Fertilization failure in IVF: why and what next?

Abstract

Among 297 couples who underwent 587 oocyte collection procedures, 95 (16%) total fertilization failures (FF) were observed. This frequency is similar in couples with either normal or only mildly deficient spermatozoa (16.2 and 13.7% respectively) but is almost doubled in cases of moderately and severely defective sperm (26.5%). However, this latter group accounts for only 19% of FF events. The fertilization rate per oocyte (FR) follows an inverse trend. FR was correlated with the final (i.e. after swim-up) sperm count and with initial and final motility of the sperm sample. If the final count and motility were less than 2 x 10(6)/ml and 40% respectively, the FF frequency in the group with partner's spermatozoa was significantly higher and FR significantly lower. FR was inversely correlated with the number of oocytes recovered but FF was found significantly more frequently only when fewer than three eggs were retrieved. No correlation was found between FF and either female causes of infertility, age or dosage of stimulation treatment. However, in the group with donor spermatozoa the FR was significantly lower amongst tubal, endocrinopathic and endometriotic patients (67.6, 67.2 and 56.6 respectively versus 79.7% in harvests from idiopathic cases). FR was decreased and FF increased when ovulation induction resulted from a spontaneous LH peak supplemented with human chorionic gonadotropin (HCG), as compared to induction by HCG alone. In the group using normal or mildly defective spermatozoa, if FF occurs at the first attempt, the frequency of recurrence in further trials is high (29%) and the probability of pregnancy after completed trials is low (12.5%).(ABSTRACT TRUNCATED AT 250 WORDS)

Should ICSI be recommended routinely in patients with four or fewer oocytes retrieved?

“…Though definitions of poor response vary with regard to number of oocytes retrieved, many studies have suggested that low responders have lower fertilization rates, pregnancy rates, and implantation rates after an IVF cycle [13,19]. Complete fertilization failure, which occurs in approximately 16% of IVF cycles, was significantly more frequent in cycles that resulted in 3 or fewer oocytes [14,20]. Though it has been suggested that 6-10 oocytes is the ideal quantity to optimize the number of embryos ultimately transferred [21], retrospective analyses of poor response cycles and subsequent fertilization and pregnancy rates suggest that embryo transfer is still possible in this patient population and cycles should not be cancelled [19,22,23].…”

“…An association between lower number of retrieved oocytes and lower fertilization rates and IVF outcome has been described [12,13]. Additionally, fertilization failure is a common finding when less than 3 oocytes are retrieved [14] The high fertilization rates, small numbers of fertilization failures, and lack of apparent long term drawbacks make ICSI an appealing solution for IVF [15,16]. Hence, it has been proposed that ICSI could improve fertilization rates and the likelihood of successful embryo transfer when the number of recovered oocytes is low [17].…”

Clinical issues during ART

“…1 Fertilization rates strongly predict the outcome of the ART cycle. [75][76][77][78] In cases where TFF occurs, there is a 29% chance of it recurring. TFF happens in 5-16% of IVF cycles.…”

Successful pregnancy by vitrified–warmed embryo transfer for a woman with Kallmann syndrome

“…ICSI is usually used when the quantity or quality of motile sperm is poor and when fertilization failure has occurred in previous IVF cycles. However, normospermia is observed in 5-10 % cases that fail to fertilize and form a zygote [4,5]. Because this type of failure is difficult to predict, results for obtaining zygotes are better for ICSI than IVF.…”