(CNN)Here's a look at conjoined twins.
Conjoined twins are physically connected to one another at some point on their bodies.
Conjoined twins occur once every 200,000 live births, according to the University of Minnesota.
About 70% of conjoined twins are female.
Conjoined twins are identical - they are the same sex.
According to the Mayo Clinic, conjoined twins may be joined at any of these areas: chest, abdomen, spine, pelvis, trunk or head.
Scientists believe that conjoined twins develop from a single fertilized egg that fails to separate completely as it divides.
The term "Siamese twins" originated with Eng and Chang Bunker, a set of conjoined twins who were born in Siam (now Thailand) in 1811. They lived to age 63 and appeared in traveling exhibitions. Chang and Eng both married and fathered a total of 21 children between them.
In 1955, neurosurgeon Dr. Harold Voris of Mercy Hospital in Chicago performed the first successful procedure separating conjoined twins.
Selected Cases
Lea and Tabea Block
Born August 9, 2003, in Lemgo, Germany, to Peter and Nelly Block. They are joined at the head. On September 16, 2004, the girls are separated. Tabea dies shortly thereafter.
Born August 9, 2003, in Lemgo, Germany, to Peter and Nelly Block. They are joined at the head. On September 16, 2004, the girls are separated. Tabea dies shortly thereafter.
Jade and Erin Buckles
Born February 26, 2004, to Melissa and Kevin Buckles at National Naval Medical Center in Bethesda, Maryland. They share a liver. On June 19, 2004, they are successfully separated.
Born February 26, 2004, to Melissa and Kevin Buckles at National Naval Medical Center in Bethesda, Maryland. They share a liver. On June 19, 2004, they are successfully separated.
Tatiana and Anastasia Dogaru
Born January 13, 2004, in Rome to Romanian parents Claudia and Alin Dogaru. They are connected at the head. In August 2007, doctors at University Hospital's Rainbow Babies & Children's Hospital in Cleveland announce that they will not perform a separation of the girls because the surgery is too risky.
Born January 13, 2004, in Rome to Romanian parents Claudia and Alin Dogaru. They are connected at the head. In August 2007, doctors at University Hospital's Rainbow Babies & Children's Hospital in Cleveland announce that they will not perform a separation of the girls because the surgery is too risky.
Abbigail and Isabelle Carlsen
Born November 29, 2005, in Fargo, North Dakota, to Amy and Jesse Carlsen. They are joined at the abdomen and chest. On May 12, 2006, a team of 30 people, including 18 surgeons from various specialties at the Mayo Clinic in Rochester, Minnesota, perform a successful operation to separate the girls.
Born November 29, 2005, in Fargo, North Dakota, to Amy and Jesse Carlsen. They are joined at the abdomen and chest. On May 12, 2006, a team of 30 people, including 18 surgeons from various specialties at the Mayo Clinic in Rochester, Minnesota, perform a successful operation to separate the girls.
Regina and Renata Salinas Fierros
Born August 2, 2005, in Los Angeles to Sonia Fierros and Federico Salinas. Born facing each other and joined from the lower chest to the pelvis, they are fused in several places including the liver and genitals, and they share a large intestine. Regina is born with one kidney. On June 14, 2006, the twins are separated during a day-long surgery at Children's Hospital Los Angeles.
Born August 2, 2005, in Los Angeles to Sonia Fierros and Federico Salinas. Born facing each other and joined from the lower chest to the pelvis, they are fused in several places including the liver and genitals, and they share a large intestine. Regina is born with one kidney. On June 14, 2006, the twins are separated during a day-long surgery at Children's Hospital Los Angeles.
Abygail and Madysen Fitterer
Born August 8, 2006, to Stacy and Suzy Fitterer from Bismarck, North Dakota. They are born joined at the abdomen and share a liver. On January 3, 2007, they are separated in a surgery at the Mayo Clinic.
Born August 8, 2006, to Stacy and Suzy Fitterer from Bismarck, North Dakota. They are born joined at the abdomen and share a liver. On January 3, 2007, they are separated in a surgery at the Mayo Clinic.
Preslee Faith and Kylee Hope Wells
Born October 25, 2008, in Oklahoma City to Stevie Stewart and Kylie Wells. They are attached at the chest and are believed to be the first Native American conjoined twins. On January 19, 2009, they are separated at Children's Hospital at OU Medical Center in Oklahoma City. On February 19, 2011, Preslee Faith dies.
Born October 25, 2008, in Oklahoma City to Stevie Stewart and Kylie Wells. They are attached at the chest and are believed to be the first Native American conjoined twins. On January 19, 2009, they are separated at Children's Hospital at OU Medical Center in Oklahoma City. On February 19, 2011, Preslee Faith dies.
Arthur and Heitor Rocha Brandao
Born April 2009 in Bahia, Brazil, to Eliane and Delson Rocha. They are joined at the hip and share a bladder, intestines, liver and genitals. The twins only have three legs between them. On February 24, 2015, the five-year-old twins undergo a 15-hour separation surgery after months of preparation. Arthur dies three days later after he suffers cardiac arrest.
Born April 2009 in Bahia, Brazil, to Eliane and Delson Rocha. They are joined at the hip and share a bladder, intestines, liver and genitals. The twins only have three legs between them. On February 24, 2015, the five-year-old twins undergo a 15-hour separation surgery after months of preparation. Arthur dies three days later after he suffers cardiac arrest.
Angelica and Angelina Sabuco
Born August 2009 in the Philippines to Fidel and Ginady Sabuco. They are joined at the chest and abdomen. On November 1, 2011, they are successfully separated after a 10-hour surgery at Lucile Packard Children's Hospital in San Jose, California.
Born August 2009 in the Philippines to Fidel and Ginady Sabuco. They are joined at the chest and abdomen. On November 1, 2011, they are successfully separated after a 10-hour surgery at Lucile Packard Children's Hospital in San Jose, California.
Hassan and Hussein Benhaffaf
Born December 2, 2009, in London to Angie and Azzedine Benhaffaf from East Cork, Ireland. They are attached at the chest but share no major organs. On April 8, 2010, they undergo a 14-hour separation surgery at Great Ormond Street Hospital. Both survive.
Born December 2, 2009, in London to Angie and Azzedine Benhaffaf from East Cork, Ireland. They are attached at the chest but share no major organs. On April 8, 2010, they undergo a 14-hour separation surgery at Great Ormond Street Hospital. Both survive.
Maria and Teresa Tapia
Born April 8, 2010, in the Dominican Republic to Lisandra Sanatis and Marino Tapia. They are joined at the lower chest and abdomen and share a liver, pancreatic glands, and part of their small intestine. On November 8, 2011, they are successfully separated following a 20-hour procedure.
Born April 8, 2010, in the Dominican Republic to Lisandra Sanatis and Marino Tapia. They are joined at the lower chest and abdomen and share a liver, pancreatic glands, and part of their small intestine. On November 8, 2011, they are successfully separated following a 20-hour procedure.
Joshua and Jacob Spates
Born January 24, 2011, in Memphis, Tennessee, to Adrienne Spates. They are joined back to back at the pelvis and lower spine, each with separate hearts, heads and limbs. On August 29, 2011, they are successfully separated after a 13-hour surgery. In October 2013, Jacob passes away.
Born January 24, 2011, in Memphis, Tennessee, to Adrienne Spates. They are joined back to back at the pelvis and lower spine, each with separate hearts, heads and limbs. On August 29, 2011, they are successfully separated after a 13-hour surgery. In October 2013, Jacob passes away.
Rital and Ritag Gaboura
Born September 22, 2010, in Khartoum, Sudan, to Abdelmajeed and Enas Gaboura. They are joined at the head. On August 15, 2011, they are successfully separated after a four-stage operation. Two operations took place in May, one in July and the final operation in August.
Born September 22, 2010, in Khartoum, Sudan, to Abdelmajeed and Enas Gaboura. They are joined at the head. On August 15, 2011, they are successfully separated after a four-stage operation. Two operations took place in May, one in July and the final operation in August.
Allison June and Amelia Lee Tucker
Born March 1, 2012, to Shellie and Greg Tucker. They are attached at the lower chest and abdomen and share their chest wall, diaphragm, pericardium and liver. On November 7, 2012, they are successfully separated after a seven-hour surgery at Children's Hospital Philadelphia.
Born March 1, 2012, to Shellie and Greg Tucker. They are attached at the lower chest and abdomen and share their chest wall, diaphragm, pericardium and liver. On November 7, 2012, they are successfully separated after a seven-hour surgery at Children's Hospital Philadelphia.
A'zhari and A'zhiah Lawrence
Born October 10, 2012, in Virginia to Nachell Jones and Carlos Lawrence. They are joined from the chest to the abdomen and have a conjoined liver. On April 22, 2013, they are successfully separated following 14 hours of surgery. On October 14, 2013, A'zhari passes away.
Born October 10, 2012, in Virginia to Nachell Jones and Carlos Lawrence. They are joined from the chest to the abdomen and have a conjoined liver. On April 22, 2013, they are successfully separated following 14 hours of surgery. On October 14, 2013, A'zhari passes away.
Emmett and Owen Ezell
Born July 15, 2013, in Dallas to Jenni and Dave Ezell. They are joined at the liver and the intestine. On August 24, 2013, they are successfully separated.
Born July 15, 2013, in Dallas to Jenni and Dave Ezell. They are joined at the liver and the intestine. On August 24, 2013, they are successfully separated.
Knatalye Hope and Adeline Faith Mata
Born April 11, 2014, in Houston to Elysse and John Matta. They are joined at the chest, sharing a liver, heart lining, diaphragm, intestines and colon. On February 17, 2015, a team of 12 surgeons separate the twins during a 26-hour procedure.
Born April 11, 2014, in Houston to Elysse and John Matta. They are joined at the chest, sharing a liver, heart lining, diaphragm, intestines and colon. On February 17, 2015, a team of 12 surgeons separate the twins during a 26-hour procedure.
Erika and Eva Sandoval
Born August 10, 2014, in California to Aida and Arturo Sandoval. They are joined at the lower chest and upper abdomen and share a liver, bladder, two kidneys and three legs. On December 6-7, 2016, they are successfully separated after 17 hours of surgery at Lucile Packard Children's Hospital Stanford in California.
Born August 10, 2014, in California to Aida and Arturo Sandoval. They are joined at the lower chest and upper abdomen and share a liver, bladder, two kidneys and three legs. On December 6-7, 2016, they are successfully separated after 17 hours of surgery at Lucile Packard Children's Hospital Stanford in California.
Acen and Apio Akello
Born September 23, 2014, in Uganda to Ester Akello. They are joined at the hip and pelvis. On September 3, 2015, more than 30 medical specialists help separate the twins' spinal cord during a 16-hour surgery at Nationwide Children's Hospital in Ohio. To prepare for the surgery, medical specialists used 3-D printing to create anatomies similar to the girls.
Born September 23, 2014, in Uganda to Ester Akello. They are joined at the hip and pelvis. On September 3, 2015, more than 30 medical specialists help separate the twins' spinal cord during a 16-hour surgery at Nationwide Children's Hospital in Ohio. To prepare for the surgery, medical specialists used 3-D printing to create anatomies similar to the girls.
Carter and Conner Mirabal
Born December 12, 2014, in Jacksonville, Florida, to Michelle Brantley and Bryan Mirabal. They are joined at the sternum and abdomen and share a liver and part of their small intestines. On May 7, 2015, the twins are successfully separated after 12 hours of surgery at Wolfson Children's Hospital in Florida.
Born December 12, 2014, in Jacksonville, Florida, to Michelle Brantley and Bryan Mirabal. They are joined at the sternum and abdomen and share a liver and part of their small intestines. On May 7, 2015, the twins are successfully separated after 12 hours of surgery at Wolfson Children's Hospital in Florida.
Scarlett and Ximena Torres
Born May 16, 2015, in Corpus Christi, Texas, to Silvia Hernandez and Raul Torres. Scarlett and Ximena are connected below the waist, sharing a colon and a bladder. On April 12, 2016, the twins are separated during a 12-hour procedure at the Driscoll Children's Hospital in Texas.
Born May 16, 2015, in Corpus Christi, Texas, to Silvia Hernandez and Raul Torres. Scarlett and Ximena are connected below the waist, sharing a colon and a bladder. On April 12, 2016, the twins are separated during a 12-hour procedure at the Driscoll Children's Hospital in Texas.
Anias and Jadon McDonald
Born on September 9, 2015, in Chicago to Nicole and Christian McDonald. They are joined at the head. On October 13-14, 2016, Anias and Jadon are successfully separated after 27 hours of surgery at the Children's Hospital at Montefiore Medical Center in New York.
Born on September 9, 2015, in Chicago to Nicole and Christian McDonald. They are joined at the head. On October 13-14, 2016, Anias and Jadon are successfully separated after 27 hours of surgery at the Children's Hospital at Montefiore Medical Center in New York.
Dawa and Nima Pelden
Born on July 13, 2017, in Bhutan to Bhumchu Zangmo. They are joined at the abdomen. On November 9, 2018, Dawa and Nima are successfully separated after a six-hour surgery at Melbourne Royal Children's Hospital in Australia.
Born on July 13, 2017, in Bhutan to Bhumchu Zangmo. They are joined at the abdomen. On November 9, 2018, Dawa and Nima are successfully separated after a six-hour surgery at Melbourne Royal Children's Hospital in Australia.
Safa and Marwa Ullah
Born January 7, 2017, in Pakistan to Zainab Bibi. They are joined at the head. On February 11, 2019, Safa and Marwa are successfully separated after 50 hours of surgery, that took place over a four month period, at London's Great Ormond Street Hospital.
Born January 7, 2017, in Pakistan to Zainab Bibi. They are joined at the head. On February 11, 2019, Safa and Marwa are successfully separated after 50 hours of surgery, that took place over a four month period, at London's Great Ormond Street Hospital.
Ervina and Prefina Bangalo
Born June 29, 2018, in the Central African Republic to Ermine Nzutto. They share a skull and a majority of blood vessels. On June 5, 2020, the twins are successfully separated during an operation in Vatican City lasting 18 hours and involving 30 doctors and nurses.
Born June 29, 2018, in the Central African Republic to Ermine Nzutto. They share a skull and a majority of blood vessels. On June 5, 2020, the twins are successfully separated during an operation in Vatican City lasting 18 hours and involving 30 doctors and nurses.
Abigail and Micaela Bachinskiy
Born December 30, 2019, in Sacramento, California. The twins are joined at the head. On October 23-24, 2020, the twins are successfully separated during a 24-hour operation at UC Davis Children's Hospital in Sacramento, California.
Born December 30, 2019, in Sacramento, California. The twins are joined at the head. On October 23-24, 2020, the twins are successfully separated during a 24-hour operation at UC Davis Children's Hospital in Sacramento, California.
Siphosethu and Amahle Tyhalisi
Born January 30, 2021, in South Africa to Ntombikayise Tyhalisi. They are joined at the head. On February 24, 2021, the twins are successfully separated during an operation at Red Cross War Memorial Children's Hospital in Cape Town.
Born January 30, 2021, in South Africa to Ntombikayise Tyhalisi. They are joined at the head. On February 24, 2021, the twins are successfully separated during an operation at Red Cross War Memorial Children's Hospital in Cape Town.
Hassana and Hasina
Born in January 12, 2022 in Kaduna, Nigeria to Omar Rayano. They share an abdomen, pelvis, liver, intestines, urinary and reproductive system, and pelvic bones. On May 18, 2023 the twins are successfully separated during an operation at King Abdullah Specialized Children's Hospital in Riyadh, Saudi Arabia.
Born in January 12, 2022 in Kaduna, Nigeria to Omar Rayano. They share an abdomen, pelvis, liver, intestines, urinary and reproductive system, and pelvic bones. On May 18, 2023 the twins are successfully separated during an operation at King Abdullah Specialized Children's Hospital in Riyadh, Saudi Arabia.
