Diamniotic Conjoined Fetuses in a Triplet Pregnancy: An Insight into Embryonic Topology

Abstract

We present a case of triplets, 2 of whom were monochorionic diamniotic conjoined fetuses, and the other triplet was in a separate chorion. The pregnancy followed in vitro fertilization with 2 embryo transfers and the conjoined fetuses developed from a single embryo. An early ultrasound showed 2 embryos attached to 1 yolk sac. Further monitoring of the pregnancy showed these 2 triplets to be diamniotic with a short umbilical cord/body stalk anomaly. After fetal loss a postmortem examination demonstrated that these fetuses were conjoined with a body stalk anomaly/short umbilical cord syndrome with fusion of the coelomic cavities and small bowel (minimally united/conjoined twins). There were dividing amniotic membranes. This case demonstrates the development of an unusual type of conjoined twin with characteristic features. Conjoined fetuses with this pattern have fused small bowel and cloacal anomalies and often diamniotic placentation, when this is recorded. Various terms including minimally united/conjoined omphalopagus/ischiopagus have been used for this characteristic pattern, but this pattern may warrant a specific term. "Diamniotic vitellopagus" may best reflect the pathogenesis of this pattern.

Gnatho-Thoracopagus Conjoined Twins with near Di-Symmetry: A Case Report of an Unusual form of Conjoined Twinning

“…When the present case is compared to the interesting case presented by Charles et al [16] of diamniotic conjoined fetuses in a triplet placenta with short umbilical cord syndrome and coelomic cavity fusion, both cases had fused small bowel with a Meckel's diverticulum, an omphalocele, and fused cords. However, the cloacal dysgenesis seen in the case of Charles et al was not seen in the present case, in which both twins had patent anuses.…”

Multiple Pregnancies

“…Reversal of circulation in the smaller twin was considered. Finally, Charles et al ( 2005 ) described triplets following IVF and two embryo transfers in which early sonography identi fi ed omphalopagi; the placenta, however, had a diamnionic status in the omphalopagi, and a separate placenta was present.…”

A case of conjoined twins after a transfer of a multinuclear embryo

“…To our knowledge, this is the first report of conjoined twins after a transfer of embryo with multinuclear blastomeres. In literature, sixteen cases [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22] of conjoined twins after ART have been reported to date ( Table 1). Description of embryos transferred is included in only five case reports: thoracopagus twins are reported after a transfer of a 4-cell embryo with even-sized blastomeres and <10% fragmentation on day 2 [7], a transfer of three good quality 8-cell embryos on day 3 [8], a transfer of two blastocysts (early and 4BB) on day 5 [9] and 6-and 7-cell embryos on day 3 [10].…”