What are the pros and cons to using drains with a tummy tuck?

Drains are used after tummy tucks to remove excess fluid so it does not collect and need to be drained with a needle.
You can reduce the need for drains altogether by using fibrin glue. However it is a pool human blood product, and does not guarantee that fluid will not form. It also requires special consent forms because it is a blood product, and we do not use it for these reasons.
Some doctors advocate quilting sutures, but these can leave puckering marks and fluid can still form.
Almost all patients want a pain pump these days, so a tube is necessary to deliver the pain medicine anyway.
Nobody likes to use drains, but they serve a very good purpose given the alternatives.

When a tummy tuck is done, the skin and fat are surgically lifted off the underlying muscle layer. This creates a space into which serum and blood can collect after the surgery. Drains remove that liquid so that the two layers stick down to each other again. In the days after surgery, healing occurs and there is less serum leaking into this space, then the drains can be removed.
There are procedures that can be done to help the two layers stick together immediately, but these are associated with some increased risk in wound breakdown and infection, so I choose to use drains. Tummy tuck is a big operation and in my opinion, the added temporary hassle of drains is worth a safer outcome.

Hi there-
After a tummy tuck, there is a large space under your skin (the tunnel in which your muscles were tightened) that needs to heal in order for your body to achieve the best shape possible, and to prevent fluid from collecting (a seroma).
While some surgeons avoid placing drains by placing quilting sutures, it is my opinion that the increased time required to place these sutures and the increase in risks to your health that come from extending the length of the surgery are not worth the benefit of avoiding having drains for a few days.
Further, it has been my experience that while placement of quilting sutures can minimize the risk of seroma formation, this risk is still higher than when drains are placed.
Finally, I would strongly caution you against using this as a criterion for choosing a surgeon. Patients get themselves into all kinds of trouble when they start micro-managing the technical details of their operation.
The best advice I could possibly give you is to find a surgeon you like and feel you can trust- then TRUST THEM to do their very best to achieve your best outcome and minimize your risks.
Need advice on what you SHOULD be looking for in a surgeon? Read this:

The vast majority of surgeons still use drains. A small percentage do not. The reason for placement is to evacuate the space that is created between the muscle and skin. Surgeons who do not use the drains sew this layer closed with special stitches called quilting sutures.

As the other responses have explained, drains are used to prevent accumulation of fluid in a space where there has been dissection. Since a tummy tuck involves a lot of undermining in order to pull the skin tight, there is normally a lot of fluid buildup. However, there are some ways to minimize this, notably the use of what are called Progressive Tension Sutures. I started using them about 12 years ago and noted that drainage was way down so that we could get the drains out in a couple of days instead of about a week which is more typical. At the same time, a surgeon named Harlan Pollock (in Texas) started doing the same thing, and he no longer uses drains at all! I still use drains but I would definitely encourage you to find someone who does the PTS technique.