Evaluation of yolk sac size and embryonic heart rate in first trimester and pregnancy outcome


  • Waleed M. Tawfik Department of Obstetrics and Gynecology, Benha University, Benha, Egypt




Yolk sac, First trimester, Pregnancy outcome


Background: Accurate differentiation between normal pregnancy and pregnancy loss in early gestation remains a clinical challenge-previous studies have described the association between embryonic well-beings and the characteristics of gestational sac. The aim of the study was to evaluate the yolk sac size and embryonic heart rate as a prognostic factor for the first trimester pregnancy outcome.

Methods: This was a prospective cohort observesional study. It included 52 pregnant women in their first trimester from 6 week till 12 weeks gestation. Transvaginal sonographic examination after explanation and agreement of each patient. All pregnancies were followed for their pregnancy outcome after completion of 12 weeks. The adverse outcome was spontaneous miscarriage occurring before or at 12 weeks of gestation. These patients allocated into four study groups: according to gestational age at presentation and pregnancy outcome. Group I included women who were examined during (6-7 weeks+6 days). Group II included women who were examined during (8-9 weeks+6 days). Group III included women who were examined during (10-12 weeks). Group IV included women who had their pregnancies resulted into first trimester spontaneous miscarriage.

Results: The validity of YS diameter regarding the prognosis of first trimester pregnancy outcome shows that; YSD had 100% specificity and 97.8% sensitivity in prediction of miscarriage. Regarding embryonic heartbeat, there was a statistically significant difference between group IV and the other groups. There was embryonic bradycardia in the miscarriage group. EHR had a sensitivity of 97.5% and specificity of 100% in prediction of first trimester pregnancy outcome.

Conclusions: Abnormal yolk sac diameter, in the form of small, enlarged, absent or irregular yolk sac, and embryonic bradycardia are associated with poor pregnancy outcome.


Adija P, Selvi C, Rai L and Hebbar S. Evaluation of yolk sac diameter and embryonic heart rate as prognostic factor of gestational outcome in early singleton pregnancies. Scholars J Applied Med Sci. 2015;3(2):543-50.

Beckman DA, Koszalka TR, Jensen M, Brent RL. Experimental manipulation of the rodent visceral yolk sac. Teratology. 1990;41(4):395-404.

Brown S. Miscarriage and its associations. Semin Reprod Med. 2008;26(5):391-400.

Burton GJ. Placental functional morphology. In: Augustin HG, Arispe ML, Rogers PAW, Smith SK, eds. Vascular Morphogenesis in the Female Reproductive System. Switzerland, AG: Springer; 2001: 285-300.

Carp H, Toder V, Aviram A, Daniely M, Mashiach S, Barkai G. Karyotype of the abortus in recurrent miscarriage. Fertil Steril. 2001;75(4):678-82.

Chama CM, Marupa JY, Obed JY. The value of the secondary yolk sac in predicting pregnancy outcome. J Obstet Gynaecol. 2005;25(3):245-7.

Cho FN, Chen SN, Tai MH, Yang TL. The quality and size of yolk sac in early pregnancy loss. Aust N Z J Obstet Gynaecol. 2006;46(5):413-8.

Cho FN, Kan YY, Chen SN, Yang TL, Hsu PH. Very large yolk sac and bicornuate uterus in a live birth. J Chin Med Assoc. 2005;68(11):535-7.

Choong S, Rombauts L, Ugoni A, Meagher S. Ultrasound prediction of risk of spontaneous miscarriage in live embryos from assisted conceptions. Ultrasound Obstet Gynecol. 2003;22(6):571-7.

Coulam CB, Britten S, Soenksen DM. Early (34-56 days from last menstrual period) ultrasonographic measurements in normal pregnancies. Hum Reprod. 1996;11(8):1771-4.

Crowley LV. An introduction to clinical embryology. Chicago: Yearbook Medical; 2019: 91-120.

Daya S. Recurrent spontaneous early pregnancy loss and low dose aspirin. Minerva Ginecol. 2003;55(5):441-9.

Srivastava G, Nagwani M, Pasricha N, tewari V, Siddiqui MS, Sthapak Eti. Size of yolk sac by ultrasonography and its correlation with pregnancy outcome. Int J Anatomy Res, 2016;4(1):2052-7.

Josel L, Latheef NA. Sonographic evaluation of yolk sac. Int J Scientif Eng Res. 2015;6(5):11-5.

Kallen K. Increased risk of perinatal/neonatal death in infants who were smaller than expected at ultrasound fetometry in early pregnancy. Ultrasound Obstet Gynecol. 2004;24(1):30-4.

Oztekin O. First trimester ultrasound: current approaches and practical pitfalls. J Med Ultrason. 2009;36(4):161-75.

Maged AM, Mostafa WA. The first trimester. In: Rumack CM, Wilson SR, Chaboneau JW, eds. Diagnostic ultrasound. 3rd ed. St Louis: Mosby; 2013: 1070-1100.

Oztekin O. First trimester ultrasound: current approaches and practical pitfalls. J Med Ultrason. 2009;36(4):161-75.

Nyberg DA, Hyett J, Johnson JA, Souter V. First-trimester screening. Radiol Clin North Am. 2006;44(6):837-61.

Pedersen JF, Mantoni M. Prevalence and significance of subchorionic hemorrhage in threatened abortion: a sonographic study. AJR Am J Roentgenol. 1990;154(3):535-7.






Original Research Articles