Siamese twins

Siamese twins: description

Siamese twins are twin children who have grown together in one or more places of their bodies. They may be connected by a skin bridge or even share organs. A typical Siamese twin does not exist, the malformations are individually very different.

Siamese twins: Definition of terms

The term “Siamese twins” goes back to a pair of twins who lived in the 19th century on the Gulf of Siam (today’s Thailand). The twins Chang and Eng had grown together on the flanks and were discovered by a Scottish businessman. He then exhibited them at fairs in North America. The oldest Siamese twins in the world are Ronnie and Donnie Galyon from the United States. They were born in 1951.

Siamese twins: frequency

Siamese twins are very rare in the world. According to the literature, twins born together in one million births are given birth. On the one hand, the onset of the malformation is very rare; on the other hand, many twins already die in the womb or the pregnancies are stopped if Siamese twins are detected during the check-ups.

Siamese twins: symptoms

Siamese twins can be connected in different places of the body, so there is no typical twin pair. Nevertheless, one distinguishes roughly the following forms:

• Craniopagus (twins grown together at the head)
• Thoracopagus (twins grown on the chest)
• Xipho-omphalopagus (abdominal twins)
• Pygopagus (Twinned Twins)
• Ischiopagus (twins connected to the pelvis)

Some organs may only be present once, so that the twins, for example, share a liver or a urinary tract. There may also be different numbers of arms and legs. The changes can be both symmetric and asymmetric.

According to the physical abnormalities, Siamese twins have very different medical problems. Apart from the adhesions, in 10 to 20 percent of cases, they have other malformations on other parts of the body or organs, such as heart defects.

Siamese twins: causes and risk factors

The exact reasons for the emergence of Siamese twins – and therefore also the risk factors for it – have not yet been finally clarified. Identical (monozygotic) twins are formed when a sperm-fertilized egg divides into two germs at the beginning of pregnancy. If this division occurs after the eighth day of pregnancy, the two embryos do not completely separate and the children remain as Siamese twins.

Siamese twins: investigations and diagnosis

During the checkups, Siamese twins can be detected early. After questions about the course of pregnancy and any previous multiple births, your gynecologist examines you physically.

To diagnose Siamese twins, an ultrasound (sonography) of the uterus is suitable. Especially in early pregnancy, the contours of the two children can be well represented. If they are indistinguishable from each other and remain in their posture even when repeated in different positions, this may indicate that twins have grown together.

Now the advice of pregnant women in the foreground. It is possible to deliver the children as well as to stop the pregnancy. It should include the severity of the connection, the prospect of a successful surgical separation and the resulting quality of life of the children.

Siamese twins: treatment

The most important therapy option for Siamese twins is the separation operation. These operations are often very successful. Nevertheless, there are certain risks to Siamese twins during and after the surgery. Separation and further treatment must therefore be well planned. The decision for or against an operation must always be made individually for each individual case.

Ultrasound, computed tomography (CT) and magnetic resonance imaging (MRI) are necessary for surgical planning. In addition, the digestive tract and the urinary tract are visualized with the aid of contrast media in order to be able to determine possible connections between the two children in these organ systems.

The separation operation requires a large team of experienced pediatric surgeons and anesthesiologists. It often lasts longer than 20 hours. According to technical literature, about 80 percent of patients survive a previously planned (elective) surgery, while only about 20 percent of children survive non-elective surgery (in acute danger to the children).

A planned separation operation can be performed from about the third month of life. Before, children should be given skin expander, which will stretch the skin before the procedure, so that any resulting gaps in the skin can be covered after the separation.

Siamese twins: disease course and prognosis

Siamese twins’ chances of survival and quality of life are both different and related to twin couples – very different, depending on the extent of the malformation and on the organs affected by them. Therefore, forecasts are difficult to make. In most cases, a separation operation is performed to allow the twins a better quality of life. Nevertheless, potential risks must be considered. As the oldest Siamese twinsstill connected, Ronnie and Donnie celebrated their 64th birthday in 2015. Even the twins Chang and Eng lived into their 63rd year of life.