizes safely.

All AUS cuff sizes available (3.5 cm up to 6.0 cm), catheter sizes between 12Fr- 22Fr and scope sizes 19Fr flexible /rigid, 21Fr-26Fr rigid scopes were examined. We used deflated assembled cuffs and 3 different blind observers to measure the free space left between the wall of the cuff and the catheter/scope to be sure that there was consistency. We created a scale from 1 to 3 to determine the ease of passage for each catheter/scope. We also had an MRI radiologist examine bulbar urethra thickness in 20 male patients to determine the average thickness without the bulbospongiosus muscle. Using our average bulbar urethral thickness, we were able to estimate how much free space remained within the urethral lumen and how easy and safe it was to pass each catheter/scope.

For 3.5 cm cuffs, 12Fr catheters pass easily and safely, 14Fr-16Fr catheters and 19Fr flexible/rigid scopes can pass through with some mild risk of trauma. Larger catheter/scope sizes cannot pass through without significant risk of trauma. 
For 4.0 cm cuffs, 12Fr-14Fr catheters pass easily and safely. 16Fr-18Fr catheters and 19Fr-21Fr rigids/flexibles scopes can pass with some mild risk of trauma.  Larger catheter/scope sizes cannot pass through safely.  
For 4.5 cm cuffs, 12Fr-18Fr catheters and 19Fr flexible/rigid scopes pass easily and safely. 20Fr-22Fr catheters and 21Fr rigid scopes can pass with some mild risk of trauma. Larger catheter/scope sizes cannot pass through safely.
For 5.0cm cuffs, 12Fr-22Fr catheters and 19Fr-21Fr flexible/rigid scopes can pass easily and safely. 22Fr-26Fr scopes can pass with some mild risk of trauma. 
For 5.5cm cuffs, all catheters/scopes can pass easily and safely. However, the 26Fr rigid scope can pass with some mild risk of trauma. 
For 6cm cuffs, all catheters/scopes examined can pass easily and safely.

Our recommendations are divided in 3 distinct categories. First, there is the catheters and scopes that can pass easily and can be used safely without an increased risk of trauma and erosion. The others are the ones that they can pass through with a mild risk of trauma and erosion. They should be used only if needed, carefully and if possible, on direct visualization. Finally, the catheters and scopes with difficult passage and higher risk of trauma and, obviously, we don’t recommend using them. We should state that our recommendations are extremely safe and prudent. Although we suggest not using some catheters and scopes for different cuff’s size, it is possible in clinical practice that some can still be used. We think it’ll put the AUS cuffs at higher risk and we suggest that urologists use their clinical judgment.

Our study can guide urologists in the management of patients with an AUS who need urethral catheters or endoscopy. These recommendations are based on the measurements of our study along with bulbar urethral thickness. In general, greater caution is needed with smaller cuff sizes (3.5-4.5 cm).  Our recommendations, with minimal urethral compression, are purposely conservative and safe to avoid trauma and erosion of the AUS cuffs.

Continence 2S2 (2022) 100227
DOI: 10.1016/j.cont.2022.100227