What's the worst that can happen if an abdominal seroma is not drained?

Large seromas should be drained to avoid long-term problems. A 20 mL seroma is small and probably will resolve spontaneously without any significant issues.

If several months have elapsed and there is still no resolution of the seroma, it may be necessary to excise the seroma cavity,  closing the dead space with sutures afterwards. 

It sounds like your plastic surgeon is attentive to the issue at hand.  It also sounds like if a seroma remains it is very small and the body should absorb it.  A seroma can become infected but the most likely outcome of a persistent seroma would be the development of a sac around it called a bursa.  The bursa will need to be removed

A  small seroma is not unusual after surgery. It should resolve in time as your tissue heals.  Do avoid excessive bending and lifting, and wear compression garments during the day. Also, listen to your surgeon.

Your fluid accumulation is normal and your body should be able to absorb that fluid.  You are doing the right thing by wearing the compression garments and trying to reduce the shear forces.  Make sure your compression garment is over the area of the seroma though- sometimes they start riding down low and may make the problem worse.

A small seroma should not be a concern as long as it is not palpable and not painful.  If it starts to enlarge then you may need a re operation to excise the seroma pocket.  

Seromas can be treated in different ways. One common course of treatment is the one you are undergoing. This involves aspirating the seroma whenever there is a discernible collection. If a few aspirations occur and it is still coming back your surgeon may consider placing a drain to keep the fluid continuously drained and to allow the tissues to adhere to one another. Another way to try to get the tissues to stick and get the seroma to go away is to inject a sclerosant. One agent used to do this is alcohol. The alcohol incites an inflammatory reaction that can encourage the tissues to heal together. It is unlikely that a seroma will ruin your results. They can become infected, but this is also not very common.

Hi, you can have an ultrasound to check the size of the seroma. Sometimes it is absorbed, but sometimes it looks just like a fluid filled cyst. If it is very small you can probably leave it alone, but if it is large your surgeon may have to open and remove it. Wearing spanks, tight garment will help. Good luck.

You should be visiting your plastic surgeon's office regularly to be sure everything possible is being done to ensure your safety and the best results possible. If you have a concern, share it with your plastic surgeon right away. 

Thanks for your question. Seromas following abdominoplasty surgery are not uncommon and rarely, aside from the nuisance factor, do they cause a problem. Aspirations when necessary are appropriate and should facilitate absorption and adherence of the skin to the muscles. If a large seroma went unchecked, there is the possibility of scarring that can cause puckering of the skin as the scar contracts. Your surgeon is correct to recommend aspiration and compression garments. 20 ccs or less usually takes care of itself. Enjoy your restored figure. Best wishes.