A D-quality embryo is an embryo with a low implantation rate into the uterus. This embryo will present signs of degeneration, morphological alterations, high percentage of fragmentation, etc.
However, if there are no more embryos, D-quality embryos can be transferred to a woman's uterus. Although the probability of pregnancy is low, it is true that any embryo that is transferred could implant in the uterus and lead to a gestation.
Read the full article on: How To Choose The Best Embryo? Characteristics & Techniques ( 65).