Monochorionic twins
Monochorionic twins are
fertilization.[2]
Amniocity and zygosity
gestational age of 15 weeks. There is no sign of any membrane between the fetuses. A coronal plane is shown of the twin at left, and a sagittal plane
of parts of the upper thorax and head is shown of the twin at right.Monochorionic twins generally have two
monozygotic (identical twins).[3] Monochorionic-Diamniotic twins are always monozygotic.[citation needed
]
Diagnosis
By performing an
wedge-shaped protrusion into the inter-twin space, creating a rather curved junction).[4] The "lambda sign" is also called the "twin peak sign". At ultrasound at a gestational age of 16–20 weeks, the "lambda sign" is indicative of dichorionicity but its absence does not exclude it.[5]
In contrast, the placentas may be overlapping for dichorionic twins, making it hard to distinguish them, making it difficult to discern mono- or dichorionic twins on solely the appearance of the placentas on ultrasound.[citation needed]
Complications
In addition to a shared placenta, monochorionic twins also have their
circulatory anastomoses. This can cause disproportionate blood supply, resulting in twin-to-twin transfusion syndrome (TTTS) in 20%[1]
of MoDi pregnancies. This is the main complication of monochorionic twins.
The 80% of MoDi pregnancies without TTTS still have high rates of birth weight discordance,
cesarean section deliveries.[1] One twin may also fail to develop a proper heart and become dependent on the pumping activity of the other twin's heart, resulting in twin reversed arterial perfusion.[2] If one twin dies in utero, blood accumulates in that twin's body, causing exsanguination of the remaining twin.[2]
In the case of
cord entanglement and compression.[3] However, the perinatal mortality of monochorionic twins is fairly low.[1]
See also
References
- ^ PMID 16281049.
- ^ ISBN 0-8247-2844-0.
- ^ a b Pregnancy-Info -- > Monoamniotic Twins Retrieved on July 9, 2009
- PMID 8807758.
- PMID 9052601.
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