Buccal mucosal onlay graft – or “BMG” as the cool kids call it, is one version of urethrolplasty. Because I have a urethral stricture, and because the only “real” treatment (by which I mean “a treatment where the fix has a good chance of staying fixed”) is urethroplasty, I’ve been doing more than my fair share (and more than is healthy, I’m sure) of research about it.
There are several variations of urethroplasty, going from end-to-end anastomosis all the way to “2-stage.” Those are in order of complexity and invasiveness. You can read all about each type of urethroplasty in my article, The Treatments For Stricture Of The Urethra. But there is some potential overlap between these different versions of urethroplasty.
My doctor told me that I will be having an end-to-end anastomosis, which is a fancy way of saying “cutting out a section and sewing the remaining ends together.” Of course, the section they cut out is the part containing the stricture. I was happy to hear this because in my research, it appeared as though end-to-end did not require a graft from inside my mouth. Oddly, I seem to be OK with them cutting up my urethra, but snipping a thin layer of buccal tissue (inside of the cheek) terrifies me.
The next level up in complexity and invasiveness (how much they have to invade my body with pointy things) is buccal mucosal onlay graft. They cut a slice into your urethra where the stricture is, pull the sides apart to create a sort of almond-shaped opening in the urethra, and then sew a piece of your cheek over that hole, making the diameter of the urethra much larger. Of course that lets more urine flow through much easier.
At first I was a bit confused when I read the descriptions (and saw the diagrams and pictures) about whether the stricture – a blob of scar tissue inside the urethra – was cut out when doing the buccal mucosal onlay graft (I’ll just call it a BMG from now on since I am a cool kid:)). I didn’t know if the slice/incision was made through the middle of the stricture, of if the stricture were cut out, etc. I mean, it seemed like the stricture should be removed since it causes pain, right?
Well my doctor set me straight on that. First of all, no – the stricture is not cut out or sliced during a BMG. It is just left alone. The fix occurs due to the permanent widening of the urethra at that site. And the pain that is felt by folks with urethral stricture disease is actually caused by the bladder trying to force pee through the narrowing (like a neck) caused by the stricture. If you remember your fluid dynamics, you’ll remember that as the cross-sectional area (basically the diameter) of a pipe decreases, the velocity increases (like squirting water out of a hose faster by putting your thumb across the opening, decreasing the cross-sectional area). Add that to the bladder’s attempt to push harder to get the pee out, and you get pain. But when you widen the neck caused by the stricture, the velocity goes down and the bladder stops trying so hard to push. THAT is why the stricture doesn’t hurt any more after a BMG, even though it’s still there.
I found that very interesting and thought you would too.
And as for the graft and the whole cutting-cheek-tissue thing, my doc says that if a surgeon just leaves the site alone after harvesting the graft, it heals in a few days just fine. It’s only when they decide to try and stitch the graft site closed that you get tightening inside the cheek, and likely more pain.
So that’s basically a BMG in a nutshell (no pun intended).