Are Abnormal Yolk Sac Characteristics Important Factors in Abortion Rates?

Background: This study was undertaken to determine if there were different abortionrates between normal and abnormal yolk sacs.Materials and Methods: In this cohort study, the yolk sac characteristics of 193 consecutivepregnant women, of 5-6.5 weeks gestation, with normal body mass index (BMI) were prospectivelyevaluated. All patients underwent two-dimensional transvaginal ultrasonography, whichwas performed by the same sonographer. We considered the following yolk sac characteristicsas normal for classification: diameter: 2-5 mm; round shape; absence of degenerative changes;equal number with embryos; echogenic rim and hypoechoic center. Yolk sacs that had diameterssmaller than 2 mm or larger than 5 mm; a shape that was not round (i.e., oval or distorted);the presence of degenerative changes; hyper- or hypo-echogenic rim; hyperechoic center andunequal number with embryos were considered abnormal. Based on the above classification,patients were divided into two groups, study (abnormal yolk sac) and control (normal yolksac). The study group contained 22 cases and the control group consisted of 164 cases. The primaryoutcome measure was the abortion rate between both groups. Chi-square and students’ttest were used for data analysis.Results: A total of 193 cases were evaluated. We excluded 2 cases. Among the remaining191 cases, 22 (11.51%) had abnormal yolk sacs of which spontaneous abortion occurredin 14 (63.63%) cases. In the control group, out of 169 (89.49%) cases, spontaneous abortionwas noted in 6 (3.55%). There was a statistically significant difference in abortionrates between the two groups (p=0.000).Conclusion: According to the results of this study, it is obvious that abnormal yolk saccharacteristics are associated with spontaneous abortion.