Approximately 30% to 40% of all pregnancies are associated with some vaginal bleeding, and approximately half of these are spontaneously aborted.
- Threatened abortion: any vaginal bleeding during the first half of pregnancy, cervix closed.
- Missed abortion: fetal death with retention of products of conception (POC), cervix closed.
- Inevitable abortion: cervical dilation with or without ruptured membranes.
- Incomplete abortion: partial passage of POC, cervix open.
- Complete abortion: expulsion of all POC from the uterine cavity, cervix closed.
Presentation and clinical features.
Classically, patients present with vaginal bleeding and crampy midline lower abdominal pain. Bleeding from the urethra or rectum or from lacerations of the cervix or vagina should be excluded. Passage of tissue may represent a complete or incomplete abortion.
Vital signs are within normal ranges unless extensive vaginal bleeding or septic abortion occurs with resultant tachycardia and hypotension. Septic abortions can cause elevated temperatures, marked suprapubic tenderness, or purulent discharge through the cervical os.
Hgb and Hct. Plasma volume expansion in pregnancy may result in a lower mean Hgb during the second trimester. With acute blood loss, the Hgb and Hct can be normal until compensatory mechanisms restore normal plasma volume.
White blood cell (WBC) count with differential is useful to evaluate febrile morbidity. Septic abortion is associated with a left shift and an elevated WBC count.
Blood type and screen are essential to identify Rh-negative patients at risk for isoimmunization. Any woman with pregnancy-related vaginal bleeding who is Rh-negative should be given Rho immune globulin (RhoGAM) if she has not received it within the last 12 weeks (see Section I.A.6.g).
Quantitative β subunit of human chorionic gonadotropin (hCG). The sensitivity of a pregnancy test (urine or serum) can vary depending on the type of test performed (i.e., latex agglutination, enzyme-linked immunosorbent assays,radioimmunoassay). A urine pregnancy test gives a rapid qualitative result, although the sensitivity is variable. Serum pregnancy tests are more sensitive and yield a quantitative level of hCG that assists in evaluating the status of a pregnancy. Serial serum hCG values may be used along with ultrasonography to distinguish an early viable pregnancy from an abnormal pregnancy. In most normal intrauterine pregnancies (IUPs) near 6 weeks’ gestation, hCG increases by at least 66% every 48 hours (ACOG Practice Bulletin 3. In: Compendium of Selected Publications. Washington, DC: American College of Obstetrics and Gynecology; 2007:883). Patients with stable clinical examinations can be followed with serial hCG values until they reach the sonographic threshold values at which ultrasound visualization of an IUP is possible (see Section I.A.5).
Progesterone levels in excess of 15 ng/mL usually are associated with a normal IUP. Below this range, pregnancy is likely abnormal.
Ultrasonography may be useful in demonstrating a viable pregnancy. Vaginal probe ultrasonography should demonstrate an intrauterine gestational sac (if it exists) at hCG levels greater than 1,500 to 2,000 mIU/mL. For abdominal ultrasonography, the threshold is greater than 6,000 mIU/mL. Cardiac activity can be seen at 10,000 mIU/mL.
Threatened abortion. Patients with a pregnancy that is viable or of indeterminate viability, vaginal bleeding, and a closed internal cervical os are followed expectantly with either a repeat ultrasound in 7 days, repeat hCG in 48 hours, or both. A normal IUP should show at least a 66% increase in hCG level every 48 hours.
Missed abortion. Patients may be followed expectantly or undergo evacuation. If they are followed expectantly, weekly coagulation studies [i.e., complete blood cell (CBC) count, prothrombin time, partial thromboplastin time, fibrinogen, and fibrin degradation products] should be monitored because of the risk of disseminated intravascular coagulopathy (DIC). Patients should be counseled to bring any tissue passed back to the hospital for pathologic verification. If the patient has not passed the tissue within 3 weeks, evacuation should be scheduled.
For inevitable abortion, the uterus usually begins to contract, resulting in expulsion of products. Patients occasionally are followed expectantly with monitoring for infection but typically undergo uterine evacuation. If fever develops, intravenous antibiotics with polymicrobial coverage are administered, followed by evacuation of the uterus. These patients require admission and careful monitoring of coagulation factors because they are at risk of DIC.
For incomplete abortion, bleeding, cramping, and an open internal os usually are found. Uterine evacuation is indicated. If POC are not recovered, ectopic pregnancy should be considered.
For complete abortion, all POC have been expelled, and the cervix is closed. Bleeding and cramping are minimal. Only short-term observation is necessary.
Evacuation of the uterus. Suction curettage is done safely in the first trimester and can be performed in the emergency room if significant cervical dilation exists. A stable patient with a first-trimester missed abortion can undergo dilation and curettage (D & C) as an outpatient. In the second trimester, a dilation and evacuation or medical induction of labor under gynecologic consultation is performed. After curettage, prophylactic antibiotics (doxycycline, 100 mg orally two times a day for 7 days), ergot alkaloids (methylergonovine maleate, 0.2 mg orally three times a day for 2 to 3 days) for uterine contraction, and antiprostaglandins (ibuprofen, 800 mg orally every 8 hours as needed for pain) commonly are prescribed. If heavy vaginal bleeding, abdominal pain, or fever occurs after evacuation, investigation for retained POC, uterine perforation, and endometritis is warranted.
Rho immune globulin is given to any pregnant patient with vaginal bleeding who is Rh negative and has a negative antibody screen. The recommended dose of RhoGAM is 300 µg intramuscularly after the first trimester. Forfirst-trimester events, 50 µg intramuscularly is sufficient (ACOG Practice Bulletin 4. In: Compendium of Selected Publications. Washington, DC: American College of Obstetrics and Gynecology; 2007:475).