Subchorionic Hematoma Size Guide report

Subchorionic hematoma is a frequently observed pathological phenomenon during routine ultrasonography in the first trimester. Since subchorionic hematoma was first reported in the literature in 1981, it has become a hot spot in the field of pregnancy pathology, and many related studies have been published one after another.

Studies have shown that there is little increase in the risk of miscarriage if the size of the subchorionic hematoma is small. However, as the size of the hematoma increases, the risk of miscarriage increases gradually.

Currently, there are various methods for evaluating the size of the hematoma, including the subjective evaluation method, subchorionic hematoma area/gestational sac area ratio method, and volume calculation method. However, none of these methods are well-recognized and harmonized, making it impossible to accurately observe hematoma progression and compare hematoma sizes in different pregnancies. Let's learn more about the general size of subchorionic hematoma.

Subchorionic Hematoma Size Guide

Subchorionic hematoma (SCH) refers to the accumulation of blood in the subchorionic area between the gestational sac due to leaflet chorionic hemorrhage. The hematoma is separated from the uterine cavity by at least the decidua, not in the uterine cavity. Still, it is a blood collection (hematoma) between the chorion and the uterine wall. Subchorionic hematoma occurs in approximately 3.1% of early pregnancies, and it is the most common ultrasound abnormality and cause of bleeding during early pregnancy.

One of the important indicators for evaluating a subchorionic hematoma is size. The following four methods are used to assess the size of the hematoma.

  1. Subjective evaluation: use small, medium, and large to describe;
  2. Subchorionic hematoma area/gestational sac area ratio: use ≤10%, 11%-25%, 26%-50%, and >50% to describe;
  3. Subchorionic hematoma surrounded by gestational sac ratio: described by ≤10%, 11%-25%, 26%-50%, and >50%;
  4. Volume calculation: 3 vertical diameters of the hematoma were measured by ultrasound.

Subchorionic Hematoma Size Chart

According to the proportion of the hematoma to the circumference of the gestational sac, if the length of the subchorionic hematoma is less than 20% of the circumference of the gestational sac, it is a small hematoma; 20% to 50% is medium-sized, and>50% is large.

SCH SizeCompared With the circumference of the gestational sac
Smalllength is less than 20%
Mediumlength is about 20% to 50%
Largelength is more than 50%

Sonographic appearance and diagnosis

The sonographic appearance of subchorionic hematoma is that the fluid collects between the gestational sac and the uterine wall, which can be in various shapes, crescent or round. The shape of the fluid depends on the morphological changes of the uterus. It is important to note the echogenicity of the hematoma. The echo level of the hematoma is related to the bleeding time. There are differences in the echo performance of hematoma after different bleeding times:

  1. Acute hematoma (0-48 h): the echo of the hematoma is higher than the gestational sac wall or phyllodes chorion.
  2. Subacute stage of hematoma (3-7 days): The echo of hematoma is similar to that of the gestational sac wall or phyllodes chorion, and the echo performance in the hematoma tends to be complex, such as fibrous band-like, lump-like and so on.
  3. The chronic phase of hematoma (>7 days): The hematoma is low or anechoic.

Conclusion

In most cases, the hematoma gradually decreases in size on follow-up and can resolve over 1-2 weeks. A subchorionic hemorrhage places the gestation at an increased risk of placental abruption or preterm labor. Only about 20% of subchorionic hematomas can be accompanied by clinical symptoms of vaginal bleeding and lower abdominal pain. At the same time, most of the rest have no obvious clinical symptoms and signs, so symptoms and signs cannot be used to evaluate the severity of subchorionic hematoma. Ultrasonography is the preferred diagnostic modality. You should contact your doctor for more advice and treatments if you have been diagnosed with a subchorionic hematoma.


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