Siamese Twins Case Study

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The term Siamese twins is used on individuals that are of a single gestation . Those twins whose bodies are still conjoined after birth. This tends to occur in one of every 200,000 births, 50% of the cases are born dead and 75% belong to the female gender . The percentage of survival in Siamese twins ranges between 5% and 25%. The origin is not yet well defined, but it is thought that Siamese twins are the result of an aberration in the process of the formation of monozygotic twins, i.e. twins of the product of the same ovum and the same sperm. In fact, monozygous twins are in themselves considered an aberration of the normal development, therefore, the Siamese represent a defect even more severe in which single ovum twin fails in its complete separation. The incomplete separation is seen as the result of a partial replication that occurs in the embryonic disk before the third week of intrauterine life. The division of embryos of normal twins typically occurs in the first ten days after fertilization, however in case of Siamese twins this embryo-splitting occurs later, normally day 13 or 14, this delay signifies that the divisions is not completed properly . The extent and origin of duplication determines the type of Siamese twins, and varies in a …show more content…
The Internal Anatomy varies; usually they have separate organs except liver . Pigópagos (18-19%): Connecting the back, usually in the pelvis with sacrum and coccyx are common, and digestive tube ending in a common anus and rectum. Often there are genito-urinary malformations. Conjoined (6%): Connection level of the lower pelvis, pelvic region fused to the bodies navel ; above and separated bodies are normal. Craniopagus (1-2%): Generally are connected by the middle of the head; almost always the brains are separated or only slightly

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