n. Plastic surgery performed on the navel, usually for cosmetic reasons.
First it was the Botox craze, then umbilicoplasty (that's belly button surgery). Here's a tip: Nobody else stares at you as much as you stare at yourself.
—Leigh-Ann Jackson, “Should they stay or should they go?,” Austin American-Statesman, January 09, 2003
[T]this year a new body part went under the knife: the navel. Last spring plastic surgeons began reporting a curious spike in the number of women requesting navel reconstruction — or "umbilicoplasty," as the pros call it. Sometimes it was part of a tummy tuck; sometimes the tummy was fine, but the navel rankled. "I get about three or five inquiries a week now," says Jim Romano, a San Francisco surgeon who performs the outpatient procedure for about $3,500. Calls have "gone way up, with all the midriffs showing."

Ah, yes — the midriff. In umbilicoplasty, we have final proof of the midriff's total cultural triumph. Hidden for decades, the navel is now the center of what's considered sexy, flaunted in a wave of stomach-baring outfits and above-the-fold news articles pondering Britney Spears's bellybutton.
—Clive Thompson, “Umbilicoplasty,” The New York Times, December 15, 2002
2002 (earliest)
Subzero February temperatures might not be bikini-worthy, but the falling mercury won't keep midriffs under wraps. The low-slung hip-huggers favored by the likes of J. Lo and Britney are spurring a new trend — umbilicoplasty.
—Kristi L. Gustafson, “Cosmetic ins and outs,” The Times Union (Albany, NY), February 07, 2002
The most common umbilicoplasty procedure is to turn a protruding navel — an outie (1973) — into an indented one — an innie (1973), thus conforming the navel's host with the vast majority (90% of the populace has an innie). What's surprising here isn't so much that people who are apparently sane in every other respect would do this to themselves (excess in the service of vanity has become commonplace), but that no one seems to know why there are two species of bellybutton (1877) in the first place. Some authorities claim it's the way the umbilical cord is tied off after being cut; others insist that it depends on how the cord remnant falls off the body; there's even a popular theory that an outie is actually a tiny, harmless hernia. Something to contemplate during your next navel-gazing session.