All the following are techniques used for preimplantation genetic testing except:

Preimplantation Genetic Testing for couples undergoing in vitro feilization (IVF), may provide valuable information regarding the chromosomal complement and singlegene disorders. There are two separate categories of testing, preimplantation genetic diagnosis and preimplantation genetic screening each with different indications. There are three techniques that are used for both categories of preimplantation genetic testing:1. Polar body analysis is a technique used to infer whether a developing oocyte is affected by a maternally inherited genetic disorder. The first and second polar bodies are normally extruded from the developing oocyte following meiosis I and II, and their sampling should not affect fetal development 2. Blastomere biopsy is done at the 6- to 8-cell (cleavage) stage when an embryo is 3 days old, and it is the technique most commonly used for preimplantation testing. One cell is typically removed through a hole made in the zona pellucida. The technique is associated with a 10-percent reduction in the pregnancy rate 3. Trophectoderm biopsy involves removal of 5 to 7 cells from a 5- to 6-day blastocyst. An advantage is that because the trophectoderm cells give rise to the trophoblast no cells are removed from the developing embryo. Disadvantage is because the procedure is performed later in development, if genetic analysis cannot be performed rapidly, then cryopreservation and embryo transfer during a later IVF cycle may be required.(Ref: William's Obstetrics; 25th edition)