Hero experienced complications following his surgery. You wouldn't know it now. |
Feline urinary tract disease
can be challenging and frustrating to treat. Recurrence of obstruction is
common, although the reasons can vary. When I treated my cat Hero for urethraland bladder stones over Christmas he seemed to be recovering well. But he experienced
a complication.
I want to discuss it here
because a) complications are a normal part of medicine and surgery and I think
we need to discuss them more; b) turns out this one is a lot more common than I
thought and c) I’ll feel more like Hero didn’t suffer the experience in vain if
others can learn from it. And suffer he did. Suffer everyone around him did.
Many sleepless nights were had over the festive season and none of them were
the celebratory sleepless kind!
It was day four post-op.
Hero had been eating, drinking and becoming more active. He seemed bright and
happy. His surgical wound looked beautiful. Then I watched him go to the litter
tray. Not once to pass a nice stream, but twice. And he passed a few drops. And
cried. My heart sank.
I palpated his bladder. It
was large, despite the fact that he’d just “voided”. He reacted when I touched
his tummy. There had to be a stone obstructing that little urethra of his. It
sent my mind my mind into a vortex of retrospectoscopy…
At the time of surgery we
counted the stones on radiographs and those we retrieved, and thought there may
be a discrepancy. His first wee post-op had contained more blood than I’d
hoped. The patches of urine in the litter tray were getting subtlely smaller. I’m not going to lie. I did not like what this
was telling me and did the whole “oh Anne, you’re just being a paranoid
hyperchondriac by proxy”. It’s easy to do. But a little voice inside me said “or
is this a complication?”.
Potential complications of
cystotomy including uroabdomen (urine leaks into the abdominal cavity), urinary
tract infection, surgical site infection, recurrence of stones (usually
secondary to infection), lower urinary tract obstruction (mechanical or
functional) and incomplete removal of uroliths (Appel et al 2012). I was concerned about the
latter.
When it comes to uroliths
that hang around post-cystotomy, MOST of these can be prevented by passing a
urinary catheter and flushing stones back into the bladder intra-operatively,
or - as US veterinary surgeon Howie Seim does in his fantastic video on urinary
tract surgery – performing the “urogenital floss”.
In addition, post-operative
radiographs of the entire urethra following surgery can identify stones that
are left. A review of literature on veterinary cystotomies found that
radiographically detectable uroliths remained in 14 to 20 per cent of dogs
(Grant et al 2010).
BUT not all uroliths are
radiographically detectable. Even if they show up on the rads, if they’re
hiding behind the pelvis or beside a catheter in the lateral view, or below the
spine on the ventrodorsal view, you won’t see them. How can they escape a
catheter? Well, if they’re narrow enough a catheter can slip past them. You can
urogenital floss all you like but there’s a chance they won’t be dislodged.
In a Canadian study of 106
veterinarians who performed cystotomies, 42 per cent reported that patients had
recurrent uroliths, although it’s hard to know how many of these were true
recurrences as opposed to those not removed at surgery. When I did the
ring-around, lots of colleagues had experienced the pain (indirectly, of course
– it’s the patient who feels it first-hand) of a retained stone.
But the data illustrates
that even in the best hands (ie world-class veterinary teaching and referral
hospitals) some uroliths inevitably escape the surgeon. Post-op rads confirmed my worst nightmare. A urolith the size of Tasmania (almost) in his distal urethra. I won’t lie: I felt
sick. But I couldn’t leave that stone in there.
Evil, evil urolith. |
So I flushed it back into
his bladder and performed the second cystotomy in four days on little Hero. Are
there alternatives? In humans, cystotomy is rare these days. In the US,
open-surgical removal of uroliths was described in only 0.3-4 per cent of human
patients (Defarges et al 2013). But non-invasive alternatives aren’t well
established in companion animals. Voiding urohydropulsion is contraindicated in
male cats because of the high risk of obstruction (sorry to say it Hero, but
male cats have a tiny penis with a narrow urethra that is easily blocked),
lithotripsy is still experimental, and laparoscopy remains uncommon in
first-opinion practice.
My concern was that he was
in pain. His urine was full of blood and that stone was tearing his urethral
mucosa. The surgery was
straightforward. Cystotomies are beautiful surgeries and I’ve said before that
the bladder and urethra have extraordinary healing capacity. When I opened him
up there was Hero’s bladder looking quite healthy despite being opened four
days earlier.
I incised once again,
locating and removing the stone within minutes. Its removal was confirmed (as
much as it could be) on radiographs. Again I used multimodal analgesia (multiple
drugs) to minimise his pain and of course checked on him through the night.
The following morning I
helped him into his litter tray (he had kept the drip on overnight this time)
and his post-operative wee was like Niagra Falls compared to the first post-op
wee.
MUCH BETTER. |
A few lessons learned here…
- The first, which I didn’t realise, is that the incidence of uroliths leftover after surgery (even in the hands of a specialist) is higher than I thought.
- The urogenital floss is good – but doesn’t prevent sneaky uroliths from hiding out in the pelvic urethra. And a catheter can pass adjacent to a particularly recalcitrant urolith embedded in the urethral wall.
- Post-cystotomy radiographs are essential but don’t absolutely rule out uroliths. In retrospect I should have taken a post-op rad of Hero WITHOUT the urinary catheter in just to be sure there was nothing in the urethra hiding beside the catheter.
- Know your cat’s wee. I was celebrating about a post-op wee that wasn’t as voluminous as it should have been.
- Phone a friend. I called a specialist friend for a debrief after cystotomy number two. He was the one who suggested I look at the literature about incompletely removed uroliths, and I have to say that was both educational and therapeutic.
Of course, all of this
fiddling with Hero’s urethra – all done as gently as possible – wasn’t
unnoticed by his urethral mucosa. Predictably, he developed a functional
urethral obstruction (essentially his urethra just threw a hissy and clamped shut).
So he was readmitted, I placed an indwelling urinary
catheter, and kept Hero in hospital. Then plan was 48 hours of catherisation.
Despite the world’s biggest Elizabethan collar, Feliway, a private cat
grass/mint/nip garden in his cage and drugs galore, he protested. He removed
collars. He removed catheters (urinary and intravenous), he threw a rockstar
rampage in his cage and misbehaved for colleagues. But he put in 36 hours before I caved and took him home.
The urolith analysis
returned a result of 100 per cent calcium oxalate. These types of stones tend
to be sharp and prickly, whereas struvite (the other very common stone in cats)
produces very smooth stones. So I had an inkling.
The bummer about calcium
oxalate uroliths is that they can return after months or years even with IDEAL
management. So whilst modifying Hero’s diet will hopefully slow the rate of
recurrence, we’ll need to be vigilant. Fortunately I’ve taught him to tolerate
a daily bladder palpation session by convincing him it’s a weird new patting
style.
Interestingly, a very close
family member of the human variety has experienced the woe that is a kidney
stone. The medical team didn’t bother with x-rays and instead performed a CT
scan to detect the 3mm-diameter offender (but amazingly, didn't show him a picture of it). In twenty years we might all be doing
pre-and post- or even intra-op CTs or cystoscopies (with tiny, tiny, tiny
cat-penis sized scopes) and we will be laughing about “ye olde days” when
people had to worry about sneaky uroliths evading detection.
References
Appel S, Otto SJ & Weese
JS (2012) Cystotomy practices and complications among general small animal
practitioners in Ontario, Canada. Canadian
Veterinary Journal 53 (March):303-310.
Defarges A, Dunn M &
Berent A (2013) New alternatives for minimally invasive management of uroliths:
lower urinary tract uroliths. Compendium:
Continuing Education for Veterinarians January 2013:E1-E7.
Grant DC, Harper TAM &
Were SR (2010) Frequency of incomplete uroliths removal, complications, and
diagnostic imaging following cystotomy for removal of uroliths from the lower
urinary tract in dogs: 128 cases (1994-2006).