Missed abortions and still-births can be studied by karyotyping and FISH to detect chromosomal abnormalities. A high frequency of chromosome aneuploidy is found in spontaneous abortions. Aneuploidy detection by FISH can include combinations of chromosomes 13, 21 / 18, X, Y / 16 / 22.
Karyotyping from ‘products of conception’ (POC) of a spontaneous or missed abortion is done by fibroblast culture to rule out a chromosome abnormality, which is a likely cause of the abortion. To avoid contamination of tissue, the sample from early abortions should be taken directly in a sterile Menstrual Regulation (MR) syringe and transported in a sterile container with normal saline to which 2-3 drops of sodium heparin and Gentamycin are added. The sac surrounded by chorionic villi is the tissue of choice in early abortions while a 1” piece of placenta and fetal skin should be collected from 2nd and 3rd trimester abortions. Cord blood (0.5-1ml) should also be collected in sodium heparin vaccutainers whenever possible, from 3rd trimester abortions. The samples can be stored in the refrigerator overnight if required, before transportation at room temperature. Samples should never be put into formalin for karyotyping or FISH. Incase karyotyping fails in our laboratory due to contamination, FISH for chromosomes 13, 18, 21, X and Y is carried out at no extra cost. We also accept back-up samples of chorionic villi stored in Carnoy’s fixative from other laboratories, for FISH.