Background
Embryo incubation and assessment are vital steps in IVF and ICSI. Traditionally, embryos are removed from a conventional incubator for assessment of quality and stage of development under a light microscope. In this review, we have called that 'conventional incubation'. TLSs can take digital images of embryos at frequent time intervals. This allows assessment of embryos without removing them from the incubator. The use of a TLS often adds a significant extra cost onto an IVF or ICSI cycle. We wanted to determine whether a TLS would improve the chances of a pregnancy and live born baby, and whether a TLS reduces the risk of miscarriage and stillbirth.
Study characteristics
The evidence was current to November 2014. The three included studies involved 994 couples; 62 couples were undergoing IVF and the remainder ICSI. These studies took place in Spain, Hungary and Turkey. One study is ongoing but the other studies were 6 and 17 months in duration. Some couples received donor eggs from younger women. Two studies (138 couples) replaced one embryo at a time, at the blastocyst stage; 856 couples had multiple embryos replaced at a time (1.86 per couple on average), at the cleavage stage or blastocyst stage, in the other study. The age of women ranged between 20 and 38 years. One study disclosed that the instrumentation and utensils used were fully paid for by IVI. IVI is a shareholder in UnisenseFertiliTech A/S, a manufacturer of a TLS, but none of the authors had any economic affiliation with UnisenseFertiliTech A/S.
Key results
The results did not demonstrate evidence of a difference in the live birth, miscarriage, stillbirth or clinical pregnancy rate per couple randomly assigned to either a TLS or conventional incubation.
Quality of the evidence
The quality of the evidence was moderate or low. This was due to the scarcity of studies, two of which were very small in terms of numbers of participants, with high risk of bias in the largest study.
Authors' conclusions:
There is insufficient evidence of differences in live birth, miscarriage, stillbirth or clinical pregnancy to choose between TLS and conventional incubation. Further data explicitly comparing the incubation environment, the algorithm for embryo selection, or both, are required before recommendations for a change of routine practice can be justified.