This happens a lot with abdominal pain. Abdominal pain in kids is most often constipation and it fits a pretty consistent pattern. Most parents who present with their children to the ER for abdominal pain think their child has appendicitis. That also fits a fairly consistent pain pattern. This is not to say you can put ALL kids into one of these two camps (because sometimes kids actually have both or one presenting like the other) but you can reassure parents who feel like the next step for their child is the OR by saying something like:
"This could be appendicitis but based on my experience, your child's symptoms fit more into a constipation issue. You'll get a doctor's exam and they'll diagnose you but you will not be going to the OR in say . . . the next ten minutes."
And then I get that knowing eye roll that says . . . "Well, why believe her. She's just the nurse."
And nine times out of ten do you know what the discharge diagnosis is? Constipation.
It's not rocket science. I don't have a crystal ball. But what I have is nearly twenty-two years in nursing . . . almost twenty years in pediatric ER and critical care. What that says is I've seen, literally, thousands of kids present with abdominal pain. I know the classic signs of constipation. I also know the classic signs of appendicitis. They do present differently. I can educate (this is a nurse's job) on the signs and symptoms of these two illnesses and what the doctor will likely choose to do-- to prepare the family for what they face.
After an ER shift, I got home and the first thing my husband says is, "Harley let out the weirdest yelp when he was just lying down. We have no idea what it was about."
I call Harley over and immediately notice blood in his fur near his neck. Now, it wasn't a lot of blood and my husband hadn't noticed it. Why did I? Because I see blood every day and am in tune to noticing even the smallest amounts of it.
I comb through his coat with my fingers and there isn't a cut underneath. How else would a dog get blood on his coat in that area? We're used to asking ourselves this with kids-- because kids may not always be developmentally able or willing to tell us.
Which led me to think that he'd scratched himself and the blood came from a paw. Then I see droplets of blood on the floor-- like when we accidentally cut his toenail too close. Yes, I had done this myself.
I see one of his toes looks bloody.
"Where was he laying?"
My husband points to the spot and I see a full-length toe nail on the carpet. He'd been scratching himself and caught the nail in his chain collar which ripped it fully off.
Mystery solved in under five minutes. My husband was somewhat baffled.
Not me. It's not a miracle. It's my experience in injury mechanism that I practice every day.
This is how it can be for your medical characters. Have them use their experience in other situations to make them come to life in your novels. They don't just have to stay in the hospital.