What makes an innie an innie? And more belly button mysteries

Innies, outies, in-betweenies. We had such an overwhelming response to our recent post on a new study examining belly button bacteria (ew) that we decided we didn't know nearly enough about our navels, and must investigate further.

Our incredibly scientific reader poll showed that 88 percent of readers have innies. For those of you with outies or something in between, who are unhappy about it -- a plastic surgeon can "sculpt" a new navel for you with a little nip and tuck -- and at a cost of several grand. Belly button surgery, called umbilicoplasty, is not just for the rich and famous. And people willing to go under the knife aren't necessarily underwear models, belly dancers or strippers who regularly expose their navels.

"It's usually done for cosmetic reasons and it takes about 45 minutes," says Dr. Curtis Cetrulo, Jr., a plastic surgeon at Massachusetts General Hospital in Boston. The procedure can be done as part of a tummy tuck or in people who have had umbilical hernias and need to have a hole in the abdominal wall surgically repaired. It's often done on women whose skin hasn't bounced back after pregnancy.

Some people want to remodel their belly button simply because they loathe its look, whether it's the shape, size, or protruding skin. Perhaps a woman had an innie all her life, but after giving birth, it became more of an "in betweenie" because the tissue in the abdominal wall has stretched. Worse still (in some people's minds), it has become -- or always was -- an outie and sticks out. Heaven forbid!

Created by the snip of the umbilical cord at birth, your belly button gets its appearance when the stalk from the leftover cord dries up leaving an abdominal scar.

Whether you have an innie or an outie has nothing to do with the handiwork of the physician who delivered you, explains Cetrulo. It's related to the presence of space between the skin and the abdominal wall, he says.

If the soft tissue protrudes through, you've got an outie, which is much rarer in people than the more-desired innie. 

Cetrulo has never had a patient request an outie and says most people ask for "a vertical dime slot of a belly button that's small and thin."

Reconstructing a belly button is done under local anesthesia on an outpatient basis and results in a little pain from soreness afterwards.

Although many umbilicoplasties are done as part of a tummy tuck (and statistics for this are not kept separately), there were more than 2,100 reconstructions done in the US without a tummy tuck in 2005, according to the American Society for Aesthetic Plastic Surgery. (This is the last year the Society reported statistics for this procedure.) That figure in 2005 put the number of people having belly button surgery in a category comparable to those receiving butt implants.