What exactly do we mean by 'recurrent implantation failure'? A systematic review and opinion.

Recurrent implantation failure (RIF) is an iatrogenic condition, being the result of repetitive unsuccessful cycles of IVF or intracytoplasmic sperm injection (ICSI) treatment. The aim of this review was to assess the definitions of RIF used in literature as well as suggest a uniform definition of this condition. A systematic search of MEDLINE, Embase and Cochrane Library was conducted. The most commonly stated definitions described RIF as 'three or more failed treatment cycles' or 'two or more failed cycles'. Other identified definitions were based solely on the number of embryos transferred in previous cycles or combined the number of previously failed cycles with the number of transferred embryos. Several other definitions were also identified. This review highlights the lack of uniformity of the definition of RIF. Based on the available literature and the expert opinion of the authors, RIF should be defined as the absence of implantation after two consecutive cycles of IVF, ICSI or frozen embryo replacement cycles where the cumulative number of transferred embryos was no less than four for cleavage-stage embryos and no less than two for blastocysts, with all embryos being of good quality and of appropriate developmental stage.

Influence of gain adjustment on 3-dimensional power Doppler indices and on spatiotemporal image correlation volumetric pulsatility indices using a flow phantom.

Spatiotemporal image correlation can be used to acquire 3-dimensional power Doppler information across a single cardiac cycle. Assessment and comparison of the systolic and diastolic components of the data sets allow measurement of the recently introduced "volumetric pulsatility index" (vPI) through algorithms comparable with those used in 2-dimensional Doppler waveform analysis. The vPI could potentially overcome the dependency on certain machine settings, such as power, color gain, pulse repetition frequency, and attenuation, since these factors would affect the power Doppler signal equally throughout the cardiac cycle. The objective of this study was to compare the effect of color gain on the vascularization index (VI), vascularization-flow index (VFI), and vPI using an in vitro flow phantom model. We separated gains into 3 bands: -8 to -1 (no noise), -1 to +5 (low noise), and +5 to +8 (obvious noise). The vPI was determined from the 3-dimensional VI or VFI using the formula vPI = (maximum - minimum)/mean. Using no-noise gains, we observed that although the VI and VFI increased linearly with gain, the vPI was substantially less dependent on this adjustment. The VI and VFI continued to increase linearly with gain, whereas the vPI decreased slightly using low-noise gains. When gain was increased above the lower limit of obvious noise (+5), the VI and VFI increased noticeably, and there were marked reductions in both vPI values. We conclude that the vPI is less affected by changes in color gain than the VI and VFI at no-noise gains.

Endometrial spatio-temporal image correlation (STIC) and prediction of outcome following assisted reproductive treatment.

OBJECTIVE: The aim of this study was to correlate manual and spherical endometrial spatio-temporal image correlation (STIC) vascularity indices with assisted reproductive treatment (ART) outcomes. STUDY DESIGN: STIC ultrasound assessments of the endometrium were carried out at three time-points in 127 women in a prospective observational study. RESULTS: Biochemical pregnancy rate was 69% (88/127), with a biochemical and clinical pregnancy loss of 17%. Endometrial STIC vascularity indices in the assessed time-points did not differ between subjects who achieved a clinical pregnancy and those who did not (P>0.05). For first trimester miscarriage, minimal manual vascularization index (VI) at oocyte collection (cut-off value ≥0.7; sensitivity 80.0% and specificity 68.1%) demonstrated the highest area under the curve (AUC) of 0.8. CONCLUSION: In summary, STIC modality is not a useful tool to predict ART outcome, however manual STIC analysis of endometrial vascularity seems to be more accurate in predicting first trimester pregnancy loss.

4-D Assessment of Endometrial Vascularity Using Spatiotemporal Image Correlation: A Study Comparing Spherical Sampling and Whole-Tissue Analysis.

Our aim in the study described here was to assess the feasibility of spatiotemporal image correlation power Doppler quantification of the endometrium with two techniques: spherical samples and whole tissue. We scanned 51 women in the midluteal phase of the menstrual cycle: STIC assessment of the whole endometrium was not possible in 10% of cases, whereas spherical analysis was possible in all. The time taken for data set analysis was much longer for the whole endometrium compared with spherical analysis (1478.9 ± 291 s vs. 266.8 ± 39.3 s, p < 0.05). Intra-class correlation coefficients for the vascularization flow index (VFI) were similar for both methods. Volumetric vascularity indices were higher when spherical sampling was conducted. Significant cycle-to-cycle variability in the vascularity indices was present, with coefficients of variation exceeding 20% for both techniques. We found that STIC power Doppler quantification of the whole endometrium is possible in the majority of cases, however, it is time consuming and limited by significant cycle-to-cycle variability.