One of my personal interests is urologic surgery, that's part of one of the focuses of my surgical training.

So I'm here to talk to you about subcutaneous ureteral bypass, or sub-surgery in cats.

So the reason we do this, you may already know, is to help bypass an obstructed ureter.

So when the kidney needs to empty urine into the bladder, if the ureter is blocked it cannot do that.

So the sub is a way for us to bypass that blocked ureter and allow urine to empty from the kidney.

So we have a little diagram here of a cat's abdomen.

The kidneys, there are two.

Your cat may or may not have one or two of those ureters blocked, so the ureters are these white tubes running down through the abdomen into the bladder, which is this little circle here.

So if those are blocked, if there is something blocking the way, typically a stone in cats, those are able to be bypassed by the use of our subcutaneous ureteral bypass system.

We have some of the implants here to help outline exactly what's involved, but in a very simple sense, we insert a tube into the pelvis part of the kidney.

So this down here is a transverse section of a kidney, so the brown outer parts here are what generate the urine as it is filtered from the blood, and it empties into this triangular section here, which is called the renal pelvis.

So in most cases with ureteral bypass, the ureter and renal pelvis is more dilated than normal, which in terms of us placing these implants actually makes it more straightforward.

So what we need to do when we're placing that is insert a tube into this renal pelvis, which is then sealed with some glue on the outside.

So here is one of the ureteral catheters.

This is the end of the nephrostomy catheter, so the nephrostomy tube is the bit that goes into the kidney.

So the important parts that we have at the end here, we have this curled J-shaped section with little fenestrations, little holes along the end, which allow urine to be passed through, and then the little string that you can see here at the end is also part of the locking loop.

So you'll see if I pull on the string at the other end, that will hold that locked, which then allows this locked portion at the end to become less likely to then pull back out of the kidney.

So the last bit is this little cuff here, which is then super glued in place on the outside of the kidney, which helps form a seal around the edge of the hole that's passing through the tissue of the kidney to limit leakage.

Once we've placed this tube, it is then passed through the outside of the body wall, so this tube here ends up sitting at this end section here and curling around, and then it's passed outside the body wall, and that then allows us to connect one of these subcutaneous ports.

So the port has three main parts.

So there is the nephrostomy connection tube and the cystostomy connection tube, so this is the end that goes to the kidney, comes from the kidney rather, and this is the end that then drains into the bladder.

This central portion here is a little silicon diaphragm, which allows us to pass a special needle called a Huber needle, which is designed not to cut any little cores out of the silicon diaphragm itself, so you can see it has a slightly bent end so that the tip of the needle doesn't cut a core through and leave a hole so it can leak, and that allows us to flush and drain the system and help avoid any further mineral collection, which can sometimes result in obstruction of the tubing.

So that then gets sutured to the outside of the body wall after the tube from the kidney is connected to one end, and then a corresponding tube, so a second tube that is placed similarly to how it's placed into the kidney, doing the same thing, placed into the bladder to help then complete the circuit.

So it then gets connected to the other end of our subcutaneous port, and then connected through into the bladder.

So instead of having this blocked ureter, the urine is able to flow through the tube that's inserted into the kidney, through this injection port which sits subcutaneously, and then that then follows through and drains into the bladder, thus bypassing the obstructed ureter.

So now the other benefit of having this subcutaneous port rather than just directly connecting the two, is that this injection port allows us to both easily collect urine samples and and also to flush the system, because the main reason for these problems happening is that these cats are prone to forming mineral stones, so those mineral stones can also form within the tubes themselves, so by regularly flushing them, it allows us to help control the, helps us control the likelihood of those blocking further down the track.

When we're inserting these catheters, because the abdomen is open, we can visualise that they go into the kidney itself, but we still can't see the inside part of this, the end of this tube once it's been inserted, so, and although most of the cases have urine flowing back through the tube to confirm that it's in the right place, we also use fluoroscopy, which is video x-ray, to help identify the position by, after insertion of the tube, by injecting a contrast liquid into the tube itself, which then helps fill up the section of that renal pelvis, and helps both confirm the location, and the other thing it can do is help outline the size and diameter of the ureter further down, and typically also help locate the obstruction that's occurring as well.

So that typically allows us to be more confident that the nephrostomy portion of the catheter is exactly where we need it to be.

And then once that's in place, we typically go about placing the rest of the bits which don't necessarily need fluoroscopy, but the other thing we do at the end of surgery, once everything is in place, is we'll inject some contrast into the subcutaneous port, which helps confirm the patency of all of the tubing, to make sure that both liquid can flow back and forth into the kidney, but also back and forth into the bladder as well, to help us ensure that the system is doing what it needs to do.

So thanks very much for listening to our video about placement and the use of subcutaneous ureteral bypass, so if you do have any questions, please feel free to get in contact with us at veterinary specialist services, and cat specialist services, and we'll be very happy to try and answer any questions you have.

Thank you.