Tuesday, January 20, 2015

Complication

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.
Flushed retrograde into the bladder to allow it to be retrieved via cystotomy (bladder surgery) rather than by traumatising the urethra further. Why do that? Trauma to the uretha may cause scarring which can cause major problems in cats and may require removal of the end of the urethra (and the penis with it) - a procedure called a perineal urethrostomy. Worth doing if you have to but worth avoiding if you can.
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…

  1. 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.
  2. 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.
  3. 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.
  4. Know your cat’s wee. I was celebrating about a post-op wee that wasn’t as voluminous as it should have been.
  5. 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).

1 comment:

  1. The most important thing is that all went well and Hero feeling well enough to be a naughty patient is a bonus (although not for staff!).
    \Perspective on your own animal is almost impossible! I once drove Licorice 2 hours down the coast to where I was working (was visiting my parents in Sydney) to see my boss as he had a lump in his mouth (and cried when I opened mouth).I was convinced it was a tumour and of course he was going to die. My boss figured he'd bit the inside of his lip and tried very hard to be sympathetic and not laugh at me.

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