Sometimes the placenta itself looks normal.
But next to it, there is an area that doesn’t quite look like placental tissue.
It may be:
dark and fluid-like,
heterogeneous,
or
surprisingly echogenic.
Then the word hematoma appears on the ultrasound report.
For parents, that often translates immediately into:
“Is my placenta separating?”
Not necessarily.
A placental hematoma simply means there is a collection of blood in relation to the placenta or membranes.
What it means clinically depends on several things:
Where is it?
How large is it?
How old does it appear?
Is there active bleeding?
And most importantly—how is the baby doing?
First, What Is a Hematoma?
A hematoma is a localized collection of blood outside the normal blood vessels.
During pregnancy, bleeding can collect in different locations around the gestational sac, membranes, or placenta.
On ultrasound, these collections can have very different appearances.
And this is where things get tricky:
Blood does not always look black on ultrasound.
Its appearance changes with time.
Why Can a Hematoma Look So Different?
Fresh blood may appear relatively echogenic or heterogeneous.
As the blood organizes and breaks down, the collection can become:
- mixed in echogenicity
- hypoechoic
- increasingly fluid-like
- eventually almost anechoic
So the same hematoma may look very different on two ultrasounds performed weeks apart.
This is one reason I am cautious about identifying a placental collection from one still image alone.
Location Matters More Than the Word “Hematoma”
There are several terms you may encounter.
They describe where the blood is located.
Subchorionic hematoma
Blood collects beneath the chorion.
This is particularly familiar from early pregnancy ultrasounds.
Retroplacental hematoma
Blood collects between the placenta and uterine wall.
Preplacental or subamniotic hematoma
Blood lies closer to the fetal surface of the placenta, beneath the amnion.
These are not interchangeable findings.
Their clinical significance can differ considerably.
What Is a Subchorionic Hematoma?
A subchorionic hematoma is one of the most commonly discussed pregnancy-related blood collections.
It may be discovered because the patient has:
vaginal bleeding
or it may be found incidentally during ultrasound.
In early pregnancy, it often appears as a crescent-shaped collection adjacent to the gestational sac or placenta.
Many small subchorionic hematomas gradually decrease or resolve.
Does a Subchorionic Hematoma Mean Miscarriage?
No.
This is an important distinction.
A subchorionic hematoma can be associated with an increased risk of certain pregnancy complications depending on its size, location, gestational age, and clinical context.
But:
finding a hematoma does not mean miscarriage will occur.
Many pregnancies continue normally.
A tiny incidental collection and a very large symptomatic hematoma are not equivalent situations.
What Is a Retroplacental Hematoma?
A retroplacental hematoma is located:
behind the placenta, between the placenta and uterine wall.
This location deserves particular attention because retroplacental bleeding can be associated with:
placental abruption.
But ultrasound needs to be interpreted carefully.
Not every unusual area behind the placenta represents acute abruption.
And importantly:
a normal ultrasound does not completely exclude placental abruption.
Placental abruption is fundamentally a clinical diagnosis supported by the patient’s symptoms, examination, fetal status, and sometimes imaging findings.
Can Ultrasound Diagnose Placental Abruption?
Ultrasound can sometimes demonstrate:
- retroplacental hematoma
- placental thickening
- abnormal placental contour
- collections near the placental margin
But sensitivity is limited.
Abruption can occur even when a clear hematoma is not visible.
So if a pregnant patient has symptoms such as:
significant vaginal bleeding,
persistent abdominal or uterine pain,
frequent contractions,
or
concerning fetal symptoms,
a reassuring-looking placental image should not be used to dismiss those symptoms.
What Is a Subamniotic Hematoma?
A subamniotic hematoma develops near the fetal surface of the placenta, beneath the amnion.
It may sometimes occur near the umbilical cord insertion.
On ultrasound it can appear as a cystic or complex collection projecting from the fetal placental surface.
That appearance can overlap with other placental lesions.
This is where:
location + internal appearance + Doppler
become useful.
Placental Hematoma vs Placental Cyst
These can sometimes look surprisingly similar.
Placental cyst
Usually a well-defined fluid-containing structure without internal vascularity.
Hematoma
A blood collection whose echogenicity can change as it ages.
An older hematoma may become very hypoechoic or almost anechoic.
So simply saying:
“It’s black, therefore it’s a cyst”
is not reliable.
Clinical history and change over time can be extremely helpful.
Does Color Doppler Show Blood Flow Inside a Hematoma?
Usually, an established hematoma should not demonstrate normal internal vascular flow.
This can help differentiate it from a vascular placental lesion such as a chorioangioma.
But Doppler findings must still be interpreted carefully.
Nearby placental or fetal vessels can produce color signals around a collection.
The goal is to determine:
whether flow is truly inside the lesion or simply adjacent to it.
Does the Size Matter?
Yes—but there is no magic number that tells the entire story.
A larger hematoma may be more concerning than a tiny collection, especially when associated with:
- ongoing bleeding
- placental abnormalities
- fetal growth problems
- abnormal fluid
- maternal symptoms
But size alone cannot predict the outcome of an individual pregnancy.
The proportion of the placenta or gestational sac involved and the location may also matter.
Why Do We Measure It in Three Dimensions?
A hematoma is a three-dimensional structure.
So the sonographer may record:
length × width × depth.
But don’t be surprised if the measurements change somewhat between scans.
Collections are often:
- irregular
- curved
- partially collapsed
- difficult to reproduce exactly
A difference of several millimeters does not necessarily mean the hematoma suddenly grew or shrank.
The overall trend is more useful.
Can a Hematoma Get Bigger?
Yes.
Some hematomas enlarge, particularly if bleeding continues.
Others remain stable.
And many gradually become smaller as the blood is reabsorbed.
This is why follow-up ultrasound may be recommended in selected cases.
But:
appearance can change even while the hematoma is resolving.
A darker collection on a later scan does not necessarily mean it is getting worse.
It may simply represent aging blood.
Can a Hematoma Disappear?
Yes.
Many hematomas gradually decrease in size and may eventually no longer be visible.
The blood is broken down and reabsorbed over time.
Sometimes a collection becomes flatter and more difficult to distinguish before disappearing completely.
Does Vaginal Bleeding Mean the Hematoma Is Getting Worse?
Not necessarily.
A patient may experience vaginal bleeding as blood drains from a collection.
The color can range from:
bright red
to
dark red
to
brown.
But symptoms should be discussed with the maternity team because ultrasound alone cannot determine the significance of bleeding.
Heavy bleeding, significant pain, contractions, dizziness, or other concerning symptoms require prompt clinical assessment.
What Else Do We Check on Ultrasound?
When a placental hematoma is present, I don’t spend the entire scan measuring the collection.
Depending on gestational age and clinical circumstances, I also want to know:
How is the baby growing?
How much amniotic fluid is present?
What does the rest of the placenta look like?
Is fetal movement reassuring?
Is Doppler assessment indicated?
Later in pregnancy, fetal growth becomes particularly important when there are ongoing placental concerns.
Can a Placental Hematoma Affect Fetal Growth?
Some significant or persistent placental hematomas have been associated with fetal growth restriction.
But:
a hematoma does not automatically cause a small baby.
If the collection is substantial or there are other placental concerns, serial growth assessment may be considered.
Again, fetal response is more informative than the label alone.
Does a Hematoma Mean Placental Insufficiency?
No—not automatically.
A small resolving hematoma can coexist with completely normal placental function.
If placental dysfunction is suspected, clinicians consider:
- fetal growth
- amniotic fluid
- maternal condition
- fetal surveillance
- Doppler findings when indicated
The hematoma is one piece of the picture.
Do I Need Bed Rest?
This is one of the most common questions.
Routine strict bed rest is not automatically recommended simply because a hematoma is visible.
Activity advice depends on:
- gestational age
- bleeding
- hematoma size and location
- symptoms
- cervical findings
- obstetric history
- your clinician’s assessment
If your healthcare provider gives you individualized restrictions, follow those recommendations.
But don’t assume that lying completely still will make a hematoma disappear faster.
Did I Cause the Hematoma?
In most cases:
No.
Normal activities such as walking, working, or ordinary daily movement do not mean you caused a placental hematoma.
Parents often search for something they did “wrong” after bleeding begins.
Usually, there is no such action to identify.
Does It Mean I Need a C-Section?
Not simply because a hematoma exists.
A small stable or resolving hematoma may have no effect on mode of delivery.
Delivery planning changes when there are significant clinical problems such as:
- placental abruption
- fetal compromise
- severe bleeding
- maternal instability
- other obstetric indications
The decision is based on the clinical situation, not the ultrasound word “hematoma.”
A Practical Example
Consider two scans.
Case A
A small marginal collection.
No current bleeding.
Baby growing normally.
Normal fluid.
Collection becoming smaller.
Case B
A large retroplacental collection.
Acute abdominal pain and vaginal bleeding.
Abnormal fetal heart rate.
Both may involve a:
placental hematoma.
But clinically, they are completely different situations.
That’s why location, symptoms, and fetal wellbeing matter so much.
Questions to Ask Your Doctor
If a placental hematoma is mentioned, useful questions include:
- Where exactly is the hematoma?
- How large is it?
- Does it look recent or older?
- Is it changing in size?
- Does the placenta otherwise look normal?
- Is my baby growing normally?
- Do I need another ultrasound?
- Do I need fetal growth or Doppler follow-up?
- Are there any activity restrictions for my situation?
- What symptoms should make me seek urgent care?
And the question I would put near the top is:
“Is this simply a blood collection, or are there signs that it is affecting the placenta or baby?”
Key Takeaway
A placental hematoma means that blood has collected somewhere in relation to the placenta or membranes.
But the term alone doesn’t tell you how serious it is.
Location matters.
Size matters.
Symptoms matter.
Gestational age matters.
And:
the baby’s condition matters most.
The appearance of blood also changes with time, which means a hematoma can look solid, heterogeneous, or almost cystic depending on when it is scanned.
So when I see a collection near the placenta, I don’t begin with:
“How dark is it?”
I begin with:
“Where is it, what does the rest of the placenta look like, and how is the baby doing?”
That tells us much more. 🩷
About the Author
This article was written by a sonographer with over 20 years of hands-on clinical ultrasound experience, including fetal, breast, and thyroid imaging.
Placental hematomas are a good reminder that ultrasound is dynamic. Blood doesn’t keep the same appearance as it ages. When I see a collection near the placenta, I look at its exact location, shape, internal echoes, relationship to the placenta, and Doppler appearance, but I also compare it with any prior scan whenever possible. A changing image doesn’t always mean a worsening condition—it may simply be blood evolving over time.
This article is for general educational purposes and does not replace individualized prenatal diagnosis or urgent obstetric assessment. Significant vaginal bleeding, persistent abdominal pain, contractions, dizziness, or concerns about fetal movement should be assessed promptly by your maternity care team.
