Definition and Statistics
* Identical twins that are physically joined at birth
* Referred to as Siamese twins which comes from the famous twins Eng and Bunker who were born in Siam (Thailand) in 1811
Twinning occurs in one of two ways:
1) a woman releases two eggs instead of the usual one
2) a woman produces only one egg that divides after fertilization
In the case of conjoined twins
* A woman only produces one single egg, which does not fully separate after fertilization * Developing embryo starts to split into identical twins during the first few weeks after conception but the process stops before its complete * Another theory suggests that two separate embryos may somehow fuse together in early development
* There aren’t any specific signs and symptoms that a woman is carrying conjoined twins * As with other twin pregnancies, the uterus may grow more rapidly than expected, and mothers of twins may also have more fatigue, nausea and vomiting early in the pregnancy * Conjoined twins are classified by where they are joined * Medical experts use words to identify conjoined twins that contain “pagus” meaning “fastened” in Greek * Thoracopagus twins are joined at the chest, share a heart and may also share a liver and upper intestine * Omphalopagus twins are joined near the bellybutton, share the liver, and some share the lower part of the small intestine (ileum) and colon
* Pygopagus twins are joined at the base of the spine, share the lower gastrointestinal tract, and a few share the genital and urinary organs * Ischiopagus twins are joined at the pelvis, share the lower gastronintestinal tract, as well as the genital and urinary tract organs * Craniopagus twins are joined at the heard, share a skull and possibly brain tissue, some also share cerebral cortex—the part of the brain that plays a central role in memory, language and perception
* Conjoined twins often do not survive more than a few days past birth because of a high rate of malformed organs and other severe birth abnormalities
* However, surgical separations have been successful in twins that have a superficial physical connection
* Occur once in every 200 000 births
* Always identical of the same sex
* Female: male
* 40%- 60% of conjoined twins arrive stillborn, and about 35% survive only one day
* Overall survival rate is somewhere between 5%- 25%
* 70% of conjoined twins are girls
* Mortality rates for twins who undergo separation vary, depending on their type of connection, and the organs they share * After conjoined twins are born, the parents and doctors must decide whether to attempt separation surgery * If one of the twins dies, develops a life- threatening condition or threatens the survival of the other twin, an emergency separation may be required * Many factors weigh heavily in the decision to pursue separation surgery: * Do the twins share vital organs?
* Are the twins healthy enough to withstand separation surgery?
* Whatare the odds of successful separation?
* What type of reconstructive surgery might be needed for each twin and successful separation?
* What issues would the twins face if left conjoined?
* If separation surgery isn’t possible or the parents decide not to pursue the surgery, comfort care such as nutrition, fluids, human touch and pain relieve is provided as needed * After separation, most twins need intensive rehabilitation because of the malformation and position of their spines
Real Life Example
* Doctors in Philadelphia successfully separated conjoined twins who shared a chest wall, diaphragm and liver at birth * The two girls (8 months old at the time the article) named Alison June and Amelia Lee Tucker, had been monitored since birth * A team of 40 doctors and nurses let by Dr. Holly L Hedrick, a pediatric general, thoracic and fetal surgeon worked for a total of seven hours to separate the twins * “Like all separations of conjoined twins, this was a very complex surgery, but it went very well and as expected” –Hedrick