As dicephalic parapagus twins, conjoined twins like Abby and Brittany are rare
Abby and Brittany have a condition known as dicephalic parapagus, which is defined as two heads developing over a shared pelvis. According to the Journal of Clinical Ultrasound, this congenital malformation “occurs if twinning is initiated after the embryonic disc and rudimentary amniotic sac have been formed.” Occurrences of conjoining make up about 1% of monochorionic (identical) twin cases, happening once in every fifty to one hundred thousand births. A report published in Case Reports in Obstetrics and Gynecology in 2016 stated female genders predominate these twin gestations at a ratio of 3:1, and, unfortunately, 60% result in miscarriages or stillbirths.
All this information serves only to prove just how rare and lucky Abby and Brittany’s case is. The girls have their own lungs, hearts, spines, esophagi, stomachs, and gallbladders, but share the rest of their organs from the waist down (including three kidneys). The fact that they survived into adulthood makes them one in a trillion.
Photo: Facebook (Abigail and Brittany Hensel)