Monstra duplicia
Monstra duplicia form when the zygote does not split completely,
therefore the fetus has some body parts once and others twice.
Clinical signs
- incidence: 1 : 50 000 – 1 : 100 000
- 3/4 are female
- the most frequent form is thoracopagus (shared thorax and thoracic organs)
- other congenital malformations which are not caused by the “fusion” in 50% of cases
- prognosis:
- depends on the degree of organ sharing, especially the heart
- stillborn rate is high
- some types can live a long time, however
Etiology
Monozygotic twins, late twinning (13 – 14th day after fertilization).