Final answer:
The most likely chromosomal abnormality to be found in the karyotypic evaluation of the products of conception in this case is triploidy.
Step-by-step explanation:
Based on the information provided, the most likely chromosomal abnormality to be found in the karyotypic evaluation of the products of conception in this case is triploidy. Triploidy refers to a condition where there is an extra set of chromosomes, resulting in a total of 69 chromosomes instead of the usual 46. It is associated with the presence of three copies of each chromosome instead of the usual two. The dilated cervix with blood and tissue, along with the heavy vaginal bleeding, are consistent with a miscarriage or spontaneous abortion.