This is a trick that I have leaned in my first steps of urology, In the beginning of the nineties.
In the emergency room most of the times no 3-ways prostatic catheter was available (especial at night). So if we received a patient with hematuria, with a need of bladder irrigation and drainage, we performed a vigorous bladder washing and extraction of all the clots, using a large feeding tube or Nelaton tube (20 - 24 Fr).
you could use 2 catheters in parallel. For example a nelaton 20 fr attached with a small nasogastric catheter.
You could attach the nelaton with the small nasogastric catheter with linen sutures and irrigate continuous with the small cat ether and remove the clots with the nelson.
Other option is to put a suprapubic catheter (like arrow) and a nelson transuretral. This procedure is contraindicated in the suspicious of bladder cancer or antecedents of bladder cancer.
we had also used the idea of2 catheters, but instead of a Nelaton catheter we used a Foley catheter, thus, the fixation of these 2 catheters is not a problem. However, what we gain in the fixation, we loose in the softness of the catheter if a bladder washing is needed.