Whenever the news reports on the separation of conjoined twins, the world pays attention, as it did with the most recent surgery separating 10-month-old Chilean twins Maria Paz and Maria Jose. After all, not only is the occurrence of conjoined twins rare (one out of every 200,000 live births globally), a mere 5 to 25 percent survive, and only some of them are ever separated successfully.
Separating conjoined twins is not always possible
Conjoined twins are always the same sex, and approximately 70 percent of them are girls. The twins develop from the same fertilized egg, which does not completely separate after it is fertilized. The developing embryo begins the process of separating into identical twins after conception, but then the process stops, and the result is a conjoined fetus.
According to the University of Maryland Medical Center, about 40 percent of conjoined twins are thoracopagus twins, which means they are connected at the upper region of the torso and share a heart. Approximately one-third of conjoined twins are connected from the breastbone to the waist, and this category is known as omphalopagus. While these twins rarely share a heart, they do share a liver and gastrointestinal or genitourinary functions. About 2 percent of conjoined twins are joined at the head.
To determine if conjoined twins are candidates for separation, physicians can use magnetic resonance imaging, angiography, and ultrasound to identify which organs the children share and the extent function of those organs is also shared. If a medical team decides the twins have a good chance of surviving separation, the long medical journey begins.
In the case of the recent Chilean twins, the latest reported surgery was not the first but the seventh, but this 20-hour procedure was the one that now allows them to be two separate children. Until then, the girls had shared many of the same internal organs. Earlier surgeries had been undertaken to separate the twins’ legs, pulmonary systems, urinary tracts, and other body parts.
Conjoined twins can occur in any part of the world, and occurrence crosses ethnic, religious, and socioeconomic lines. Two recent reports of conjoined twin births come from opposite sides of the world: a 21-year-old single mother in the Chicago area gave birth in early September to girls who were fully connected at the torso and share a heart, two lungs, two kidneys, and two legs, while each child had one good arm. The girls passed away on September 29.
Around the world in China, two girls born on November 29 are awaiting separation. They are joined at the chest, belly, and liver, and despite some heart defects, the Hunan Children’s Hospital was noted in the Telegraph as saying surgery was possible and the heart defects could be fixed.
While most conjoined twins are girls, a recent case of twin boys was featured on CBS News. Joshua and Jacob Spates were born on January 24, 2011, and separated on August 29 after 13 hours of surgery at Le Bonheur Children’s Hospital in Memphis, Tennessee. The boys represented an especially rare form of conjoined twins in that they were joined back to back at the pelvis and lower spine, and each have their own heart, head, and limbs.
Separating conjoined twins is an extremely complex undertaking, and not one that most hospitals or physicians can handle. In Saudi Arabia, King Abdulaziz Medical City is internationally known for separating conjoined twins, and has completed at least 21 such procedures. Wherever separations are performed, it truly takes a village. In the Chilean case, 25 surgeons and anesthesiologists were involved in this latest surgery, and about 100 people participated overall in the 20-hour ordeal.
Although the majority of separations are performed on babies and young children, one well-publicized case involved 29-year-old twins Ladan and Laleh Bijani, Iranian law graduates, who sought separation from physicians in Singapore in 2003. Joined at the head, the women underwent the procedure on July 6 with 28 surgeons and more than 100 support staff in attendance. The women died two days later.
Conjoined twins are a rarity, and scientists are still a long way from knowing how to prevent its occurrence. With advances in medical technology, the chances of successful separation may improve.
Picture credit: Wikimedia Commons