Early pregnancy ultrasound measurements and prediction of first trimester pregnancy loss: A logistic model

Abstract

Our objective was to prospectively validate the use of gestational sac (GS), yolk sac (YS) diameter, crown-rump length (CRL), and embryonal heart rate (HR) dimensions to identify early pregnancy loss. This was a prospective cohort study of first trimester pregnancies. GS and YS diameter, CRL, and HR measurements were serially obtained in singleton and twin pregnancies from 6 through 10 weeks' gestation. Non-parametric tests and logistic regression models were used for comparisons of distributions and testing of associations. A total of 252 patients were included, of which 199 were singleton pregnancies, 51 were twins, and 2 were triplets (304 total fetuses). Fifty-two patients had 61 losses. We built nomograms with the changes of the parameters evaluated in ongoing, as well as in pregnancy loss. In the pregnancies which failed, all the parameters showed significant changes, with different temporal onsets: GS and YS were the first to become abnormal, deviating from normality as early as 6 weeks' gestation (OR 0.01, 95% CI 0.0-0.09, and OR 3.36, 95% CI 1.53-7.34, respectively), followed by changes in HR, and CRL, which became evident at 7 and 8 weeks (OR 0.96, 95% CI 0.92-1.0, and OR 0.59, 95% CI 0.48-0.73, respectively). Our observations showed that, after 5 complete weeks' gestation, a small GS and a large YS reliably predicted pregnancy loss. The YS reliably identified the occurrence of a miscarriage at least 7 days prior its occurrence. CRL and HR became abnormal at a later time in pregnancy and closer to the event. These findings have important implications for patient counseling and care planning, as well as a potential bearing on cost effectiveness within early pregnancy care.

Figure 1

Correct cursor position for the measurement of the parameters under investigation: (A) Gestational sac (GS); (B). Yolk sac (YS); (C). Crown-rump length (CRL); (D). Heart Rate (HR). E = Embryo.

Figure 2

Median measurements of the parameters under investigation in the two groups, pregnancy loss and continuing pregnancy, plotted against the gestational age: (A). Gestational sac (GS); (B). Yolk sac (YS); (C). Crown-rump length (CRL); (D). Heart Rate (HR).

Figure 3

(A) Ultrasound and hysteroscopic images of the yolk sac in a partial mole pregnancy (Karyotype: 69, XXY at microarray analysis). (A) Ultrasound picture showing an enlarged yolk sac at 6 weeks and 1 day of gestation; (B). Ultrasound picture showing an enlarged yolk sac at 8 weeks and 2 days of gestation; (C). Hysteroscopic view of the yolk sac at the time of pregnancy evacuation at 8 weeks and 2 days of gestation, after embryonal demise. (D) A portion of the yolk sac can be noted just outside of the amniotic sac, with the embryo within it, in the background. GS = gestational sac; YS = yolk sac.