AUTHOR AND EDITOR INFORMATION

Section 1 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

INTRODUCTION

Section 2 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Background

Threatened abortion is a clinically descriptive term that applies to women who are at less than 20 weeks' gestation, have vaginal spotting or bleeding, a closed cervical os, and, possibly, mild uterine cramping.

Pathophysiology

Threatened abortions may progress to inevitable, spontaneous, incomplete, or complete abortions.

Threatened abortion

Vaginal spotting or frank bleeding is very common and is experienced in approximately 25% of clinically apparent pregnancies at less than 20 weeks' gestational age. The bleeding and pain that accompany threatened abortion are not usually intense. Threatened abortion rarely manifests with severe vaginal bleeding. Often, the bleeding is temporary and self-limited and possibly due to trophoblastic implantation within the decidualized endometrium.

Approximately half the women with threatened abortions abort, and the remainder continue to have viable pregnancies. Approximately 15% of clinically recognized pregnancies spontaneously abort, and 75% of the losses occur in the first 8 weeks of gestation. The loss rate is estimated to be 2-3 times higher with very early and, often, clinically unrecognized pregnancies.

Threatened abortion is defined by the absence of passing/passed tissue and the presence of a closed cervical os. These findings in the setting of a known or presumed viable pregnancy differentiate threatened abortion from later stages of abortion.

Inevitable abortion

Vaginal bleeding is accompanied by dilatation of the cervical canal, no passage of fetal tissue, and, occasionally, gross rupture of the membranes. Bleeding is usually more severe than with threatened abortion and is often associated with abdominal pain.

Incomplete abortion

Vaginal bleeding is usually heavy and accompanied by abdominal pain. The cervical os is open, with passage of only part of the products of conception. Incomplete abortion is more likely to occur at 6-14 weeks of pregnancy. Some products of conception are still present in the uterus; these typically appear as echogenic material on ultrasonography.

Complete abortion

Patients usually present with a history of bleeding, abdominal pain, and passing of tissue. By the time miscarriage is complete, bleeding and pain have usually subsided and the cervix is closed. Diagnosis may be confirmed by observation of the aborted fetus with the complete placenta. Ultrasonography reveals a vacant uterus with close apposition of relatively thin and regular endometrial interfaces.

Frequency

United States

The World Health Organization estimates that 15% of all clinically recognizable pregnancies end in spontaneous abortion.

Mortality/Morbidity

Surveillance data from 1987-1990 reveal a total of 1459 pregnancy-related deaths in the United States. Spontaneous and induced abortions account for 5.6% of these deaths.

CLINICAL

Section 3 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

History

Any woman of reproductive age with abnormal vaginal bleeding should be considered pregnant until proven otherwise.

• Obtain a careful history, including the following:
• • Menstrual history: Deviations from the normal menstrual period may reflect bleeding from implantation of a normal or abnormal pregnancy, which can make accurate dating difficult.
    • First date of the last menstrual period (LMP)
    • Previous menstrual period
    • Usual menstrual interval
    • Regularity of menses
  • Date of conception, if known
  • Medication use since LMP; alcohol, tobacco, and recreational drug use
  • Current and past medical problems such as diabetes mellitus, recent infections, bleeding diathesis, thyroid disease, or autoimmune disorders
  • Surgical history, particularly operations involving the uterus and adnexa
  • Past obstetric history
    • Number of term and preterm deliveries
    • Number of spontaneous and induced abortions
    • Number of living children and major complications associated with deliveries or abortions (eg, blood transfusions, perforated uterus)
  • Gynecologic history, including abnormal Papanicolaou test (Pap smear) results, sexually transmitted diseases, and contraception
  • Include screening questions regarding sexual abuse or domestic violence.
• Patients with spontaneous abortion usually present with vaginal bleeding and/or abdominal pain.
• Vaginal bleeding may vary from slight spotting to significant hemorrhage. Quantifying the amount of bleeding (number of soaked pads or tampons per hour) is very important, as is noting whether the bleeding is improving or worsening.
• Bleeding from threatened abortions frequently is slight, but it may persist for days or weeks.
• The presence of blood clots or tissue may be an important sign of progression of spontaneous abortion.
• Associated pain or cramping should be recorded, including the location, severity, and duration of pain.
• Other symptoms such as fever or chills are more characteristic of a septic abortion.

Physical

Make an immediate assessment of patients who are hemodynamically unstable or experiencing severe vaginal bleeding, including orthostatic vital signs and abdominal and pelvic examination. If orthostatic hypotension is present, initiate intravenous fluid resuscitation and blood cross-match.

• Examine the abdomen, with particular attention to tenderness, bloating, or peritoneal signs suggestive of intraperitoneal hemorrhage.
• Identify the source of bleeding by means of a visual speculum and digital pelvic examination of the cervix. Determine whether the bleeding originates from the vaginal walls, the surface of the cervix, or through the cervical os.
• Determine the intensity of bleeding, examining for the presence of blood clots or tissue fragments.
• Examine for cervical motion tenderness because this finding increases the possibility of ectopic pregnancy.
• Determine the status of the cervical os. If open, it indicates an inevitable or incomplete abortion; if closed, it is a threatened abortion.
• Examine for uterine size, consistency, and tenderness and for the presence of adnexal tenderness or masses. If a mass is suggested, palpation should be gentle because iatrogenic rupture of an ectopic pregnancy or an ovarian cyst is possible.
• If the vaginal or cervical discharge appears abnormal, a wet preparation and cervical cultures (or other testing) for gonorrheal and chlamydial organisms should be performed.

Causes

• Embryonic abnormalities account for approximately 80% of first-trimester abortions.
• • Chromosomal abnormalities are the most common cause of spontaneous abortion. Autosomal trisomies account for more than half of the abnormal karyotypes (due to nondisjunction or translocation), and monosomy is the next most common anomaly.
  • More than 90% of cytogenic and morphologic errors are eliminated through spontaneous miscarriages.
  • Chromosomal abnormalities are found in more than 75% of fetuses aborted in the first trimester.
  • The rate of chromosomal abnormalities increases with maternal age. In women younger than 30 years, the rate of miscarriage is approximately 12%; thereafter, the rate increases rapidly, exceeding 50% in women older than 45 years.
• Maternal factors account for the majority of second-trimester abortions.
• • Chronic maternal health factors
    • Maternal insulin-dependent diabetes mellitus: Up to 30% of pregnancies in patients with poorly controlled diabetes mellitus result in spontaneous abortion.
    • Severe hypertension
    • Renal disease
    • Antiphospholipid syndrome and other thrombophilias
    • Systemic lupus erythematosus
    • Thyroid disease
    • Wilson disease
  • Acute maternal health factors
    • Infections (eg, cytomegalovirus, rubella, toxoplasmosis, Listeria, Ureaplasma, Mycoplasma, and syphilis)
    • Trauma
  • Abnormalities of the reproductive system
    • Congenital (eg, septate uterus) or acquired defects (eg, uterine synechiae)
    • Fibroids
    • Cervical incompetence
    • Abnormal placental development
  • Exogenous factors
    • Alcohol
    • Tobacco
    • Cocaine
    • Radiation
    • Caffeine: Although some studies suggest that drinking excess coffee (more than 4 cups per day) appears to slightly increase the risk of abortion, evidence is not conclusive.

DIFFERENTIALS

Section 4 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Other Problems to be Considered

Foreign body

WORKUP

Section 5 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Lab Studies

• Beta-human chorionic gonadotropin
• • The test for serum human chorionic gonadotropin can be both qualitative and quantitative.
  • It is first detectable in the plasma as early as 8 days following ovulation (which, in most women, is approximately 22-24 d after the last menstrual period). This is around the time of implantation.
  • When the quantitative human chorionic gonadotropin (QhCG) measurement is greater than approximately 1500 mIU/mL international reference preparation (IRP), a normal intrauterine pregnancy should be visualized on transvaginal sonography (TVS) images. This discriminatory number, the value of QhCG for which a normal intrauterine pregnancy should be seen, is 6500 mIU/mL IRP for transabdominal sonogram. Failure to detect an intrauterine gestational sac when the QhCG value exceeds the discriminatory level indicates a risk of ectopic pregnancy.
  • Even if results are not readily available, a QhCG level should generally be determined in cases of first-trimester bleeding because serial QhCGs values can be helpful in follow-up care.
  • Traditionally, the QhCG level is believed to generally rise by at least 66% every 48 hours in a viable intrauterine pregnancy. However, recent studies have shown that the rise of hCG levels may be even more gradual than that in some early viable pregnancies. Thus, be aware of the normal trends in these values, yet be cautious and try to avoid aggressive intervention based on serum hCG levels alone.
  • Serial QhCG values that level off or fall before 10 weeks' gestation usually indicate an abnormal pregnancy. This should also raise suspicion of a possible ectopic pregnancy.
  • An abnormally high QhCG level may indicate multiple gestation, gestational trophoblastic disease, or, very rarely, ovarian tumor.
• Hemoglobin and hematocrit: These values can be used to establish a baseline and to help detect hemorrhagic anemia.
• Blood type and antibody screen
• • A woman who is Rh-negative and has an abortion (either spontaneous or therapeutic) is at a 2-4% risk of becoming Rh-sensitized.
  • The Rh factor status must be documented for every pregnant patient with vaginal bleeding.
  • If patients are Rh-negative, administer Rho (D) immune globulin (RhoGAM) to prevent isoimmunization.
• Serum progesterone level
• • Progesterone levels rise after ovulation and continue to rise throughout pregnancy.
  • Several investigators have studied the role of serum progesterone during early pregnancy with regard to the differential diagnosis of early pregnancy disorders. A level of less than 5 ng/mL is invariably associated with pregnancy nonviability, whereas a level greater than 25 ng/mL is almost always associated with a viable pregnancy.
  • In most clinical settings, the value is 5-15 ng/mL and, therefore, is of limited clinical value. Furthermore, in clinical settings in which the QhCG titers and TVS findings can be correlated promptly, the role of serum progesterone evaluation is limited and may not be cost-effective or available in a timely manner.

Imaging Studies

• Ultrasonography is widely available and is the imaging study of choice.
• • Advantages include safety, bedside use, low cost, and noninvasiveness. Disadvantages include operator dependency.
  • TVS images can help determine presence of an embryo/fetus, the presence of heart motion, intactness of the choriodecidua, location (intrauterine or extrauterine), and gestational age.
  • Serial or repeat ultrasonographic examinations may be necessary if the initial scan findings are inconclusive and the patient's condition is stable.
  • A pregnancy should not be terminated based on findings from a single sonographic examination that demonstrate a lack of fetal heart motion during the embryonic stage (3-5 mm crown-rump length [CRL]) of development. A follow-up scan is usually indicated to confirm the lack of embryonic or fetal activity.
  • Embryos with low fetal heart rate ( <120 bpm) noted on transvaginal ultrasonography may have a higher chance of pregnancy loss. Thus, in these cases, repeat ultrasonography would be indicated to confirm viability
  • In general, an embryo or yolk sac should be seen in a gestational sac larger than 6-9 mm, and embryonic heart motion should be seen when the sac is 10-14 mm in size or when an embryo is longer than 5 mm. Embryos of CRL longer than 5 mm and who do not have a heartbeat are nonviable.
  • In a normal pregnancy, heart motion should be demonstrated on TVS images of embryos that are longer than 5 mm or are of 5-6 weeks' gestation.
  • Fetal heart activity demonstrated on ultrasonographic images is associated with a viable outcome in more than 90% of cases.
  • Early embryonic demise has a variety of appearances, ranging from a gestational sac devoid of a yolk sac or embryo to a yolk sac/embryo complex with no embryonic heart motion.
  • Patients who experience first-trimester vaginal bleeding may demonstrate areas of retrochorionic hemorrhage on TVS images, which appear as relatively hypoechoic areas behind the chorionic layer. If the hemorrhage is small and remote to the decidua basalis, the chance for pregnancy completion is better than if the hemorrhage extends behind the decidua basalis or is more than 25% of the size of the gestational sac.

TREATMENT

Section 6 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Medical Care

No effective therapy is available for a threatened intrauterine abortion.

• Bed rest, although often advocated, is not effective. No consistent evidence shows that bed rest can affect pregnancy outcome in threatened abortion. However, it is not harmful and may provide the patient with some emotional comfort.
• In general, most do not administer progesterone or sedatives. In most instances of threatened abortions that ultimately result in complete abortion, the embryo is already dead; thus, the administration of progesterone drugs is ineffective and only prolongs the natural course of abortion. However, progesterone (vaginal administration) may be indicated in unique circumstances, including viable pregnancies achieved with advanced reproductive technology or patients with a history of an inadequate luteal phase. Studies have shown that although progesterone administration may not necessarily change the outcome of threatened abortion, it may help reduce the severity of symptoms such as pain from cramping and uterine contractions.
• Institute appropriate counseling for all patients. A sympathetic attitude and continuing support and follow-up care are important to patients. This includes a tactful explanation about the pathologic process and favorable prognosis when the pregnancy is viable.
• Treat any vaginal infections.

Surgical Care

Continued observation is indicated as long as the cervix remains closed, bleeding and cramping are mild, QhCG levels are increasing normally, and a normal embryo/fetus is visualized on follow-up sonogram images.

The prognosis worsens with (1) progressively increasing bleeding and cramping, (2) QhCG levels that fall or level off, (3) failure to find sonographic evidence of embryonic/fetal growth, (4) fetal bradycardia, and (5) size smaller than appropriate for dates.

• When the pregnancy is confirmed nonviable based on transvaginal ultrasonography or because the cervical os is dilated or excessive bleeding is present, perform suction curettage. This prevents delayed hemorrhage and infection related to retention of necrotic tissue. It also diminishes the chances for the development of disseminated intravascular coagulation, a rare but potentially life-threatening complication associated with the retention of a dead conceptus for longer than 4 weeks.
• In women with minimal intrauterine tissue based on ultrasonographic images, waiting for spontaneous passage of the products of conception is possible (expectant management). If complete abortion does not occur within this waiting period, ensure adequate counseling regarding risks of infection, bleeding, disseminated intravascular coagulation, and chance of requiring surgical intervention (suction curettage).
• Currently, evidence is insufficient to support medical therapy (prostaglandins and progesterone receptor inhibitors) for spontaneous abortions.

MEDICATION

Section 7 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

The goals of pharmacotherapy are to reduce morbidity and to prevent complications.

Drug Category: Oxytocic agents

Enhance uterine contractility after evacuation and diminish bleeding.

Drug Category: Immunoglobulins

Suppress immune response and antibody formation.

Drug Category: Hormone Therapy

Supports physiologic hormone levels required during pregnancy.

Also used for luteal phase deficiency, and recurrent pregnancy loss.

FOLLOW-UP

Section 8 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Further Inpatient Care

• For incomplete abortions or threatened abortions that progress to become nonviable, inpatient treatment includes suction curettage.
• Laparoscopy or laparotomy is available for patients with ectopic pregnancies who are not candidates for medical management with methotrexate.
• Patients undergoing suction curettage should be observed for 4-6 hours and then discharged if stable.

Further Outpatient Care

• A follow-up visit with an obstetrician/gynecologist should be scheduled for within 1 week.
• Serial QhCG levels and TVS evaluations may be required.
• If spontaneous abortion occurs, the patient should be seen within 1 week.
• Allow sufficient time for counseling.
• May offer psychologist or social work services for additional support as necessary, particularly if coping with pregnancy loss.
• Etiologies and prognosis can be addressed further at this point.
• Include a sensitively approached focus on the patient's emotional reactions.

In/Out Patient Meds

• For patients who are Rh-negative and at less than 13 weeks' gestation, administer RhoGAM at 50 mcg intramuscularly.
• If the patient undergoes suction curettage, any of the following may be administered if needed:
• • Methergine (0.2 mg PO q4h 6 times) - To diminish postevacuation uterine bleeding
  • Ibuprofen (800 mg PO q6h prn) - For analgesia
  • Doxycycline (100 mg PO bid for 4-7 d) - For prophylaxis if risk factors for infection are present
  • Iron supplementation - For anemia
  • Contraception agent, if desired

Deterrence/Prevention

• Contraceptive counseling

Complications

• Preexisting anemia may make patients more susceptible to hypovolemic shock.
• Potential complications from suction curettage include hemorrhage and uterine perforation with possible injury to bowel, bladder, ureter, and uterine artery.
• Other complications include the following:
• • Postabortion bleeding
  • Retained products of conception
  • Hematometra
  • Depression
  • Anesthesia complications
  • Infection - endometritis

Prognosis

• In women who have had 1 prior miscarriage, the rate of spontaneous abortion in a subsequent pregnancy is approximately 20%. In women who have had 3 consecutive losses, the rate is up to 50%.
• The live-birth rate after documentation of fetal cardiac activity at 5-6 weeks of gestation in women with 2 or more unexplained spontaneous abortions is approximately 77%.
• Patients can be reassured that in most cases, spontaneous abortions do not recur. However, after 2-3 early pregnancy losses, further investigations for causes of recurrent abortions may be indicated.
• Evidence of an association between threatened abortion and birth defects is limited and inconsistent. One epidemiologic study found an increased risk of birth defects (polydactyly, undescended testicle, and hypospadias) in the follow-up observation of patients with threatened abortion. Another study looking at perinatal outcome of pregnancies continuing after threatened abortion found no significant difference in preterm deliveries, low birth weight, and overall perinatal outcome.

Patient Education

• Advise patients to return for follow-up care upon the occurrence of any of the following symptoms:
• • Profuse vaginal bleeding and/or severe abdominal cramping
  • Severe pelvic pain
  • Temperature higher than 38°C (100.4°F)
  • Passage of tissue
• For excellent patient education resources, visit eMedicine's Pregnancy and Reproduction Center. Also, see eMedicine's patient education articles Pregnancy, Bleeding, Miscarriage, Abortion, Dilation and Curettage (D&C), Birth Control Overview, and Birth Control FAQs.

MISCELLANEOUS

Section 9 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Medical/Legal Pitfalls

• Failure to diagnose pregnancy: Every woman of reproductive age with lower abdominal pain and/or vaginal bleeding should have a pregnancy test.
• Failure to diagnose an ectopic pregnancy: An ectopic pregnancy must be excluded in every pregnant woman with abdominal pain and/or vaginal bleeding. With early diagnosis, ectopic pregnancy in a patient who is stable can be treated nonsurgically.
• Failure to provide important follow-up care: In patients who are being monitored with serial QhCG titers and sonograms, documenting a contact person with telephone number and address is prudent in the event that the patient is lost to follow-up.
• Failure to ensure patient compliance when making clinical decisions regarding definitive or expectant management.
• Failure to document discussion and patient understanding of warning symptoms and complications that require immediate medical attention.
• Failure to prevent isoimmunization: Unsensitized Rh-negative women should receive the appropriate dose of RhoGAM.
• Failure to assess the true intensity of hemorrhage: External bleeding may not accurately reflect total blood loss. Blood can be concealed in the vagina or uterus, or a hemoperitoneum may exist.

REFERENCES

Section 10 of 10

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

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Article Last Updated: Aug 23, 2006