Is it possible to get a fistula between belly button and incision?

Generally these wound healing problems are quite straightforward to solve.   You should see your board certified surgeon to take a look and likely do a minor procedure to help your problem.

You may well have an undiagnosed seroma.  The seroma needs to be drained from below and it should resolve in a week.  It needs the gravity to help in drain from below otherwise it will persist.

The semantics can get a bit confusing when talking about an encapsulated fluid collection and its connections to other organs or the outside world.  Regardless, if this is a prolonged issue, it likely needs to be surgically revised to remove the fluid sac and its scar capsule liningBest of luck!
Dr. SubbioBoard-Certified Plastic SurgeonNewtown Square/Philadelphia, PA

There certainly can be an opening that could develop or form from the umbilicus to a seroma cavity or perhaps a permanent suture.I would recommend being evaluated by your plastic surgeon to see what the issue happens to be.If you are not able to see your previous surgeon then you can visit with a board certified plastic surgeon who is interested in taking over your case.Hope that helps.

I suppose that it would be possible to develop a fistula after a tummy tuck, but this would be rare. A fistula could form from a persistent infection of nonabsorbable sutures or could be related to an encapsulated fluid collection. If you are noticing a fistula, I would get in touch with your surgeon so that you can be examined. 

Dear sugarlumpspony,yes, it is possible to get fistula after tummy tuck surgery. However, without an examination it is hard to tell whether you have a fistula. I would suggest you to consult your plastic surgeon. Only after a thorough examination you will get more information and recommendations.Daniel Barrett, MD, MHA, MS 
Certified, American Board of Plastic Surgery  
Member, Am. Society of Plastic Surgery

and a photo where would allow the gallery to better understand what you are concerned about.  Best to continue seeing your surgeon for guidance and recommendations on how to best deal with this.

Fluid drainage from the belly button can happen either from edema post op or from a seroma collection in your abdomen. Usually capsule formation takes a couple of months. In early stages, just draining the seroma will lead to closure of the draining area. In prolonged cases some surgeons might inject the area with a sclerosoling agent and sometimes it will need a surgical resection of the capsule and placement of a drain for a couple of weeks. 

It is certainly possible to develop a fistula after tummy tuck surgery; often, the "culprit" is an underlying suture or sutures. In other words, the sutures that may have been used for muscle plication may be the underlying problem. My best advice: follow-up with your plastic surgeon who will be your best resource when it comes to helping you with accurate diagnosis, advice, and treatment recommendations. Best wishes.

This is a very unusual occurrence after a tummy tuck but quite possibly represents an ongoing infection of some or all of the sutures that were placed to tighten your muscles.  If so, surgery to explore and remove all of those sutures will probably be necessary if you do not respond quickly and permanently to a course of antibiotics.  Once permanent sutures are infected it is difficult or impossible to clear the infection without removing them.  Be sure to see your surgeon for evaluation and best advice.  Best wishes,Jon A Perlman M.D., FACSDiplomate, American Board of Plastic SurgeryMember, American Society for Aesthetic Plastic Surgery (ASAPS)ABC-TV Extreme Makeover SurgeonBeverly Hills, CaliforniaIG: jonperlmanmd