TO ASSESS VALUE OF YOLK SAC IN PREDICTING PREGNANCY OUTCOME DURING FIRST TRIMESTER: OBSERVATIONAL STUDY

Abstract

Objective: To find out normal size and shape of yolk sac in pregnancies between 5-12 weeks of gestation, its association with pregnancy outcome and correlation of various fetal parameters with mean yolk sac diameter.

Method: 95 pregnant women of 20-30 years age group with amenorrhoea 1 month 5 days to 7 days selected randomly for this study from August 2009 to October 2010, underwent TVS fortnightly from 5-11 weeks of gestation and at 12 weeks either of the TVS or TAS to visualize changes in mean yolk sac diameter (MYSD) and yolk sac (YS) shape and pregnancy outcomes. Results analyzed by Z-test and correlation coefficient found out between various parameters.

Results: In Pregnancies with normal outcome (n=72), MYSD was progressively increased from 3.17 mm at 5-5.2 weeks of GA to 5.03 mm at 9-9.2 weeks of GA. At 11 weeks YS either disappeared (73.61%) or MYSD decreased (26.38%) with round & regular shape. Highly significant difference with p value <0.001, was detected between MYSD of pregnancy with normal outcome and missed abortion (n=19). Four cases of missed abortion had irregular shaped YS. In anembryonic pregnancies YS was not seen. Highly significant (p value <0.001)correlation was found between MYSD and GA by LMP (r=+0.740),MYSD and MGSD ( r =+0.739) and significant correlation was detected between MYSD and CRL (r =+0.355), p value <0.005.

Conclusions: Abnormalities of the yolk sac size or shape ,and absence can be used as poor predictive indicators of early pregnancy ,even before fetal morphology can be studied sonographically.