Large yolk sac
Citation, DOI & article data
A large yolk sac is one measuring >5-6 mm in pregnancies between a gestational age of 5-10 weeks. One study had shown that a yolk sac diameter of >5 mm can be associated with an increased risk of spontaneous miscarriage although few other authors have mentioned the existence of a very large yolk sac (e.g. around 8 mm) in a normal live pregnancy 2.
Abnormally large yolk sac may indicate a poor obstetric outcome and close follow-up with sonography is often recommended for these pregnancies.
- indeterminate abnormal yolk sac abnormality that should not be considered alone for the diagnosis of failed early pregnancy
- follow-up ultrasonography at 7-14 days to assess the pregnancy for viability is generally appropriate
- 1. Sinan Tan. Sonographic Evaluation of the Yolk Sac. JUM. 2012;31 (1): 87-95. JUM (full text)
- 2. Cho FN, Chen SN, Tai MH et-al. The quality and size of yolk sac in early pregnancy loss. Aust N Z J Obstet Gynaecol. 2006;46 (5): 413-8. doi:10.1111/j.1479-828X.2006.00627.x - Pubmed citation
- 3. Cepni I, Bese T, Ocal P et-al. Significance of yolk sac measurements with vaginal sonography in the first trimester in the prediction of pregnancy outcome. Acta Obstet Gynecol Scand. 1998;76 (10): 969-72. Pubmed citation
- 4. Küçük T, Duru NK, Yenen MC et-al. Yolk sac size and shape as predictors of poor pregnancy outcome. J Perinat Med. 1999;27 (4): 316-20. doi:10.1515/JPM.1999.045 - Pubmed citation
- 5. Varelas FK, Prapas NM, Liang RI et-al. Yolk sac size and embryonic heart rate as prognostic factors of first trimester pregnancy outcome. Eur. J. Obstet. Gynecol. Reprod. Biol. 2008;138 (1): 10-3. doi:10.1016/j.ejogrb.2007.06.023 - Pubmed citation