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Clinical and Experimental Obstetrics & Gynecology  2020, Vol. 47 Issue (1): 65-69    DOI: 10.31083/j.ceog.2020.01.5023
Original Research Previous articles | Next articles
Is laser-assisted hatching better than mechanical method for enhancing pregnancy rate in frozen-thawed blastocyst transfer cycles?
Y. J. Lee1, S. C. Kim1, J. K. Joo1, H. G. Kim1, G. R. Ko2, C. W. Kim3, K. S. Lee1, *()
1Departments of Obstetrics and Gynecology, Medical Research Institute, Pusan National University School of Medicine, Busan, Korea
2Infertility Center, Pusan National University Hospital, Busan, Korea
3Departments of Obstetrics and Gynecology, Samsung Changwon Hospital, Sungkyunkwan University School of Medicine, Changwon, Korea
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Objective: To investigate the effect of laser-assisted hatching (LAH) compared with mechanical-assisted hatching (MAH) for enhancing clinical outcomes in frozen-thawed blastocysts (FTBs) transfer cycles. Materials and Methods: The culture of all pronucleate embryos to the blastocyst stage and the selection of blastocysts ≥ grade 3BB (Gardner and Schooleraft score), followed by FTBs transfer cycles with LAH (n=105) or with MAH (n=101). Clinical outcomes including clinical and ongoing pregnancy rates were investigated.Results: There were no significant differences in clinical and ongoing pregnancy rates between LAH and MAH groups in FTBs transfer cycles. Conclusion: LAH does not improve pregnancy outcomes significantly compared to MAH in FTBs transfer cycles.

Key words:  Laser-assisted hatching      Mechanical-assisted hatching      Frozen-thawed blastocyst     
Published:  15 February 2020     
*Corresponding Author(s):  K. S. Lee     E-mail:

Cite this article: 

Y. J. Lee, S. C. Kim, J. K. Joo, H. G. Kim, G. R. Ko, C. W. Kim, K. S. Lee. Is laser-assisted hatching better than mechanical method for enhancing pregnancy rate in frozen-thawed blastocyst transfer cycles?. Clinical and Experimental Obstetrics & Gynecology, 2020, 47(1): 65-69.

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Figure 1.  — Laser-assisted hatching. A) Zona pellucida showing to dissect approximately one-quarter after laser assisted hatching. B) The hatching blastocyst.

Figure 2.  — Mechanical-assisted hatching. A) The fixation by the assisted hatching pipette at a 9 o’ clock direction after locating a shrunken blastocyst at a 12 o’ clock direction, and the penetration by the injection pipette from a 4 o’ clock direction. B) The penetration by the injection pipette to a 8 or 9 o’ clock direction, and the rubbing and dissecting procedures using the edge of the holding pipette and the middle part of the infection pipette. C) Zona pellucida with a split after assisted hatching (partial zona dissection). D) The hatching blastocyst.

Table 1  — Demographic results of patients.
Variables LAH (n=105) MAH (n=101) p-value
Age (yrs) 35.0 [33.0-37.0] 33.0 [33.0-37.0] 0.08
Duration of infertility (yrs) 4.0 [2.0-5.0] 3.0 [2.0-4.0] 0.14
Infertility, n (%)
Primary 57 (54.3) 61 (60.4)
Secondary 48 (45.7) 40 (39.6)
Infertility diagnosis, n (%)
Male 21 (20.0) 34 (33.7)
Tubal 25 (23.8) 26 (25.7)
Ovulation 16 (15.2) 14 (13.9)
Unexplained 18 (17.1) 10 (9.9)
Endometriosis 6 (5.7) 6 (5.9)
Diminished ovarian reserve 2 (1.9) 2 (2.0)
Mixed 1 (1.0) 1 (1.0)
Others 16 (15.2) 8 (7.9)
BMI (kg/m2) 22.0 [20.3-24.2] 23.4 [21.2-25.0] 0.23
AMH (ng/mL) 4.2 [2.4-6.1] 4.1 [2.4-6.4] 0.70
Basal FSH (mIU/mL) 6.0 [4.4-8.1] 6.0 [4.2-8.2] 0.79
Basal LH (mIU/mL) 4.0 [2.5-6.9] 4.8 [3.0-8.9] 0.10
Stimulation protocol, n (%)
Antagonist 61 (58.1) 58 (57.4)
Long 35 (33.3) 40 (39.6)
Ultra-long 4 (3.8) 2 (2.0)
Ultra-short 5 (4.8) 1 (1.0)
Table 2  — Comparison of laboratory variables and clinical outcomes between LAH and MAH groups
Variables LAH (n=105) MAH (n=101) P-value
FTBs per COS cycle 1.78±0.62 1.90±0.64 0.17
Transferred FTBs per ET 1.52±0.50 1.62±0.49 0.14
Endometrial thickness at ET (mm) 8.99±1.42 9.12±1.55 0.53
Implantation (%) 52(49.5) 56(55.4) 0.41
Clinical pregnancy (%) 46(43.8) 43(42.6) 0.89
Ongoing pregnancy (%) 35(33.3) 38(37.6) 0.56
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