She needs food in her to help her poop. The vet will probably give her an enema if she doesn't poop on her own.
Another member here (Growler) who is very knowledgable on cat nutrition recommends giving Heinz Organics or Earth Organics butternut squash baby food instead of the pumpkin. She says cats seem to prefer the taste better.
Sugarcatmom (the cat guru here) may also have some other suggestions.
Good luck with Patsy.