The PICSI technique (physiological intracytoplasmic sperm injection), also known as physiological ICSI, is a variant of intracytoplasmic sperm injection (ICSI) used in assisted reproduction to inject sperm directly into the egg under a microscope.
It involves selecting mature, high-quality sperm according to their ability to bind to hyaluronic acid, a substance that naturally coats the eggs.
The main difference between PICSI and ICSI lies in the method used to select sperm before microinjection. In conventional ICSI, embryology specialists select sperm mainly based on criteria such as morphology and motility before injecting a single sperm directly into the egg.
The PICSI technique incorporates an additional step of sperm selection before performing ICSI. Sperm are brought into contact with hyaluronic acid, and those capable of binding to this substance can then be selected for microinjection. This ability to bind to hyaluronic acid has been associated with sperm maturity and provides the embryology team with an additional criterion for selection.
Therefore, PICSI does not replace ICSI but rather complements it by incorporating a physiological sperm selection method before microinjection into the egg.
| Aspect | ICSI | PICSI |
| Sperm selection | Visual, mainly based on motility and morphology | Adds the ability to bind to hyaluronic acid as a selection criterion |
| Selection criterion | Characteristics observable under the microscope | Functional ability to bind to hyaluronic acid |
| Relationship with sperm maturity | Assessed indirectly through morphological and motility characteristics | Binding to hyaluronic acid is associated with certain markers of sperm maturity |
| Indication | Mainly in cases where sperm microinjection is indicated | An additional sperm selection method in certain cases, although its clinical benefit has not been clearly demonstrated |
| Cost | Standard | May involve an additional cost |
In the PICSI process, sperm are placed on a special plate that contains drops of a substance similar to hyaluronic acid. Only the highest-quality and most mature sperm adhere to these drops, allowing embryology specialists to select the best for microinjection into the egg.
This method helps select sperm with lower DNA fragmentation, which can increase success rates in fertilisation and reduce the risk of miscarriages.
The PICSI technique is used in the following cases:
The PICSI technique incorporates an additional criterion for sperm selection based on their ability to bind to hyaluronic acid. This ability has been associated with certain markers of sperm maturity and provides the embryology team with an additional criterion before performing microinjection.
Unlike conventional selection, in which sperm are assessed mainly according to characteristics observable under the microscope, such as motility and morphology, PICSI also incorporates a functional criterion: the ability to bind to hyaluronic acid.
Sperm capable of binding to hyaluronic acid have been associated in various studies with certain characteristics related to sperm quality, including greater maturity and, in some studies, lower levels of DNA fragmentation. However, these associations do not mean that PICSI can directly determine sperm DNA integrity, nor has it been consistently demonstrated to improve pregnancy or live birth rates compared with conventional ICSI.
Therefore, PICSI can be considered a complementary sperm selection tool that adds an additional criterion to conventional assessment. Its use should be evaluated on an individual basis according to the characteristics of each patient and treatment.
