Unseparated twins (Siamese twins, conjoined) is a rare malformation involving the presence of a pathological connection between the body parts belong to monozygotic twins. The frequency of defects is estimated as one in 50 or 100 thousand. births (prevalence does not include fetuses miscarried in the early stages of pregnancy). In most cases, children burdened with this defect are stillborn or are spontaneously miscarried in early period of pregnancy, but some of them are born alive. According to various data, the percentage of stillborn conjoined twins is 40-86%. Interracial and regional differences were found. Most reports of conjoined twins births comes from the developing countries (so-called Third World). Read full text »