Table 3 Advantages and disadvantages of immotile sperm selection techniques

Hypo-osmotic swelling test (HOST)

HOST is based on the semi-permeability of intact cell membranes. The tail of viable sperm curves or swells after exposure to a hypo-osmotic medium.

• Simple and economical

• Repeatable and reliable

• Recommended in the WHO laboratory manual

• Need for prior treatment

• Time-consuming

• Not suitable for cryopreserved sperm

[75,76,77,78,79]

Pharmacological stimulation

The mechanism of drug-induced motility is mainly to activate signaling pathways related to sperm motility.

• Relatively easy to use

• Easy identification of viable sperm

• Need for pharmacological agents

• Need for prior treatment

• Possible side effects

[111,112,113]

Mechanical testing

The ICSI pipette is used to test the elasticity of the sperm tail. If sperm exhibiting elastic tails is presumed to be viable.

• Simple and economical

• No need for additional reagents and equipments

• Highly dependent on practical experiences

• Not easy to identify viable sperm

• A relatively small number of relevant literatures

[73, 114]

Laser-assisted selection

The end of the sperm tail was targeted with a laser pulse. Those sperm that presented with curling of the tails were regarded as viable.

• Time-saving

• Easy to perform

• Noncontact

• Can be performed during ICSI

• Need for laser equipment

• Still not standardized

[79, 80, 83, 84, 86,87,88,89]