Conjoined Twins in a Triplet Pregnancy

Conjoined twins in a triplet pregnancy: early prenatal diagnosis with three‐dimensional ultrasound and review of the literature

“…Tan et al 3 found only nine cases of conjoined twins complicating a triplet pregnancy published in the medical literature until 1971, six involving thoracopagus twins and one each of craniopagus, cephalopagus and omphalopagus twins. Because at that time ultrasound was not available, the conjoined twins were usually diagnosed at delivery when obstructed labor had already occurred.…”

Conjoined twins: Morphogenesis of the heart and a review

“…The reported incidence of conjoined twins ranges from 1:192,000 births in southern Africa, through 1:33,000 to 1:165,000 in North America, [Rudolph et al, 1967; Benirschke and Kim, 1973; Myrianthopoulos, 1975; Edmunds and Layde, 1982], 1:100,000 in Japan, [Imaizumi, 1988] 1:75,000 in Sweden [Källén and Rybo, 1978], 1:68,000 in Hungary [Métneki and Czeizel, 1989]. Nine cases of conjoined twins as part of a triplet set have been described [Tan et al, 1971]. These variations reflect the relative proportion of monozygotic twins in these populations.…”

Multiple Pregnancies

“…Numerous triplets have included conjoined twins (Koontz et al 1985 ;Seo et al 1985 ;Gardeil et al 1998 ) . In triplets, the placentas may be monochorionic (Tan et al 1971b ) , with the conjoints living in their separate amnionic cavity, or they may be dichorionic (Vestergaard 1972 ) . We have recently observed term thoraco-omphalopagous girls with a monochorionic (diamnionic) normal female co-twin.…”

“…It is similar to those described by Kreutner et al ( 1963) , de Leon ( 1974) , and Itoh et al ( 1974 who observed that the co-twins had a fused subdiaphragmatic aorta whence the umbilical arteries originated. Gilbert et al ( 1972 ) and Tan et al ( 1971b ) described thoracopagi with one artery coming from one twin and the other from the second twin, who also received the single vein. The twins of Fig.…”