Table 5. Advantages and disadvantages of the various sperm selection techniques.

Method	Advantages	Disadvantages
ICSI	There is a positive and reproducible correlation between teratozoospermia index and sperm DNA damage [118,119].	There is no clear statement that every sperm which is morphologically normal will have a non-damaged DNA. The relationship between sperm morphology and sperm DNA damage still remains unclear [121].
	There is an inverse correlation between progressive motility and sperm DNA damage [119,120,122].
	Both reasons confirm ICSI as an appropriate technique to reduce sperm DNA damage.
IMSI	Provide better results in reducing SDF [123], since sperm with fragmented DNA tend to present vacuoles and ultra-morphological alterations.	Although the ultra-high magnification enables the operator to see the sperm clearer and better, there seems to be a lack of evidence to prove that IMSI is better than ICSI in selecting better sperm in terms of sperm DNA integrity [124].
		The use of expensive equipment and the long processing time is also a drawback of using this technique.
P-ICSI	Some studies demonstrated that this technique allows the selection of spermatozoa with a normal nucleus and without SDF [114].	No specific drawbacks to P-ICSI are known at present [128], except in testicular sperm samples where no motile sperm is present.
	Sperm that are mature and have intact DNA tend to bind to the hyaluronic acid, making them slow down, for easy choosing [112,125].
	Clinical evidence supporting its use is available [126]. Preferred for use in older females [127].
DGC	DGC is easy to do, and already become the most widely used sperm preparation technique prior to ART [115].	There is no consensus in the literature regarding the effect on DNA integrity, some studies demonstrated an improvement in SDF [115,129] while others report an increase in SDF [130].
MACS	Several authors have shown the ability of this technique to select spermatozoa with reduced DNA fragmentation [116,131,132].	Requires the use of expensive equipment [123].
	Preferred to be used in females younger than 30 years old [127].	Several reports show no clinical benefits, probably because its use is not focused on the right population of patients [133,136].
Microfluidics	The ability to reduce SDF [134,135].	Not widely available, and high cost [135].
	Easy to use.	Low volumes of ejaculate being processed, a considerable loss of sperm cells.

ART: assisted reproductive technology, DGC: density gradient centrifugation, ICSI: intracytoplasmic sperm injection, IMSI: intracytoplasmic morphologically selected sperm injection, MACS: magnetic activated cell sorting, P-ICSI: physiologic intracytoplasmic sperm injection, SDF: sperm DNA fragmentation.