Association between increased yolk sac diameter and abnormal karyotypes

Study on the correlation between the ultrasound phenotype and copy number variation of abnormal embryo in spontaneous abortion

OBJECTIVE

This study aimed to explore the correlation between the ultrasound phenotype and copy number variation (CNV) of abnormal embryos in spontaneous abortion by investigating the abnormal chromosome copy number of embryos at different developmental stages in early spontaneous abortion.

METHODS

A total of 539 patients who had early spontaneous abortion in our hospital between 2015 and 2019 were divided into seven groups according to the phenotype of abnormal embryonic development during pregnancy, and the embryonic tissues of the patients were subjected by single nucleotide polymorphism (SNP) microarray.

RESULTS

Among 377 cases with abnormal CNV, 295 (78.25%) cases had chromosome trisomy, and 28 (7.43%) cases had a combination of more than two chromosomes. Triploidy, tetraploidy, chromosome microdeletion/duplication, uniparental disomy, and monosomy 45,X were found in 32 (8.48%), five (1.32%), 31 (8.22%), four (1.02%), and eight (2.12%) cases, respectively. Two (0.53%) cases had autosomal chromosome 21 monosomy. Normal karyotype had the highest proportion in the empty sac group; trisomy 16 accounted for the bulk of chromosomes in the normal yolk sac group, complex triploidy occupied the most part in the abnormal yolk sac group, and no remarkable difference in chromosomal abnormality proportion was found between the normal and abnormal yolk sac groups; the most frequent chromosomal anomaly in a group of germ without cardiac activity and germ<5 mm was trisomy 16; triploidy was the most common in the group with 5 mm ≤ germ ≤ 15 mm, whereas the main distribution of chromosome karyotype was normal, followed by trisomy 13 in a group with germ>15 mm.

CONCLUSION

Abnormal embryos with different ultrasound phenotypes in early spontaneous abortion have various CNV types and characteristic distribution. Thus, ultrasound combined with SNP array can provide a basis for the etiological analysis of embryos in spontaneous abortion.

The human yolk sac size reflects involvement in embryonic and fetal growth regulation

INTRODUCTION

The human yolk sac provides the embryo with stem cells, nutrients, and gas exchange. We hypothesized that more maternal resources, reflected in body size and body composition, would condition a a larger yolk sac, ensuring resources for the growing embryo. Thus, we aimed to determine the relation between maternal size in early pregnancy and yolk sac size.

MATERIAL AND METHODS

This subsidiary study was embedded in the multinational World Health Organization fetal growth project that included healthy women with a body mass index of 18-30, reliable information of their regular last menstrual period and singleton pregnancies. Yolk sac diameter, crown-rump length, and maternal height, weight, body mass index, and body composition were assessed before 13 weeks of gestation, and the fetal biometry was repeated during the pregnancy.

RESULTS

Of 140 participants, 122 with a successful yolk sac measurement were entered in the present analysis. Maternal weight was negatively associated with the yolk sac diameter (P = 0.007) and so was maternal height (P = 0.011), fat mass (P = 0.037), and lean body mass (P = 0.018), but not body mass index (P = 0.121). Significant effects were predominantly due to the female embryos and could be traced at 24 weeks of gestation. That is, a small yolk sac : crown-rump length ratio in early pregnancy was associated with a high fetal abdominal circumference (P < 0.001) and estimated fetal weight (P = 0.001).

CONCLUSIONS

The human yolk sac is involved in the regulation of embryonic growth, but contrary to our hypothesis, the yolk sac has a compensatory capacity, being larger when the mothers are smaller; and the effect can be traced on fetal size at 24 weeks of gestation.

Correlation analysis between ultrasound findings and abnormal karyotypes in the embryos from early pregnancy loss after in vitro fertilization-embryo transfer

PURPOSE

The purpose of the study is to evaluate the correlation between ultrasound findings and abnormal karyotypes in early pregnancy losses (EPLs) after in vitro fertilization-embryo transfer (IVF-ET).

METHODS

This retrospective analysis assessed 2172 cases of EPL after IVF-ET occurring between January 2008 and December 2013. The cases were examined via transvaginal ultrasonography (TVS). Embryonic tissue karyotyping following miscarriage was performed using a comparative genomic hybridization (CGH) analysis with fluorescence in situ hybridization (FISH). The correlations between the ultrasound findings and the karyotypes were evaluated.

RESULTS

Six categories of ultrasound findings were observed: normal ultrasound, empty sac, yolk sac only, small gestational sac, small embryonic pole, and early symmetrical arrested growth. The overall rate of abnormal karyotypes was 44.9 % (976/2172), and the rate of abnormal karyotypes associated with a normal ultrasound, empty sac, yolk sac only, small gestational sac, small embryonic pole, and early symmetrical arrested growth was 49.5 % (218/440), 28.1 % (138/491), 43.4 % (197/454), 50.0 % (43/86), 49.8 % (155/311), and 57.7 % (225/390), respectively. Compared with the other groups, the prevalence of chromosomal abnormalities was significantly higher in the early symmetrical arrested growth group but was markedly lower in the empty sac group in all cases and when cases of 46,XX were excluded (p < 0.05). Trisomy 16 was the most common chromosomal abnormality in the yolk sac only, small embryonic pole and early symmetrical arrested growth groups. In the empty sac, small gestational sac and normal ultrasound groups, monosomy X was the most frequent abnormality.

CONCLUSIONS

Chromosomal anomalies may be associated with specific types of ultrasound findings in EPLs after IVF-ET.