Threatened abortion is the most common variety of abortion encountered. Any woman with early pregnancy bleeding who has a closed cervix and has an apparently viable intrauterine pregnancy is given this diagnosis. One does not know what will happen for sure, and the diagnosis of a “normal pregnancy” is only made retrospectively in these cases, but most of these women will maintain
their pregnancy. If the fetus is visible on ultrasound and is appropriately grown with a heart rate over 100 beats per minute (bpm), the chance the pregnancy will miscarry is <10%. When a patient complains of cramping, the risk of miscarriage is somewhat increased, but many of these pregnancies end well. The acute loss of early-pregnancy nausea (morning sickness) may be more ominous, but when that change is related to a miscarriage, the fetus has usually already died.

When the diagnosis of a threatened abortion is made, women are usually counseled to limit their physical activity and avoid sexual activity. While this may seem logical, there is no scientific evidence that any particular behavior on the woman’s part will hasten or prevent a miscarriage. Consequently, the patient must understand that these interventions are merely traditional recommendations. Helping the patient understand the lack of benefit of “bed rest” is important because when strict limitations are placed on activity, yet the patient is noncompliant and miscarries, she may be burdened with guilt thinking, “If only I had stayed in bed like I was told…” In truth, if a miscarriage is going to happen, there is nothing available to change that fact.

One question that does come up with early bleeding is whether Rh-negative women need prophylactic Rh immunoglobulin. Rh antigens appear on fetal red cells as early as 38 days of gestation, so sensitization is possible. Because fetomaternal hemorrhage has been documented as early as 7 weeks of gestation, some authorities have advocated the administration of a standard dose of Rh immunoglobulin (300 µg) to Rh-negative women with first trimester bleeding. Nonetheless, the incidence of Rh D alloimmunization related to threatened abortion is exceedingly small. Consequently, the American College of Obstetricians and Gynecologists (ACOG) have not taken a formal stand on this, and many practitioners do not offer any anti-D immune globulin to women with threatened abortions and live fetuses prior to 12 weeks of gestation (2). If one prefers to give prophylaxis, a 50-µg “minidose” of Rh immunoglobulin is sufficient. After 12 weeks’, all at-risk women should be given the full 300-µg dose of Rh immunoglobulin.

The diagnosis of “missed abortion” is made when ultrasound confirms the presence of a nonviable intrauterine pregnancy but the cervix is closed. This condition may be seen with an early fetal demise, with an obvious fetus on the ultrasound, or when there is no identifiable fetus. This latter case, which represents either an embryonic demise or failure of the embryo to form, is referred to as an “anembryonic gestation” and was formerly referred to as a “blighted ovum.” Before the advent of ultrasound, this diagnosis was made when the uterus failed to grow in size over an 8-week period (3). The historical concept was that the uterus had not miscarried but had “missed” the fetal demise. When a missed abortion is diagnosed, women generally have three options (4). The first option is to manage the condition expectantly, commonly referred to as “letting nature take its course.” This option is appealing to women who wish to manage the loss as naturally and “nonmedically” as possible. It is a reasonable option, particularly with first trimester losses. As the gestational age of the loss increases, the risk of disseminated intravascular coagulation increases, but this is not seen in the first trimester. The main disadvantage of this option is that a miscarriage may be more painful and involve more bleeding than a woman is comfortable with, and the timing of the event is uncertain. The second option would be a medical augmentation. Most commonly, misoprostol is prescribed for first trimester pregnancy failure. Misoprostol is a synthetic prostaglandin E1 analogue, which has been marketed for the treatment of gastric ulcers. It has been used by itself or in conjunction with other medications for a wide range of off-label indications in obstetrics including medical termination of pregnancy, management of
early and late pregnancy loss, induction of labor, and cervical ripening at term. A number of regimens have been used for the completion of a missed abortion, such as misoprostol 600 to 800 µg intravaginally with a repeat dose given in 24° if the miscarriage had not occurred (5,6). ACOG recently recommended either 800 µg vaginally or 600 µg sublingually with the option of repeating the dose every 3° for two additional doses (7). The author’s institution currently uses the 800-µg dose with a 24° repeat option. These methods carry an 80% to 90% success rate. The issues with pain and bleeding at home remain with this method, but the timing is more predictable for the patient. Failures of this medical method at 48° from the first dose are usually treated with a suction curettage. The dilation with suction curettage is also available as the third option. It carries a small risk of uterine perforation with potential bowel or bladder damage, but it is rare. Some patients feel this risk is balanced by the opportunity to avoid the discomfort, bleeding, and uncertain timing of a miscarriage. Misoprostol is often used to prepare the cervix preoperatively before suction curettage (e.g., misoprostol 400 µg 4° prior to the procedure). Any of the three options are reasonable in the first trimester, and women who choose a less invasive option can always later opt for a more invasive option. Once she is out of the first trimester, home medical management is generally not offered, and the choices are limited to expectant management, dilation and evacuation with suction or induction of labor in the hospital. If expectant management is chosen after the first trimester, platelet counts and fibrinogen should be measured weekly, especially as the gestational age of the loss approaches 20 weeks’, as the risk of disseminated intravascular coagulation begins to increase at that gestational age.

This diagnosis is made in the first trimester when the cervix is dilated or some of the products of conception (e.g., membranes, fetus, placenta) are visible at the dilated cervix. Once this diagnosis is made, there is no hope for retention of the pregnancy regardless of whether there is fetal heart activity or not. Women essentially have the same three options they have for a missed abortion, although less is published on the use of misoprostol for inevitable abortion. In some cases, the miscarriage may be completed simply by grasping the protruding products of conception with ring forceps and gently teasing them out of the uterus. The ring forceps may even be maneuvered into the uterine cavity blindly, though ultrasound guidance is preferred. In many cases though, suction curettage will be necessary. The use of a small uterine curette to gently scrape the sides of the endometrial cavity to confirm all the tissue has been removed is common; however, one must be very careful not to scrape too aggressively, because this may lead to Asherman syndrome. When the endometrium is scraped off by too aggressive a curettage, the anterior and posterior uterine walls may scar together, resulting in a small cavity and future infertility. The suction curettage may be performed in the operating room under IV sedation or deeper anesthesia, but in many emergency rooms, it is performed in the emergency department using IV sedation ± paracervical block.

Incomplete abortion is diagnosed when a portion of the products of conception have been passed but there are still some retained. In this case, the patient may report that she has passed tissue (although sometimes blood clots are mistaken for tissue), and in some instances, she will have brought it in. Ultrasound is the primary means of determining whether all the tissue has passed or not. Misoprostol has also been used to complete an incomplete abortion with the best evidence suggesting a single dose of 600 µg (8). This dose has also been recommended by ACOG (7). However, in common practice in the United States,
the most frequent choice is to proceed with a suction curettage. As noted above, the suction curettage is often performed in the emergency department under IV sedation, and the patient is able to go home shortly thereafter.

This final type of abortion refers to a miscarriage that has been completed with all tissue passed. This is a frequent outcome up to about 6 weeks of gestation but less common afterwards. Women will notice a dramatic and relatively acute reduction in both cramping and bleeding when the abortion is complete. Once again, ultrasound is the primary means of confirming that all of the products of conception have been expelled from the endometrial cavity.

After a pregnancy loss, it is important that women receive follow-up care. After the patient completes her miscarriage, she should be vigilant for evidence of infection or increased bleeding. Some physicians follow β-hCGs after the use of misoprostol to complete a miscarriage to provide additional reassurance that all of the products of conception have been passed. It is also reasonable to send the products of conception for pathologic examination to rule out gestational trophoblastic disease (GTD). Rh-negative patients should be given Rh immunoglobulin 300 µg for prophylaxis within 72° of their miscarriage if they are past 12 weeks’ gestation. Prior to 12 weeks, while it is not clear that it is necessary, many practitioners give prophylaxis to be safe, and some use the 50-µg dose. The only exception to this is when the father of the pregnancy is known and is known to be Rh negative himself. Published estimates of mistaken paternity range widely (0.8% to 30%; median 3.7%), and inquiring about the chance of mistaken paternity can be quite sensitive (9). Consequently, given the risk of Rh sensitization is 2% to 4% after 12 weeks, prophylaxis is sometimes given as a matter of course without even testing the presumptive father.

Normally, women are seen for follow-up by their obstetrician, midwife or potentially in an emergency department follow-up clinic about 2 weeks after their miscarriage has completed.