In the vast majority of cases, threatened abortion does not result in a pregnancy loss, but may be associated with poor outcomes later in pregnancy. In a study of 347 patients with a first-trimester pregnancy documented by ultrasonography, the overall rate of pregnancy loss was 6.1% to 4.2% in patients without bleeding and 12.4% in patients with bleeding (4). In a review of over 800 women presenting with first trimester vaginal bleeding or abdominal pain, nearly 14% with bleeding had spontaneous abortion compared with 2.5% in patients without bleeding (5). There is no effective therapy for a threatened intrauterine pregnancy. Bed rest and progesterone treatment, although often advocated, are not effective (16–18). Women with first trimester vaginal bleeding who do go on to have continuing pregnancies have nearly three times the risk of preterm birth between 28 and 31 weeks as women without bleeding, and a 50% higher likelihood of preterm birth between 32 to 36 weeks (19). First trimester bleeding may predict higher risk for intrauterine growth restriction, preterm premature rupture of membranes, and placental abruption (20). Bacterial vaginosis, if present, should be treated, as this is associated with increased risk for spontaneous abortion (21).
Inevitable Abortion With an inevitable abortion, the volume of bleeding is often greater than with other types of abortion, and the cervical os is open and effaced, but no tissue has passed. Most patients have crampy lower abdominal pain, and some have cervical motion or adnexal tenderness. When it is certain that the pregnancy is not viable because the cervical os is dilated or excessive bleeding is present, the patient should be offered medical or surgical management. Blood type and Rh determination and a complete blood count should be obtained if there is any concern about the amount of bleeding. Rh0(D) immune globulin (RhoGAM) should be given if the patient’s blood is Rh negative (22). It is acceptable to give a dose of 50 μg until 12 completed weeks; if this dose is not available, the standard 300 μg dose may be given.
Incomplete Abortion An incomplete abortion is a partial expulsion of the pregnancy tissue. Although most patients have vaginal bleeding, only some have passed tissue. Lower abdominal cramping is invariably present, and the pain may be described as resembling labor. On physical examination, the cervix is dilated and effaced, and bleeding is present. Often, clots are admixed with products of conception. If the bleeding is profuse, the patient should be examined promptly for tissue protruding from the cervical os; removal of this tissue with a ring forceps may reduce the bleeding. A vasovagal bradycardia may occur and responds to removal of the tissue. A complete blood count, maternal blood type, and Rh determination should be obtained; Rh-negative patients should receive RhoGAM. If the patient is febrile, broad-spectrum antibiotic therapy should be administered.
Management of Spontaneous Abortion
In women with stable vital signs and mild vaginal bleeding, three management options exist: expectant management, medical treatment, and suction curettage. Despite a wide range (25% to 76%) of success cited in the literature, expectant management may remain a desirable option for a stable and carefully counseled patient (23,24). Medical management with 800 μgof misoprostol placed vaginally can be up to 84% effective in achieving complete abortion (25). For incomplete abortion, the misoprostol dose can be reduced to 600 μg orally or 400 μg sublingually, with efficacy greater than 90% (26). Suction curettage should be performed in women with excessive bleeding, unstable vital signs, or in whom reliable follow-up is a concern.