De or het urinebuisopening?

The correct Dutch article is:

de urinebuisopening

Rule Words ending in -ing: almost always de. See the rule

How to use urinebuisopening

the urinebuisopeningde urinebuisopening
this urinebuisopeningdeze urinebuisopening
that urinebuisopeningdie urinebuisopening
our urinebuisopeningonze urinebuisopening
your urinebuisopeningjouw urinebuisopening
every urinebuisopeningelke urinebuisopening
which urinebuisopening?welke urinebuisopening?
a big urinebuisopening / the big urinebuisopeningeen grote urinebuisopening, de grote urinebuisopening