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

The most common complication of pregnancy is spontaneous abortion, which is estimated to occur in 10-15% of pregnancies. Spontaneous abortion can be classified as threatened, inevitable, incomplete, complete, or missed. Spontaneous abortions can further be categorized as sporadic or recurrent (>3 occurrences). By definition, a complete abortion is the expulsion of all products of conception before the 20th week of gestation.

Pathophysiology

Pathophysiology of a spontaneous abortion may be suggested by the timing of miscarriage. Chromosomal defects commonly are seen in spontaneous abortions, especially those that occur during 4-8 weeks' gestation. Genetic etiologies are common in early first-trimester loss but may be seen throughout gestation. Trisomy chromosomes are the most common chromosomal anomaly. Insufficient or excessive hormonal levels usually result in spontaneous abortion before 10 weeks' gestation. Infectious, immunologic, and environmental factors generally are seen in first-trimester pregnancy loss. Anatomic factors usually are associated with second-trimester loss. Factor XIII deficiency and a complete or partial deficiency of fibrinogen are associated with recurrent spontaneous abortions.

Frequency

United States

Many pregnancies are not viable. An estimated 50% of pregnancies are terminated spontaneously before the first missed menstrual period and, therefore, usually are not clinically recognized. Spontaneous abortion typically is defined as a clinically recognized (eg, by blood test, ultrasound) pregnancy loss before 20 weeks' gestation. This loss occurs in an estimated 10-20% of pregnancies.

Mortality/Morbidity

Surveillance data from the US between 1987 and 1990 revealed a total of 1459 pregnancy-related deaths. Spontaneous and induced abortions accounted for 5.6% of these deaths.

Race

Surveillance data for pregnancy-related deaths between 1987 and 1990 demonstrated that more black mothers died after ectopic pregnancies and abortions, both spontaneous (14%) and induced (7%), than white mothers (8% and 4%, respectively).

Age

• Age and increased parity affect a woman's risk of a miscarriage. In women younger than 20 years, miscarriage occurs in an estimated 12% of pregnancies; in women older than 20 years, miscarriage occurs in an estimated 26% of pregnancies.
• Age primarily affects the oocyte. When oocytes from young women are used to create embryos for transfer to older recipients, implantation and pregnancy rates mimic those seen in younger women. The number of miscarriages and chromosomal anomalies decreases, suggesting that the uterus is not responsible for poor outcomes in women of advanced reproductive age.

CLINICAL

Section 3 of 10  

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

History

• Date of last menstrual period
• Estimated length of gestation
• Bleeding
• • Degree - Important to establish whether the patient has been spotting or bleeding in a fashion similar to a heavy menstrual period
  • Duration
  • Presence or passage of tissue
• Bleeding disorders

Physical

• On pelvic examination, the cervix should be closed, and the uterus should be contracted.
• If adnexal tenderness is present, suspect the presence of an ectopic pregnancy.

Causes

Proposed etiologies for spontaneous abortions include the following:

• Genetic factors
• • Approximately 5% of spontaneous abortions occur because of genetic factors.
  • Trisomy chromosomes commonly are encountered. Trisomy 16 accounts for approximately a third of chromosomal abnormalities in early pregnancy.
• Anatomic factors: Congenital or acquired anatomic factors reportedly are present in 10-15% of women who have recurrent spontaneous abortions.
• • Congenital anatomic lesions include müllerian duct anomalies (eg, septate uterus, diethylstilbestrol [DES]-related anomalies). Müllerian duct lesions usually are found in second-trimester pregnancy loss. Anomalies of the uterine artery with compromised endometrial blood flow are congenital.
  • Acquired lesions are intrauterine adhesions (ie, synechiae), leiomyomas, and possibly, adhesions due to endometriosis.
• Endocrine factors
• • Endocrine factors potentially contribute to recurrent abortion in 10-20% of cases.
  • The most common abnormality contributing to spontaneous abortion is luteal phase insufficiency, which occurs when abnormal corpus luteum function results in insufficient progesterone production.
  • Hypothyroidism, hypoprolactinemia, poor diabetic control, and polycystic ovarian syndrome contribute to pregnancy loss.
• Infectious factors
• • Presumed infectious etiology may be found in 5% of cases.
  • Bacterial, viral, parasitic, fungal, and zoonotic infections are associated with recurrent spontaneous abortion.
• Immunologic factors
• • Immunologic factors may contribute in up to 60% of recurrent spontaneous abortions.
  • Both the developing embryo and the trophoblast may be considered immunologically foreign to the maternal immune system. Antiphospholipid antibody syndrome generally is responsible for more second-trimester pregnancy losses than for first-trimester losses.
• Miscellaneous factors
• • Miscellaneous factors may account for as many as 3% of recurrent spontaneous abortions.
  • Other contributing factors implicated in sporadic and recurrent spontaneous abortions include environment, drugs, placental abnormalities, medical illnesses, and male-related causes.

DIFFERENTIALS

Section 4 of 10  

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

WORKUP

Section 5 of 10  

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

Lab Studies

• Complete blood count with differential
• Blood type and Rh factor
• Qualitative and quantitative human chorionic gonadotropin-beta
• Factor XIII and fibrinogen
• Serum inhibin A was found experimentally as a good predictor of a complete miscarriage; however, it is considered a novel biochemical marker and is not widely used currently.

Imaging Studies

• Ultrasonography
• • This procedure aids identification of retained products of conception, fetal demise, incomplete abortion, ectopic pregnancy, or empty uterus; therefore, it provides a clinically relevant classification of early pregnancy loss.
  • Following spontaneous first-trimester complete abortions, endovaginal ultrasonography has been found 81% sensitive and 94% specific in detection of retained products of conception.
  • An empty uterus noted on endovaginal ultrasound suggests a complete abortion; however, sonographic diagnosis includes ectopic pregnancy and early intrauterine pregnancy. Careful scanning for adnexal masses and/or free fluid is advised.
  • No single ultrasound measurement of the different anatomical features in the first trimester has demonstrated a high predictive value for determining early pregnancy outcome. Recent research suggests the finding of blood flow in the intervillous space in cases of first-trimester miscarriage using color Doppler as useful in the prediction of successful expectant management. Miscarriages with intervillous space blood flow were 4 times more likely to complete with expectant management.

Procedures

• Transabdominal ultrasound of the pelvis provides an overall view of the pelvic structures. A full bladder is required as a sonographic window.
• Endovaginal ultrasound gives a detailed view of the endometrium of the uterus, ovaries, adnexa, and cul-de-sac. An empty bladder is required for optimal imaging.

TREATMENT

Section 6 of 10  

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

Prehospital Care

• Maintain routine universal precautions in view of potentially heavy vaginal bleeding. Emergency medical services (EMS) personnel should be aware of the potential for hemorrhagic shock and should treat any hemodynamic instability.
• Encourage the patient to bring any passed tissue to the hospital for evaluation, if possible.

Emergency Department Care

• Treatment of a patient who has had a complete abortion varies depending upon the degree of certainty of the diagnosis. Diagnosing complete abortion in the ED can be difficult, unless an intact gestational sac was expelled.
• Determine hemodynamic stability and treat instability.
• Establish IV access.
• Make laboratory determination of hematocrit (Hct) level and Rh status.
• Perform ultrasonography to determine uterine (fetal heart activity) or extrauterine contents.
• If pelvic examination produces fetal tissue (or material of similar appearance), send it to the laboratory for identification of possible products of conception.

Consultations

• Consult obstetrics and gynecology (OB/GYN), especially for difficult diagnoses and follow-up care of clearly complete 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 prevent complications.

Drug Category: Immune globulins

These agents suppress immune response and antibody formation.

FOLLOW-UP

Section 8 of 10  

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

Complications

• Potential complications include septic abortion and hypovolemic or septic shock (see Abortion, Complications).
• Preexisting anemia may make patients more susceptible to hypovolemic shock.

Prognosis

• Etiology of previous spontaneous abortion(s) helps determine probability of having a successful pregnancy.
• • Correction of an endocrine abnormality that has caused recurrent abortion increases the probability of having a successful pregnancy. Correction results in successful pregnancy for at least 90% of patients.
  • For women with an unknown etiology of prior pregnancy losses, the probability of achieving successful pregnancies is 40-80%.
  • The live birth rate is approximately 77% for women with 2 or more unexplained spontaneous abortions who have documented fetal cardiac activity at 5-6 weeks' gestation.

Patient Education

• Advise the patient to return to the ED if any of the following symptoms occur.
• • Profuse vaginal bleeding
  • Severe pelvic pain
  • Temperature above 100.4°F
• Patient may experience intermittent menstrual-like flow and cramps during the following week. The next menstrual period usually occurs in 4-5 weeks.
• Patient may resume regular activities when able but should refrain from intercourse and douching for approximately 2 weeks.
• For excellent patient education resources, visit eMedicine's Pregnancy and Reproduction Center and Procedures Center. Also, see eMedicine's patient education articles Miscarriage, Abortion, and Dilation and Curettage (D&C).

MISCELLANEOUS

Section 9 of 10  

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

Medical/Legal Pitfalls

• Endometrial shedding, which clinically simulates miscarriage, may occur with an ectopic pregnancy. This misdiagnosis is the greatest potential pitfall.
• An empty uterus on ultrasonography may represent an ectopic pregnancy.

Special Concerns

• Offer grief counseling to all patients after a miscarriage.

REFERENCES

Section 10 of 10

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

• Abbott J, Emmans LS, Lowenstein SR. Ectopic pregnancy: ten common pitfalls in diagnosis. Am J Emerg Med. Nov 1990;8(6):515-22. [Medline].
• Achiron R, Tadmor O, Mashiach S. Heart rate as a predictor of first-trimester spontaneous abortion after ultrasound-proven viability. Obstet Gynecol. Sep 1991;78(3 Pt 1):330-4. [Medline].
• Albayram F, Hamper UM. First-trimester obstetric emergencies: spectrum of sonographic findings. J Clin Ultrasound. Mar-Apr 2002;30(3):161-77. [Medline].
• Alcazar JL, Baldonado C, Laparte C. The reliability of transvaginal ultrasonography to detect retained tissue after spontaneous first-trimester abortion, clinically thought to be complete. Ultrasound Obstet Gynecol. Aug 1995;6(2):126-9. [Medline].
• Alcazar JL, Ortiz CA. Transvaginal color Doppler ultrasonography in the management of first- trimester spontaneous abortion. Eur J Obstet Gynecol Reprod Biol. Apr 10 2002;102(1):83-7. [Medline].
• Burns WN, Schenken RS. Pathophysiology of endometriosis-associated infertility. Clin Obstet Gynecol. Sep 1999;42(3):586-610. [Medline].
• Elson J, Tailor A, Salim R. Expectant management of miscarriage--prediction of outcome using ultrasound and novel biochemical markers. Hum Reprod. Aug 2005;20(8):2330-3. [Medline].
• Inbal A, Muszbek L. Coagulation factor deficiencies and pregnancy loss. Semin Thromb Hemost. Apr 2003;29(2):171-4. [Medline].
• Jauniaux E, Johns J, Burton GJ. The role of ultrasound imaging in diagnosing and investigating early pregnancy failure. Ultrasound Obstet Gynecol. Jun 2005;25(6):613-24. [Medline].
• Koonin LM, MacKay AP, Berg CJ, et al. Pregnancy-related mortality surveillance--United States, 1987-1990. Mor Mortal Wkly Rep CDC Surveill Summ. Aug 8 1997;46(4):17-36. [Medline].
• Kutteh WH. Recurrent pregnancy loss: an update. Curr Opin Obstet Gynecol. Oct 1999;11(5):435-9. [Medline].
• Lockshin MD. Pregnancy loss in the antiphospholipid syndrome. Thromb Haemost. Aug 1999;82(2):641-8. [Medline].
• Nadukhovskaya L, Dart R. Emergency management of the nonviable intrauterine pregnancy. Am J Emerg Med. Oct 2001;19(6):495-500. [Medline].
• Sauer MV. Pregnancy wastage and reproductive aging: the oocyte donation model. Curr Opin Obstet Gynecol. Jun 1996;8(3):226-9. [Medline].
• Scott JR. Early pregnancy loss. In: Danforth's Obstetrics and Gynecology. 7th ed. Lippincott-Raven Publishers;1994:175-185.
• Scroggins KM, Smucker WD, Krishen AE. Spontaneous pregnancy loss: evaluation, management, and follow-up counseling. Prim Care. Mar 2000;27(1):153-67. [Medline].
• Simpson JL, Mills JL, Holmes LB, et al. Low fetal loss rates after ultrasound-proved viability in early pregnancy. JAMA. Nov 13 1987;258(18):2555-7. [Medline].

Article Last Updated: May 30, 2006