Triploidy occurs in 1% of all conceptions and is one of the most common chromosome abnormalities in humans [1]. The cells of fetuses contain 69 chromosomes which originate from three haploid gametes or one diploid and one haploid gamete. Two types of phenotypic presentations can be seen according to the origin of the diploid gamete; diandry (type I) if double contribution is paternal and digyny (type II) if it is maternal [2]. Phenotypic features associated with fetal triploidy have been shown to occur in a broad spectrum including placental changes and fetal structural and growth anomalies [3]. Paternallyderived cases predominate among “typical” spontaneous abortions, whereas maternally-derived cases are associated with either early embryonic demise or with relatively late demise involving a well-formed fetus. When termination of the pregnancy is regarded, the condition carries medical risks for the mother. Therefore, prenatal diagnosis and decision on termination of pregnancy should be made as early as possible. For this purpose, first and second trimester maternal serum screening tests and ultrasonographic (USG) examinations are performed during routine practice [4,5].

First and second trimester maternal serum screening tests are performed at weeks 11-14 and 15-22 of gestation. First trimester screening includes fetal nuchal translucency measurements by ultrasonography combined with maternal serum free â-human chorionic gonadotrophin (fâ-hCG) and pregnancyassociated plasma protein A (PAPP-A) levels as well as trisomy 21 risk (6). Second trimester screening includes maternal serum levels of human chorionic gonadotrophin (hCG), unconjugated estriol (uE3) and alpha-fetoprotein (AFP) combined with maternal age. Both tests have their own detection and false-positive rates regarding trisomy 21 risks. In triploid pregnancies, two patterns of maternal serum AFP, hCG and uE3 levels have been reported in the second trimester. The first is elevated AFP, elevated hCG and low or normal uE3. The second is low or normal AFP, low hCG and low uE3 [4].

Detection of triploidy based on increased translucency of nuchal thickness (NT) is effective in up to 66% of trip loid fetuses in first trimester without combining maternal age. Furthermore, crown rump length (CRL) based on first trimester fetal biometry charts has been reported to be useful in the detection of triploidy [1].

In the current study, we performed cytogenetic analysis for prenatal diagnosis and spontaneous abortion materials and detected triploidy in a total of nine cases. Our findings are discussed on the basis of routine prenatal diagnosis risks.