Intracytoplasmic injection of morphologically selected spermatozoa (IMSI) improves outcome after assisted reproduction by deselecting physiologically poor quality spermatozoa

Abstract

Purpose: We used computer assisted sperm selection (MSOME) during cycles of intracytoplasmic sperm injection to test whether this technique improves results over traditional ICSI protocols. We also used the TUNEL assay to test whether MSOME could deselect physiologically abnormal spermatozoa.

Methods: Individual spermatozoa were examined with MSOME. Normal and abnormal spermatozoa were tested for the level of DNA fragmentation using TUNEL assay. In a prospective, randomized trial, patients were selected for standard ICSI, or IMSI techniques. We tested the two groups for biological and clinical parameters.

Results: 64.8% of spermatozoa, otherwise selectable for ICSI, were characterized by abnormalities after computer-assisted sperm analysis. These sperm were also characterized by an increase in the level of DNA fragmentation. We noted an increase in embryo quality, pregnancy and implantation rates after computerized sperm selection during ICSI procedures.

Conclusions: Computerised selection of spermatozoa during ICSI procedures deselects physiological abnormal spermatozoa and improves clinical results.

Fig. 1

Characteristics of normal morphology spermatozoa with MSOME. Standard measurements of length (4.5–4.9 μm) and width (3.1–3.5 μm) of the sperm head are shown. The midpiece should also have a standard length of between 4.0–5.0 μm. The size of vacuoles is calculated as percentage of the area of the sperm head. Measurements are based on ref 9

Fig. 2

MSOME of spermatozoa selected for ICSI. 182 spermatozoa otherwise considered suitable for ICSI were analysed with MSOME. The technique reveals several morphological defects not noted in standard ICSI procedures. a and b Normal morphology and presence of a single vacuole not greater than 4% of the surface area (arrow in b.). These examples represent 64 spermatozoa analysed in the trial c–h. Abnormal morphologies. c Presence of a single vacuole greater than 4% surface area. The arrow delineates the vacuole. Similar examples were observed in 38 spermatozoa. d Spermatozoa with multiple vacuoles (delineated by arrows). This example is representative of 22 spermatozoa analysed with MSOME. e Spermatozoa with a midpiece defect and a single vacuole over 4% of surface area. f Spermatozoa with a midpiece defect and multiple vacuoles in the sperm head (representative of 5 spermatozoa analysed). g and h Amorphous spermatozoa. Such examples were found in 27 spermatozoa otherwise considered normal for ICSI

Fig. 3

TUNEL assay on MSOME-analysed spermatozoa. a Normal morphology spermatozoa. Images i. and ii. are spermatozoa with normal morphology after MSOME. iii. The image represents TUNEL assay on spermatozoa considered normal after MSOME. Blue images are DAPI-stained TUNEL negative sperm heads (i.e. not containing fragmented DNA). Green-stained sperm heads are TUNEL-positive (i.e. containing fragmented DNA). b Abnormal morphology spermatozoa after MSOME. Images i. and ii. are representative examples of spermatozoa with abnormal morphology after MSOME iii. The image represents TUNEL assay on spermatozoa considered abnormal after MSOME. Blue images are DAPI-stained TUNEL negative sperm heads (i.e. not containing fragmented DNA). Green-stained sperm heads are TUNEL-positive (i.e. containing fragmented DNA)

Fig. 4

Improvement in embryo quality after IMSI. a Embryos selected for transfer from a patient in a standard ICSI cycle. The patient did not achieve pregnancy. b Embryos selected for transfer in the same patient after an IMSI cycle. Here, embryo quality is clearly improved and the patient achieved a singleton pregnancy

Fig. 5

Correlation between semen sample sperm morphology and pregnancy rates. a Standard ICSI cycles. The semen samples are characterised by a normal distribution with mean 14.3% normal morphology and standard deviation 5.6%. A correlation of r=0.85 exists between increasing morphology and pregnancy. b Correlation between semen morphology and pregnancy after IMSI. The samples here are characterised by a normal distribution with mean 15.1% and standard deviation 6.2%. The correlation between incidence of pregnancies and initial semen morphology is 0.015