Birth Following Vitrification of Oocytes and Polar Body Diagnosis for Cystic Fibrosis

PURPOSE: Until now, polar body biopsy for monogenic diagnosis has been carried out on mature oocytes (metaphase II) after oocyte retrieval. Through the new procedure of vitrification it is possible to freeze oocytes without loss of their ability to be fertilized. Can fertilization and polar body biopsy be carried out successfully on oocytes with subsequent pregnancy and birth following vitrification? MATERIAL AND METHODS: A 33-year-old female genetic carrier of cystic fibrosis (CF), who already had given birth to a child with CF, underwent hormonal stimulation with the purpose of producing sufficient oocytes for polar body biopsy required for CF diagnosis. Because of unexpected technical problems with the testing system for polar body diagnosis before oocyte retrieval, vitrification of the eleven collected metaphase II (MII) oocytes after retrieval was decided upon with the patient. The polar body biopsy was carried out on the thawed oocytes three months later during an artificial cycle. RESULTS: Eight MII oocytes survived after thawing. Five of these oocytes could be fertilized (pronucleated oocytes) after ICSI. Two pronucleated oocytes were discarded because of evidence of mutation and one oocyte because of loss of the second polar body. Accordingly two oocytes with maternal wild-type allele were cultivated further and transferred. A subsequent singleton pregnancy was achieved. Due to severe gestosis a healthy but immature male newborn was delivered to the patient in the 26th week of gestation via cesarean section. CONCLUSION: To our knowledge this is the first report of a successful pregnancy after vitrification of MII oocytes and polar body diagnosis for monogenic disorders.