MACS stands for Magnetic Activated Cell Sorting, also known as annexin columns or annexin V columns and it is a new technique to treat male infertility.

This technique is used when a man presents severe fertility problems caused by a high number of dead spermatozoa or fragmented DNA. It consists in separating the healthy spermatozoa through magnetic attraction. However, it doesn’t affect those spermatozoa with a high DNA fragmentation rate.

It is important to separate these low-quality spermatozoa when carrying out an assisted reproductive technique so that the success rates are not compromised.


When is it recommended?

This type of treatment is recommended for men with a severe case of male infertility that have already been subject to other reproductive treatments with no success. In addition to that, their sperm should also present a high degree of DNA fragmentation. This fragmentation can cause problems in the sperm motility and it is associated with defective or low-quality sperm.

This technique is used in the following cases:

  • High degree of spermatozoa with fragmented DNA.
  • Severe male factor.
  • Repeated failures with other treatments.
  • Low fertilisation rate.
  • Bad embryo quality.
  • Sterility due to unknown cause.
  • Patients that have gone through chemotherapy or radiotherapy.


There’s a process known as apoptosis or programmed cell death (PCD), which consists in eliminating the damaged cells or those with severe defects, so that they won’t affect the organism. Apoptosis also takes place in spermatozoa. It begins when the damaged spermatozoa contain phosphatidylserine in their cell membrane, which is a phospholipid used for differentiating the cells that are going to go through a process of apoptosis from the healthy cells.

The Annexine V protein, along with some metal microbeads are added to the sperm sample. The damaged sperm contains a protein named phosphatidylserine in the cell membrane. This protein has high affinity for annexine V. Once the associations have been made, the sample is put through a magnetized column system where the metal microbeads get stuck to the column walls and only those healthy spermatozoa without annexin run through the column. Those spermatozoa will later be used in the ICSI treatment.

This way the sperm sample is selected, eliminating part of the damaged spermatozoa and spermatozoa with defects. The only spermatozoa that are left for carrying out the process are the healthy ones. When performing ICSI with this highly-purified sperm there are more chances of no fertility failure. Besides, the embryos to be transferred would be of better quality, which means that the pregnancy rates will be higher in these patients.