Babies born with disorders such as myelomeningocele or other
congenital cord lesions such as sacral agenesis will often present with a neuropathic
bladder. Pre 1950’s babies born with such disorders often died until shunting
devices were developed but it wasn’t until the 1960s and 1970s that the ‘neuropathic
bladder’ was identified as a complication of these disorders and surgery such
as a vesicostomy, ileal conduit or ureterostomy were performed to protect the
upper tracts and kidneys. Renal impairment had been reported within 6 months of
age and as prevention of renal damage is a priority management of the neuropathic
bladder must start at birth with an aim to replicate, where possible, normal
bladder function. Clean intermittent catheterisation combined with an
anticholinergic has been identified as an effective initial form of management,
however, this may lead to potentially more cases of spontaneous knotting from
‘catheterising’ being reported if people are not aware of the complication.
The first reported case of knotting following transurethral
catheterisation was reported in 19762 with further cases being
reported, more commonly in neonates and children and mostly boys with almost
all cases reporting the use of a feeding tube having been used.
Feeding tubes are often used as are they are available in smaller
sizes than catheters with 4Fr/Ch and 6Fr/Ch being commonly used. However,
feeding tubes tend to be much longer than catheters with lengths of up to
125cm, encouraging clinicians to insert more tubing than necessary into the
bladder.
Feeding tubes and catheters sizes 6Fr/Ch and under are very
fine and flexible, when excessive tubing has been introduced into the bladder
it can form a loop, then as the bladder decompresses, the tubing can become
knotted or entangled. When it comes to removal of the tubing, the loop/knot may
tighten as it meets resistance on withdrawal making removal of the catheter
urethrally traumatic or impossible requiring surgical intervention.
Most reported cases felt the risk of knotting could be
avoided or prevented with a better understanding of the urethral anatomy in
neonates and young children and selecting a more suitable catheter.3,4,5
A new-born male urethra measures approximately 5cm and
increases to about 8cm by the age of 3. The female urethra is much shorter and has
a slower development time measuring approximately 2.18cm at birth, increasing
to around 2.54cm by the age of 5. It is therefore recommended that no more than
6cm of length should be inserted into a male new-born and 5cm in a female and in
babies with very low birth weight <750 grams, <5cm should be inserted in
boys and <2.5cm in girls.3
In addition, clinicians should be encouraged to pass a
catheter until urine starts to flow and then introduce the catheter
approximately another centimetre to ensure the catheter is positioned in the
bladder without excess.
Where possible the catheter should be passed, the urine
allowed to drain and the catheter removed, however, there are incidences when
the bladder may need to be on continuous drainage. When left in situ it is
important to secure the catheter effectively to prevent inadvertent advancement
of the catheter into the bladder.4
Wymedical have launched a size 5Fr/Ch catheter, at the
request of a Paediatric nurse, which is 25cm in length to try to overcome the
temptation of introducing an excessive length of tubing into the bladder and
therefore reduce the risk of knotting and licensed for purpose. The Wycath
uncoated catheter, WUP05, is DEHP free and is available on prescription
enabling parents of new-born babies to be able to undertake intermittent
catheterisation from birth and reduce the risk of damage to the upper tracts.
The families can be discharged from hospital and managed at home under a close
eye of a urology team until further surgery is required.
References
1.
Foster H, Ritchey M. Bloom D. Adventitious knots
in urethral catheters: report of 5 cases. J Urol 1992; 48 1496-8
2.
Harris VJ, Ramilo J. Guide wire manipulation of
knot in catheter used for cysto-urethrography. JUrol 1976; 116 529
3.
Carlson D, Mowery B. Standards to prevent
complications of urinary catheterisation in children: should and should knots.
J Soc Pediatric NUrs 1997; 2:37-41
4.
Arena B, McGillivary D, Dougherty G. Urethral
catheter knotting: be aware and minimise risk. Canadian Journal of Emergency
Medicine 2002; 4(2): 108-110
5.
Sarin YK.Spontaneous intravesical knotting of
urethral catheter. APSP J Case Rep 2011; 2:21
