Presence of a cytoplasmic halo and complete nucleolar alignment is predictive of implantation rates and pregnancy rates for patients 35–39 years old but not for patients less than 35

Abstract

To determine the relationship between age, the presence of a cytoplasmic halo, nuclear precursor body alignment (NPB), and pronuclear (PN) morphology grade in human embryos with respect to pregnancy outcomes. Retrospective study in a university based IVF center. All patients undergoing ART from 2001 – 2006 who gave IRB consent were considered for analysis. Zygotes with a PN grade >1.0 were considered morphologically abnormal and excluded. The remaining 1579 embryos from 714 patients were considered normal and were included in our study. Variables analyzed were cytoplasmic halo (complete or partial) and complete NPB alignment. Clinical pregnancy rate (CPR) and implantation rate (IR) for transfers where a NPB pattern or halo was homologous within the transfer cohort were statistically evaluated by Fisher's Exact Test and Wilcoxon Rank Sum test. For transfers with PN grade ≤1.0, the CPR was 51% with an IR of 29.5%. CPR and IR were analyzed based on the presence or absence of a cytoplasmic halo, for the presence or absence of complete NPB alignment, and for the presence of both features for patients <35 years (Table 1) and patients 35–39 (Table 2). Table 1Patients <35 years of ageCytoplasmic HaloComplete NPB AlignmentHalo and Complete AlignmentPresentAbsentPresentAbsentPresentAbsentTransfer2472911713871182CPR51.1%48.3%52.1%52.2%50.7%52.8%IR33.1%30.5%31.4%32.2%30.8%33.2% Open table in a new tab Table 2Patients 35–39 years of ageCytoplasmic HaloComplete NPB AlignmentHalo and complete AlignmentPresentAbsentPresentAbsentPresentAbsentTransfers911321651487CPR58.2%130.8%66.7%49.2%85.7%346.0%IR30.1%315.4%36.5%25.3%50.6%323.1%1 P=0.08, 2 P=0.10, 3 P<0.01. Open table in a new tab 1 P=0.08, 2 P=0.10, 3 P<0.01. With the current debate of PN morphology and its ability to predict embryo quality, our data supports using cytoplasmic halo and nuclear precursor body alignment as predictors for successful transfers. Several studies have proposed that pregnancy and live birth rates do not correlate with PN scoring. While differences in zygote morphology examined in this study do not affect outcome in young patients, the presence of a halo and complete NPB alignment is associated with statistically higher IR and CPR in patients 35–39. This suggests that the combined assessment of halo and NPB alignment is useful in embryo selection for patients with advanced maternal age.