Abortion, Spontaneous (Miscarriage)
- Separation of products of conception from the uterus prior to the potential for fetal survival outside the uterus
- Spontaneous abortion (SAb):
- Expulsion or extraction from the uterus of an embryo or fetus weighing ≤500 g
- Threatened abortion:
- Vaginal bleeding early in pregnancy without dilatation of the cervix, rupture of the membranes, or expulsion of products of conception
- Inevitable abortion:
- Cervical dilatation, rupture of membranes, or expulsion of products in the presence of vaginal bleeding
- Complete abortion:
- Entire contents of uterus expelled; common before 12 weeks’ gestation
- Incomplete abortion:
- Abortion with retained products of conception, generally placental tissue; more common after 12 weeks’ gestation
- Missed abortion:
- In utero death of embryo/fetus prior to 20 weeks’ gestation; products of conception retained
- Induced abortion:
- Evacuation of uterine contents or products of conception medically or surgically
- Septic abortion:
- Common complication of illegally performed induced abortions; a spontaneous or therapeutic abortion complicated by pelvic infection
- Habitual spontaneous abortion:
- 2 or more consecutive pregnancy losses at <15 weeks’ gestation
- Synonym(s): Miscarriage; habitual abortion; recurrent abortion; involuntary pregnancy loss
Predominant age: Increases with advancing age, especially >35 years; at age 40, the loss rate is twice that of age 20
- Between 8% and 20% of all clinically recognized pregnancies end in spontaneous abortion, with 80% of these in the first 12 weeks.
- When both clinical and biochemical (B-HCG detected) pregnancies are considered, up to 50% of pregnancies end in spontaneous abortion.
Most cases of spontaneous abortion occur in patients without identifiable risk factors; however, risk factors listed in order of importance include:
- Chromosomal abnormalities
- Advancing maternal age
- Uterine abnormalities
- Maternal chronic disease (diabetes mellitus, polycystic ovarian syndrome, systemic lupus erythematosus, hypertension, antiphospholipid antibodies, thyroid disease, renal disease)
- Other possible contributing factors include smoking, alcohol, infection, and luteal phase defect, although conclusive data are currently lacking.
~50–65% of first-trimester spontaneous abortions have significant chromosomal anomalies, with 50% of these being autosomal trisomies and the remainder being triploidy, tetraploidy, or 45X monosomies.
- Progestogens: Currently, there is no evidence that routine use of oral or IM progestogens prevents miscarriage in early to mid-pregnancy. However, there is some evidence that women with a history of recurrent miscarriage may benefit from this type of treatment (1)[A]. Likewise, there is no evidence that progesterone has utility as a treatment for threatened abortion (2)[A].
- Immunotherapy: There is no current evidence to support use of immunotherapy in patients with a history of recurrent miscarriage (3)[A].
- Chromosomal anomalies
- Congenital anomalies
- Maternal factors: Uterine abnormalities, infection (toxoplasma, other viruses, rubella, cytomegalovirus, herpesvirus), maternal endocrine disorders, hypercoagulable state
- Consider any reproductive-age woman with vaginal bleeding to be pregnant until proven otherwise.
- Vaginal bleeding:
- Characteristics (amount, color, consistency, associated symptoms), onset (abrupt or gradual), duration, intensity/quantity, and exacerbating/precipitating factors
- Document last menstrual period (LMP) if known—allows calculation of estimated gestational age if no prior ultrasound (US) documentation of intrauterine pregnancy (IUP)
- Abdominal pain/uterine cramping, as well as associated nausea/vomiting/syncope
- Rupture of membranes
- Passage of products of conception
- Prenatal course: Toxic or infectious exposures, family or personal history of genetic abnormalities, past history of ectopic pregnancy or spontaneous abortion, endocrine disease, autoimmune disorder, bleeding/clotting disorder
- Estimate hemodynamic stability:
- Obtain orthostatic vital signs.
- Abdominal exam for tenderness (SAb), guarding, rebound, bowel sounds (peritoneal signs more likely seen with ectopic pregnancy)
- Pelvic exam including speculum exam for visual assessment of cervical dilation, blood, products of conception, and bimanual exam for uterine size/tenderness
Diagnostic Tests and Interpretation
- Urine human chorionic gonadotropin (HCG)
- CBC with differential
- Rh type
- Cultures: Gonorrhea/chlamydia
- Serial serum HCG measurements can assess viability of the pregnancy. Serum HCG should rise at least 67% every 48 hours in early pregnancy. An inappropriate rise/plateau of HCG suggests abnormal IUP or possible ectopic pregnancy.
HCG levels are particularly useful in cases where an IUP has not been documented by ultrasound.Follow-Up and Special Considerations
ImagingInitial Imaging Approach
- In the case of vaginal bleeding with no documented IUP, follow serum HCG levels weekly to zero to ensure complete expulsion of all products of conception.
- If levels plateau, suspect ectopic pregnancy or retained products of conception, or rarely, gestational trophoblastic disease.
Follow-Up and Special Considerations
- US exam to evaluate fetal viability and to rule out ectopic pregnancy:
- HCG >2,000 U/L necessary to detect IUP via transvaginal US (TVUS), >6,500 U/L for abdominal ultrasound
- TVUS criteria for nonviable intrauterine gestation include 5-mm fetal pole without cardiac activity or 16-mm gestational sac without a fetal pole.
- Structures and timing: gestational sac of 2–3 mm generally seen by 4 weeks +1–3 days; yolk sac by 5 weeks estimated gestational age (EGA); fetal pole with + fetal heart tones (FHT) by 5.5–6 weeks EGA → requires high-resolution TVUS
- If initial HCG level does not permit documentation of IUP by TVUS, follow serum HCG in 48 hours to ensure appropriate rise.
- Follow HGC and repeat US once HCG at a level commensurate with visualization on US (see above).
- Provide patient with ectopic precautions in interim—worsening abdominal pain, significant vaginal bleeding, dizziness/syncope, and nausea/vomiting.
- Fetal heart tones can be auscultated with Doppler starting between 10 and 12 weeks’ gestation from last menstrual period for a viable pregnancy.
- 90–96% of pregnancies with fetal cardiac activity and vaginal bleeding at 7–11 weeks’ gestation result in continued pregnancy.
Products of conception, placental villi
- Ectopic pregnancy: Potentially life-threatening; must be ruled out with US in any woman of childbearing age with abdominal pain and vaginal bleeding
- Cervical polyps, neoplasias, and/or inflammatory conditions can cause vaginal bleeding.
- Hydatidiform mole pregnancy
- HCG-secreting ovarian tumor
- Physiologic bleeding in normal pregnancy (implantation bleeding)
- Long-term conception rate and pregnancy outcomes are similar for women who undergo medical or surgical evacuation.
- Postinfection rates are lower with medical versus surgical management.
- Misoprostol: Most common agent for inducing passage of tissue in missed or incomplete abortion:
- Not approved by Food and Drug Administration for treatment of early pregnancy failure
- Efficacy: Complete expulsion of products of conception in 71% by day 3, 84% by day 8
- Efficacy depends on route of administration, gestational age of pregnancy, and dose.
- Recommended dose is 800 μg vaginally (4)[A]; alternate regimens exist including the World Health Organization regimen of 800 μg vaginally or 600 μg sublingually q3h for up to 3 doses; multidose regimens and oral dosing (including buccal and sublingual) may result in increased side effects, and pure oral dosing appears somewhat less effective than vaginal/buccal/sublingual routes.
- Common adverse effects include abdominal pain/cramping, nausea, and diarrhea. Pain increases at higher doses but is manageable with analgesia. There is no increase in nausea/diarrhea with a higher dose.
- Recommended for stable patients who decline surgery but do not want to wait for spontaneous passage of products of conception
Rh-negative patients should be given Rh immunoglobulin following a spontaneous abortion (5
General Measures Evaluate for any 1st-trimester vaginal bleeding.
Issue for Referral Patients should be monitored for up to 1 year for the development of psychosomatic symptoms such as depression and anxiety (6)[A].
Complementary and Alternative Therapies
Vitamin supplementation does not appear to prevent miscarriage (7)[A].
- Uterine aspiration (dilation and curettage or via vacuum aspiration) is the conventional treatment.
- Indications: Septic abortion, heavy bleeding, hypotension, patient choice
- Risks: Anesthesia, uterine perforation, intrauterine adhesions, cervical trauma, infection that may lead to infertility or increased risk of ectopic pregnancy
- When compared with medical management, surgical intervention leads to fewer days of vaginal bleeding, with a lower risk of incomplete abortion and heavy bleeding. It does carry a higher risk of infection (8)[A].
- Vacuum aspiration may be less painful than dilatation and curettage (D&C), and does not require general anesthesia (9)[B].
- Data from induced abortions suggest that antibiotic prophylaxis with doxycycline 100 mg b.i.d. substantially reduces postprocedure infection risk; however, data for incomplete abortions treated surgically are inconclusive (10)[A].
- For patients who desire contraception after completion of a spontaneous abortion, immediate insertion of an intrauterine device is both acceptable and safe (11)[A].
Initial Stabilization If the patient has orthostatic vital signs, initiate resuscitation with IV fluids and/or blood products if needed.
IV Fluids Hemodynamically unstable patients may require IV fluids and/or blood products to maintain BP.
All patients should be seen in 2–6 weeks to monitor for resolution of bleeding, re-establishment of menses, review of contraception plan, and psychosomatic symptoms.
- Identification of products of conception within material expelled from the uterus or D&C specimen (important to distinguish villi and sac from decidua)
- If abortion is complete, observe the patient for further bleeding.
- Pelvic rest until 2 weeks after evacuation
- If spontaneous abortion occurs in setting of previously documented IUP and abortion is completed with resumption of normal menses, it is not necessary to check or follow serum HCG to 0.
NPO if patient is to undergo D&C
Patient pamphlet (no. AP090) available from the American College of Obstetricians and Gynecologists, 409 12th St., SW, Washington, DC 20090–6290; (800) 762–2264 or online at http://www.acog.org
- If bleeding ceases, prognosis is excellent.
- Habitual abortion:
- Prognosis depends on etiology.
- Prognosis is still excellent, with up to 70% rate of success with subsequent pregnancy.
- Potential complications of D&C include uterine perforation, bleeding, adhesions, cervical trauma, infection that may lead to infertility, or increased risk of ectopic pregnancy.
- Retained products of conception
- Psychological morbidity, including depression, anxiety, and feelings of guilt
Harwood B. Quality of life and acceptability of medical vs. surgical management of early pregnancy. Br J Obstet Gynaec. 2008;115(4):501–8.
- 632 Missed abortion
- 634.90 Spontaneous abortion, unspecified, without mention of complication
- 640.03 Threatened abortion, antepartum
- 637.90 Legally unspecified type of abortion, unspecified, without mention of complication
- 637.00 Unspecified type of abortion, unspecified, complicated by genital tract and pelvic infection
- O03.9 Complete or unspecified spontaneous abortion without complication
- O02.1 Missed abortion
- O20.0 Threatened abortion
- N96 Recurrent pregnancy loss
- O03.4 Incomplete spontaneous abortion without complication
- 17369002 Spontaneous abortion (disorder)
- 16607004 Missed abortion (disorder)
- 54048003 Threatened abortion (disorder)
- Any reproductive-age woman or pregnant woman with abdominal pain and vaginal bleeding must be evaluated to rule out ectopic pregnancy, which is potentially life threatening.
- As all options have similar long-term outcomes, patient preference should determine whether management is medical, expectant, or surgical.
- Assessment of psychological symptoms after spontaneous abortion should be an integral part of follow-up visits, with counseling, medication, and referral as appropriate.
Elizabeth W. Patton, MD, MPhil
Patricia K. Aronson, MD
- Haas DM, Ramsey PS. Progestogen for preventing miscarriage. Cochrane Database Syst Rev. 2008;CD003511. [PMID:18425891]
- Wahabi HA, Abed Althagafi NF, Elawad M, et al. Progestogen for treating threatened miscarriage. Cochrane Database Syst Rev. 2011;3:CD005943. [PMID:21412891]
- Porter TF, LaCoursiere Y, Scott JR. Immunotherapy for recurrent miscarriage. Cochrane Database Syst Rev. 2006;CD000112. [PMID:16625529]
- Neilson JP, Gyte GML, Hickey M, et al. Medical treatments for incomplete miscarriage (less than 24 weeks). Cochrane Database Syst Rev. 2010;1:CD007223.Prevention of Rho(D) alloimmunization. American College of Obstetricians and Gynecologists Practice Bulletin No 4. American College of Obstetricians and Gynecologists, Washington, DC; 1999.
- Lok IH, Neugebauer R. Psychological morbidity following miscarriage. Best Pract Res Clin Obstet Gynaecol. 2007;21:229–47. [PMID:17317322]
- Rumbold A, Middleton P, Pan N, et al. Vitamin supplementation for preventing miscarriage. Cochrane Database Syst Rev. 2011;1:CD004073.
- Nanda K, Peloggia A, Grimes DA, et al. Expectant care versus surgical treatment for miscarriage. Cochrane Database Syst Rev. 2006;2:CD003518.
- Forna F. Surgical procedures to evacuate incomplete miscarriage. Cochrane Database Syst Rev. 2001;1:CD001993. [PMID:11279744]
- May W, Gülmezoglu AM, Ba-Thike K. Antibiotics for incomplete abortion. Cochrane Database Syst Rev. 2007;CD001779. [PMID:17943756]
- Grimes DA, Lopez LM, Schulz KF, et al. Immediate post-partum insertion of intrauterine devices. Cochrane Database Syst Rev. 2010;5:CD003036. [PMID:20464722]
© Wolters Kluwer Health Lippincott Williams & Wilkins
Abortion, Spontaneous (Miscarriage) is a sample topic found in
5-Minute Clinical Consult .
To find other 5-Minute Clinical Consult topics
please login or purchase a subscription.