Assisted reproductive technologies (ART) offer pathways to parenthood. These medical procedures involve the careful handling and preparation of biological samples, such as sperm and eggs, outside the body. Precise laboratory preparation is fundamental for successful fertility treatments.
Defining “ICSI Washed”
ICSI, or Intracytoplasmic Sperm Injection, is a specialized fertility treatment used with in vitro fertilization (IVF). Unlike traditional IVF, where many sperm are placed with an egg in a dish, ICSI involves the direct injection of a single, carefully selected sperm into the cytoplasm of a mature egg. This method is particularly beneficial in cases of male infertility, such as low sperm count or poor sperm motility, or when previous IVF attempts have failed.
The term “washed” in “ICSI washed” refers to a laboratory process that prepares the semen sample for assisted reproductive procedures. This preparation isolates the most viable sperm from seminal fluid and other cellular components. “ICSI washed” describes sperm purified for direct injection into an egg during an ICSI procedure.
The Purpose of Sperm Washing
Sperm washing is a necessary step before ICSI for several biological and procedural reasons. One primary purpose is to separate healthy, motile sperm from immotile sperm, cellular debris, and other non-sperm cells like white blood cells, which can produce harmful reactive oxygen species. These unwanted components can interfere with fertilization and embryo development. The process also concentrates the best quality sperm for selection.
Another reason for washing is the removal of seminal plasma, the fluid portion of semen. Seminal plasma contains substances like prostaglandins, which can cause severe uterine cramping if introduced into the uterus during procedures like intrauterine insemination (IUI). It can also contain other molecules that may be detrimental to egg quality or interfere with fertilization in a laboratory setting. Washing also helps reduce the risk of introducing bacteria or viruses from the seminal fluid into the female reproductive tract or the culture media, especially for serodiscordant couples where one partner is HIV-positive.
The Sperm Washing Process
Sperm washing begins with the semen sample undergoing liquefaction, allowing it to become more fluid. The sample is then carefully layered over a density gradient medium, which consists of solutions with varying densities. This medium is often made of colloidal silica particles in suspension.
The layered sample then undergoes centrifugation, where it is spun at high speeds. This centrifugal force separates sperm based on their density and motility, with healthier, more motile sperm forming a pellet at the bottom of the tube. Less dense components, such as dead sperm, cellular debris, and seminal plasma, remain in the upper layers or at the interfaces of the gradient. The concentrated pellet of healthy sperm is then washed with a specialized culture medium to remove any remaining impurities and resuspended in a small volume of this medium, ready for the ICSI procedure.