Polar Body Biopsy
Definition - What does Polar Body Biopsy mean?
A polar body biopsy (PBB) is an indirect test that is used to evaluate the genetic composition of the egg during in vitro fertilization (IVF) by analyzing the small non-dominant cells (known as polar bodies) that are formed as an egg completes its cell division. Genetic abnormalities of eggs and the resulting embryos is a common cause of pregnancy failure in assisted reproductive methods.
Undergoing a polar body biopsy prior to fertilization of an egg increases the chance of the development of a genetically healthy embryo. Since the procedure is performed prior fertilization, it is associated with a low risk of harm to the embryo.
FertilitySmarts explains Polar Body Biopsy
A polar body is a small non-dominant cell that is formed during the division of the premature oocyte. When an immature egg completes the first step of cell division to become a mature egg the first polar body is formed, and a second polar body is formed right after fertilization. The polar body is much smaller in size compared to the egg and lacks the ability to be fertilized. It remains accompanying the egg until the egg is fertilized or completes its cycle.
The polar body resembles the genetic composition and the integrity of the egg, therefore identifying any genetic abnormalities in the polar body means that the chances of the egg carrying the same abnormalities are higher.
Although a polar body biopsy can identify abnormalities in the egg, it cannot detect fetal genetic abnormalities due to abnormalities of the sperm.
Preimplantation genetic screening (PGS) involves obtaining a sample from an embryo after fertilization and before it is transferred to a uterus. PGS can be used detect fetal genetic disorders caused by abnormalities in both maternal and paternal genetic material. But in contrast to PBB, PGS is invasive as the procedure involves taking cells for analysis after an embryo has formed.