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What is the appearance of a hematoma on an Ultrasound?
Hematomas are usually spherical or ovoid within the abdomen, and lentiform within the pleural space or abdominal wall.
They generally decrease in size with time, and usually have irregular walls. Hematomas contain a variable amount of internal echoes during the first month, and then gradually become anechoic.
The sonographic appearance is not specific; an abscess may have a similar appearance. An old, anechoic hematoma may contain a gelatinous material which cannot be aspirated.
On an ultrasound, a hematoma typically appears as a localized collection of blood within a tissue or organ. The appearance of a hematoma on ultrasound can vary depending on the age of the hematoma and the characteristics of the surrounding tissue. Here are some typical ultrasound findings for a hematoma:
- Echogenicity: In the acute phase, a hematoma may appear hypoechoic (darker) compared to the surrounding tissues due to the presence of fresh, liquid blood. As the hematoma progresses and undergoes changes, it may become more echogenic (brighter) and have a heterogeneous appearance.
- Shape and Margins: Hematomas can have various shapes and sizes depending on the location and extent of the bleeding. They may have irregular or well-defined margins, depending on the stage and organization of the hematoma.
- Fluid Collection: Hematomas often appear as fluid-filled collections on ultrasound. The size and shape of the fluid collection can help assess the extent of the hematoma.
- Doppler Imaging: Using Doppler ultrasound, blood flow within and around the hematoma can be evaluated. In the acute phase, there may be increased vascularity due to active bleeding. As the hematoma evolves and resolves, the vascularity may decrease.
- Surrounding Tissue Displacement: Depending on the location and size of the hematoma, it may cause displacement or compression of adjacent structures, such as blood vessels, organs, or tissues. This displacement can be visualized on ultrasound.
It’s important to note that the appearance of a hematoma on ultrasound can vary based on multiple factors, including the age of the hematoma, location in the body, and the specific characteristics of the ultrasound machine used. The interpretation of the ultrasound findings is best performed by a qualified healthcare professional, such as a radiologist or sonographer, who can correlate the ultrasound findings with the patient’s clinical history and perform further evaluation if necessary.
A hematoma may have a variety of appearances on an Ultrasound depending on when it is imaged.
If imaged acutely, a hematoma often appears as an ill-defined but predominantly hyperechoic collection.
A hematoma starts to resorb from the periphery inward, becoming smaller and more echogenic.
In the end, a residual anechoic fluid collection or seroma may persist indefinitely.
A subacute hematoma becomes more hypoechoic, although a heterogeneous appearance is common.
Hematoma of the liver usually results from trauma and is caused by bleeding into a tissue laceration. Iatrogenic causes, such as percutaneous needle biopsy, interventional radiology procedures involving catheters or wires, and biliary lithotripsy, are often involved.
Hepatic hematomas arising from spontaneous bleeding are rare. Hepatic hematoma appears as a well‐defined, round (intraparenchymal hematomas), or curvilinear (subcapsular hematomas) mass.
What does research says about Appearance of a hematoma on an Ultrasound?
Latest Scientific Evidence on Ultrasound Appearance of Hematomas
The ultrasound appearance of hematomas is a critical diagnostic feature that helps clinicians identify, characterize, and manage these collections effectively. Recent evidence demonstrates that hematoma appearance varies based on the stage of evolution, and this characterization guides clinical management decisions.
Sonographic Classification System
Current ultrasound practice classifies hematomas into four primary echotexture categories based on their internal appearance:
Hypoechoic hematomas account for approximately 23% of musculoskeletal hematomas and represent predominantly fluid collections with minimal echogenic content. These appear dark on ultrasound, indicating relatively homogeneous liquid blood products. Hypoechoic hematomas are significantly easier to aspirate compared to other appearances, with an odds ratio of 3.77 when compared to complex, heterogeneous, and echogenic hematomas combined (p=0.010p=0.010).
Complex hematomas represent 35.8% of musculoskeletal hematomas and are characterized by internal septations, creating compartmentalized fluid collections. These hematomas have a distinct geometric mean age of 5.64 days, making them approximately 60% younger than other echotexture types (p=0.058p=0.058). The presence of septations suggests active clot organization and membrane formation.
A study report retrospectively reviewed 2 cases of organizing hematomas and 2 cases of intravascular organizing thrombi and investigated correlations between sonographic and pathologic findings. In all 4 cases, a well-defined hypoechoic heterogeneous mass with surrounding increased echogenicity was evident in the subcutaneous fat layer.
Organizing hematomas and thrombi have sonographic features similar to those of benign-looking soft tissue tumors. These lesions should therefore be considered in the differential diagnosis of superficial soft tissue masses.
Recent studies confirm that hematoma echogenicity on B-mode ultrasound varies widely and is not reliably predictable by age alone, though certain trends can guide interpretation and management.
1. Variable Echotexture Unrelated to Hematoma Age
A cohort study of 148 patients undergoing ultrasound-guided aspiration found no significant correlation between hematoma age and its sonographic appearance. Across all ages, hematomas exhibited four primary echotextures: hypoechoic (23.0%), complex (35.8%), heterogeneous (31.5%), and echogenic (9.7%). The odds of moderate or complete aspiration were greater for hypoechoic hematomas, but appearance or age should not deter intervention.[1]
2. Acute vs. Chronic Appearance Trends
- Acute Stage (hours to days):
- Often hyperechoic or mixed echogenicity due to fresh coagulated blood.
- May appear compressible on probe pressure.
- Chronic Stage (weeks to months):
- Tends toward anechoic or hypoechoic regions as blood breaks down and fluid accumulates, with possible septations from organizing fibrin and cellular ingrowth.[2]
3. Role of Contrast-Enhanced Ultrasound (CEUS)
Contrast-enhanced ultrasound improves detection of active bleeding within a hematoma, delineating arterial extravasation even when conventional B-mode fails to show flow. CEUS is rapid, bedside-compatible, and avoids ionizing radiation, making it valuable in emergency settings and in coagulopathic patients.[2]
Clinical Application:
- Characterization: Expect a broad spectrum of echo patterns; do not infer hematoma age solely from echogenicity.
- Management Decisions: Do not delay aspiration or drainage based on appearance; hypoechoic collections may be easier to aspirate, but complex or echogenic hematomas are also amenable to ultrasound-guided intervention.[1]
- Active Bleeding Assessment: Employ CEUS when ongoing hemorrhage is suspected to guide urgent embolization or surgical intervention.[2]
Sources
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- https://fetalmedicinebarcelona.org/wp-content/uploads/2024/06/placentalhematomasandplacentalabruption_FETAL-ID-Education.pdf
- https://academic.oup.com/ptj/article/85/4/352/2805021
- https://www.nature.com/articles/s41390-025-04000-5
- https://www.sciencedirect.com/science/article/pii/S1743919114010309
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- https://ajronline.org/doi/10.2214/AJR.19.22752
- https://pmc.ncbi.nlm.nih.gov/articles/PMC11563537/
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- https://pmc.ncbi.nlm.nih.gov/articles/PMC11079242/
- https://pmc.ncbi.nlm.nih.gov/articles/PMC5885482/
- https://radiopaedia.org/articles/haemorrhage-on-mri-1
- https://emedicine.medscape.com/article/404971-overview
