Obstetric outcome after threatened miscarriage with and without a hematoma on ultrasound

To examine the effect of threatened miscarriage on second-trimester maternal serum alpha-fetoprotein (MSAFP) levels and pregnancy outcome; and to study the significance of ultrasound evidence of an intrauterine hematoma on pregnancy outcome in these patients.

A retrospective, case-control study was performed on 144 women presenting with bleeding in the first trimester and 144 age-matched control subjects who attended for routine dating scans during the same time scale. The presence or absence of an intrauterine hematoma, MSAFP, and pregnancy outcomes were recorded.

The incidence of adverse pregnancy outcome was significantly (P=.02) higher in women with a history of first-trimester threatened miscarriage than in the control group. The relative risk (RR) of an adverse pregnancy outcome for the study group was 2.22 (95% confidence interval [CI] 1.12, 4.39) compared with the control group. The RR of delivering a baby of less than 1000 g was 4.43 (95% CI 0.5, 39.2) in women with first-trimester threatened miscarriage. This was independent of the presence of an intrauterine hematoma. The RR of MSAFP being raised to more than 2.5 multiples of the median (MoM) in the study group was 6.25 (95% CI 0.77, 50.6). There was no difference between women with threatened miscarriage who had or did not have ultrasound evidence of an intrauterine hematoma.

Threatened miscarriage in the first trimester is associated with an increased incidence of adverse pregnancy outcome, independently of the presence of an intrauterine hematoma. Higher MSAFP in threatened miscarriage suggests a direct placental injury even in the absence of a hematoma.