Hyperemesis gravidarum: is an ultrasound scan necessary?

BACKGROUND: Traditionally, in cases of hyperemesis gravidarum (HG), an ultrasound evaluation is recommended to confirm viability and to exclude multiple pregnancies and gestational trophoblastic disease (GTD). Our aim was to perform a case-control study to evaluate the incidence of these findings. METHODS: Each case of HG was matched for gestational age with the next ultrasound examination performed in an asymptomatic pregnancy. The findings were compared between the two groups. RESULTS: Two hundred and eighty-six cases of HG were matched with 286 asymptomatic women. The total number of viable pregnancies was higher in the HG group (280/286, 97.9%) than that in the control group (265/286, 92.6%; P = 0.006). The incidence of twins was 3.1% in each group (P > 0.999). The incidence of early pregnancy failure was 0.7% in women with HG compared to 7.0% in asymptomatic women (odds ratio 0.09, 95% CI 0.01-0.04, P < 0.0001). The one case of GTD was in the HG group; however, this case also presented with vaginal bleeding. CONCLUSIONS: Pregnancies complicated by HG had a similar risk of twin pregnancy, and a lower risk of early pregnancy failure compared to controls. In the absence of vaginal bleeding, there was no increase in GTD in women with HG. We conclude that an ultrasound scan is not clinically necessary in women presenting with HG, other than for maternal reassurance.