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Together forever? Twins who ape physically connected to each other face a difficult decision: to separate or remain joined for life.

For 16-year-old twins Abigail and Brittany Hensel Abigail "Abby" Loraine Hensel and Brittany "Britty" Lee Hensel (born 7 March 1990, Carver County, Minnesota, United States), are dicephalic conjoined twins. They have two spines which join at the pelvis. , everything takes teamwork, whether it's playing basketball, typing IMs, or walking across the room. That's because these girls share a body, with each twin controlling one arm and one leg.

Abigail and Brittany are conjoined twins conjoined twins
 or Siamese twins

Identical twins (see multiple birth) whose embryos did not separate completely. Conjoined twins are physically joined (typically along the trunk or at the front, side, or back of the head) and often share some organs.
 meaning they are physically connected. Each girl has a separate head, heart, stomach, and spinal column spinal column, bony column forming the main structural support of the skeleton of humans and other vertebrates, also known as the vertebral column or backbone. It consists of segments known as vertebrae linked by intervertebral disks and held together by ligaments. , but they join together at the torso and share their lower organs (see Inside Brittany and Abigail, p. 14). Neither girl can feel any sensation from her sister's side of the body, but they coordinate their movements to swim and play on school sports teams. On their 16th birthday, they even got their driver's licenses. Abigail controls the pedals and shifter, Brittany the blinkers blinkers

1. rigid pieces of leather fitted to a head harness at a point where they will obstruct the horse's lateral vision.

2. a more sophisticated piece of harness worn by expensive horses consisting of a canvas head-covering with holes for the ears to protrude and two
 and lights, and both girls steer. They had to pass the driver's test twice--once for each twin.

Abigail and Brittany say they're satisfied with life as a twosome, but the same is not true for all conjoined twins. In each case, families and doctors face a tough question--whether or not to attempt a risky surgery to separate them.


Why are some twins conjoined conjoined /con·joined/ (kon-joind´) joined together; united.


joined together.

conjoined monsters
two deformed fetuses fused together.
? In a mother's womb, a single zygote zygote: see reproduction. , or fertilized fer·til·ize  
v. fer·til·ized, fer·til·iz·ing, fer·til·iz·es
1. To cause the fertilization of (an ovum, for example).

 egg, usually grows into a single baby. If the egg splits in two, then two babies develop. These twins are commonly called identical twins identical twins
Twins derived from the same fertilized ovum that at an early stage of development becomes separated into independently growing cell aggregations, giving rise to two individuals of the same sex, identical genetic makeup, and
. But since no two people are completely identical, some experts prefer the term monozygotic monozygotic /mono·zy·got·ic/ (mon?o-zi-got´ik) pertaining to or derived from a single zygote; as monozygotic twins.

 (from one zygote), or MZ twins. Most doctors believe that conjoined twins start off like other MZ twins, but the zygote doesn't split completely (see Nuts & Bolts, p. 15), so the embryos, or developing young, remain joined as they grow.

"The places where they can be joined are variable," says Dr. Hardy Hendren, former chief of surgery at Children's Hospital Boston Children's Hospital Boston is a children's hospital located in the Longwood Medical and Academic Area of Boston, Massachusetts. Located at 300 Longwood Avenue, Children's is adjacent both to its teaching affiliate, Harvard Medical School, and to Dana-Farber Cancer Institute. . Some are attached at the head, while others are joined at the chest, abdomen, or pelvis.

Conjoined twins are rare--only one in every 40,000 to 60,000 births. But most die before or shortly after birth. Dr. James O'Neill James O'Neill can refer to:
  • Tip O'Neill (baseball player), Canadian Baseball Hall of Fame inductee
  • Jim O'Neill, baseball player
  • James O'Neill (politician), New Zealand politician
  • James O'Neill (actor), father of the playwright Eugene O'Neill
, a pediatric pediatric /pe·di·at·ric/ (pe?de-at´rik) pertaining to the health of children.

Of or relating to pediatrics.
 surgeon at Vanderbilt University Medical Center The Vanderbilt University Medical Center (VUMC) is a collection of several hospitals and clinics associated with Vanderbilt University in Nashville, Tennessee. It comprises the following units:[2]
  • Vanderbilt University Hospital
  • Monroe Carell, Jr.
 in Tennessee, explains, "The majority of conjoined twins are joined in ways that are not compatible with life." For instance, they may share a brain or heart that is abnormally developed or too weak to support both twins.


Whether or not doctors can attempt separation depends on which organs the twins share. "We try to quickly assess the major structures that lie in the region of the bridge between the two," says Dr. Hendren. In some cases, such as with a shared brain, doctors determine that separation is impossible. But other organs are different. For example, twins joined at the abdomen and pelvis often share a colon. "What we do in that circumstance is divvy up Verb 1. divvy up - give out as one's portion or share
portion out, apportion, share, deal

hand out, pass out, give out, distribute - give to several people; "The teacher handed out the exams"
 the colon, so that each baby gets haft a colon, in terms of length. And they will thrive with that. You can do perfectly well with half a colon," says Dr. Hendren. This is what Dr. Hendren did for 4-month-old Hussein and Hassan Mohamed Hassan Mohamed Hussain (Arabic: حسن محمد حسين) (born in 1962), is a UAE football (soccer) player who played as a midfielder for the UAE national football team and Al-Wasl  of the United Arab Emirates United Arab Emirates, federation of sheikhdoms (2005 est. pop. 2,563,000), c.30,000 sq mi (77,700 sq km), SE Arabia, on the Persian Gulf and the Gulf of Oman. . During the 25hour surgery, he also divided the boys' shared liver. This was possible because the liver regenerates, or grows replacement tissue. The boys are now active, healthy 7-year-olds.

Once doctors decide to go ahead with surgery, medical technologies such as ultrasound, CAT scans CAT scan (kăt) [computerized axial tomography], X-ray technique that allows relatively safe, painless, and rapid diagnosis in previously inaccessible areas of the body; also called CT scan. , and MRI 1. (application) MRI - Magnetic Resonance Imaging.
2. MRI - Measurement Requirements and Interface.
 give them an edge they didn't have in the past. These imaging techniques can create 3-D visualizations of the internal organs they'll attempt to separate. "That has made a huge difference, because you can take those images and turn them around, and turn them upside down, and look at them from various views," says Dr. O'Neill. "With better imaging, it means that the surgical teams are much more prepared and can avoid unforeseen problems."

Such technology turned out to make all the difference in the case of Maria de Jesus Maria de Jesus dos Santos (born September 10, 1893) is a Portuguese supercentenarian, and, as of August 13, 2007, the second-oldest person in the world. She has been the oldest verified living person in Portugal since the death of fellow 114-year-old Maria do Couto Maia-Lopes on  and Maria Teresa Alvarez. These conjoined twins were born in Guatemala on July 25, 2001. They spent the first 12 months of their lives attached at the head. Everyday tasks, such as bathing, were next to impossible; one sister had to be held upside down while the other was dipped right side up into the tub.

When deciding if surgery was possible for the girls, doctors used high-energy x-rays to create a radiograph radiograph /ra·dio·graph/ (-graf?) the film produced by radiography.

. This image showed that the twins were conjoined at the skull but they have two separate brains. With that knowledge, the parents decided to go ahead with the surgery--which proved to be successful.


Even when doctors believe separation is possible, surgery can be a difficult choice for families. The surgery

is extremely complicated, and there's always the risk that one or both twins won't survive or that they'll develop infections or other problems afterward. If doctors successfully separate them, the twins will have to follow up with reconstructive surgeries and rehabilitation rehabilitation: see physical therapy. . The Alvarez twins, for instance, have had surgeries to reposition bones. Maria Teresa also suffered a brain infection that caused physical and mental damage, but she's come a long way through therapy. The girls, now pre-schoolers, spend 10 to 15 hours a week on physical therapy to help strengthen their bodies. And when they get older, they'll need surgery to replace the missing skull portions on top of their heads that resulted from separation. Their caregiver, Jenny Hull, explains that between surgeries they live much like other little girls, playing with friends and swimming. "They're the happiest little girls you'll ever meet," says Hull.

Doctors sometimes feel that the risks of leaving conjoined twins together are greater than the risks of surgery. Because of the strain on shared organs, some sets wouldn't live long if they remained joined. The toughest situation for families comes when doctors know they can save only one baby. When conjoined twins named Amy and Angela Lakeberg were born in 1993, they shared one heart that couldn't support both babies. Doctors went into the surgery knowing that Amy would die. Angela also died 10 months later from respiratory problems.

Even when both conjoined twins are healthy, families may decide to risk separation because they worry that their children won't be able to live traditional lives if they remain joined. But Abigail and Brittany's parents decided that the risks of separation were too high. If the girls survived the surgery, they would be severely disabled because they weren't born with two full sets of limbs. In Joined for Life: Abby and Brittany Turn 16, a documentary that recently aired on television, Abigail said, "We never wish we were separated, because then we wouldn't get to do all the things that we can do," such as running and playing sports. Brittany agreed, adding, "We don't know Don't know (DK, DKed)

"Don't know the trade." A Street expression used whenever one party lacks knowledge of a trade or receives conflicting instructions from the other party.
 any other way."

To view a segment of the documentary, Joined for Life: Abby and Brittany Turn 16, visit: content/shows/jfl16.htm

1. What is the main idea of this article?

(A) The Alvarez twins were successfully separated.

(B) Families of conjoined twins and their doctors must decide if the benefits of separation outweigh the risks of surgery.

(C) Conjoined twins are rare--only one in every 40,000 to 60,000 births.

(D) If doctors separate conjoined twins, the twins will have to undergo rehabilitation.

2. What do doctors use to determine which organs conjoined twins share?

(A) Ultrasound (B) CAT scans (C) MRI (D) All of the above

3. What is another term used to describe identical twins?

(A) Monozygotic (B) Embryonic (C) Fraternal fraternal /fra·ter·nal/ (frah-ter´n'l)
1. of or pertaining to brothers.

2. of twins; derived from two oocytes.

1. Of or relating to brothers.
 (D) Dizygotic dizygotic /di·zy·got·ic/ (di?zi-got´ik) pertaining to or derived from two separate zygotes.

di·zy·got·ic or di·zy·gous
Derived from two separately fertilized eggs.


1. b 2. d 3. a


Jump-start your lesson with these pre-reading questions:

* Although more male conjoined twins develop in the womb than female conjoined twins, the female twins are more likely than the male twins to be born alive. Approximately 70 percent of all living conjoined twins are girls. What are some factors that determine the chances of survival for conjoined twins?

* Approximately 40 to 60 percent of conjoined twins emerge stillborn stillborn /still·born/ (-born) born dead.

Dead at birth.

n an infant who is born dead.


born dead.
, and about 35 percent survive for only one day. The overall survival rate of conjoined twins is between 5 percent and 25 percent. Conjoined twins are extremely rare. One of about how many births do you think produce conjoined twins?


* Hold a class debate on this topic: Do you think it's ethical to separate conjoined twins when it's likely that one will die during the surgical procedure?


MATH: In 2002, there were 4,021,726 births in the U.S. Of the births, 125,134 produced twins. Approximately what percent of the births that year produced twins? (Answer: 3.1 percent)

In 2002, 6,898 births in the U.S. produced triplets and 434 births produced quadruplets. Approximately what percent of the births that year produced triplets and quadruplets. (Answer: 0.17 percent; 0.01 percent)


* For an article that explains the surgical process that separated Maria Teresa and Maria de Jesus Alvarez, read "Separating Sisters," by Nicole Dyer, Science World, November 29, 2002.

* Conjoined twins who are attached only at the upper part of the skull are called craniopagus twins. To learn other terms that describe conjoined twins based on the body parts at which the twins are joined, visit:

* For a historic time line on known cases of conjoined twins, visit:

* For a lesson plan on twins and information on how to purchase a copy of the Discovery Channel program Mystery of Twins, visit this Web site:


DIRECTIONS: Defend or dispute the following. (Hint: Defend means to explain why a statement is correct. Dispute means to explain why a statement is incorrect.)

1. A single zygote can produce identical twins, including conjoined twins.

2. Conjoined twins have a high survival rate. In most cases, they can be easily separated.


1. Defend: When a single zygote splits in two, two identical embryos will form. These embryos develop into identical, or monozygotic, twins. Most doctors believe that conjoined twins start off like other monozygotic twins monozygotic twins Identical twins Twins resulting from the division of a single fertilized egg, which usually share a common chorion and placenta; usually each has a separate amnion. Cf Fraternal twins. , but the zygote doesn't split completely, so the embryos remain joined as they grow.

2. Dispute: Most conjoined twins die before or shortly after birth. That's because the majority of conjoined twins are joined in ways that are not compatible with life. For instance, they may share a brain or heart that is abnormally developed or too weak to support both twins. Whether or not doctors can attempt separation depends on which organs the twins share. Doctors must assess the major structures that lie in the region of the bridge between the twins. In some cases, such as with a shared brain, doctors determine that separation is impossible. Even if a separation is possible, the surgery is extremely complicated. There's always the risk that one or both twins won't survive or that they will develop infections or other problems afterward.
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Author:Adams, Jacqueline
Publication:Science World
Date:Apr 2, 2007
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