Going into the uterus at this stage is an old school treatment, and I don't know know any vet who recommends that as the first route of therapy or intervention for not cleaning off after calving. The lutalyse shot should work to cause enough uterine contractions to expel any tissue that should be expelled, and you stand no chance of introducing more contamination into the uterine environment.
I have used the boluses (years ago) and they do work. They're just not the best option we have today for treatment at this stage. And if you're not absulutely sure what to do or how to do it, a lutalyse shot is not apt to cause more harm than good! If I would give the shot if she wasn't cleaned off within 24 hours, and if that doesn't finish the job within 2-3 days, you need somebody who knows what he or she is doing to get the job done. She'll need to be cleaned out and infused with antibiotic (ie penicillin).