Classiﬁ cation of Twins and Principles of TheirPrenatal Ultrasonographic Diagnostics

Czech version

Authors: J. E. Jirásek ¹; P. Calda ²; L. Krofta ¹; E. Kučera ¹; Z. Malý ³; J. Šantavý ⁴
Authors‘ workplace: Ústav pro péči o matku a dítě, Praha, ředitel doc. MUDr. J. Feyereisl, CSc. 2Gynekologicko-porodnická klinika, 1. LF UK a VFN, Praha, přednosta prof. MUDr. J. Živný, DrSc. 3Institut Unica, Brno, ředitel prof. MUDr. Z. Malý, DrSc. 4Ústav lékařské genetiky, ¹
Published in: Ceska Gynekol 2004; (1): 27-32
Category:

Overview

Objective:
Systematic classiﬁ cation of all forms of twins and mechanisms of twinning.Design: Review of published cases. Morphogenesis based on personal experience related to humanblastogenesis including observation of anterior twinning in two early human embryos.Setting: Institute for the Care of Mother and Child, Prague, Department of Gynecology and Obstetrics,1st Medical Faculty, Charles University, Prague, Department of Medical Genetics, MedicalFaculty, Palacký University Olomouc, Institut Unica, Brno.Methods: Analysis of cases described in literature completed by observed cases.Results: Classiﬁ cation of twins.A) Separated twins: 1. dichorial a) monozygotic (very rare), b) dizygotic (most frequent); 2. monochorial(always monozygotic) a) diamnial, b) monoamnial.B) Conjoined twins (always monozygotic) 1. isopagi (equal conjoined twins) a) originatingfrom peripheral fusions of two germ discs, b) originating from duplications of axial structures;2. heteropagi (unequal conjoined twins): autosit (main twin), heterosit (parasitic twin).Conclusion: The developmental mechanisms of twinning are discussed, special attention ispaid to equal conjoined twins and to the possibilities of their early prenatal ultrasonographicdiagnostics.

Key words:
separated twins, conjoined twins, unequal twins, classiﬁ cation, prenatal ultrasonographicdiagnostics

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