Gestational sac
Updates to Article Attributes
The gestational sac (GS) is the first sign of early pregnancy on ultrasound and can can be seen with endovaginal ultrasound at at approximately 3-5 weeks gestation when themean sac diameter (MSD) would approximately measure 2-3 mm in diameter.
Some suggest that if the beta-hCG level is >1800 mIU/ml (second international standard) a transabdominal ultrasound should be able to identify an intrauterine gestational sac, however, this value is debatable, and beta-hCG levels >2000 (or even >3000) without a visualized intrauterine gestational sac does not rule out an intrauterine pregnancy 4. Treatment should not be initiated on a hemodynamically stable woman on the basis of a single single beta-hCG level 5.
If one cannot identify a yolk sac when the gestational sac is 8mm or an embryo, when the sac is 16mm, the prgnancy is at risk.
A true gestational sac can be distinguished from a pseudogestational sac by noting:
- its normal eccentric location: it is embedded in endometrium, rather than centrally within the uterine cavity
- presence of a yolk sac: seen at approximately 5.5 weeks
- presence of the double decidual sign (most helpful at 4-6.5 weeks)
However, caution should be exercised with a diagnosis of a pseudogestational sac. In a woman with a positive beta-hCG, any intrauterine sac-like fluid collection seen on ultrasound is highly likely to be a gestational sac 3.
A normal gestational sac grows by 1 mm per day.
See also
-<p>The<strong> gestational sac (GS)</strong> is the first sign of <a href="/articles/early-pregnancy">early pregnancy</a> on ultrasound and can be seen with endovaginal ultrasound at approximately 3-5 weeks gestation when the <a href="/articles/mean-sac-diameter">mean sac diameter (MSD</a>) would approximately measure 2-3 mm in diameter.</p><p>Some suggest that if the <a href="/articles/beta-hcg-levels">beta-hCG level</a> is >1800 mIU/ml (second international standard) a transabdominal ultrasound should be able to identify an intrauterine gestational sac, however, this value is debatable, and beta-hCG levels >2000 (or even >3000) without a visualized intrauterine gestational sac does not rule out an intrauterine pregnancy <sup>4</sup>. Treatment should not be initiated on a hemodynamically stable woman on the basis of a single beta-hCG level <sup>5</sup>.</p><p>A true gestational sac can be distinguished from a <a href="/articles/pseudogestational-sac-1">pseudogestational sac</a> by noting:</p><ul>- +<p>The<strong> gestational sac (GS)</strong> is the first sign of <a href="/articles/early-pregnancy">early pregnancy</a> on ultrasound and can be seen with endovaginal ultrasound at approximately 3-5 weeks gestation when the <a href="/articles/mean-sac-diameter">mean sac diameter (MSD</a>) would approximately measure 2-3 mm in diameter.</p><p>Some suggest that if the <a href="/articles/beta-hcg-1">beta-hCG level</a> is >1800 mIU/ml (second international standard) a transabdominal ultrasound should be able to identify an intrauterine gestational sac, however, this value is debatable, and beta-hCG levels >2000 (or even >3000) without a visualized intrauterine gestational sac does not rule out an intrauterine pregnancy <sup>4</sup>. Treatment should not be initiated on a hemodynamically stable woman on the basis of a single beta-hCG level <sup>5</sup>.</p><p>If one cannot identify a yolk sac when the gestational sac is 8mm or an embryo, when the sac is 16mm, the prgnancy is at risk.</p><p>A true gestational sac can be distinguished from a <a href="/articles/pseudogestational-sac-1">pseudogestational sac</a> by noting:</p><ul>
-<li><a href="/articles/eccentric-gestational-sac-1">eccentric gestational sac</a></li>- +<li><a href="/articles/abnormally-eccentric-gestational-sac">eccentric gestational sac</a></li>
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