AUTHOR AND EDITOR INFORMATION

Section 1 of 9  

• Authors and Editors
• Introduction
• Differentials
• CT SCAN
• MRI
• Ultrasound
• Intervention
• Multimedia
• References

INTRODUCTION

Section 2 of 9  

• Authors and Editors
• Introduction
• Differentials
• CT SCAN
• MRI
• Ultrasound
• Intervention
• Multimedia
• References

Background

Subchorionic hemorrhage (subchorionic hematoma) is the most common sonographic abnormality in the presence of a live embryo. Vaginal bleeding affects 25% of all women during the first half of pregnancy and is a common reason for first-trimester ultrasonography. Sonographic visualization of a subchorionic hematoma is important in a symptomatic woman because pregnant women with a demonstrable hematoma have a prognosis worse than women without a hematoma. However, small, asymptomatic subchorionic hematomas do not worsen the patient's prognosis.

In women whose sonogram shows a subchorionic hematoma, the outcome of the fetus depends on the size of the hematoma, the mother's age, and the fetus's gestational age. Rates of miscarriage increase with advancing maternal age and increasing size of hematoma. Late first- or second-trimester bleeding also worsens the prognosis.

Related eMedicine topics:
Pregnancy, Postpartum Hemorrhage

Related Medscape topics:
Resource Center  Pregnancy
Resource Center  OB/GYN and Women's Health Nursing
Resource Center  Neonatal Medicine
CME  Stemming the Rising Tide of Prematurity
CME/CE  Misoprostol May Help Prevent Postpartum Hemorrhage 
Abnormal Vaginal Bleeding in Women of Reproductive Age: A Descriptive Study of Initial Management in General Practice
Recurrent Pregnancy Loss

Pathophysiology

The subchorionic hemorrhage (subchorionic hematoma) collects between the uterine wall and the chorionic membrane and may leak through the cervical canal. Later in the first trimester and early second trimester, the subchorionic hematoma may partially strip the developing placenta away from its attachment site. Therefore, the prognosis of patients with this type of hematoma is worse than the prognosis of patients with hematoma early in first trimester¹ (see Images 2-3).

The subchorionic hematoma often regresses, especially if it is small or moderate in size. Large hematomas, which strip at least 30-40% of placenta away from endometrium, may enlarge further, compressing the gestational sac and leading to premature rupture of membranes with consequent spontaneous abortion.

Frequency

United States

The incidence of subchorionic hemorrhage (subchorionic hematoma) is 1.3% of all pregnancies. In pregnant patients with first-trimester vaginal bleeding, the incidence increases to almost 20%. Bennett et al² reported a spontaneous abortion rate of 9.3% in patients with first-trimester vaginal bleeding who had a live fetus and subchorionic hematoma. Overall, hematoma is associated with a 4-33% rate of miscarriage depending on the gestational age when the complication occurs.

Mortality/Morbidity

• The presence of sonographically detected subchorionic hemorrhage (subchorionic hematoma) increases the risk of miscarriage, stillbirth, abruptio placentae, and preterm labor.
• The rate of spontaneous abortion directly varies with the size of subchorionic hematoma and the mother's age. The rate of spontaneous abortion is inversely related to gestational age. The frequency of fetal demise is higher with retroplacental hematoma than with marginal subchorionic hematoma.

Race

No significant racial differences have been reported with subchorionic hemorrhage (subchorionic hematoma).

Age

Bennett et al² reported that the spontaneous abortion rate in women aged 35 years or older is twice as high as that in younger women. After age 35 years, the first-trimester miscarriage rate reflects maternal age.

Anatomy

Before the fertilized ovum reaches the uterus, the mucous membrane of the body of the uterus increases in vascularity and thickness; it is then called the decidua. The part that covers the ovum is named the decidua capsularis. The portion that intervenes between the ovum and the uterine wall is named the decidua basalis; the placenta subsequently develops here. A small amount of bleeding may result from the implantation of the fertilized ovum in the first trimester.

The chorion consists of 2 layers: an outer layer formed by the trophoblast and an inner layer formed by the somatic mesoderm. The trophoblast undergoes rapid proliferation and forms numerous processes called chorionic villi, which invade the uterine decidua and simultaneously absorb from it nutritive materials for embryonic growth. The chorionic villi increase in size and ramify, while the mesoderm, which carries branches of the umbilical vessels, grows into them; in this way, they are vascularized. Branches of the umbilical arteries carry blood to the villi. After circulating through the capillaries of the villi, the umbilical veins return blood to the embryo.

The placenta connects the fetus to the uterine wall and is the organ by which the nutritive, respiratory, and excretory functions of the fetus are performed. The placenta is composed of fetal and maternal portions. The fetal portion consists of the villi of the chorion, and the maternal portion is formed by the decidua placentalis containing the intervillous space.

Chorionic separation from its site of endometrial attachment can lead to hemorrhaging (hematomas) in various locations in the vicinity of its original implantation. These hematomas are referred to as marginal subchorionic hematomas, in which only the placental margin is separated; retroplacental hematoma, in which bleeding is behind the placenta; and subamniotic (preplacental) hemorrhage, in which a hematoma collects anterior to the placenta and is limited by the umbilical cord.³

Subchorionic hemorrhage (hematoma) is the most common, and preplacental hematoma is the rarest. The incidence of retroplacental hematoma increases in the third trimester.

Clinical Details

Most patients with a small subchorionic hemorrhage (subchorionic hematoma) in the first trimester are asymptomatic.⁴ Common manifestations of subchorionic hematoma are idiopathic premature labor, painless vaginal bleeding, abdominal pain, and threatened abortion in the first or second trimesters.⁵

Symptoms of third-trimester placental abruption, observed in approximately 1% of gestations, are vaginal bleeding, a painful and tense uterus, fetal distress,⁶ and disseminated intravascular coagulation. Marginal abruptions are more common than retroplacental abruptions in women with mild clinical symptoms.

Preferred Examination

Ultrasonography is the imaging modality of choice for subchorionic hemorrhage (subchorionic hematoma) because it can be performed rapidly at the patient's bedside and because it has no known risk, as with radiation.^{7, 8}

Limitations of Techniques

The sensitivity of sonography is low and varies between 2% and 20%, as blood may pass vaginally and not collect in the subchorionic space. Hematomas may also appear isoechoic relative to the placenta.

DIFFERENTIALS

Section 3 of 9  

• Authors and Editors
• Introduction
• Differentials
• CT SCAN
• MRI
• Ultrasound
• Intervention
• Multimedia
• References

Other Problems to be Considered

Focal myometrial contraction (see Image 8)
Chorioamnionic separation (see Image 5)
Intra-amniotic hemorrhage (see Image 10)
Umbilical-cord hematoma
Prominent retroplacental veins (see Images 4, 11-13)
Empty gestation sac in a twin pregnancy (see Image 8)

CT SCAN

Section 4 of 9  

• Authors and Editors
• Introduction
• Differentials
• CT SCAN
• MRI
• Ultrasound
• Intervention
• Multimedia
• References

Findings

CT scanning is relatively contraindicated during pregnancy because of the risk of radiation to the fetus. Pregnant patients may undergo CT for reasons such as an evaluation of trauma or acute abdomen. Scans may show an incidental or injury-related hyperattenuating subchorionic hemorrhage (subchorionic hematoma).

Degree of Confidence

The sensitivity of CT may be high compared with that of sonography. However, because of the risk of radiation with CT, no large comparisons of the 2 modalities have been reported.

False Positives/Negatives

Normal chorioamniotic separation should not be confused with placental abruption.

MRI

Section 5 of 9  

• Authors and Editors
• Introduction
• Differentials
• CT SCAN
• MRI
• Ultrasound
• Intervention
• Multimedia
• References

Findings

MRI is not routinely performed to detect subchorionic hemorrhage (subchorionic hematoma); a more common indication is the detection of fetal anomalies.⁹ MRI may incidentally show a subchorionic hematoma and help in characterizing and determining the acuity of the hematomas by showing changes in signal intensity produced by various blood products. T1-weighted spin-echo and gradient-echo images are particularly useful in evaluating the hemorrhage.

Degree of Confidence

Fetal motion sometimes limits MRI. However, the observer can confidently determine the age of the blood products.

ULTRASOUND

Section 6 of 9  

• Authors and Editors
• Introduction
• Differentials
• CT SCAN
• MRI
• Ultrasound
• Intervention
• Multimedia
• References

Findings

Acute subchorionic hemorrhages (subchorionic hematomas) vary in echogenicity and are seen between the chorion and the uterine wall on sonograms (see Images 1-7). Isoechoic hematomas may be missed on initial sonograms, or they may be recognized as heterogeneous and thickened placentas.

Color Doppler sonography may help in distinguishing the avascular hematoma from the highly vascular placenta. Follow-up sonography may also help in resolving hematomas.

A subchorionic hematoma can be considered large if it is greater than 50% of the size of the gestation sac, medium if it is 20-50%, and small if it is less than 20%. Large hematomas by size (>30-50%) and volume (>50 mL) worsen the patient's prognosis.

Hematomas may resolve over 1-2 weeks. During this time, they may be seen as complex fluid collections with mixed echogenicity. In addition, sonographic findings also confirm fetal viability¹⁰ and can help in differentiating and diagnosing other conditions associated with miscarriage in the first trimester, such as ectopic pregnancy, blighted ovum, and twin gestation.

Degree of Confidence

Ultrasonography lacks high sensitivity for small bleeds. However, it is the most useful modality in a pregnant patient with vaginal bleeding. The finding of a subchorionic or retroplacental hematoma as demonstrated on sonography performed immediately after an episode of vaginal bleeding indicates a prognosis worse than that expected if no hematoma were seen.

False Positives/Negatives

Uterine fibroids or focal myometrial contractions (see Image 8) can cause the placenta to appear thickened, or they may look like subchorionic or retroplacental hematomas. Hematomas are avascular on color Doppler scanning. Fibroids have a characteristic hypoechoic appearance with or without calcifications and typical peripheral blood flow in color Doppler images. Color flow is seen in contracted myometrium, and transient myometrial contractions usually resolve within 30 minutes of scanning.

Chorioamniotic separation has an anechoic appearance and usually resolves by 16 weeks. It can be distinguished from an anechoic hematoma by finding elevation of the membrane in chorioamniotic separation that extends over the fetal surface of the placenta and that terminates at the origin of the umbilical cord. The amniotic membrane is also thinner than the chorionic membrane (see Image 5).

Primary intra-amniotic hemorrhage can occur with a large subchorionic hematoma, with trauma, or with an invasive procedure such as chorionic villous sampling¹¹ or amniocentesis. Floating echoes (see Image 10) or echogenic clots may be seen in the amniotic cavity.

Hematomas of the umbilical cord are rare and may result from amniocentesis and sampling of blood from the umbilical cord. These hematomas are seen as echogenic masses limited to the cord itself.

Prominent retroplacental and myometrial vessels should be distinguished from heterogeneous bleeding. The vessels appear as serpentine, anechoic structures and demonstrate flow on color Doppler sonography (see Images 4, 11-13); these features differentiate them from avascular hematomas.

INTERVENTION

Section 7 of 9  

• Authors and Editors
• Introduction
• Differentials
• CT SCAN
• MRI
• Ultrasound
• Intervention
• Multimedia
• References

Bed rest is usually advised for patients with first-trimester bleeding, and serial ultrasonography may be performed as clinically indicated to monitor fetal viability and the size of the hematoma.

Medical/Legal Pitfalls

• Isoechoic hematomas should be suspected in cases of first-trimester bleeding with a thickened and heterogeneous placenta.
• Follow-up ultrasonography should be performed as clinically indicated.

MULTIMEDIA

Section 8 of 9  

• Authors and Editors
• Introduction
• Differentials
• CT SCAN
• MRI
• Ultrasound
• Intervention
• Multimedia
• References

Media file 1:  Transverse endovaginal scan of the uterus in a 45-year-old woman in eighth week of gestation. Small subchorionic hematoma is anterior to a gestational sac.
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Media file 2:  Sagittal endovaginal scan of the uterus in a 19-year-old woman in 20th week of gestation demonstrates a small anterior subchorionic hematoma adjacent to the lower edge of the placenta.
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Media file 3:  Transverse scan demonstrates a hematoma in the same patient as in Image 2.
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Media file 4:  Sagittal endovaginal scan of the uterus demonstrates a small subchorionic hematoma (red arrow) in a 26-year-old woman in the seventh week of gestation. Also note the prominent retroplacental veins (blue arrow), which are normally in pregnancy.
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Media file 5:  Transverse endovaginal scan of the uterus in 45-year-old woman in the 13th week of a dichorionic-diamniotic twin pregnancy demonstrates an anterior subchorionic hematoma (cursors). Also note the normal chorioamniotic separation in the posterior sac.
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Media file 6:  Sagittal endovaginal scan of the uterus in 37-year-old woman in the 13th week of a dichorionic-diamniotic twin pregnancy demonstrates an anterior subchorionic hematoma.
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Media file 7:  Sagittal endovaginal scan in the same patient as in Image 6 shows extension of the hematoma in the intertwin membrane cleft, where the 2 placentas fuse.
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Media file 8:  Sagittal endovaginal scan of a dichorionic-diamniotic twin pregnancy in the 13th week of gestation in a 45-year-old woman. An empty gestation sac mimics a subchorionic collection (red arrow). Also note the transient uterine contraction (yellow arrow).
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Media file 9:  Sagittal endovaginal scan of the uterus in a 29-year-old woman in 9th week of gestation demonstrates nonfusion and separation of chorion and amnion.
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Media file 10:  Transverse endovaginal scan in a 29-year-old woman in 21st week of gestation demonstrates intra-amniotic hemorrhage as fine echoes dispersed in the amniotic fluid.
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Media file 11:  Sagittal gray-scale endovaginal scan (top) of the uterus in a 16-year-old mother in 25th week of gestation demonstrates a hypoechoic area adjacent to the lower edge of the placenta; this finding suggests a small subchorionic hematoma. However, color Doppler scan (bottom) at the same level confirms that this finding represents prominent vessels mimicking a subchorionic hematoma.
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Media file 12:  Sagittal endovaginal gray-scale scan in a 21-year-old woman in 33rd week of pregnancy demonstrates prominent retroplacental vessels mimicking a retroplacental hematoma.
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Media file 13:  Color Doppler scan in a 21-year-old woman in 33rd week of pregnancy (same patient as in Image 12) demonstrates prominent retroplacental vessels mimicking a retroplacental hematoma.
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REFERENCES

Section 9 of 9

• Authors and Editors
• Introduction
• Differentials
• CT SCAN
• MRI
• Ultrasound
• Intervention
• Multimedia
• References

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2. Bennett GL, Bromley B, Lieberman E, Benacerraf BR. Subchorionic hemorrhage in first-trimester pregnancies: prediction of pregnancy outcome with sonography. Radiology. Sep 1996;200(3):803-6. [Medline].
3. Nagy S, Bush M, Stone J, et al. Clinical significance of subchorionic and retroplacental hematomas detected in the first trimester of pregnancy. Obstet Gynecol. Jul 2003;102(1):94-100. [Medline].
4. Trop I, Levine D. Hemorrhage during pregnancy: sonography and MR imaging. AJR Am J Roentgenol. Mar 2001;176(3):607-15. [Medline].
5. Hodgson DT, Lotfipour S, Fox JC. Vaginal bleeding before 20 weeks gestation due to placental abruption leading to disseminated intravascular coagulation and fetal loss after appearing to satisfy criteria for routine threatened abortion: a case report and brief review of the literature. J Emerg Med. May 2007;32(4):387-92. [Medline].
6. Yoshida S, Kikuchi A, Sunagawa S, Takagi K, Ogiso Y, Yoda T, et al. Pregnancy complicated by diffuse chorioamniotic hemosiderosis: obstetric features and influence on respiratory diseases of the infant. J Obstet Gynaecol Res. Dec 2007;33(6):788-92. [Medline].
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8. Ball RH, Ade CM, Schoenborn JA, Crane JP. The clinical significance of ultransonographically detected subchorionic hemorrhages. Am J Obstet Gynecol. Mar 1996;174(3):996-1002. [Medline].
9. Gupta R, Sharma R, Jain T, Vashisht S. Antenatal MRI diagnosis of massive subchorionic hematoma: a case report. Fetal Diagn Ther. 2007;22(6):405-8. [Medline].
10. Poulose T, Richardson R, Ewings P, Fox R. Probability of early pregnancy loss in women with vaginal bleeding and a singleton live fetus at ultrasound scan. J Obstet Gynaecol. Nov 2006;26(8):782-4. [Medline].
11. Akhlaghpoor S, Tomasian A. Safety of chorionic villus sampling in the presence of asymptomatic subchorionic hematoma. Fetal Diagn Ther. 2007;22(5):394-400. [Medline].
12. Johns J, Hyett J, Jauniaux E. Obstetric outcome after threatened miscarriage with and without a hematoma on ultrasound. Obstet Gynecol. Sep 2003;102(3):483-7. [Medline].
13. Kurjak A, Schulman H, Zudenigo D, et al. Subchorionic hematomas in early pregnancy: clinical outcome and blood flow patterns. J Matern Fetal Med. Jan-Feb 1996;5(1):41-4. [Medline].
14. Nyberg DA, Cyr DR, Mack LA, et al. Sonographic spectrum of placental abruption. AJR Am J Roentgenol. Jan 1987;148(1):161-4. [Medline].
15. Pearlstone M, Baxi L. Subchorionic hematoma: a review. Obstet Gynecol Surv. Feb 1993;48(2):65-8. [Medline].
16. Pedersen JF, Mantoni M. Prevalence and significance of subchorionic hemorrhage in threatened abortion: a sonographic study. AJR Am J Roentgenol. Mar 1990;154(3):535-7. [Medline].
17. Richards DS, Bennett BB. Prenatal ultrasound diagnosis of massive subchorionic thrombohematoma. Ultrasound Obstet Gynecol. May 1998;11(5):364-6. [Medline].

Article Last Updated: Jul 24, 2008