12 days post op Liposuction, my tummy is hard and bigger. Is this normal?

It is very common to develope hardness (induration) and swelling after liposuction of the abdomen and/or waist. It is good to hear that your stomach was flat - that means it will very likely go back to being that way. It is always important to talk to your doctor and have an exam to make sure everything is normal. You can develope what is called a "seroma". This is a collection of fluid and can be tender. Sometimes they  need to be drained. One option to try and improve the hardness and swelling is to have low frequency ultrasound performed. I am not absolutely sure if it really speeds up the process, but my patients do say that it feels good to have done.

How long will the
bruising and swelling last?The duration of
bruising and swelling after liposuction usually depends on the post-operative
care technique used by the surgeon. The amount of bruising varies considerably
between patients.The tumescent
technique for liposuction used together with the "open-drainage"
technique (skin incisions are not closed with stitches) reduces the amount of
bruising after liposuction. With tumescent liposuction, bruising is nearly
absent one to two weeks after surgery in most patients.By not using
stitches to close incision sites, the rate of drainage of the blood-tinged
anesthetic solution is accelerated. This minimizes the amount of bruising. How long will the
swelling last?With
open-drainage (incisions are not closed with stitches) and appropriate
compression garments (worn for 3 to 6 days) swelling is 90% resolved 4 weeks
after liposuction. When incisions are closed with stitches (trapping residual
blood-tinged tumescent fluid beneath the skin) swelling persists for much
longer, and is typically 90% resolved after 8 to 12 weeks. With ultrasonic
assisted liposuction (UAL) significant swelling can persist for many months. How can postoperative
swelling, bruising, and tenderness be minimized?New techniques
for post-liposuction care allow more rapid recovery, less bruising, less
swelling and less prolonged tenderness. This is achieved by encouraging rapid
"open drainage" of residual blood-tinged solution of tumescent local
anesthesia. By allowing the tiny incision sites to remain open without being closed
by stitches and by using special absorptive pads (HK Pads) together with
post-operative elastic compression garments bruising, swelling and pain can be
minimized. With open drainage, patients can usually see dramatic improvements
within two to four weeks after surgery, and they can expect to see 90 percent
of the final result within 4 to 6 weeks. With older techniques that closed
incisions with sutures, the ultimate results following liposuction usually
require 12 to 16 weeks to become fully apparent.information from liposuction websiteBy Dr. Norma Kassardjian

The fat removed by liposuction is replaced at least in part by fluid after the procedure. This can increase the caliber of the area and create firmness. It will get better as time passes.