What Is Assisted Hatching?
Assisted hatching is a laboratory procedure designed to facilitate implantation or attachment of the dividing embryos to the wall of the uterus. In order for implantation and pregnancy to occur, the embryo must “hatch” out of the zona pellucida (the egg’s outermost membrane). In some patients, failure to establish a pregnancy after IVF may be related to the inability of the embryos to get out of the zona.
When transfer is done 3 days after retrieval, a small opening is created in the zona pellucida under microscopic control, thus aiding the hatching process. Assisted hatching is not done on day 2 and day 5 transfers. Patients whose embryos undergo hatching, receive extended antibiotic and steroid treatment for 5 days.
Assisted hatching 3 days after retrieval
Although assisted hatching has been around as long as ICSI, its clinical value remains highly controversial. Whereas in the past we utilized this technique widely, more recently we have restricted its application to select cases where poor implantation rate may occur.
Reasons for Delay or Cancellation of a Treatment Cycle
Infection of the male reproductive tract (prostatitis) may be evident on semen analysis or semen culture, even though the man may be entirely without symptoms. Since infection can be associated with decreased fertilization rate and also introduce contamination into the laboratory, we attempt to first eradicate the infection with antibiotics before proceeding with ICSI-IVF. Sometimes prolonged treatment is required.
About 10% of women fail to respond to the ovulatory medications as expected. Some develop no or few follicles and others may develop only a single dominant follicle as in a spontaneous cycle. These stimulation cycles are usually canceled before egg retrieval. Individual patients are directly involved in the decision-making process about the retrieval cancellation. Ovarian reserve testing (How Do We Test Ovarian Reserve?) identifies many of the patients who are likely to respond poorly to ovarian stimulation.
A small percentage of patients ovulate prematurely before retrieval because their pituitary gland releases LH hormone surge before the hCG trigger. The use of GnRH analogs has markedly reduced the frequency of premature ovulation but it has not been eliminated entirely. Occasionally patients develop such a large number of follicles that they are at very high risk of ovarian hyperstimulation syndrome and the hCG trigger is withheld and retrieval canceled or the hCG trigger is reduced and all the embryos are frozen for a future transfer (How to Avoid OHSS).
The maturity of oocytes varies considerably and not all fertilize. The average fertilization rate is about 65%. In rare cases no eggs fertilize. Sometimes the sperm prove incapable of fertilization despite a normal semen analysis. In such cases, ICSI can be done the day after retrieval (“rescue ICSI”). While fertilization can usually be established, the pregnancy rate with “rescue ICSI” is lower than in cycles with timely fertilization. At other times the eggs are not as ready to be fertilized as they appear to be by ultrasound and blood tests. Finally, cell division and embryo development may fail to occur despite apparently normal fertilization. In some cases embryo quality may not be optimal or the embryos may stop developing.
Obviously the embryo transfer would have to be canceled if one of these problems arose, but fortunately they are quite uncommon and over 90% of patients in our program either undergo transfer of fresh embryos or have embryos frozen for a future transfer.
Handling of the eggs, which are very minute, outside of the body is inherently hazardous and requires great skill and care. On occasion, an egg or an embryo, fresh or frozen, may get stuck to the side of a culture dish and cannot be found. These kinds of mishaps are rare but you need to be aware of their possibility.