What is the danger period (time frame) to watch for bleeding out after a spay?

That was a loaded question. Hope things are okay. Have had one the same day as the surgery; she was saved because I insisted the tech go look at her again before they left her for the night. I now insist on taking them home if I can watch them overnight and keep them crated and quiet. Have known of folks who had the girl chew the stitches 3 days later and have everything falling out. I have had a girl react to the ligature SIX WEEKS later with a pouch like a drawn purse of infection (pus ball inside, showing on the outside) and need to have it removed as it was not dissolving.That kind was more like a cable tie than like sutures. That was not bleeding out. I no longer like that vet, who is otherwise good, to do most of my spays. That being said, the other spays he did, unrelated girls, did not have the problem.

I had my bitch spayed in the end of Jan this year. It was done in the morning and in the same night... she started to have some internal bleeding. So I rushed her to the vet again who took blood samples of her and did some sonar. She got some fluid into her sistem and more antibiotics and pain medicine... We took her again on the next day and it was better and the internal bleeding had stopped. So I would say... the first 24 hours are critical. But I could be wrong.

Yes. The first 24 hours is the most critical period. However, I have had one patient with clotting problems that I fought to keep alive for 3 days. Thankfully, she survived.