Document Type : Imaging in Reproductive Medicine
Authors
We present a conjoined twin (CT) case of pregnancy
in a 31-year-old woman (gravida 2, para
1) who came for her first routine ultrasound at 18
weeks of gestation. She conceived by spontaneous
conception. The patient had a healthy child from a
previous pregnancy. The initial ultrasound revealed
two fetuses with a fused thorax and abdomen, two
spines with an unusual extension, one beating heart,
shared liver across the fetuses, four kidneys, two
bladders, four normally formed arms and legs, and
the pelvic were separate with two female external
genitalia (
Ultrasound of conjoined twins (CT). These individuals share an anterior connection of the trunk at the thorax and the abdomen. Abdomen of both fetuses was notable for moderate ascites. The pelvic areas were separate with four kidneys and two bladders.
The parents did not give permission to publish any picture of the twins after termination.
Conjoined fetuses are a rare phenomenon of a
monochorionic, monoamniotic twin when the embryo
divides at 13-15 days from conception. The
incidence ranges from 1/50000-1/100000 live
births (
CT are classified according to the anatomical site of union with suffix pagus meaning fixed. The most frequent ventral union is the thoracopagus. Fusion of the abdomen is called omphalopagus and fusion of the thorax and abdomen is known as a thoraco-omphalopagus.
An early ultrasound finding suggestive of CT is the bifid appearance of the fetal pole. The ultras. ound criteria for diagnosis of CT consist of :
Bifid appearance of a 1st trimester fetal pole (V- or Y- shaped twin pregnancy)
The heads and bodies of the twins are at the same level
Single amniotic cavity with no dividing amniotic membranes
Fetus inseparable with fixed position even after maternal movement
More than three vessels in the cord
Single heart
Unusual extension of the spines
Unusual proximity of the extremities (
The presence of these sonographic signs depends
on the different types of CT. When amonochorionic
and monoamniotic pregnancy is suspected, the
presence of these signs must be considered. Two
top differential diagnoses are twin reverse arterial
perfusion (TRAP) and monoamniotic twin (