Sperm tail flexibility test: a simple test for selecting viable spermatozoa for intracytoplasmic sperm injection from semen samples without motile spermatozoa.
OBJECTIVE
The objective was to describe the results of the injection of immotile spermatozoa with flexible tails when only immotile spermatozoa are present in the semen sample.


METHODS
A retrospective study was conducted to analyze the procedure results for 10 couples who participated in our intracytoplasmic sperm injection program. The sperm tail was considered flexible when it moved up and down independently of the head movement, and it was considered inflexible when the movement occurred together (tail plus head). The fertilization and pregnancy rate were analyzed.


RESULTS
The normal fertilization rate (presence of 2 pronuclei) was 30.3% (40/132), and the abnormal fertilization rate (presence of less than or more than 2 pronuclei) was 6.81% (9/132). A total of 52 embryos were obtained with 9 transfer procedures performed (pregnancy rate: 11.12%).


CONCLUSIONS
The sperm tail flexibility test (STFT) is an easy and cost-effective way for selecting viable immotile spermatozoa and can be used as an alternative method for determining the viability of spermatozoa. This test seems to be a simple and risk-free method when compared to the swelling test.
Soares
Jonathas Borges
JB
Human Reproduction Unit, Albert Einstein Jewich Hospital, São Paulo, SP, Brazil.
Glina
Sidney
S
Antunes
Nelson
N
Wonchockier
Roberta
R
Galuppo
Andrea Giannotti
AG
Mizrahi
Françoise Elia
FE
D000328:Adult; D004755:Enterobacteriaceae / Q000302:isolation & purification; D005260:Female; D006801:Humans; D007248:Infertility, Male / Q000209:etiology; D008297:Male; D008875:Middle Aged; D011247:Pregnancy; D018873:Pregnancy Rate; D012189:Retrospective Studies; D020554:Sperm Injections, Intracytoplasmic / Q000592:standards*; D013081:Sperm Motility / Q000502:physiology*; D013082:Sperm Tail / Q000502:physiology*