Laser-Assisted Hatching (LAH) Treatment in IVF

The developing embryo contained within a layer of proteins called the zona pellucida must hatch from these proteins before it can successfully implant in the lining of the uterus. This process occurs due to the embryo stretching and rupturing the zona pellucida.

Embryo’s assisted hatching process takes place in a laboratory. In this procedure, zona of a fertilized egg is gently thinned using an ultramodern laser. The elasticity and thinness of the zona pellucida is a fundamental requirement for successful hatching, which is considered a basic requirement 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 different observational studies clarifying that in humans the natural hatching site usually develops near the inner cell mass (ICM) of blastocysts. The laser is an ideal tool for microsurgical procedures, as the energy from it is easily focused on the target area and creates a controlled and precise hole between the 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.

Advantages of Pregnancy Outcomes

  1. With the help of LAH technology the clinical pregnancy rate has significantly increased in all LAH technology increases the hatching success rate from 75% to pregnancy rates up to 95%.
  2. Assisted hatching appears to significantly increase pregnancy and implantation rates for women with at least two more unexplained recurrent implantation failures in the previous IVF cycle.
  3. Embryos with artificial gaps in their zona initiate hatching earlier than zona-intact embryos.
  4. Therefore, it is said that assisted hatching facilitates implantation and then allows embryo-endometrium contact.
  5. Significant increase in implantation and pregnancy rates after AH was done for frozen embryos.
  6. A study involving assisted hatching showed that patients with a zona pellucida thicker than 15 μm had better implantation rates.
  7. Essential to conduct a Polar body biopsy.

Procedure of Laser Hatching in IVF

  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 increase the success rate.
  3. In this process, the frozen embryo is first thawed and cultured till Day 5.
  4. The embryologist places the embryo at a distance from the laser to avoid cellular damage. The laser beam is focused on the outer shell of the embryo and within 0.8 milliseconds of reflection of the laser beam creates a 5-10 micron hole in the embryo, making the embryo viable for hatching.
  5. The hatching embryo via Laser will successfully be attached to the endometrial cavity ensuring pregnancy.
  6. LAH helps to reduce 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. Making an opening in the zona will help the embryo’s chances of hatching and getting implanted into the lining of the uterus to achieve pregnancy using LAH technology.