The Silver Lining

By | 2017-01-13T20:43:41+00:00 August 1st, 2009|
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Q: Recently I’ve been seeing advertisements for “silver-coated” catheters. What is the deal on these?
— Dave

A: Dave, it turns out bacteria are anti-capitalistic — they do not like silver or gold. The Ancient Greeks and Romans figured this out and would put silver or gold in wounds to stop “festering” (bacterial infection). Laying gold leaf (thin pounded out pieces of gold) in a wound is one of the original anti-bacterial healing treatments.

Silver fights bacteria by interfering with a bacterial cells’ ability to bond, which causes the cell to fall apart. Fortunately, human cells have thick walls that are not bothered by silver. The metal is used as an antibacterial agent in many hospital applications ranging from an additive in biocides for cleaning and sterilizing to silver-imbedded surgical tools.

Using silver as an antibacterial agent on catheters proves to be a little trickier. A PubMed search on silver-coated catheters pulled up four pages of research papers dating back to 1989. The early studies found that not all silver coatings are created equal. Studies on silver oxide coated catheters found no reduction in urinary tract infections. Trial and error led to finding out that silver alloy (silver blended with other metals) is the most effective compound and has been used in all of the studies from about ’99 on.

All of the PubMed papers were done on indwelling (Foley) catheters. When an indwelling catheter is in the urethra, a layer of biofilm develops on the catheter. Bacteria can migrate up this biofilm layer into the bladder and cause a urinary tract infection. The idea behind a silver-coated catheter is the silver alloy coating will stop bacteria from traveling up the biofilm layer thus and prevent UTIs.

In trying to find a definitive answer as to whether silver-coated indwelling catheters reduce UTIs or not, I narrowed my PubMed search from 2000 to the present. Of the thirty-two studies found, twenty-seven showed that the use of silver-coated indwelling catheters resulted in a significant reduction of UTIs. Five showed no significant reduction. There were no side effects mentioned in any of the papers except financial. Silver-coated catheters cost an extra $6 per cath.

A caveat on the studies — most were done in hospital settings and none involved people with SCI. To paraphrase a common theme from many of the papers, “Using silver-coated catheters to reduce incidence of UTIs shows promise, and further and broader studies should be done.”

As always, the purpose of this column to present readers with options. For somebody that uses an indwelling or suprapubic catheter, using a silver-coated catheter to help prevent UTIs is another option you may want to discuss with your urologist.

Silver-coated catheters are available from Bard Medical.

Q: I’ve been a T6 para for 19 years. I manage my bladder by intermittent catheterization and never had any problems until about six months ago when I tried to cath one evening and the catheter simply wouldn’t go through to the bladder; it would go part way, and stop. I tried putting the catheter in the freezer to stiffen it up — still no luck. I was finally successful the next morning. The same thing happened a week later and it was getting more difficult to pass a catheter each time.
I went to see a urologist. He did a cystoscopy and said that I had a urethral stricture and scheduled me for cystostomy two days later. I was put under general anesthesia, he inserted the cystoscope, cut the stricture, inserted a Foley and I went home the same day. Three days later I removed the Foley and have had no problems since.
My question is, how common is this and is there a way to avoid it happening again?
— Tom

A: Tom, a urethral stricture is an abnormal narrowing of the urethra caused by inflammation or scar tissue. Causes include pressure from an enlarging tumor near the urethra (rare), scarring from sexually transmitted disease, and trauma from inserting a catheter. I asked several urologists about urethral strictures. They said that although the urethra is fragile and easily scarred, urethral stricture is uncommon in intermittent catheterization when proper technique is used — but it does happen.

Proper technique to avoid a stricture includes using at least a 16-French catheter with plenty of lube. If there is any difficulty inserting a straight catheter, using a Coudé tip catheter — a catheter with a curve at the tip that helps the catheter go around the sphincter muscle and into the bladder — can help. Some wheelers find hydrophilic catheters (a catheter coated with a substance that becomes extremely slippery when water is added) are easier to insert, and may cause less trauma than using a regular catheter and lube. (For more on Coudé and hydrophilic catheters see the October 2008 Bladder Matters.

For anybody managing the bladder with intermittent cathing, the inability to insert a catheter and inability to void will cause the bladder to overfill — and this is a medical emergency. Overfilling of the bladder can cause stretching and scarring of the bladder and reflux — urine backing up into the kidneys.

As far as diagnosing and treating urethral stricture — yours was textbook. Diagnosis is made through a cystoscope — a catheter with a tiny camera on the end. Strictures can usually be repaired through a cycstoscope with a tiny scalpel on the end. During the procedure, even though a person with SCI may have no sensation, anesthesia is used to prevent autonomic dysreflexia. The cystoscope is inserted into the urethra and the surgeon cuts out the scar tissue. Following the surgery a Foley catheter is put in place to stop bleeding and allow the area to heal. The Foley is generally removed in three days.

For longer strictures a urethroplasty may need to be performed. A urethroplasty is an open surgery — the surgeon opens up tissue to access the urethra. If the damaged area is small enough it can be cut out and the two ends of the urethra sewn together. With more extensive damage the surgeon takes a graft from the bladder or membrane of the cheek and rebuilds the damaged area. Recovery from a urethroplasty usually involves a two-day hospital stay, leaving a Foley catheter in for five days, and avoiding strenuous activity for two weeks.