Updated: Jun 25, 2006
An abortion is the spontaneous or induced loss of an early pregnancy. The period of pregnancy prior to fetal viability outside of the uterus is considered early pregnancy. Most consider early pregnancy to end at 20-24 weeks' gestation. The term miscarriage is used often in the lay language and refers to spontaneous abortion.
A spontaneous abortion is a process that can be divided into 4 stages—threatened, inevitable, incomplete, and complete.
Threatened abortion consists of any vaginal bleeding during early pregnancy without cervical dilatation or change in cervical consistency. Usually, no significant pain exists, although mild cramps may occur. More severe cramps may lead to an inevitable abortion.
Threatened abortion is very common in the first trimester; about 25-30% of all pregnancies have some bleeding during the pregnancy. Less than one half proceed to a complete abortion or miscarriage. On examination, blood or brownish discharge may exist in the vagina. The cervix is not tender, and the cervical os is closed. No fetal tissue or membranes have passed. The ultrasound shows a continuing intrauterine pregnancy. If an ultrasound was not performed previously, it is required at this time to rule out an ectopic pregnancy, which could present similarly. If the uterine cavity is empty on ultrasound, obtaining a human chorionic gonadotropin (hCG) level is necessary to determine if the discriminatory zone has been passed.
The discriminatory zone is the level of hCG beyond which an intrauterine pregnancy is consistently visible. The discriminatory zone may vary depending on a number of factors, including hCG assay type and reference calibration standard used, ultrasound equipment resolution, the skill and experience of the sonographer, and patient factors (eg, obesity, leiomyomas, uterine axis, multiple gestations). Also, the discriminatory zone will vary depending on whether the ultrasound is performed abdominally or vaginally. Therefore, having a universal discriminatory zone is difficult, and it optimally should be calculated at each site.
However, some studies recommend that an estimate would be that a gestational sac should be visualized by 5.5 weeks' gestation; a gestational sac should be visualized with an hCG level of 1500-2400 mIU/mL for transvaginal ultrasound or with an hCG level over 3000 mIU/mL for a transabdominal ultrasound. If the hCG level is higher than the discriminatory zone and no gestational sac is visualized in the uterus, then consider that an ectopic pregnancy may be present.
Inevitable abortion is an early pregnancy with vaginal bleeding and dilatation of the cervix. Typically, the vaginal bleeding is worse than with a threatened abortion, and more cramps are present. No tissue has passed yet.
Incomplete abortion is a pregnancy that is associated with vaginal bleeding, dilatation of the cervical canal, and passage of products of conception. Usually, the cramps are intense, and the vaginal bleeding is heavy. Patients describe passage of tissue, or the examiner observes evidence of tissue passage within the vagina. The ultrasound confirms that some of the products of conception are still present in the uterus.
Complete abortion is a completed miscarriage. Typically, a history of vaginal bleeding, abdominal pain, and passage of tissue exists. After the tissue passes, the patient notes that the pain subsides and the vaginal bleeding significantly diminishes. The examination reveals some blood in the vaginal vault; a closed cervical os; and no tenderness of the cervix, uterus, adnexa, or abdomen. The ultrasound demonstrates an empty uterus.
These 4 stages of abortion described above form a continuum. Most studies do not differentiate separately between the epidemiology and pathophysiology of each entity described above.
A fifth term that does not follow the continuum but is important to be aware of is missed abortion. A missed abortion is a nonviable intrauterine pregnancy that has been retained within the uterus without spontaneous abortion. Typically, no symptoms exist besides amenorrhea, and the patient finds out that the pregnancy stopped earlier when a fetal heartbeat is not observed or heard at the appropriate time. An ultrasound usually confirms the diagnosis. No vaginal bleeding, abdominal pain, passage of tissue, or cervical changes are present.
The overall miscarriage rate is reported as 15-20%, which means 15-20% of recognized pregnancies result in miscarriage. The frequency of spontaneous miscarriage increases further with maternal age. With the development of highly sensitive assays for hCG levels, pregnancies can be detected prior to the expected next period. When these highly sensitive hCG assays are used early, the magnitude of pregnancy loss significantly increases to about 60-70%. Late implantation by the conceptus beyond the usual 8-10 days after ovulation also has an increased risk of miscarriage.
About 80% of miscarriages occur within the first trimester. The frequency of miscarriage decreases with an increasing gestational age. Recurrent miscarriage, defined as 2-3 pregnancy losses, affects about 1% of all couples.
No significant difference exists between international rates and the rates in the United States.
A complete abortion is unlikely to cause any significant risk of mortality unless significant blood loss or infection occurs. Morbidity would be increased if an anemia or infection develops. Patients who are pregnant may bleed quickly and significantly. Distinguishing the causes of bleeding during pregnancy is important.
Threatened abortions usually bleed, a viable intrauterine pregnancy is visible on ultrasound, and the cervical canal is closed. A complete abortion will have a history of bleeding and significant cramping with passage of tissue, followed by a marked reduction in bleeding and resolution of cramping. With a complete abortion, the ultrasound demonstrates an empty uterus and the examination is notable for a closed cervical os. Incomplete or inevitable abortions have bleeding and an open cervical os on examination. The ultrasound may show clots or an intrauterine pregnancy.
These latter 2 conditions (incomplete and inevitable abortions) are a cause for concern when significant bleeding or infection occurs. If a suction dilatation and curettage (D&C) is not performed in a timely manner, significant morbidity and mortality may occur. Retained products of conception also may occur after a spontaneous abortion or after a suction D&C.
Patients with retained products usually return for medical care with symptoms of increased bleeding, increased cramping, and/or infection. Caring for these patients quickly with intravenous antibiotics is important, and, after the antibiotics are administered, then a suction D&C or a repeat suction D&C is performed. These patients will be at risk for developing Asherman syndrome, which consists of adhesions within the uterine cavity. Patients who develop Asherman syndrome may present with amenorrhea or decreased menstrual flow. Asherman syndrome may compromise future fertility. When significant bleeding occurs, fluid management and transfusions may be required while stabilizing the patient prior to a suction D&C.
A complication of D&C is perforation of the uterus, which may be handled by observation. If the patient shows signs of uncontrolled bleeding on ultrasound, then proceeding to a laparoscopy or laparotomy with cauterization of the bleeding area may be necessary. The choice for laparoscopy or laparotomy depends on the stability of the patient. Occasionally, the perforation is in the area of the uterine vessels or other area where the bleeding is difficult to control and a hysterectomy may be necessary. When bleeding is out of control, the patient easily can go into hypovolemic shock or disseminated intravascular coagulopathy (DIC). Both of these situations need prompt attention and treatment.
Complete abortions may occur in any race without distinction.
Complete abortions only affect females.
Complete abortions only occur in reproductive-aged women unless in vitro fertilization was used with donor eggs in menopausal women. As women mature, the incidence of spontaneous miscarriages increases. Typically, the distribution of miscarriage rates by age occurs as follows: younger than 35 years old, 15% miscarriage rate; 35-39 years old, 20-25% miscarriage rate; 40-42 years old, about 35% miscarriage rate; and older than 42 years old, about 50% miscarriage rate.
Patients with spontaneous complete abortion usually present with a history of vaginal bleeding, abdominal pain, and passage of tissue. After the tissue passes, the vaginal bleeding and abdominal pain subsides.
Patients who are pregnant and bleeding vaginally need immediate evaluation.
| Abortion | Hematologic Disease and Pregnancy |
| Adnexal Tumors | Ovarian Cysts |
| Amenorrhea, Secondary | Threatened Abortion |
| Cervical Cancer | von Willebrand Disease |
| Cervical Ripening | |
| Cervicitis |
Abortion, incomplete
Abortion, inevitable
Acute appendicitis
Cervical polyps, ectropion, or malignancy
Ovarian torsion
Pregnancy, molar
Pregnancy, subchorionic hemorrhage
Vaginal/vulvar condylomata
A complete abortion usually needs no further treatment, medically or surgically.
With missed, incomplete, or inevitable abortion before 13 weeks' gestation, the standard therapy has been suction D&C. However, at least 2 randomized controlled trials show that misoprostol is an effective medical therapy. In 1 study of incomplete abortion, the subjects were randomized between oral misoprostol (600 mcg) or suction D&C with a 96.3% versus 91.5% success rate in completed abortion with low complications (0.9% for misoprostol) (Weeks, 2005).
The other study was a randomized controlled trial with a 3:1 ratio in favor of medical therapy and it included subjects with the following diagnoses: missed abortion (with or without a fetal pole; no fetal heart motion when the fetal pole was present), incomplete abortion, or inevitable abortion. In this study, the initial dose of misoprostol was 800 mcg (4 tab 200 mcg placed vaginally) and the subject was reevaluated on day 3. If the expulsion had not occurred then a second dose of 800 mcg of misoprostol was placed vaginally. The results showed that 71% had completed abortion after the first dose by day 3 and 84% had success with misoprostol by day 8 (95% confidence interval, 81-87%). The risks for bleeding and infection were similar to surgical management (Zhang, 2005).
Medical therapy using misoprostol is an acceptable alternative to surgical therapy for most women based upon these early data.
No surgical care is used for complete abortion.
Consult an obstetrician/gynecologist any time uncertainty about the diagnosis exists and to administer treatment.
The patient should rest for a few days to 2 weeks for a complete abortion. The rest schedule needs to be adjusted if one of the other diagnoses is correct.
For a complete abortion, no medication is likely to be needed. Usually, the uterus contracts well after expelling the entire contents and the cervix is closed. The risk for infection is minimal.
Used to suppress the immune system when the mother is Rh negative.
Suppresses immune response of mother who is nonsensitized Rh O (D) negative exposed to Rh O (D) positive blood from the fetus as a result of a fetomaternal hemorrhage, abdominal trauma, amniocentesis, abortion, full-term delivery, or transfusion accident.
<13 weeks' gestation: 50 mcg IM within 72 h of exposure
>13 weeks' gestation: 300 mcg IM
Administer as in adults
None reported
Documented hypersensitivity; patients who have received Rho (D)–positive blood within the last 3 mo
C - Safety for use during pregnancy has not been established.
Caution in thrombocytopenia, bleeding disorders, or IgA deficiency
Occasionally, the uterus does not contract well, and a clot may form in the uterine cavity. If the physician notes a boggy uterus after expulsion of the products of conception, the physician may consider methylergonovine in the appropriate candidate. In most cases in which a clot forms within the uterus, a surgical D&C finally is warranted.
Acts directly on uterine smooth muscle, causing a sustained tetanic uterotonic effect that reduces uterine bleeding and shortens the third stage of labor.
Administer IM after a D&C, during puerperium, after delivery of placenta, or after delivering anterior shoulder. Also may be administered IV over no less than 60 sec, but should not be administered routinely because it may provoke hypertension or a stroke. Monitor blood pressure closely when administering IV.
0.2 mg PO tid for 3 d
Not established
Concurrent administration of methylergonovine with vasoconstrictors or other ergot alkaloids may produce additive effects
Documented hypersensitivity; glaucoma; Tourette syndrome; anxiety
C - Safety for use during pregnancy has not been established
Caution in sepsis, obliterative vascular disease, or hepatic or renal insufficiency
These agents inhibit cell growth and proliferation.
Antimetabolite that inhibits dihydrofolate reductase, thereby hindering DNA synthesis and embryonic cell reproduction.
50 mg/m2 IM once
Not established
Oral aminoglycosides may decrease absorption and blood levels of concurrent oral methotrexate (MTX); charcoal lowers MTX levels; coadministration with etretinate may increase hepatotoxicity of MTX; folic acid or its derivatives contained in some vitamins may decrease response to MTX; probenecid, NSAIDs, salicylates, procarbazine, and sulfonamides (including TMP-SMZ) can increase MTX plasma levels; may decrease phenytoin plasma levels; may increase plasma levels of thiopurines
Documented hypersensitivity; alcoholism; hepatic insufficiency; documented immunodeficiency syndromes; preexisting blood dyscrasias (eg, bone marrow hypoplasia, leukopenia, thrombocytopenia, significant anemia); renal insufficiency
X - Contraindicated in pregnancy
Has toxic effects on hematologic, renal, GI, pulmonary, and neurologic systems; fatal reactions reported when administered concurrently with NSAIDs
Misoprostol, a prostaglandin agent, has been recently reported as safe and effective medical treatment for missed abortion, inevitable abortion, or incomplete abortion. It is used as off-labeled indication and is not FDA approved for this indication.
Prostaglandin agent also categorized as an anti-ulcer (protective) and endocrine metabolic agent. As a prostaglandin agent, misoprostol will increase uterine smooth muscle contractions and soften the cervix to allow passage of products of conception from missed abortion, inevitable abortion, or incomplete abortion. Not FDA approved for medical treatment of these types of abortions; yet, recent literature suggests is that it is safe and effective. Administered orally or vaginally. Comes in 200 mcg tablets.
Dose is with 3-4 tab (600-800 mcg total) vaginally or orally for one dose or repeat dose on day 3
Not established
None reported
Documented hypersensitivity to product or components
X - Contraindicated in pregnancy
Caution in renal impairment and the elderly;
Adverse reactions include diarrhea 15%,
nausea 7%, cardiovascular (rare), and
hematological anemia (rare)
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Hurd WW, Whitfield RR, Randolph JF Jr, et al. Expectant management versus elective curettage for the treatment of spontaneous abortion. Fertil Steril. Oct 1997;68(4):601-6. [Medline].
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Nielsen S, Hahlin M. Expectant management of first-trimester spontaneous abortion. Lancet. Jan 14 1995;345(8942):84-6. [Medline].
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Weeks A, Alia G, Blum J, et al. A randomized trial of misoprostol compared with manual vacuum aspiration for incomplete abortion. Obstet Gynecol. Sep 2005;106(3):540-7.
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first-trimester pregnancy loss, miscarriage, spontaneous abortion, abortion, pregnancy loss, voluntary pregnancy termination, pregnancy termination, induced pregnancy termination, pregnancy complications, spontaneous complete abortion, ectopic pregnancy, incomplete abortion, inevitable abortion
Elizabeth E Puscheck, MD, Associate Professor, Department of Obstetrics and Gynecology, Wayne State University School of Medicine; In Vitro Fertilization Director, Medical Director, Gynecologic Ultrasound Director, Clinical Endocrine Laboratory Consultant, Department of Obstetrics and Gynecology, University Women's Care
Elizabeth E Puscheck, MD is a member of the following medical societies: American College of Obstetricians and Gynecologists, American Institute of Ultrasound in Medicine, American Society for Reproductive Medicine, Association of Professors of Gynecology and Obstetrics, Endocrine Society, International Society for Clinical Densitometry, North American Menopause Society, Sigma Xi, Society for Assisted Reproductive Technologies, and Society of Reproductive Surgeons
Disclosure: Ferring Grant/research funds Other
Archana Pradhan, MD, MPH, Staff Physician, Department of Obstetrics and Gynecology, Nassau University Medical Center
Disclosure: Nothing to disclose.
Suzanne R Trupin, MD, Clinical Professor of Obstetrics and Gynecology, University of Illinois College of Medicine-Champaign; CEO and Owner, Women's Health Practice; CEO and Owner, Hada Cosmetic Medicine and Midwest Surgical Center
Suzanne R Trupin, MD is a member of the following medical societies: American Association of Gynecologic Laparoscopists, American College of Obstetricians and Gynecologists, American Institute of Ultrasound in Medicine, American Medical Association, Association of Reproductive Health Professionals, International Society for Clinical Densitometry, and North American Menopause Society
Disclosure: Nothing to disclose.
Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine
Disclosure: Nothing to disclose.
Richard S Legro, MD, Professor, Department of Obstetrics and Gynecology, Division of Reproductive Endocrinology, Pennsylvania State University College of Medicine; Consulting Staff, Milton S Hershey Medical Center
Richard S Legro, MD is a member of the following medical societies: American College of Obstetricians and Gynecologists, American Society for Reproductive Medicine, Endocrine Society, Phi Beta Kappa, and Society of Reproductive Surgeons
Disclosure: Nothing to disclose.
Frederick B Gaupp, MD, Consulting Staff, Department of Family Practice, Assumption Community Hospital
Frederick B Gaupp, MD is a member of the following medical societies: American Academy of Family Physicians
Disclosure: Nothing to disclose.
Lee P Shulman, MD, Professor of Obstetrics and Gynecology, Feinberg School of Medicine, Northwestern University; Chief, Division of Reproductive Genetics, Department of Obstetrics and Gynecology, Prentice Women's Hospital, Northwestern Memorial Hospital
Lee P Shulman, MD is a member of the following medical societies: American College of Medical Genetics, American College of Obstetricians and Gynecologists, American Medical Association, American Society for Reproductive Medicine, American Society of Human Genetics, Association of Reproductive Health Professionals, Central Association of Obstetricians and Gynecologists, Chicago Medical Society, Illinois State Medical Society, North American Society for Pediatric and Adolescent Gynecology, Phi Beta Kappa, Society for Gynecologic Investigation, Society for Maternal-Fetal Medicine, and Tennessee Medical Association
Disclosure: Nothing to disclose.
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