Threatened miscarriage-vaginal bleeding before 20 gestational weeks-is the commonest complication in pregnancy, occurring in about a fifth of cases.w1 Miscarriage is 2.6 times as likely, 1 and 17% of cases are expected to present complications later in pregnancy.
2Although general practitioners and gynaecologists often see this condition, management of threatened miscarriage is mostly empirical. Bed rest is routinely recommended, and about a third of women presenting with threatened miscarriage are prescribed drugs. However, two thirds of the general practitioners recommending this do not believe it affects outcome. In this review, we present available evidence on the initial evaluation and management of threatened miscarriage, focusing mainly on the first trimester of pregnancy and primary healthcare settings.
Sources and selectionWe searched literature in English with Medline (January 1965 to April 2004), Embase (January 1980 to April 2004), and the Cochrane database using the keywords "threatened" and "abortion" or "miscarriage" and "pregnancy" and "first trimester" or "early" and "bleeding". We scanned abstracts and got the full text of relevant articles. We also scanned the references of retrieved articles. The more recent or randomised, prospective, or large studies focusing on women with symptoms of threatened miscarriage were primarily cited; we excluded studies on recurrent pregnancy loss or women without symptoms, unless otherwise stated.
EvaluationBleeding in the first trimester can originate from the uterus, cervix, or vagina, or it can be extragenital. Thorough physical examination is essential to differentiate between genital and extragenital causes. After exclusion of extragenital causes, several parameters have been associated with prognosis (table 1).
HistoryOlder women are at increased risk of miscarriage in the general population.w3 A prospective study on women with threatened abortion reported that women older than 34 years had an odds ratio of 2.3 for miscarriage, however, the 95% confidence interval was wide (0.76 to 7.10), and the contribution of maternal age in regression analysis was not significant (P = 0.13). 4 Having had previous miscarriages is also associated with increased risk in future pregnancies, especially in older women, w4 whereas data from the general population show that the rate of fetal loss declines with advancing gestational age.