During a pregnancy ultrasound, you may hear:
“There is a small cyst in the umbilical cord.”
Seeing the word cyst anywhere on an ultrasound report can immediately sound concerning.
But an umbilical cord cyst is not one single diagnosis.
Its significance depends heavily on:
When it is found
Where it is located
Whether it disappears
Whether it is isolated
Whether other fetal abnormalities are present
A small cyst seen early in pregnancy can have a very different meaning from a persistent cord cyst identified later in pregnancy.
What Is an Umbilical Cord Cyst?
An umbilical cord cyst is a fluid-filled or cyst-like structure within or adjacent to the umbilical cord.
On ultrasound, it usually appears as a:
round or oval
dark fluid-filled area
associated with the cord.
The sonographer may assess:
- size
- location
- relationship to the umbilical vessels
- cord insertion
- fetal anatomy
- whether the cyst persists on follow-up
These details help determine how the finding should be interpreted.
Are All Umbilical Cord Cysts the Same?
No.
Umbilical cord cystic lesions are traditionally divided into two categories:
True cysts
and
Pseudocysts
They can look similar on prenatal ultrasound, and distinguishing them confidently by imaging alone may not always be possible.
What Is a True Umbilical Cord Cyst?
True cysts have an epithelial lining and are thought to arise from embryologic remnants.
They may be related to structures such as:
the allantois
or
the omphalomesenteric duct.
True cysts are often located closer to the fetal insertion of the umbilical cord.
However, ultrasound appearance alone does not always tell us exactly what type of cyst is present.
What Is an Umbilical Cord Pseudocyst?
A pseudocyst does not have a true epithelial lining.
It generally represents localized changes within Wharton’s jelly, the protective connective tissue surrounding the umbilical vessels.
On ultrasound, a pseudocyst can appear very similar to a true cyst.
So in everyday prenatal imaging, the clinically useful questions are often not simply:
“Is it a true cyst or pseudocyst?”
but rather:
“Is it isolated?”
“Does it persist?”
“Is the rest of the anatomy normal?”
Why Does Gestational Age Matter?
This is one of the most important points.
First-trimester cord cyst
Small umbilical cord cysts can occasionally be identified during early pregnancy.
Many isolated first-trimester cysts subsequently disappear.
When the cyst resolves and fetal anatomy and screening are otherwise reassuring, the outlook is often favorable.
Persistent or later-pregnancy cord cyst
A cyst that:
persists beyond the first trimester
or
is first identified later in pregnancy
deserves more careful evaluation.
Persistent cord cystic lesions have been reported in association with fetal structural abnormalities and chromosomal conditions.
But:
Persistence does not automatically mean the baby has an abnormality.
It means the rest of the fetus should be evaluated carefully.
What Does It Look Like on Ultrasound?
A cord cyst usually appears as an anechoic or hypoechoic area associated with the umbilical cord.
The sonographer may use grayscale ultrasound to evaluate its shape and size.
Color Doppler is particularly useful.
Why?
Because the umbilical cord normally contains important fetal blood vessels.
Doppler can help determine:
where the arteries are
where the vein is
and
how the cyst relates to those vessels.
This helps distinguish a cystic structure from a vascular structure.
Why Is Color Doppler Important?
A dark round structure is not automatically a cyst.
Blood vessels can also appear dark on grayscale imaging.
Color Doppler can demonstrate blood flow within vessels.
A simple cystic space should not show internal vascular flow like a vessel does.
Doppler can also help determine whether the lesion is:
compressing
displacing
or simply lying beside the umbilical vessels.
That anatomical relationship can be important when the cyst is large.
Does the Location Matter?
Yes.
The sonographer may document whether the cyst is:
near the fetal abdominal insertion
in the free cord
or
closer to the placental insertion.
A cyst near the fetal insertion may prompt careful evaluation of the fetal abdominal wall and urinary tract depending on its appearance and suspected origin.
Location alone does not provide the diagnosis, but it helps guide the examination.
What If the Cyst Is Near the Baby’s Abdomen?
When a cystic structure is close to the fetal insertion of the cord, the sonographer may examine:
- abdominal wall
- bladder
- kidneys
- cord insertion
- umbilical vessels
Some embryologic remnants involving the allantois or urachus can create cystic abnormalities near the fetal end of the cord.
These situations are different from a tiny transient cyst seen in the free cord early in pregnancy.
Can an Umbilical Cord Cyst Disappear?
Yes.
This is particularly common with some cysts identified in the first trimester.
A follow-up scan may show that the cyst has:
become smaller
or
completely disappeared.
Resolution is generally reassuring, especially when the finding was isolated.
However, the rest of the fetal evaluation still matters.
What If It Doesn’t Disappear?
Persistence does not automatically mean a poor outcome.
But it usually makes the finding more clinically significant.
Your healthcare provider may consider:
detailed fetal anatomy assessment
follow-up ultrasound
genetic screening or diagnostic testing depending on the overall findings
and sometimes
maternal-fetal medicine consultation.
The decision depends heavily on whether other abnormalities are present.
Is an Umbilical Cord Cyst a Soft Marker?
Not exactly in the same way as classic ultrasound soft markers such as an isolated echogenic intracardiac focus.
A persistent cord cyst or pseudocyst can be associated with chromosomal abnormalities in some pregnancies.
However, the risk depends strongly on:
gestational age
persistence
number of cysts
and
associated fetal abnormalities.
An isolated transient first-trimester cyst is therefore very different from a persistent cyst accompanied by structural abnormalities.
Does It Mean My Baby Has a Chromosomal Abnormality?
No.
A cord cyst does not diagnose a chromosome condition.
If the cyst persists or additional abnormalities are identified, your provider may review your previous screening results.
Depending on the situation, options may include:
cell-free DNA screening (NIPT)
or
diagnostic testing such as amniocentesis.
NIPT is a screening test.
Amniocentesis is a diagnostic test.
The appropriate choice depends on the complete clinical picture and your preferences.
Can a Large Cord Cyst Affect Blood Flow?
Potentially.
A very large cystic lesion may distort or compress nearby umbilical vessels.
That is different from a tiny cyst that has no effect on the cord.
When a cyst is large, the sonographer may pay particular attention to:
- vessel position
- blood flow
- fetal growth
- cyst size
- change over time
Fortunately, many small cord cysts do not cause significant vascular compression.
Does It Cause Fetal Growth Restriction?
Not necessarily.
A small isolated cord cyst does not automatically mean fetal growth will be abnormal.
If a lesion is persistent, large, or associated with other placental or cord abnormalities, later growth assessment may be considered.
Again, the cyst should not be interpreted in isolation from the rest of the pregnancy.
Will I Need Another Ultrasound?
Often, yes—especially when a cord cyst is detected early.
Follow-up can answer one of the most useful questions:
“Is it still there?”
The next scan may assess:
- whether the cyst has resolved
- whether it has changed in size
- fetal anatomy
- cord vessels
- fetal growth when appropriate
A disappearing isolated cyst and a persistent complex cyst represent very different clinical situations.
Does It Mean I Need a C-Section?
No—not simply because a cord cyst exists.
Most small isolated cord cysts do not determine the mode of delivery.
Delivery planning may change if there is:
a very large persistent lesion affecting the cord
or
another fetal or obstetric complication.
But the ultrasound label alone does not automatically mean cesarean delivery.
Can I Do Anything to Make It Disappear?
No.
There is no:
food
supplement
exercise
sleeping position
or
activity restriction
that makes an umbilical cord cyst disappear.
You did not cause it.
Its evolution depends on the underlying anatomy and development of the cord.
First Trimester vs Later Pregnancy: The Easy Way to Think About It
Early + small + isolated + disappears
Often reassuring.
Persistent + later pregnancy + additional abnormalities
Requires closer evaluation.
That doesn’t mean the second situation automatically predicts a poor outcome.
It means more information is needed.
This distinction is far more useful than simply searching:
“Are umbilical cord cysts dangerous?”
Questions to Ask Your Doctor
If an umbilical cord cyst is found, useful questions include:
- How many weeks pregnant am I when it was found?
- How large is the cyst?
- Where exactly is it located?
- Is it near the fetal abdominal insertion?
- Does it affect the umbilical vessels?
- Is blood flow normal on Doppler?
- Is the rest of the fetal anatomy normal?
- Is this an isolated finding?
- Should we check whether it disappears?
- When should the ultrasound be repeated?
- Do my genetic screening results change the interpretation?
- Would additional testing be appropriate if it persists?
And perhaps the most useful question:
“Is this an isolated early cord cyst, and does it disappear on follow-up?”
Key Takeaway
An umbilical cord cyst is a cystic structure associated with the umbilical cord.
But its significance depends strongly on context.
A small isolated cyst detected early in pregnancy may disappear and have little clinical significance.
A cyst that persists into later pregnancy—or occurs with other fetal abnormalities—deserves more detailed evaluation.
So don’t interpret the word cyst by itself.
The bigger picture is:
When was it found?
Where is it?
Does it persist?
Are the cord vessels normal?
Is the rest of the baby normal?
Those answers tell you far more than the word “cyst” ever could. 👶🩷
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 I see a cystic structure in the umbilical cord, I first want to know its relationship to the cord vessels, fetal abdominal insertion, and gestational age. Then follow-up becomes important: a tiny isolated first-trimester cyst that disappears is a very different ultrasound story from a persistent lesion accompanied by other findings.
This article is for general educational purposes and does not replace individualized prenatal diagnosis, genetic counseling, maternal-fetal medicine evaluation, or medical advice from your healthcare provider.
