Epidemiology

Spontaneous abortion, also known as miscarriage, occurs when a pregnancy ends before the fetus has reached viability. Viability correlates to a fetus larger than 500 g—or approximately the size at 20 to 22 weeks of gestation. Miscarriage is common and occurs in 25% to 30% of all pregnancies. Eighty percent of miscarriages occur before the 12th week of gestation, and up to 25% occur in pregnancies that are not even recognized clinically; in such cases human chorionic gonadotropin (HCG) can be detected in urine but the patient has no missed menses.¹

Approximately 25% of patients will experience some bleeding in the first trimester of pregnancy, with half of these patients proceeding to miscarriage. Risks for spontaneous abortion include advanced maternal age, previous spontaneous abortion, and prolonged time from ovulation to implantation. Other risk factors are smoking, alcohol, cocaine, caffeine, and use of nonsteroidal antiinflammatory drugs.

Presenting Signs and Symptoms

Spontaneous abortion is classified as threatened, inevitable, incomplete, complete, missed, or septic. Table 119.1 lists characteristics of these categories. Symptoms of spontaneous abortion include vaginal bleeding, suprapubic cramping or pain, and passage of tissue. Bleeding can vary from minor spotting to severe hemorrhage.

Table 119.1 Classification of Spontaneous Abortion

Threatened abortion is defined by vaginal bleeding with or without mild suprapubic cramping or pain. It is the most common manifestation of spontaneous abortion seen in the emergency department (ED). Examination shows a closed cervix, uterine size that correlates to gestational age, and bleeding varying from scant to heavy. Ultrasound imaging confirms an intrauterine pregnancy and fetal heart tones in appropriate gestational ages. Threatened abortion may resolve with progression to normal pregnancy, or it may progress to other forms of miscarriage.

Before the 12th week of gestation, most spontaneous abortions will progress to completion with few complications. After this time, patients are more likely to have an incomplete abortion and require medical or operative intervention.

A septic abortion occurs when infection develops during any stage of the abortion process. Implicated agents include Staphylococcus aureus, gram-negative rods, gram-positive cocci, and anaerobes. Risk factors include elective abortion, cytomegalovirus infection, amniocentesis, and incomplete abortion.

Differential Diagnosis and Medical Decision Making

As mentioned previously, bleeding in early pregnancy is common. It may represent benign bleeding from implantation or marginal separation of the placenta. Many cases are idiopathic. Pathologic processes in the differential diagnosis include ectopic pregnancy, gestational trophoblastic disease, cervicitis, subchorionic hemorrhage, and cervical or vaginal malignancy. Vaginal lacerations from intercourse or trauma may be to blame. Occasionally, nongynecologic sources such as rectal bleeding or hematuria are mistaken for vaginal bleeding.

Pregnancy should be confirmed by a positive urine HCG test. A speculum examination should be performed to assess the degree of bleeding and cervical dilation, as well as to inspect for expelled products of conception. Bimanual examination can assess uterine size, cervical opening, and any abnormal masses or tenderness.

Laboratory studies include a complete blood count, quantitative HCG, and blood type with Rh status. With significant bleeding or other medical disease, coagulation parameters and typing and crossmatching for blood products should be ordered. Ultrasonography is essential for a full diagnosis and for guiding further management (Fig. 119.1). Even if it appears that the patient has passed the embryo, she should undergo ultrasound imaging to evaluate for any retained products.

Fig. 119.1 Algorithm for evaluation of vaginal bleeding in a pregnant patient.

D&C, Dilation and curettage; HCG, human chorionic gonadotropin; IUP, intrauterine pregnancy.

Treatment

Many patients with spontaneous abortion often need little or no intervention following accurate diagnosis and exclusion of other pathology. Expectant management is the only option for threatened abortion; education and ensuring adequate follow-up care are essential. The presence of fetal heart tones in women with symptoms of threatened abortion is reassuring; less than 5% of women younger than 36 years will miscarry, but this risk rises to 29% in those older than 40.³

Inevitable abortions may be managed either expectantly or by dilation and curettage. Both methods are generally acceptable. If products of conception are visible in the cervical os, gentle removal with ring forceps may allow the cervix to close and may control the bleeding. A complete abortion requires no further treatment as long as ultrasound scanning confirms that no retained products are present. Any retrieved tissue should be examined for villi, which will have a frondlike appearance.

Incomplete or missed abortions can be managed expectantly as long as shock, fever, or significant ongoing bleeding are absent. The time course for completion of a spontaneous abortion is highly variable, and patients will need education and routine gynecologic care to plan for dilation and curettage if tissue does not pass spontaneously or if the bleeding becomes heavy. Patients should attempt to collect the products of conception for examination and should undergo subsequent ultrasonography to assess whether all products of conception have passed. Studies have proved the safety of this practice.⁴ Approximately 90% of patients with incomplete and 76% of those with missed abortions require no surgical treatment when managed expectantly for 4 weeks. Complications occur in 1%, less than in those managed medically.⁵

Prostaglandins such as misoprostol can effectively induce abortion for pregnancy failure of longer than 12 weeks and may help control bleeding in patients with inevitable or incomplete abortions. The dose of misoprostol is 800 mcg administered vaginally or rectally, but this drug should be given only after consultation with a gynecologist. One large study showed an 84% success rate.⁶ Misoprostol induces spontaneous abortion, so any possibility of a desired viable pregnancy must be excluded.

Surgical management includes dilation and curettage or dilation and evacuation. Indications are listed in Box 119.1. Risks associated with surgical management are small and include uterine perforation, infection, adhesions, and anesthetic complications.

Women with significant hemorrhage or hemodynamic instability should first receive crystalloid volume replacement. If no response is seen or if the bleeding persists, either type-specific or type O-negative blood should be administered. Patients with septic abortions should be given broad-spectrum antibiotics in addition to dilation and curettage.

Next Steps in Care and Follow-Up

Emergency gynecologic consultation is needed for patients with significant hemorrhage or signs of infection. Others may be managed expectantly or with close follow-up as long as adequate outpatient care is ensured. Patients with missed abortions may ultimately need surgical management if they do not spontaneously pass tissue.

Patients should be instructed to contact their physician or return to the ED if heavy bleeding, severe pain, or fever develops. Bleeding should resolve over the course of a few weeks, and menses will generally resume within 6 weeks. Pelvic rest (no vaginal intercourse, tampons, or douching) for 2 weeks is often recommended because of the theoretic risk for infection, although no studies support this risk. Patients are often advised to not become pregnant for 2 to 3 months, but again no studies show worse outcomes if another pregnancy is achieved during this interval.

Psychosocial issues surrounding miscarriage are common, including feelings of guilt and sadness. Reassuring women that most miscarriages are due to genetic abnormalities and are not the result of their actions is essential. Women with substance abuse leading to abortion should be counseled appropriately. Referral for grief counseling may be appropriate. Patients with recurrent miscarriages should be offered referral for fertility treatment and genetics counseling.

Epidemiology

Ectopic pregnancy, in which the developing embryo implants outside the uterine cavity, is responsible for the greatest morbidity and mortality in early pregnancy. The incidence of ectopic pregnancy in the United States has increased over the past 30 years, and it now accounts for 2% of all pregnancies.⁷ This increase has been attributed to rising rates of pelvic inflammatory disease, as well as the advent of assisted reproductive technologies.

At the same time there has been a decrease in the morbidity and mortality associated with ectopic pregnancy because of more widespread use of ultrasound and methotrexate. Despite advances in diagnosis and management, ruptured ectopic pregnancy remains responsible for 10% of pregnancy-related deaths.

Pathophysiology

Risk factors for ectopic pregnancy are outlined in Box 119.3. Tubal pathology, the most significant risk factor, leads to abnormal transport and implantation of the embryo. The majority of cases arise in women with a history of pelvic inflammatory disease, and women with a previous ectopic pregnancy have a 15% recurrence rate. However, up to 50% of patients with an ectopic pregnancy have no identifiable risk factor.⁸

Genetic abnormalities in the embryo have not been found to be a risk factor for abnormal implantation. Although women using an intrauterine device or those who have undergone a sterilization procedure are at decreased overall risk for pregnancy, the incidence of ectopic pregnancy is increased in those who do become pregnant. For example, the pregnancy rate after tubal ligation is 0.1% to 0.8%, but as many as one third of these pregnancies are ectopic.

The most common location for ectopic implantation is the fallopian tube, which accounts for 95% of all ectopic pregnancies. The growing blastocyst leads to tubal distention and bleeding into the peritoneal cavity. If the pregnancy continues and is undetected, it can lead to rupture of the tube with subsequent hemorrhage. Less commonly, ectopic pregnancies implant on the ovary, abdominal viscera, or cervix. In these cases, significant hemorrhage or perforation of abdominal structures may occur. See Figure 119.2 for sites of ectopic implantation.

Fig. 119.2 Sites and rate of occurrence at each site of ectopic implantation.

Presenting Signs and Symptoms

Most ectopic pregnancies are detected 6 to 8 weeks after missed menses, and significant tubal distention and bleeding have usually occurred by that point. Symptoms may mimic the signs of spontaneous abortion. The classic triad consists of abdominal pain, vaginal bleeding, and a missed menstrual period, although these symptoms vary with the stage of the pregnancy. Patients with early ectopic pregnancies may have no abdominal tenderness or vaginal bleeding, and the ectopic implantation may be found only incidentally on ultrasonography.

In contrast, a woman with tubal rupture may display hemodynamic instability and signs of a surgical abdomen. Approximately one half of patients are asymptomatic before tubal rupture. Of those with rupture, 99% have abdominal pain, 74% have amenorrhea, and 56% have vaginal bleeding.