A chap with a 6 month old ileal conduit for urinary diversion rocks up to your ED feeling more than a little unwell.

A VBG done at triage is like this:

What’s the deal?

The reference

Tanrikut C, McDougal WS. Acid-base and electrolyte disorders after urinary diversion. World J Urol. 2004 Jul 29;22(3):168–71. [PubMed]

you can make a urinary diversion out of lots of bits and bobs lying around in the abdomen. I’m sure there’s a very technical side to choosing which bit or bob to use gastric jejunum ileum and colon (this seems to be what I see)



decline in renal function (thought to be due to obstruction and reflux)

infection

stones somewhere along the system (which are linked to infection)

metabolic disturbances – this is the interesting one we’ll tackle today

normal bladder does not alter the urine – there are no funny ion pumps changing concentrations and fiddling with your wee wee

whichever section of gut your urologist randomly plucks from within the abdominal cavity chooses their venous drainage will all be to the liver. This can be an issue if your urinary diversion starts sending lots of urea to your liver especially if it’s already struggling.

chooses their venous drainage will all be to the liver. This can be an issue if your urinary diversion starts sending lots of urea to your liver especially if it’s already struggling. this all changes when you use a bit of gut and different bits of gut cause different issues if you use stomach then you can get a hypochloremic metabolic alkalosis imagine it a bit like continual vomiting with Cl loss you can even use PPIs to reduce the action of the H+/K+ pump and reduce H+ loss thus lowering the pH again if ileum or colon then you get a hyperchloremic metabolic acidosis. There is net absorption of both ammonium and Cl back into the circulation that was just trying to get rid of it.)

Minimising contact time reduces all of these. If the urine isn’t in the pouch for very long then the acid base problems don’t happen. If this is happening then you have to question how well the urinary diversion is working.