Most parents expect the ultrasound to focus on the baby.
So it can be surprising when the sonographer spends extra time looking at the placenta.
Then you hear:
“There is a small mass in the placenta.”
That word—mass—can immediately sound frightening.
But a placental mass is not automatically cancer, and one of the better-known benign placental tumors is called a:
placental chorioangioma.
Most small chorioangiomas cause no significant problem.
Large or highly vascular lesions, however, deserve a different level of attention because they can sometimes affect fetal circulation.
That difference—size, blood flow, and what the baby is doing—is much more important than the word “tumor” itself.
What Is a Placental Chorioangioma?
A chorioangioma is a benign vascular tumor of the placenta.
It arises from placental tissue and contains blood vessels.
It is not a fetal tumor.
And importantly:
It is not the same thing as placental cancer.
Small chorioangiomas are often clinically insignificant and may even go unnoticed during pregnancy.
What Does It Look Like on Ultrasound?
A chorioangioma may appear as a relatively well-defined mass within or projecting from the fetal surface of the placenta.
It is often located near the:
umbilical cord insertion.
Its ultrasound appearance can vary.
The lesion may be:
- relatively homogeneous
- heterogeneous
- hypoechoic
- mixed in echogenicity
This variability means grayscale appearance alone may not always establish the diagnosis.
This Is Where Color Doppler Becomes Important
When I see a placental mass, one of the things I want to know is:
“Does it have blood flow?”
Color Doppler can demonstrate vessels within or around a chorioangioma.
A vascular connection to the fetal circulation may also be visible.
That information helps distinguish a vascular placental lesion from other structures that may look mass-like on grayscale imaging.
Does Every Placental Mass With Blood Flow Mean Chorioangioma?
No.
Ultrasound findings must be interpreted carefully.
The differential diagnosis of a placental mass can include other placental abnormalities.
The examiner considers:
- location
- margins
- internal echogenicity
- vascularity
- relationship to the cord insertion
- change over time
Sometimes follow-up imaging is more informative than a single examination.
Why Does Size Matter?
This is one of the most clinically important points.
Small chorioangiomas usually do not cause complications.
Larger lesions—particularly those several centimeters in size—are more likely to be clinically significant.
Why?
Because a large vascular tumor can behave somewhat like an additional vascular circuit connected to the fetus.
That can change fetal hemodynamics.
So with chorioangioma:
bigger and more vascular generally deserves closer attention.
But size alone still does not predict exactly what will happen.
How Can a Large Chorioangioma Affect the Baby?
A highly vascular chorioangioma may allow substantial fetal blood flow through the lesion.
In some cases, this can increase the workload on the fetal heart.
Potential complications reported with large lesions include:
fetal anemia
high-output cardiac failure
cardiomegaly
fetal hydrops
polyhydramnios
fetal growth abnormalities
preterm birth
That list sounds intimidating.
But it mainly reflects the more significant end of the spectrum.
A small isolated chorioangioma is a very different situation.
Why Can Fetal Anemia Occur?
Because the lesion is vascular, a large chorioangioma can alter fetal circulation.
If fetal anemia is suspected, clinicians may assess:
Middle Cerebral Artery Peak Systolic Velocity — MCA-PSV.
MCA-PSV is a Doppler measurement used in appropriate clinical settings to screen for moderate-to-severe fetal anemia.
But it is not automatically required for every tiny placental lesion.
Again, the clinical context determines the workup.
Why Is the Fetal Heart Checked?
If a large vascular chorioangioma creates significant circulatory demand, the fetal heart may need to work harder.
Ultrasound may therefore look for:
- cardiomegaly
- cardiac function
- signs of volume overload
- venous Doppler abnormalities
- hydrops
The point is not simply to keep measuring the placental mass.
We want to know whether the fetus is being affected by it.
What Is Fetal Hydrops?
Hydrops refers to abnormal fluid accumulation in fetal compartments.
Ultrasound may show findings such as:
- ascites
- pleural effusion
- pericardial effusion
- skin edema
A large chorioangioma can rarely contribute to hydrops through significant fetal circulatory stress.
This is a serious situation requiring specialist assessment.
But:
the presence of a chorioangioma does not mean hydrops will develop.
Why Can Polyhydramnios Occur?
Large chorioangiomas can sometimes be associated with:
polyhydramnios — increased amniotic fluid.
The exact mechanism can be complex and may relate to altered fetal circulation and increased fetal urine production.
If the lesion is significant, amniotic fluid is therefore one of the things followed on ultrasound.
What Else Do We Check?
When a chorioangioma is suspected, the scan becomes more than:
“How big is the mass?”
Depending on its size and appearance, assessment may include:
Tumor size
Is it stable or growing?
Vascularity
How much internal blood flow is present?
Fetal growth
Is the baby growing appropriately?
Amniotic fluid
Is polyhydramnios developing?
Fetal heart
Is there evidence of increased cardiac workload?
MCA Doppler
Is there concern for fetal anemia?
Hydrops
Is abnormal fetal fluid accumulation present?
This gives a much more meaningful picture.
Can a Chorioangioma Grow?
Yes.
Some lesions remain relatively stable.
Others may enlarge as pregnancy progresses.
That is one reason a clinically significant chorioangioma may be followed with serial ultrasound.
But the most important trend is not necessarily just:
2 cm → 3 cm → 4 cm.
It is also:
“Is the fetus still doing well?”
Can It Disappear?
A chorioangioma does not usually behave like a temporary cord position that simply moves away.
Its vascularity and appearance may change, and some lesions can undergo degenerative changes.
But once identified, the relevant issue is usually how it behaves over time and whether it affects the pregnancy.
Does a Small Chorioangioma Need Treatment?
Often, no specific fetal treatment is required.
If the lesion is small and the fetus is unaffected, management may consist primarily of observation according to the clinical situation.
This is important because reading about complicated cases online can give a distorted impression.
Published case reports naturally tend to describe:
the unusual and severe cases.
They do not represent every pregnancy with a small placental chorioangioma.
What If the Chorioangioma Is Large?
Large, highly vascular lesions with evidence of fetal compromise may require care from a maternal-fetal medicine or fetal therapy team.
Management depends on:
- gestational age
- lesion size
- vascularity
- fetal anemia
- cardiac function
- hydrops
- amniotic fluid
- fetal wellbeing
In selected severe cases, specialized fetal interventions have been reported.
But those treatments are not routine management for every chorioangioma.
Does It Mean I Need a C-Section?
Not simply because a chorioangioma exists.
Mode and timing of delivery depend on the complete obstetric situation.
A small lesion with a healthy fetus may have little effect on delivery planning.
A large lesion causing fetal compromise may create a completely different situation.
Again:
the baby’s condition drives management more than the name of the placental lesion.
Is Chorioangioma the Same as a Placental Lake?
No.
This distinction is useful because both may attract attention during placental scanning.
Placental lake
A maternal blood-filled space within the placenta.
Chorioangioma
A discrete benign vascular placental tumor.
Color Doppler and morphology can help differentiate them.
A placental lake should not automatically be labeled a chorioangioma simply because it appears as an unusual area in the placenta.
Is It the Same as a Hematoma?
No.
A placental hematoma is a collection of blood.
A chorioangioma is a vascular placental lesion.
The ultrasound appearance, location, Doppler vascularity, clinical history, and evolution over time can help distinguish them.
A Practical Way to Think About It
Imagine two ultrasound reports.
Pregnancy A
1.5 cm placental chorioangioma
Minimal concern.
Normal fetal growth.
Normal fluid.
No signs of fetal circulatory stress.
Pregnancy B
7 cm highly vascular placental mass
Polyhydramnios.
Fetal cardiomegaly.
Elevated MCA-PSV.
Both may carry the same diagnostic label:
chorioangioma.
But clinically, they are not remotely the same situation.
That’s why the diagnosis alone is not enough.
Questions to Ask Your Doctor
If a placental chorioangioma is suspected, useful questions include:
- How large is the lesion?
- Where is it located?
- Is it close to the cord insertion?
- Does Color Doppler show significant blood flow?
- Is my baby growing normally?
- Is the amniotic fluid normal?
- Does the fetal heart look normal?
- Is there any evidence of fetal anemia?
- Do I need MCA Doppler?
- Do I need serial ultrasound follow-up?
- Does this affect delivery timing?
But the question I would put first is:
“Is this lesion affecting my baby in any way right now?”
Key Takeaway
The word “placental tumor” sounds frightening.
But placental chorioangioma is:
benign.
And many small lesions do not cause significant pregnancy complications.
The lesions that deserve the most attention are generally those that are:
large, highly vascular, or associated with fetal changes.
That’s why ultrasound assessment goes beyond simply measuring the mass.
We look at:
Color Doppler vascularity
fetal growth
amniotic fluid
fetal cardiac findings
MCA Doppler when indicated
and
signs of hydrops.
When I see a placental mass, the most useful question isn’t:
“Is there a tumor?”
It’s:
“What is this lesion doing—and is the baby being affected?”
That distinction makes the ultrasound finding much more meaningful. 🩷
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.
When a placental mass appears on the screen, I don’t like to jump straight from “mass” to a diagnosis. I first look at where it arises, whether it is near the cord insertion, what its internal texture looks like, and especially what Color Doppler shows. Then I go back to the fetus—because the fetal response often tells us more about the clinical significance than the placental image alone.
This article is for general educational purposes and does not replace individualized prenatal diagnosis, maternal-fetal medicine or fetal therapy evaluation, fetal surveillance, or medical advice from your healthcare provider.
