pArtiaL zonA pelluciDa Removal by assisteD hatchINg of Blastocysts

Does Partial Zona Pellucida Removal From Vitrified-warmed Human Blastocysts Improve Delivery Rate in IVF? A Multicentric RCT on Laser Assisted Hatching

The aim of study is to assess the possible impact of assisted hatching on delivery rate after transfer of vitrified-warmed human blastocysts.

Zona pellucida (ZP) manipulation, termed "assisted hatching" (AH), has been introduced in order to favor embryo hatching and ultimately improve assisted reproductive technology success but with poor proofs of safety and biological plausibility. Vitrifying and warming of blastocysts may impair the successful hatching process of the embryo out of its ZP and its following implantation into the uterus. Theoretically, AH may facilitate the hatching process and subsequently increase implantation rates. In this prospective randomized controlled trial (RCT), the hypothesis is to test whether the application of a partial AH to vitrified/warmed blastocysts might affect patients' delivery rate. Patients with vitrified blastocysts will be randomized at the time of blastocyst warming to a study group (with AH) or a control group (without AH). AH will be performed at the expanded blastocyst stage using a laser technique and a laser opening will be initiated at the 1 o'clock position. Consecutive laser shots will be applied to reach the 5 o'clock position of the blastocyst. The blastocysts will then be cultured at least 2 h and subsequently transferred into the patient's uterus.

Subjects whose vitrified/warmed blastocysts will be subjected to the treatment of laser assisted hatching

Subjects whose vitrified/warmed blastocysts will be subjected to the same procedures except for the treatment of laser assisted hatching

After warming, blastocysts are subjected to laser assisted hatching (LAH) following the standard procedure.The LAH procedure lasts one minute per blastocyst.

the number of gestational sacs observed at echographic screening at 6 weeks of pregnancy divided by the number of transferred embryos

the ultrasonographic demonstration of an intrauterine gestational sac divided by the number of included women

Pregnancies failing to progress to the point of ultrasound confirmation divided by the number of women with a positive pregnancy test on blood

the ultrasonographic demonstration of an intrauterine gestational sac with fetal hearth divided by the number of included women

a pregnancy in which more than one fetus develops in the uterus at the same time divided by the number of women with a clinical pregnancy

birth defects, congenital disorders, congenital malformations, or congenital abnormalities, are conditions of prenatal origin that are present at birth, potentially impacting an infant's health, development and/or survival divided by the number of livebirths

Inclusion Criteria: single embryo transfer of vitrified/warmed blastocyst (SET) first or second frozen IVF (with or without Intracytoplasmic Sperm Injection) cycle of blastocysts first or second oocyte retrieval Exclusion Criteria: Preimplantation Genetic Testing (PGT) cycle BMI > 35 kg/m2 severe male factor abnormal uterine cavity

Alteri A, Vigano P, Maizar AA, Jovine L, Giacomini E, Rubino P. Revisiting embryo assisted hatching approaches: a systematic review of the current protocols. J Assist Reprod Genet. 2018 Mar;35(3):367-391. doi: 10.1007/s10815-018-1118-4. Epub 2018 Jan 19.

Alteri A, Guarneri C, Corti L, Restelli L, Reschini M, Giardina P, Papaleo E, Somigliana E, Vigano P, Paffoni A. ALADDIN study: does assisted hatching of vitrified/warmed blastocysts improve live birth rate? Protocol for a multicentric randomised controlled trial. BMJ Open. 2020 Jul 19;10(7):e031544. doi: 10.1136/bmjopen-2019-031544.