I disagree that just because serology and urology are both medical terms, they should be treated the same way in Chihuahua. To me that is just like saying that because a horse and a skink are both animals, they should also be treated the same in Chihuahua.
Urology is a rather common medical specialty in the United States, and I can't imagine that men in other parts of the world are so little concerned about this aspect of their health that urology is rendered uncommon in their respective countries. My husband, being of a certain age, sees a urologist every six months. Serology, on the other hand, is less visible. Laboratories have serologists, but ordinary patients do not go to see a serologist; they simply have their blood drawn by a technician at the lab and then go on their way.