Commonest cause of first trimester aboion is:
Ans. is b i.e. Trisomy 'Majority (50%) of early miscarriages are due to chromosomal abnormality in the conceptus. Autosomal trisomy is the commonest (50%) cytogenetic abnormality." "Autosomal trisomy is the most frequently identified chromosomal anomaly associated with first trimester aboions." Genetic causes Genetic anomalies are the most frequent and most impoant cause of (early pregnancy) 1st trimester lossesdeg. Majority of genetically originated aboions occur before 8 weeksdeg and are blighted ovadeg. The chromosomal anomaiies most frequently found in aboions are It is the M/C chromosomal abnormality in 1st trimester (60% cases) aboions MC chromosomal trisomy is of chromosome 16deg Other common trisomies are of chromosome 13, 18, 21& 22, although any chromosome except chromosome 1deg can be involved It consists of mean chro? mosome number = 69 MC cause of triploidy is double feilisation of a single ovum In triploidy without molar degeneration the extra chromosomal set is maternal in origin It is aiw obvious abnormalities viz -- Omphatocele, syndactyly, cleft lip, cleft palate and hydro? pic degeneration of placenta Monosomy (X) 45X About one of every 15 fetus with 45X karyotypes are aboed and will be identified as Turner syndrome at bih Tstraploidy It consists of mean chromosomal number 92 Such fetuses abo early Also know : Euploid aboions i.e. aboions with normal chromosomal numbers. They tend to abo later in gestation than those with aneuploid. Peak euploid aboions occur at 13 weeks . Incidence of euploid aboions increase dramatically after 35 years of mother age.
Monosomy
Trisomy
Triploidy
Aneuploidy