Conjoined twins: living lives together and separate

Conjoined twins have been in the news over the past couple of years, including recent news about the birth of conjoined twin boys in Ireland and the successful separation of conjoined twin girls in Australia. What’s not common knowledge is information about how conjoined twins are formed, and their survival rates. The following addresses those points.

How are conjoined twins formed?
Conjoined twins are formed when a woman produces a single egg, which does not fully separate after fertilization. The separation process is halted before it is complete, resulting in the development of a conjoined fetus.

Doctors are not able to assess how the shared organs of conjoined twins function while the twins are still in the womb. Instead, they have to wait until after the twins are delivered to use MRI, ultrasound and angiography technology to assess the situation, and to determine the feasibility of separation.

What are the different ways twins can be conjoined?
Twins can be joined three different ways: mid-torso (at the chest wall or upper abdomen), lower torso (sharing hips, legs or genitalia), and upper torso (connected at the head).

• Twins joined at the front are considered to have a Ventral union (Ventral refers to the area of the abdomen).
• Twins joined side-by-side with shared umbilicus, abdomen, and pelvis are considered to have a Lateral union.
• Twins joined at the back are considered to have a Dorsal union.

It’s important to remember that when you see photos of the various types of conjoined twins, some types will look very similar. However, the only way to truly tell the type of conjoined twins is through x-rays and other medical tests (like MRIs).

Click here for a graphic depiction of the various ways twins can be conjoined.

Conjoined twins in history
Conjoined twins Mary and Eliza Chulkhurst were born in England in 1100 and are one of the earliest documented cases of conjoined twins. The sisters were joined at the hip and lived for 34 years.

The highest-profile set of conjoined twins are Eng and Chang Bunker, who were born in Siam (now Thailand) in 1811. The brothers were joined at the lower chest. The phrase ‘Siamese twins’ came from these brothers who achieved worldwide fame because of their condition. Eng and Chang traveled in circus shows around the world before settling in the United States. They were also successful businessmen and ranchers, and were married to two sisters and had nearly two-dozen children. They died in 1874 at the age of 63.

There were also other conjoined twins born in the 19th century and earlier. The 20th and 21st centuries have also seen their share of conjoined twins. Advances in modern medicine over the past fifty years have enabled surgeons to complete more and more separation procedures, and with greater results.

Examples of successful separation surgeries

Kendra and Maliyah Herrin were separated in 2006 at the age 4. The girls were born with only one kidney between them. Maliyah received a kidney transplant from her mother in 2007. The girls’ mother wrote a book, When Hearts Conjoin, which details her experiences. This is currently the only book about conjoined twins written by a parent of conjoined twins.

Alex and Angel Mendoza, conjoined twins joined from below their sternums to their pelvises, were born in the summer of 2008. The boys were successfully separated in January 2009.

Click here to read about the successful separation surgery of Bangladeshi conjoined twins Trishna and Krishna, born in 2006. The twins had been joined on the tops of their skulls, and were separated in Melbourne, Australia, in a 32-hour operation, in November 2009.

Examples of conjoined twins living meaningful and productive lives

Born in Dayton, Ohio on October 28, 1951, Ronnie and Donnie Galyon are the world’s oldest living set of conjoined twins. The twins were raised by their father after they were rejected by their mother at birth, and spent most of their lives on exhibition in the United States, Latin America, and Mexico.

Ronnie and Donnie were featured in the 1981 movie, Being Different, a “tribute to the spirit and humanity of people who are physically different from the average.” The twins are now retired from show business and living somewhere in Ohio. Their exact whereabouts are kept discreet due to past harassment, vandalism, and threats.

Lori and Dorrie Schappell are craniopagus (joined at the head) twins born on September 18, 1961, in Reading, Pennsylvania. The twins disliked that their names rhymed, so Dorrie later changed her name to Reba. By 2007 Reba (Dorrie) was going by George. Dorrie is a country singer, and has performed around the United States, as well as in Germany and Japan, and won the L.A. Music Award for Best New Country Artist in 1997.

Lori is able-bodied but George has spina bifida, which caused growth retardation to her lower body. George designed an innovative bar-stool-height wheel chair for her use, putting her at the same height as her sister. This makes it easier for the two to move around while also avoiding undue strain on Lori’s neck and back.

The twins have appeared in a number of television documentaries about their lives as well as on talk shows. They also appeared in an episode of Nip/Tuck on FX, playing conjoined twins Rose and Raven Rosenburg. The twins also took part in the grand opening of “Ripley’s Believe It Or Not!” in 2007.

Abigail and Brittany Hensel, now 19, are dicephalic conjoined twins (two heads, two arms, two legs, who cannot be separated). They graduated from high school in 2008 and began college at Bethel University in St. Paul, Minnesota. The girls appeared in Joined for Life in April 2006, a documentary produced by Advanced Medical and distributed on the Discovery Health Channel. They also appeared on The Oprah Winfrey Show in 1996 and in a follow-up documentary on The Learning Channel in 2006, and have been featured on the cover of Life, and within the pages of Life and Time. You can follow the girls on Facebook.

Facts and statistics about conjoined twins
- Conjoined twins are always the same sex because they are genetically identical
- Conjoined twins are extremely rare and only occur on average once in every 200,000 live births
- Approximately 40 to 60 percent of conjoined twins arrive stillborn, and about 35 percent survive only one day
- Of those born alive, on average just one-in-three are deemed medically suitable for separation operations
- The majority of cases involve twins being joined at the torso—either by their chest or stomachs
- In most cases, separation procedures are deemed impossible when the twins share a major organ such as the heart or liver.
- Only a minority of cases involve twins being joined at the head.
- The overall survival rate of conjoined twins is somewhere between 5 percent and 25 percent
- It is estimated that about 70 percent of conjoined twins born are likely to be female
- Female conjoined twins tend to have a better chance of survival over their male counterparts
- The first surgical separation of conjoined twins occurred in 1953

For more information about the science of conjoined twins, check out this YouTube video.

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