Anomalies in twins

There is an increased prevalence of congenital anomalies in twins (6-10%). This inerease in malformations is due to both constraint deformities and malformations associatecl with monozygotic (MZ) twins.
Classification of anomalies in twins should be as follows:
1. Anomalies ıınicjue to mııltiple conception (Conjoined twins, Acardiac twins, Fetus in-fetu).
2. Anomalies not uniqııe to multiple conception, but that oecur more often in twins (Hydrocephalus, CHD - congenital lıeart defects).
3. Anomalies not unicjue to iwins, but more frecjuent becauşe of mechanical or vascular factors associated with twinning (Clubfoot, CDH - congenital dislocation of hip).
The rate of concorclance for congenital malformations in twins varies from 3/6-18.8%, and this nite is influenced by zygosity and type of anomaly.
Obstetrical problems associatecl with anomalies in twins inelude: a. Ultrasound demonstration of a twin pregnaney with cliscordant anomalies; b. amniocentesis with discordaney for abnormal karyotype. Selective fetocide is the solution for cliscordant anomalies, however, there risks to the procedure inclııding abottion/death of the second twin and permanent clamage to brain and renal tissue of the remaining fetus.
Prenatal diagnosis using ultrasonography for the various types of anomalies in twins, will be presented.