Obstetric and perinatal outcome in 200 infants conceived from vitrified oocytes

Assisted reproduction and fertility preservation techniques in cancer patients

PURPOSE OF REVIEW

This study aims to review the current state of different fertility preservation options in patients facing the risk of gonadal failure.

RECENT FINDINGS

Various malignant and nonmalignant diseases have been successfully treated with high-dose chemotherapy or radiotherapy. Even though many young patients receiving these treatments are at risk of developing reproductive failure, a number of fertility preservation options ranging from embryo cryopreservation to ovarian tissue cryopreservation are now available.

SUMMARY

Embryo cryopreservation is a well established technique to preserve fertility. The success rate with oocyte cryopreservation has been on the rise. Both oocyte and embryo freezing require ovarian stimulation and novel ovarian stimulation regimens utilizing aromatase inhibitors which have been developed for ovarian stimulation in women with estrogen sensitive cancer. Even though ovarian tissue cryopreservation is a novel technology, it is the only fertility preservation option for children and the only treatment strategy that can restore ovarian function. In-vitro maturation is a promising technology and can be applied in combination with ovarian tissue cryopreservation.

Human oocyte cryopreservation in infertility and oncology

PURPOSE OF REVIEW

To evaluate the present state of research and clinical application of human oocyte cryopreservation in infertility and oncology.

RECENT FINDINGS

Recent literature documents have an increasing interest in cryopreserving human eggs. A number of studies report on different freezing protocols and various types of clinical application. Increasing attention is paid to vitrification as an alternative to slow cooling for oocyte cryopreservation. Several studies cover the modification of meiotic spindle during cryopreservation in order to assess the less damaging cryopreservation system. The first births with cryopreserved oocytes in cancer patients are reported.

SUMMARY

Egg freezing may circumvent the ethical and legal concerns regarding embryo cryopreservation, increase assisted reproduction flexibility and be a concrete option to save fertility in women with cancer. Recently, egg survival and pregnancy rates improved, with the birth of more than 500 children. The birth rate per thawed oocyte is around 5-6%. As regards safety, data on birth defects seems to be reassuring so far but must be monitored by an international registry. Comparative studies between slow freezing and vitrification in the same patient population are needed to elucidate pros and cons of each technique.

Comparison of survival and embryonic development in human oocytes cryopreserved by slow-freezing and vitrification

OBJECTIVE

To compare the survival, fertilization, early embryonic development, and meiotic spindle assembly and chromosome alignment in frozen-thawed human oocytes after slow-freezing and vitrification.

DESIGN

A randomized study.

SETTING

A university-affiliated assisted reproductive center.

PATIENT(S)

Donated extra eggs from women undergoing assisted reproduction treatment.

INTERVENTION(S)

A total of 605 mature oocytes were divided into a slow-freezing group and a vitrification group for cryopreservation.

MAIN OUTCOME MEASURE(S)

After frozen-thawing, the oocyte survival rate, spindle assembly, and chromosome alignment were compared. The surviving oocytes were inseminated by intracytoplasmic sperm injection, and the rate of fertilization and embryo development were also compared in two groups.

RESULT(S)

The oocyte survival rate was statistically significantly lower in the slow-freezing group (75 out of 123, 61.0%) than the vitrification group (268 out of 292, 91.8%). The fertilization rate was the same for both groups, but the cleavage rate of zygotes was statistically significantly different between two groups: (slow-freezing, 25/46 (54.4%) versus vitrification, 142 out of 182 (78.0%). There was a considerable difference in the percentage of high-quality embryos between slow-freezing and vitrification groups: 6 out of 25 (24.0%) versus 60 out of 142 (42.3%), respectively. The percentage of blastocyst development was statistically significantly higher in the vitrification group (47 out of 60, 33.1%) than in the slow-freezing group (3 out of 25, 12.0%). There was a much higher percentage of oocyte abnormalities in terms of spindle assembly and chromosome alignment in the slow-freezing group (25 out of 64, 39.1%) compared with the vitrification group (11 out of 62, 17.7%).

CONCLUSION(S)

Vitrification is superior to the slow-freezing method, leading to improved oocyte survival rate, fertilization, and embryonic development in vitro. These results may be related to vitrified human oocytes incurring less damage to spindle integrity and chromosome alignment.

Cryopreservation of a mother's oocytes for possible future use by her daughter with Turner syndrome: case report

OBJECTIVE

To report a new fertility alternative for women with Turner syndrome, who are rendered infertile, by having their mothers freeze their own oocytes for the purpose of donating to their daughters when they are adults.

DESIGN

Case report.

SETTING

Academic teaching hospital.

PATIENT(S)

A 33-year-old healthy mother of three children; and her second child, a 6-year-old daughter recently diagnosed with Turner syndrome.

INTERVENTION(S)

Mother-to-daughter oocyte donation combined with oocyte vitrification.

MAIN OUTCOME MEASURE(S)

Number of cryopreserved oocytes.

RESULT(S)

After three cycles of ovarian stimulation, 30 oocytes were cryopreserved for the daughter's possible future use.

CONCLUSION(S)

The treatment option presented here opens the door for the banking of a mother's oocytes as a possible donation to a young daughter with a medical condition that leads to infertility, for her possible future use.