When I was little and having my hair done especially curling whih takes awhile and my Mom was saying " hold still" I'd pass out after awhile especially if I was standing and even sitting and especiallly if I hadn't eaten. I'd have her have some trail mix or some type of healthy food she can fave several times a day like the above poster suggests also. I'd pass out in Church too during longer ceremonies. I imagine she just had to go to the bathroom at the time it happened as to why she urinated but I wouldn't worry too much since you took her in she's been checked and everything looks fine. If it happens again, that's when I'd worry.
I'd be more concerned as to why the doctors aren't more concerned. I wouldn't let the issue go, because that's not normal.
A sudden drop in blood pressure, or blood sugar, could cause fainting. Sudden bleeding internally can cause blood pressure to drop suddenly. I'd deduce that something burst or ruptured that caused the bleeding, like a small vein, or cluster of capillaries, or a cyst. There's also parasites that can get up in the bladder, like pinworms, which are very, very common in gradeschool.
I suppose you could also consider that she may have passed a kidney stone or bladder stone. Some doctors pass over rather obvious options because of age, but people of any age can have any almost anything. If your daughter was a 40 year old man, they'd probably consider urinary stones!
If it was a stone of some kind, it could have been completely overlooked because they can be very small, like a grain of sand even. It would have been easily missed in the blood. The rough shape can tear the skin inside the tubes as it comes down from the kidneys, or down into the bladder, and cause bleeding. Once it's gone, the problem may or may not occur again. You should get her to tell you if her urine doesn't look "like it's supposed to", at least for awhile. There are some other bleeding/urine issues that bear watching, I just cannot think of them just now.
Hope that was some help!
I would play this down/ask her to let you know if she feels
bad again her know we'll fix it. Meanwhile, call office and
get copies of all labs done to start file, just in case. I
use to faint around age 9 & blackout. Sometimes bladder would
release. That was yrs. ago when no one went to a doc unless
an emergency. It had no pattern & many times I was fine after a
20min rest w/ juice & talking to nurse. After lunch I was
perfect. I just grew out of it or so I thought. 30 some yrs.
later & dealing w/ alot of stress, I began that same funny
feeling like I had to breathe deep & light-headed. It happened
at a Dr's ofc. so we spoke abt it. He came back w/ orange jc. &
sliced apple w/ peanut butter on them for me to eat. 10 mins.
later ck'd pulse, etc. Said I can send you for an awful glucose
tolerance test where you drink this syrup w/ no food & draw
blood every hr., or believe me when I say you probably always
had 'Functional Hypoglycemia'. I ate a pastry that day & traffic
was rushed going to ofc. Stress shifts cortisol (chem. body
makes), pancreas overloads your insulin to spike. It happens
more often w/ kids that eat breakfast w/ wrong diet. Think what
or if she had eaten prior. May be that she is spiking from carbs
& do a watch & see. I remember now that I blacked-out 1-2 hrs.
before shots/tests/being late. The cortisol spiked w/ the sugar.
I never grew out of it. I just ate something right when I got
rushed by fluke. The Dr knew the perfect combo. I eat handful
of nuts every 4 hrs. & I'm balanced. Back then it was frosted-
flakes & out the door. Dried fruit helps too. Basic glucose
can be ck'd but in kids it's hard to dx w/o other symptoms.
See if she acts slow to function on a bad day w/o right food.
Kids burn calories fast. Avoid freq. junk food but she's a kid
so try to balance later. Something may have been going on that
day in her head. Get copies & play Sherlock. You're Mom so you
know what's the norm for her. Gd-luck.
did they check for a urinary tract infection? probably wouldn't cause the passing out, but sure could cause the blood in urine.
you may want her to see a cardiologist to rule out any heart arrythmia that may have caused this ...it's a pretty scary thing...i don't know if i'd just let it go being a mother myself good luck