Paratubal Cyst: Understanding Your Pathology Report

Section Editor: Kianoosh Keyhanian MD FRCPC
August 31, 2026

A paratubal cyst is a noncancerous (benign) fluid-filled space that sits beside the fallopian tube, in the tissue between the tube and the ovary. A cyst is any closed space in a tissue that contains fluid. The prefix “para” means beside, so the name describes where the cyst is.

Your report may use one of several other names for the same thing. Paraovarian cyst and parovarian cyst are used when the cyst sits closer to the ovary. Older reports sometimes say hydatid cyst of Morgagni, a term for a small cyst hanging from the fringed end of the fallopian tube. That term is no longer recommended, but it still appears in practice.

Paratubal cysts are common. They account for roughly 10 percent of masses found beside the uterus, and most are small and cause no trouble. They occur at any age and are found most often during the reproductive years. A paratubal cyst is not cancer, and most never cause a problem. This article will help you understand what this diagnosis means on your pathology report, what each term means, and why it matters for your care.

What causes a paratubal cyst?

Paratubal cysts develop from small pieces of tissue left over from the way the reproductive organs form before birth. Early in development, every fetus has two sets of paired tubes running alongside the developing kidneys. In a female fetus, one set goes on to form the fallopian tubes, uterus, and upper vagina. The other set mostly disappears. Small fragments of either set can persist in the tissue between the ovary and the fallopian tube, and a cyst can form from one of those fragments later in life.

Pathologists recognize three origins, and the lining cells often indicate which one applies.

Müllerian type — The most common. These arise from the tube-forming set of ducts and are lined by cells that resemble the lining of the fallopian tube, complete with fine hair-like projections.
Mesonephric type — These arise from the other set of ducts, the ones that largely disappear in a female fetus. They tend to have a thicker muscular wall and a plainer lining without hair-like projections.
Mesothelial type — These form when a fold of the smooth membrane covering the pelvic organs becomes sealed off.

Whichever the origin, a paratubal cyst is a developmental leftover rather than a disease.

What are the symptoms?

Most paratubal cysts cause no symptoms and are found by chance, either on an imaging test performed for another reason or during surgery. Small cysts are often discovered only when the tissue is examined in the laboratory. When symptoms occur, they usually come from the cyst’s size or a complication.

Pelvic pain or pressure — A dull ache or feeling of fullness low in the abdomen, usually on one side. Paratubal cysts can grow large, and some reach more than 10 cm.
Sudden, severe pain with nausea — A cyst can twist on its stalk, a problem called torsion, sometimes dragging the fallopian tube or ovary with it. Torsion of a paratubal cyst is one of the causes of sudden pelvic pain in teenagers and young women, and it is an emergency requiring prompt surgery.
Sudden, sharp pain — The cyst can burst, which is called rupture. This causes sudden one-sided pain and sometimes bleeding into the abdomen.

Sudden severe pelvic pain has several possible causes, some of which need urgent treatment. It should always be assessed promptly.

How is the diagnosis made?

A paratubal cyst is often suspected on an ultrasound before surgery. On a scan it appears as a smooth, thin-walled, single-chambered cyst filled with clear fluid. The most useful clue is that a normal ovary can be seen separately, next to the cyst rather than containing it. Even so, a paratubal cyst is frequently mistaken for an ovarian cyst on imaging, because the two sit close together.

A definite diagnosis is made only after the cyst is removed and examined under the microscope by a pathologist. In many cases, the cyst was not the reason for the operation, and the pathologist found it while examining a fallopian tube or ovary removed for another reason.

During the operation, the surgeon may request an intraoperative consultation, also called a frozen section. The pathologist examines a piece of the cyst while the patient is still in the operating room and gives a preliminary diagnosis within minutes. The pathologist makes the final diagnosis later, once the entire specimen has been examined.

The pathologist examines the entire lining of the cyst, not just a single piece. This matters because the rare tumors that arise in a paratubal cyst grow from the lining and may involve only a small area.

What does a paratubal cyst look like under the microscope?

A paratubal cyst is a fluid-filled space beside the fallopian tube, surrounded by a thin wall and lined by a single layer of cells. To the naked eye, it is a thin-walled, translucent sac containing clear fluid. Under the microscope, the pathologist looks for the following features.

A single layer of lining cells — The inside is lined by one thin layer of epithelium, the type of tissue that covers surfaces in the body. There is no crowding and no piling up of cells.
Ciliated or cube-shaped cells — The lining cells are either tall cells with fine hair-like projections called cilia, or plainer cube-shaped cells. Cilia are normally found in the fallopian tube, and their presence here reflects where the cyst came from.
A thin wall — The wall is made of fibrous tissue, sometimes with a layer of smooth muscle. Mesonephric-type cysts tend to have the thickest muscular wall.
A smooth inner surface — The lining follows the contour of the wall. Finger-like growths projecting into the cavity would prompt the pathologist to look more carefully, since these are a feature of the rare tumors that can arise here.
No abnormal cells — The lining cells look ordinary, with no crowding and no complex growth. This is what confirms the cyst is benign.

What other findings may be described in the report?

Along with the diagnosis of a paratubal cyst, your pathology report may describe several other features of the cyst and the tissue around it.

Cyst size — The report gives the greatest dimension in centimeters. Size does not change the fact that the cyst is benign, but it does explain whether symptoms were likely and influences how the cyst was removed.
More than one cyst — Several small paratubal cysts are often present at once, sometimes on both sides. This is a normal finding.
Intact or ruptured — The report may note whether the cyst was whole when removed or had already burst.
Changes from torsion — If the cyst twisted, the report may describe bleeding into the wall or tissue death, called infarction. These changes reflect a loss of blood supply and do not indicate cancer.
The fallopian tube and ovary — When either is removed with the cyst, it is examined and reported separately.

Can a tumor develop in a paratubal cyst?

Yes, but it is rare, and the way this is usually written makes it sound more likely than it is. A tumor arising in a paratubal cyst grows from the lining cells. Most of the reported cases have been borderline tumors, which sit between benign and cancerous and have an excellent outlook after removal. Cancers arising in a paratubal cyst are rarer still, and only a small number have ever been described in the medical literature.

You may come across a figure of about 2 to 3 percent for tumors found in paraovarian masses. That number comes from surgical series, which include only cysts that were removed because they were large, growing, or looked unusual on imaging. It does not describe the small cysts that turn up incidentally, which make up the great majority.

The practical point is this. If your report says paratubal cyst with no other qualifying words, the pathologist examined the lining and found no tumor. If a borderline tumor or a cancer had been present, the report would name it directly, nd the diagnosis would not be a simple paratubal cyst.

What happens after this diagnosis?

A paratubal cyst is benign. Once it has been removed, it is considered dealt with, and it does not turn into cancer over time. Points your doctor may raise include:

No further treatment — A benign paratubal cyst needs no chemotherapy, no radiation, and no medication. Removal is the only treatment.
What was removed — Many paratubal cysts can be taken out on their own, leaving the fallopian tube and ovary in place. If the cyst had twisted and damaged the tube or ovary, more may have been removed.
Recurrence — A cyst that has been completely removed does not come back. A different paratubal cyst can form elsewhere, since these develop from tissue present on both sides.
Fertility — Paratubal cysts do not usually affect fertility. A very large cyst can distort the fallopian tube, and surgery is generally planned to preserve the tube and ovary where possible.
Follow-up — No routine monitoring is needed for a benign paratubal cyst. If other findings were reported, those will guide any follow-up.

Sudden severe pelvic pain, especially with nausea or vomiting, should be assessed urgently, since torsion and rupture both need prompt treatment.

Questions to ask your doctor

Was the cyst found by chance, or was it the reason for my surgery?
How large was the cyst?
Was any tumor or abnormal growth found in the lining of the cyst?
Was the cyst intact, or had it ruptured or twisted?
Was more than one cyst found?
Was the fallopian tube or ovary removed, and if so, why?
Were any other findings described in the specimen?
Could another cyst develop on the other side?
Does this affect my fertility?
Do I need any follow-up imaging or appointments?
What symptoms should prompt me to contact you?