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The injection of bulking agents around the
urethra or bowel sphincter as a treatment for some bladder and bowel problems
has aroused a great deal of interest. Here we find out more.
Bladder problems
The ability of the bladder and urethra to
prevent leakage of urine during coughing, sneezing and exercise appears to rely
on two different mechanisms. The first is the support of the bladder and urethra
by the pelvic floor muscles, and the ligaments and connective tissues
surrounding the bladder base. These help to provide support during times of
physical exertion and may be damaged during pregnancy and childbirth, or
weakened by age or heavy exercise, leading to the development of stress
incontinence.
The second mechanism preventing leakage of
urine is the watertight seal provided by the urethra itself. This may also be
damaged or weakened by pregnancy, childbirth and ageing, or damaged by scarring
from surgery or radiotherapy.
Physiotherapy acts to increase the strength and
support given by the pelvic floor muscles. Most surgical operations for stress
incontinence are based on lifting and re-supporting the bladder and urethra.
Operations such as colposuspension, "sling" procedures and vaginal
repair are all designed to work mainly in this way.
The injection of materials close to the urethra
and its opening into the bladder provide pressure to help restore the seal of
the urethra and help it stay watertight. This is not a new idea - almost a
hundred years ago an injection of phenol, an irritant, was tried. The resulting
scarring may have helped narrow the urethra and cured some women, but the high
complication rate meant that this technique was quickly abandoned.
More recently, a number of different substances
have been used, much more successfully.
Fat, removed from beneath the woman's own
skin may be used for injection. It is cheap and easy to obtain and, as it comes
from the woman herself, there is no worry about infection. Unfortunately, the
results appear very short lasting, the fat cells quickly disperse and, for this
reason, this technique is rarely employed.
Collagen (GAX collagen, Contigen) has been
widely used for a number of years. It is produced from the cartilage of cattle
from the USA, which is extensively processed and sterilised to produce a viscous
paste. There is no risk of Bovine Spongiform Encephalopathy (BSE) transmission
due to the processing which would destroy any bacterial or viral particles.
A paste made from microscopic particles of
silicone suspended in a viscous gel (Macroplastique) is also currently used, and
a number of new products have recently become available (e.g. URYX, Permacol,
Coaptite).
Injection of all the periurethral bulking
agents is performed in a similar way. The procedure is quick, taking 15 to 20
minutes. No incisions are made and this means that it may be carried out with
local anaesthetic or under a regional anaesthetic such as an epidural. Using a
fine fiberoptic cystoscope the inside of the urethra and bladder can be
inspected, and a fine needle guided to inject the material at exactly the
appropriate spot. Usually three injections are made around the urethra. The
exact amount used depends on the material used and how much closure of the
urethra the surgeon feels is required.
As the operation is short and there is little
discomfort afterwards it is possible for women to go home the same day. Some
units prefer women to stay overnight to check that there are no problems with
bladder emptying. Either way, recovery from the operation is very quick.
Given that this technique is so quick and easy,
with very few complications, it would appear to be an ideal treatment for stress
incontinence. Unfortunately, the problem lies with the longer-term results. In
the short term, within three months after injection, the results are good with
at least 80% of women cured or improved. As time goes on, however, the results
become poorer. After two years, less than half of these women will still be
cured. This is due to the material injected dispersing away from the urethra
over time.
It is not clear at this time which material is
longest lasting: fat seems to be absorbed very quickly, GAX collagen and
Macroplastique persist for much longer. Newer materials under development may
improve these results. A recent study comparing URYX and Contigen suggested that
women treated with URYX were drier after one year than those treated with
Contigen.
The poorer long-term effects of periurethral
injections do not mean that they are not suitable for some women, however. As
the operation is relatively minor, it may suit older women who are less fit for
more complicated surgery. The long-term results in older women who are less
physically active also tend to be much better.
One study found that some younger women opt for
injections because they do not want a lengthy convalescence period, either
keeping them off work or preventing them caring for their small children. In
both situations, they said they would prefer a less debilitating treatment even
if regular top-ups are required.
Bowel problems
It is estimated that 2.2% of the population is
affected with faecal incontinence, with approximately 10% of these aged over 65.
This condition has a devastating impact on the social and psychological
wellbeing of those affected.
The internal anal sphincter is the main muscle
that helps prevent faecal leakage. Childbirth and surgery (such as
sphincterotomy or fistula surgery) can cause damage to the internal anal
sphincter, which can lead to leakage. The internal sphincter is not easy to
repair as it is extremely thin and, as a circular muscle, is under tension.
While antidiarrhoeal drugs such as loperamide or codeine phosphate help some
patients, this may not be an adequate long-term solution.
Uroplasty has recently developed PTP Implants
that are specifically designed for this problem. These involve an injection of a
tissue-bulking agent into the internal anal sphincter. The procedure only takes
a few minutes, performed in the hospital or clinic under local or general
anaesthetic, with the patient usually being discharged home the same day.
Some of the procedures outlined here are
relatively new, with little evidence as to how well they work. They may not be
the ideal treatment for everyone, and there are still risks involved. For more
information about any of the procedures outlined here, talk to your doctor or
continence advisor.
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