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Missed Abortion
Article Last Updated: Oct 9, 2008
AUTHOR AND EDITOR INFORMATION
Section 1 of 11  
Author: James L Lindsey, MD, Staff Physician, Santa Clara Valley Medical Center, Affiliated Clinical Associate Professor, Stanford School of Medicine, Department of Obstetrics and Gynecology, Santa Clara Valley Medical Center
James L Lindsey is a member of the following medical societies: American College of Obstetricians and Gynecologists, American Institute of Ultrasound in Medicine, American Society for Colposcopy and Cervical Pathology, and California Medical Association
Coauthor(s):
Veronica R Rivera, MD, Staff Physician, Department of Obstetrics and Gynecology, Santa Clara Valley Medical Center
Editors: 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; Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine; 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; Frederick B Gaupp, MD, Consulting Staff, Department of Family Practice, Hancock Medical Center; Michel E Rivlin, MD, Professor, Coordinator, Quality Assurance/Quality Improvement, Department of Obstetrics and Gynecology, University of Mississippi School of Medicine
Author and Editor Disclosure
Synonyms and related keywords:
blighted ovum, anembryonic pregnancy, anembryonic gestation, pregnancy failure prior to 20 weeks gestation, spontaneous abortion, early pregnancy failure, fetal demise, mifepristone, Mifeprex, RU 486, RU-486, RU486, misoprostol, fetal chromosomal abnormalities, maternal disease, embryonic anomalies, placental abnormalities, uterine anomalies, ectopic pregnancy, intrauterine pregnancy
Background
Missed abortion refers to the clinical situation in which an intrauterine pregnancy is present but is no longer developing normally. This can manifest as an anembryonic gestation (empty sac or blighted ovum) or with fetal demise prior to 20 weeks' gestation. The gestation is termed a missed abortion only if the diagnosis of incomplete abortion or inevitable abortion is excluded (ie, the cervical os is closed). Before widespread use of ultrasonography, the term missed abortion was applied to pregnancies with no uterine growth over a prolonged period of time, typically 6 weeks. Some authorities think that more specific descriptive terms should be used; however, the term missed abortion is still widely used among clinicians and is a commonly used indexing term for MEDLINE and other resources.
For further information, see Medscape's Pregnancy Resource Center.
Pathophysiology
Causes of missed abortion are generally the same as those causing spontaneous abortion or early pregnancy failure. Causes include anembryonic gestation (blighted ovum), fetal chromosomal abnormalities, maternal disease, embryonic anomalies, placental abnormalities, and uterine anomalies. Virtually all spontaneous abortions are preceded by missed abortion. A rare exception is expulsion of a normal pregnancy because of a uterine abnormality.
Frequency
United States
Frequency closely correlates with frequency of failed pregnancy in general. In clinically recognized pregnancies, spontaneous abortion occurs in up to 15% of cases. The rate is much higher for preclinical pregnancies. Diagnosis is made much more frequently because of increased use of early ultrasonography.
Mortality/Morbidity
- Associated morbidity is similar to that associated with spontaneous abortion and includes bleeding, infection, and retained products of conception.
- Previously, before the diagnosis of fetal demise could be made and before the condition could be treated easily, disseminated intravascular coagulation (DIC) syndrome associated with prolonged retention of a dead fetus (>6-8 wk) was reported. With early diagnosis and treatment, DIC is extremely rare.
Race
Incidence is similar among all races.
Age
Pregnancy failure rates increase with age and rise significantly in women older than 40 years.
History
History is of limited value. Obtaining information about when and how the pregnancy was first diagnosed, any human chorionic gonadotropin (hCG) tests or prior ultrasounds, and if abatement of symptoms of pregnancy has occurred may help the diagnosis of missed abortion.
Physical
- Physical examination is of limited value.
- A uterus that is small for dates or not increasing in size suggests missed abortion.
- Vaginal bleeding is suggestive of missed abortion.
- Loss of fetal heart tones or inability to obtain heart tones at the appropriate time leads to suspicion of the diagnosis.
Causes
Causes of missed abortion are generally the same as those causing spontaneous abortion or early pregnancy failure. Causes include anembryonic gestation (blighted ovum), fetal chromosomal abnormalities, maternal disease, embryonic anomalies, placental abnormalities, and uterine anomalies.
Ectopic Pregnancy
Hydatidiform Mole
Other Problems to be Considered
Normal intrauterine pregnancy
Complete spontaneous abortion
Incomplete abortion
Inevitable abortion
Multiple gestation
Lab Studies
Lab studies for missed abortion include the following: - Quantitative hCG levels
- Quantitative hCG levels are useful for very early pregnancy evaluation when no sac is visible in the uterus on sonogram.
- If suspicion of ectopic pregnancy exists, levels should be obtained at 48-hour intervals until the discriminatory level is reached. The discriminatory level of hCG is the level at which an intrauterine pregnancy should always be visible on vaginal probe ultrasonography. In most institutions, this is about 1500-2000 mIU/mL when standardized to the International Reference Preparation (IRP).
- Once the sac is clearly observed in the uterus, lower-than-expected levels of hCG or progesterone increase the possibility for abnormal pregnancy but are not diagnostic. Therefore, imaging studies are the studies of choice.
- Coagulation studies are generally not indicated prior to evacuation of the uterus.
- Documenting Rh status and treating appropriately if the woman is Rh negative is important.
Imaging Studies
- Ultrasonography
- Once the hCG level has reached the discriminatory level, vaginal ultrasonography replaces blood tests as the primary means of evaluation.
- If a true intrauterine gestational sac is observed, ectopic pregnancy is ruled out. For naturally conceived pregnancies, the coexistence of ectopic and intrauterine pregnancy is extremely rare (1 out of 30,000 pregnancies). However, with assisted reproduction technology, consider the coexistence of an ectopic and intrauterine pregnancy.
- After a sac has been demonstrated in the uterus, the next step is to determine if the pregnancy is normal or abnormal. Transvaginal ultrasonography is the best imaging procedure to evaluate intrauterine contents.
- While some ultrasonography criteria strongly support the diagnosis, most patients and physicians prefer to use repeat ultrasonography to confirm that the pregnancy is a missed abortion and not simply an early normal pregnancy. In most cases, a repeat ultrasonography in 1 week confirms lack of progressive development. In the case of a very early pregnancy where the sac diameter is less than 5-6 mm, repeating the study in 10-14 days may be more effective.
- Serial ultrasonography is unnecessary if ultrasonography reveals loss of previously documented heart activity.
- Transvaginal ultrasonography criteria that strongly suggest embryonic demise include a crown-rump length that is greater than 5 mm without cardiac activity. The criterion that suggests a blighted ovum is a mean gestational sac diameter greater than 16 mm with absence of embryo or a mean gestational sac diameter greater than 8 mm and no yolk sac.
Other Tests
More extensive tests, such as chromosomal analysis, are not usually indicated. However, in cases of recurrent losses, karyotyping of the parents can be useful.
Procedures
Histologic Findings
Histologic findings are similar to that of spontaneous abortion. Varying amounts of placental and/or fetal tissue should be present and are usually reported as products of conception.
Expectant management
Expectant waiting is an alternative to medical or surgical treatment for first trimester missed abortion. A recent Cochrane review found that although expectant management resulted in an increased incidence of returning tissue, bleeding, and unplanned surgical intervention, it was a reasonable alternative for women to did not wish to undergo other therapy.1
Medical Care
The most common medical regimen used to evacuate the uterus is 400-800 mcg per vagina of misoprostol (Cytotec) in single or multiple doses. Although misoprostol is commonly used for this indication, technically it is an "off label" use of the medication. Trials have found success rates ranging from 70-90%. Some studies show that oral misoprostol is also an option. Sublingual administration has equivalent efficacy to vaginal misoprostol, and this method has become more popular. Other medical agents, such as mifepristone (RU-486), have been used in combination with misoprostol, but studies have failed to show increased efficacy. The addition of mifepristone also substantially increases the expense.
Surgical Care
Surgical evacuation has been the standard of care in treating missed abortion, with suction curettage being the most common method. This procedure is typically performed in an outpatient setting. Advantages to surgical evacuation include immediate and definitive treatment with fewer medical visits. However, with the increasing experience with medical abortion, more missed abortions are being terminated with misoprostol.
Although the risk of Rho(D) alloimmunization is minimal following missed abortion, anti-D immune globulin should be administered to women who are Rho(D) negative. This is not necessary if the father is Rho(D) negative.
Drug Category: Immunoglobulins
May decrease autoantibody production and increase solubilization and removal of immune complexes.
| Drug Name | Rho(D) immune globulin (RhoGAM) |
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| Description | Suppresses immune response of nonsensitized Rho(D)-negative mothers exposed to Rho(D)-positive blood from the fetus as a result of a fetomaternal hemorrhage, abdominal trauma, amniocentesis, abortion, full-term delivery, or transfusion accident. |
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| Adult Dose | <13 weeks' gestation: 50 mcg IV within 3 h, but may administer within 72 h
>13 weeks' gestation: 300 mcg IV |
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| Pediatric Dose | Administer as in adults |
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| Contraindications | Documented hypersensitivity; patients who have received Rho(D)-positive blood within last 3 mo |
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| Interactions | None reported |
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| Pregnancy | C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus
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| Precautions | Caution in thrombocytopenia, bleeding disorders, or IgA deficiency |
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Drug Category: Prostaglandins
Used for cervical ripening and termination of pregnancy.
| Drug Name | Misoprostol (Cytotec) |
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| Description | Not approved for use in pregnancy, yet is an invaluable medication widely used for cervical preparation for abortion, labor induction, and as a medical abortifacient. Provides safe, passive method of cervical dilatation and should be considered for preabortion ripening when prior uterine surgery (ie, LEEP, C-section) are known risk factors for uterine perforation during surgical abortion. Can be administered orally or vaginally. Some studies show premoistening tablets placed vaginally helps absorption. Patients can be instructed in self-administration to help time the dose in synchrony with their abortion procedure.
In a study by Singh of primigravid women (6-11 wk gestation), 93.3% achieved dilatation of the cervix of 8 mm or greater after 3 h postintravaginal misoprostol 400 mcg, whereas only 16.7% of women achieved this after 2 h of 600 mcg. The 600-mcg group had slightly greater adverse effects (eg, bleeding, abdominal pain, fever >38șC). Dosage intended for cervical ripening can induce abortion in some patients. Oral doses of 100-400 mcg can be combined with vaginal insertion of prostaglandins to enhance cervical dilatation. |
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| Adult Dose | Cervical ripening: 25-100 mcg (vaginally) for term pregnancies, lower doses may need to be repeated q4-6h
Termination: 200-800 mcg, most patients do not need repeat dosing for 24 h |
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| Pediatric Dose | Not established |
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| Contraindications | Documented hypersensitivity |
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| Interactions | None reported |
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| Pregnancy | X - Contraindicated; benefit does not outweigh risk
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| Precautions | Caution in renal impairment and the elderly |
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Further Outpatient Care
- Rho(D)-negative patients should receive anti-D immunoglobulin after a missed abortion.
- Emotional support and education are important. Assist the patient through the grieving process.
- For patients who experience a fetal death in the second trimester, allowing them to see, hold, or photograph the fetus as would be offered after later fetal death may be helpful (see Evaluation of Fetal Death).
- Assure the patient that the prognosis for normal pregnancy in the future is excellent.
Complications
- Complications are rare and are usually associated with the uterine evacuation process. Retained products of conception can occur after medical or surgical evacuation but are more common after medical treatment. Infection and blood loss can occasionally occur after evacuation.
- If a fetal demise occurs and the dead fetus is carried for more than 4 weeks, fibrinogen levels can decrease and (rarely) cause bleeding problems.
- Uterine perforation and uterine synechiae are very rare complications of uterine curettage.
Prognosis
- Prognosis for future pregnancy is excellent. Most women do not have problems conceiving and carrying a future pregnancy. Approximately 80-90% of patients who have a single spontaneous abortion subsequently deliver a viable fetus with the next pregnancy.
- For rare patients with missed abortion and 2 or more other early pregnancy losses, prognosis is somewhat poorer and further evaluation is needed. Such a workup would include searching for evidence of the antiphospholipid syndrome and thrombophilic disorders, and/or chromosomal karyotyping.
Patient Education
- Depending on the patient, discussing in detail the pathophysiology of spontaneous abortion may be appropriate. Assure the patient that the pregnancy failure was not the result of some activity on her part.
- In most cases, the patient's primary concern is her fertility. Prognosis for future pregnancy is excellent. Most women do not have problems conceiving and carrying a future pregnancy. Reassure the patient accordingly.
- 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).
Medical/Legal Pitfalls
- The primary medicolegal pitfall in the diagnosis and management of missed abortion is the failure to recognize an ectopic pregnancy. Usually, findings on the sonogram confirm that the pregnancy is intrauterine. However, in rare instances, a pseudosac consisting of retained blood clot exists and can be confused with a missed abortion. In cases in which the sonogram does not clearly show a well-developed sac, ectopic precautions should be continued until evacuated products of conception are documented by pathologic examination. In the case of pregnancy resulting from artificial reproductive technology, a coexisting ectopic pregnancy should always be a consideration.
- A second medicolegal pitfall is misdiagnosis of an early normal pregnancy as a missed abortion. This eventuality can be prevented by use of serial ultrasonographic studies.
| Media file 1:
Second transvaginal sonogram obtained 1 week after the initial study fails to demonstrate fetal development. This confirms the diagnosis of an embryonic pregnancy. |
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Media type: Image
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Missed Abortion excerpt Article Last Updated: Oct 9, 2008
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