Hello, I understand that you are concerned for your girl. I understand your concern but it is not uncommon for dogs to not have regular stools after abdominal surgery of any sort for several days for a few reasons.
They are fasted before surgery which causes the gut to slow down its motility and there isn't anything in the gut for that day so there isn't much to make stool. And if she doesn't eat as much as she normally would after surgery her stool production will be less, so she will pass less stool.
Anesthesia slows down normal gut motility and as such stools aren't as regular.
Finally passing a stool involves using the muscles of the abdomen to push out the stool which may hurt a little, so many dogs tend to hold their stools.
If she were straining repeatedly, unsuccessfully to pass a stool, passing very small, hard, dry stools or very large, hard stools and crying, not eating at all or vomiting I would be much more concerned.
You can take her on a slow, short walk after eating as that stimulates normal gut motility and gets stool moving.
If you think she has an upset stomach at all or seems nauseous after surgery because she isn't eating well then at home you can give either:
1) Pepcid ac (famotidine) at ¼ of a 10mg tablet per 5 to 10 pounds of body weight every 12 hours
2) Prilosec (omeprazole) at ¼ of a 10mg tablet per 5 to 10 pounds of body weight every 24 hours.
These are acid reducers, are very safe, and should help her feel better. They can be used as needed.
You can also try a bland diet with increased fiber and fluids to perk her appetite and get her gut moving. A homemade diet for this is 1/3 boiled, lean hamburger or boiled, white, skinless chicken, all fats and juices drained off the meat and 2/3 white or brown rice. Add 1 to 2 tablespoons of canned pumpkin, (not pie filling, just pumpkin), to each meal for fiber. If she's a small pup start with one tablespoon and increase as needed but if she's a big girl then start with 2-3 tablespoons. You can add low salt beef or chicken broth to her meals as well to get more fluids in which should help as well.
Once she is back to eating well and passing stools you can slowly convert her back by mixing in her regular food, adding a little more regular and less bland at each meal. It should take a week to get her converted back to regular food.
If she seems very painful and she wasn't prescribed a pain medication post-surgery I would call your veterinarian and request a short prescription to help get her through this.
Best of luck with your girl, please let me know if you have any further questions.