Conjoined Twins

Twin girls born joined at the abdomen and chest get a new lease life on today.

Doctors at the Mayo Clinic in Minneapolis will operate on five-month-old Abbigail and Isabelle Carlsen.

The surgery could take as long as 12 hours.

But doctors say chances are at least 90 percent that both girls will survive.

Meantime, a doctor says conjoined twins born to a Wisconsin couple in Washington D.C. this week have a fair prognosis despite their "challenging" case.

Mateo and McHale Shaw are joined at the lower back and have conjoined spinal cords.

Doctors say they hope to separate them in three to four months but there are health problems to contend with first.