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Vaginal bleeding occurs in up to 20-40% of women during their pregnancy. Miscarriage (threatened, inevitable, incomplete, complete) is the most common cause of bleeding occurring in 15-20% of pregnancies. Ectopic pregnancy is less common occurring in 2% of pregnancies. Although uncommon, ruptured ectopic pregnancy can be life threatening and should be always considered with vaginal bleeding in a pregnant woman. Other causes of bleeding include cervical, vaginal, or uterine pathology (eg. polyps, inflammation/infection, trophoblastic disease, etc.). In addition, women may have bleeding in early pregnancy from implantation.
Transvaginal pelvic ultrasound is key for the evaluation of women in the first trimester who present with vaginal bleeding. The purpose of this test is to determine if the pregnancy is intrauterine or extrauterine (ectopic) and, if the pregnancy is viable (fetal cardiac activity - typically first detected at 5.5 to 6 weeks) or nonviable.
To define a failed pregnancy, the criteria use are based upon the development of a yolk sac or embryo once the gestational sac has reached ≥25 mm MSD. Other important components evaluated by the ultrasound include:
Patients with threatened miscarriage should be managed expectantly. Close follow up with weekly transvaginal ultrasounds is necessary until a viable pregnancy is confirmed or excluded.
In patients where fetal cardiac activity is present at 7-11 weeks, 90-96% of pregnancies do no miscarry. These cases likely represent a disruption of decidual vessels at the maternal-fetal interface.
If a Rhesus (Rh) D-negative pregnant woman is exposed to fetal D-positive red cells they are at risk for developing anti-D antibodies. If a mother has developed these antibodies from previous pregnancies then their Rh(D) positive fetuses/neonates are at risk of developing hemolytic disease of the fetus and newborn, which can be associated with serious morbidity or mortality.
To prevent Rh(D) alloimmunization, RH positive women are given anti-D immunoglobulin whenever they are at risk of exposing their fetus (eg. vaginal bleeding). Anti-D immunoglobulin is produced from pooled plasma with high titers of IgG antibodies to D-positive erythrocytes.
Multiple small studies including several meta-analyses have looked at the use of progestins to reduce the risk of threatened miscarriage. Initial results appear promising with decreased rates of fetal loss and no signs of congenital anomalies or pregnancy-induced hypertension. However, due to the small amount of data this treatment is not widely in use at this time.
Other medications and herbal treatments have been studied, but have not been shown to be efficacious.
Limiting physical activity and sexual intercourse are often advised for patients with threatened miscarriages. However, randomized trials have found that bed rest at home or inpatient is not beneficial in preventing fetal lose. In addition, there are no studies showing abstinence from sexual intercourse decreases the likelihood of fetal loss. It is unclear if extreme physical activity is a risk factor.
Subchorionic hemorrhages are common findings on transvaginal ultrasound. These hemorrhages are a risk factor for spontaneous abortion (OR 2.18), especially when the hemorrhage is 25% or more of the volume of the gestational sac. They are also a risk factor for placental abruption (OR 5.71) and preterm premature rupture of membranes (OR 1.64). Although emphasis is often put on size, location is likely to be more important (with worse outcomes with retoplacental hematomas)
Management for all subchorionic hematomas is expectant. Bed rest does not appear to decrease the risk of fetal loss. Presence of a hematoma is NOT an indication to begin a workup for thrombophilia.
A single hCG is not definitive for interpretation of the viability of a pregnancy. A widely accepted norm is that a gestational sac should be seen once the hCG has reached 1500 IU/L, however recent studies have shown wide variability in these measures. For instance, even in patients whose hCG reaches 2,000-3,000 mIU/mL, there will be 19 ectopic pregnancies and 38 nonviable pregnancies for every viable pregnancy. However, as many as 2% of women can still have viable pregnancies. Therefore, hCG levels must be used in serial measurements, usually 48 hours apart.
In general (but not always)
