Rescue of implantation potential in embryos with poor prognosis by assisted zona hatching

Abstract

The effect of the assisted zona hatching (AZH) procedure was investigated on 135 cycles with a poor prognosis of pregnancy due to: (i) maternal age > or = 38 years (45 cycles); (ii) three or more failed in-vitro fertilization (IVF) attempts (70 cycles), and (iii) patients possessing both inclusion criteria (20 cycles). The control groups (113 cycles) included patients possessing the same characteristics (42, 53 and 18 cycles respectively) and who did not undergo the AZH procedure. A total of 505 embryos was treated with AZH before transfer, resulting in: 14, 25 and 6 clinical pregnancies. The percentage of clinical pregnancies per cycle was significantly higher than controls for the first (31 vs 10% in control 1, P < 0.05) and second groups (36 vs 17% in control 2, P < 0.05). No significant difference in percentage of clinical pregnancies was found for the third group (30 vs 6%). Similarly, higher rates of implantation were obtained (11.5, 15 and 11%) compared to the respective controls (4%, P < 0.02; 6.3%, P < 0.01; and 1.5%). The rate of miscarriage in the AZH groups was similar to that obtained in the controls (22 vs 21%). Finally, the morphological analysis of the embryos transferred revealed that the poor prognosis condition is associated to a significantly slower rate of development and a higher rate of fragmentation. The present results indicate that AZH procedure improves pregnancy and implantation rates in patients with a poor prognosis of pregnancy by facilitating the hatching process in embryos which would otherwise be trapped inside the zona pellucida.

Assisted hatching in assisted reproduction: a state of the art

“…This pioneering work was followed by numerous publications. Some of these publications reported a significant increase in the pregnancy and/or implantation rate in all patients [11]; other publications reported significant improvement in patients with a poor prognosis, namely women over 38 years of age, patients with thick zonae, and patients with repeated implantation failures [12][13][14]; while a third group of publications reported a non significant improvement in the pregnancy rate in patients with poor prognosis [11,[15][16][17][18]. On the contrary, some publications reported no improvement in pregnancy or implantation [19][20][21].…”

Laser assisted zona thinning technique has no beneficial effect on the ART outcomes of two different maternal age groups

“…However, the results are conflicting. Most of them suggest that it has beneficial effects on pregnancy and implantation rates of poor prognosis group such as advanced maternal age and previous implantation failures [7-10, 18, 19], others suggest that it may be a useful method for poor prognosis patients [6] and some say it has no benefit at all [20,21]. One group indicates better results when this technique has been used routinely [5]; while the others do not [22].…”

“…However, the success rates following this procedure have considerably varied according to the patient population and the AH methods used. It has been proposed that poor-prognosis patients benefit best from the AH procedure [6]. This group includes patients with an elevated follicle stimulating hormone (FSH) [7], thick zona pellucida [7], previous invitro fertilization (IVF) failures [8], and advanced maternal age [9][10][11].…”

Chemical zona pellucida thinning with acidified Tyrode’s solution: comparison between partial and circumferential techniques

“…To promote hatching despite the abnormal zona, chemical opening of the zona first was performed in 1992 [5]. Effectiveness has been confirmed by several clinical IVF centers [9][10][11][12]. Among several assisted hatching methods, chemical opening of the zona pellucida has been performed particularly widely because of technical ease and relative cost-effectiveness.…”