Significance of yolk sac measurements with vaginal sonography in the first trimester in the prediction of pregnancy outcome

Abstract

In the first trimester, when discrepancy is detected between secondary yolk sac diameter and gestational age, additional sonographic investigation should be performed one or two weeks later, in order to estimate the pregnancy outcome.

Triple ultrasound markers including fetal cardiac activity are related to miscarriage risk

“…Although all of these embryonic characteristics have been studied alone, and some reports have ascertained the association of two of these variables with outcomes concomitantly (11,22,(29)(30)(31)(32), we are unaware of any reports that state the association of all three known predictors to pregnancy outcome.…”

Spontaneous regression of a yolk sac associated with embryonic death.

“…The primary yolk sac is not visible with sonography; however, the secondary yolk sac, which forms in the fourth menstrual week, is readily detected in normal pregnancies. [1][2][3][4][5] A normal yolk sac can usually be demonstrated in normal pregnancies when the mean sac diameter is greater than or equal to 8 mm using endovaginal sonography or 20 mm using transabdominal sonography. 1 The yolk sac normally involutes, beginning at 11 weeks' menstrual age, after which it usually is not detectable with sonography.…”

Ultrasonographic signs of poor pregnancy outcome

“…The yolk sac is the first extraembryonic structure that appears and is visible practically in all pregnancies between the 5th and the 12th week [28]. The yolk sac can be observed initially when the diameter of the gestational sac reaches 3.7 mm, in the 36th day from the LMP and is reliably observed when the diameter is from 6.7 mm, in the 40th day of amenorrhoea.…”