Laser-Assisted Hatching (LAH) Treatment in IVF

Hatching of the embryo is a process whereby the expanded blastocyst undergoes cycles of contractions and expansions until it becomes almost invisible. Elasticity and thinning of the zona pellucida are fundamental for successful Laser Assisted Hatching ( LAH ), which is a prerequisite for implantation.

One of the major hurdles to a successful IVF cycle is poor blastocyst hatching. It is due to:-

  1. Genetic problems: Abnormality in the genes encoding hatching.
  2. There may be spontaneous zona hardening due to age-related endocrine changes and/or the.
  3. Suboptimal Cultural conditions – may cause zona hardening. QC should be done.
  4. Deficiency in the production of an intrinsic embryonic lysin that promotes hatching following blastocyst expansion
  5. Thick Zona or Zona hardening
  6. Cryopreservation
  7. Poor embryo quality

There are two observational studies demonstrating that a natural hatching site usually develops in close proximity to the inner cell mass (ICM) of blastocysts in humans. Hirotoshi et al. hypothesized that the choice of AH site could be important to the development of laser hatching. Laser presents an ideal tool for microsurgical procedures as the energy is easily focused on the targeted area producing a controlled and precise hole consistent between operators.

 Indications of Laser Assisted Hatching ( LAH )

  1.  Advanced Maternal Age(≥37 years):
    • There may be spontaneous zona hardening due to age-related endocrine changes and/or the
    • Absence of lysins from surrounding tissues, which may act on embryos in vivo
    • Reduced quality and quantity of oocytes ‘ovarian reserve’,
    • An increase in the incidence of karyotypically abnormal embryos
    • A decline in uterine receptivity
  2. Repeated Implantation failure (two or more previously failed IVF attempts).
  3. Frozen-thawed embryos: Excessive in vitro culture of cryopreserved embryos, and/or exacerbated by the freeze -thaw process, is thought to induce alteration in the glycoprotein matrix leading to zona hardening.
  4. Elevated basal FSH of women
  5. Embryos with thick zona pellucida (>15 μm)
  6. Abnormal or poor embryo morphology, cytoplasmic fragmentation, and retarded developmental rate.
  7. A condition in women where cells from the uterine lining appear outside of the uterus- endometriosis.

Procedure of Laser Assisted Hatching ( LAH )

  1. LAH procedure is carried out on the 3rd or 5th day after the IVF cycle before embryo transfer
  2. LAH technique with frozen embryo transfer (FET) will significantly increases the success rate.
  3. In this process, the frozen embryo is first thawed and cultured till Day 5.
  4. The embryologist then placed the embryo a distance away from the laser to prevent cellular damage. A beam of laser is focused on the outer shell of the embryo. The laser beam reflection creates a 5-10 micron hole in the embryo within 0.8 milliseconds making embryo viability to hatch.
  5. The hatching embryo via Laser will successfully aligned with the endometrium cavity ensuring pregnancy.
  6. It further reduces the risk of complications and the birth of identical twins.
  7. Apart from FET, it is also recommended for other infertility factors especially when a couple’s embryos face the inability to hatch. The creation of an opening in the embryo shell will help the embryo’s chances of hatching and becoming implanted into the lining of the uterus to pregnancy using LAH technology.

Advantages of Laser Hatching in IVF on Pregnancy Outcomes

  1. Laser Hatching in IVF significantly increased clinical pregnancy rates in all patients. With LAH technology, the success rate of embryo hatching ranges from 75% and pregnancy rates rise to 95%.
  2. Pregnancy and implantation rates appear to be significantly increased by Laser Assisted Hatching (LAH) for women with unexplained recurrent implantation failure in at least two, and usually more, previous IVF cycles.
  3. Essential to conduct Polar body biopsy.
  4. Embryos with artificial gaps in their zona initiate hatching earlier than zona intact embryos. Therefore, it can be postulated that Laser Assisted Hatching (LAH) facilitates implantation by allowing earlier embryo–endometrium contact.
  5. Significant increase in implantation and pregnancy rates after AH done for frozen-thawed embryos.
  6. A study of assisted hatching for patients with thick zona pellucida more than 15 μm suggested an improved implantation rate.
  7. This has led some to introduce selective assisted hatching on poor prognosis embryos (thick zona pellucida, low developmental rate and excessive fragmentation), but further studies are required.