Do ultrasounds misdiagnose viable pregnancies as miscarriages?

Early ultrasounds have been used to detect pregnancy viability for the last 20 years.  Now shocking research published by Jeve et al. suggests many pregnancies diagnosed as miscarriages using ultrasonography may be misdiagnosed- leading to the early termination of wanted, viable pregnancies.

When miscarriage is suspected, current practice involves an early ultrasound.  Several measurements are used to diagnose miscarriage, which Jeve et al. argue are outdated.  The size of the gestational sac, embryo crown to rump length and cardiac activity are all measured by an initial and a follow up ultrasound (within 7-10 days).  However, variability in measurements and imprecision of instrumentation/ sonographers can lead to misdiagnosis.

The researchers found that even the most precise measurements: empty gestational sac with a diameter larger than 25 mm and absent yolk sac with mean gestational sac diameter ≥ 20 mm, may misdiagnose miscarriage in 4 out of every 100 cases.

The only conclusive criterion to diagnose miscarriage is the spontaneous expulsion of pregnancy tissue.  The researchers highlight the need for the development of new standards of miscarriage diagnosis by ultrasound in early pregnancy.  A zero false positive rate should be the goal.

Treatments for women with recurrent miscarriages

Up to 15% of women with recurrent miscarriages have been found to have antiphospholipid syndrome (APS or aPL).  Women with APS may also experience later fetal loss, pre-eclampsia and placental insufficiency.  Pregnant women are prescribed low dose aspirin or combination aspirin/heparin, but up to 30% still experience recurring miscarriages.

Now Bramham et al. show that 10 mg daily prednisone in addition to aspirin/heparin from 4-14 weeks gestation can prevent early pregnancy loss in women with APS who do not respond to aspirin/heparin combination alone.  Prior to prednisone treatment, only 4% of pregnancies resulted in live births in these women.  After the addition of prednisone, up to 61% of their pregnancies resulted in live births.

This is in contrast to earlier randomized controlled trials which showed no additional benefit of prednisone when applied to aspirin treatment (Cowchock et al., Empson et al.).  Caution should be taken when considering this treatment, as prednisone is associated with an increased risk of prematurity, gestational diabetes, infection and hypertension (Laskin et al.).  Furthermore, prednisone did not prevent APS-associated pre-eclampsia, placental insufficiency or pre-term delivery.  However, a prednisone/aspirin/heparin treatment regime may be a viable option for women experiencing APS-associated miscarriages that are not prevented by aspirin/heparin treatment alone.