Ovarian vein thrombosis (OVT) is a rare condition where a blood clot blocks blood flow in a vein between your ovary and the vena cava, the major blood vessel that returns blood to your heart. OVT can be life threatening.

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OVT is most common in the postpartum period after childbirth. It’s a complication of about 1 in 600 to 1 in 2,000 childbirths. It’s also a potential complication of some other conditions, such as:

While OVT usually occurs during pregnancy or shortly after delivery, it may happen very rarely in people who haven’t recently been pregnant or have another associated condition.

Health professionals continue to debate how to best manage OVT, but medications to break up the blood clot or surgery to remove the blood clot are the main treatment options.

Read on to learn more about this rare condition, including symptoms, treatments, and causes.

A thrombosis (plural thromboses) is a blood clot that blocks a blood vessel. Thromboses are called arterial thromboses when they form in arteries that carry blood away from your heart, and venous thromboses when they develop in veins that carry blood back toward your heart.

OVT can only develop in people who have ovaries. It forms when a blood clot blocks the veins that carry blood from each of your ovaries to the vena cava, the main vein in your abdomen.

OVT occurs as a complication in 0.05% to 0.16% of pregnancies and up to 2% of cesarean deliveries, usually occurring during the postpartum period.

OVT symptoms tend to be general and can mimic those of many other abdominal conditions.

The typical symptoms of OVT include:

  • pelvic pain
  • fever
  • abdominal mass on your right side that may be tender and feel rope-like

Other potential signs and symptoms include:

Symptoms generally appear in the first 4 weeks after childbirth. In people who have OVT after childbirth, they happen within 10 days of childbirth nearly 90% of the time.

OVT that doesn’t cause symptoms is much more common than symptomatic OVT. About 30% of people develop evidence of thrombosis on magnetic resonance imaging (MRI) in their iliac or ovarian veins after vaginal childbirth. A thrombosis in these veins occurs in about 80% of people who receive major surgery on the female reproductive system.

Medical Emergency

If you experience any of the symptoms of OVT listed above, visit your doctor or get emergency care right away, especially if you’ve recently given birth.

OVT is characterized by the formation of a blood clot in one of your ovarian veins. It’s almost always associated with certain underlying conditions, such as:

  • healing during the postpartum period after childbirth
  • cancer
  • abdominal or pelvic surgery
  • inflammatory bowel disease
  • pelvic inflammatory disease

There are several theories as to why OVT is associated with pregnancy, including:

  • poor vein circulation or vein damage
  • endometriosis, which is when tissue similar to the lining of your uterus grows outside your uterus
  • increased circulation of substances that promote blood clots due to a surge in estrogen

The right ovary is affected in about 70% to 90% of OVT cases, and both ovaries are affected in 11% to 14% of cases.

Since OVT is very rare and the symptoms are nonspecific, it is not usually the first condition a doctor may consider. However, when OVT is suspected, the following tests help diagnose this condition:

  • Laparotomy: A surgical incision into your abdomen, a laparotomy is traditionally the diagnostic tool of choice and is still the gold standard.
  • Imaging tests: Doctors can also use several types of imaging to diagnose OVT. Consensus hasn’t been reached on which type of imaging is best, but your doctor may use:

Ultrasound isn’t as accurate as CT scans or MRI but is often recommended as the initial imaging tool when diagnosing OVT.

There are currently no standardized treatment guidelines for OVT because it’s so rare. Treatment includes surgical and nonsurgical options, and research suggests both types of treatment are effective.

Nonsurgical treatment options include antibiotics to treat infection and anticoagulation medications to break up the blood clot.

Anticoagulation often involves 7 to 10 days of heparin and warfarin plus broad-spectrum antibiotics. Up to 3 months of warfarin is sometimes recommended if the blood clot reaches the veins leading to your kidneys.

Surgical options include:

  • hysterectomy
  • thrombectomy, or blood clot removal
  • ovarian vein ligation, tying off the vein
  • ovarian vein removal
  • inferior vena cava filter placement

In a 2021 case series, researchers found that the average age of diagnosis for 18 people with OVT was 40 and that most cases of OVT occurred after pregnancy.

OVT is associated with some cancers. The most common cancer it’s associated with is ovarian cancer.

It’s thought that up to 50% of people who develop OVT have a predisposition to forming blood clots due to factors such as:

Complications of OVT are rare, but they can be life threatening. They include:

  • pocket of pus on your ovary (ovarian abscess)
  • blockage of blood supply to an ovary (ovarian infarction)
  • a blood clot with inflammation and infection (septic thrombophlebitis)
  • a blood clot that moves to your lungs (pulmonary embolism)
  • death of ovarian tissue (uterine necrosis)

About 25% of people with untreated OVT have a pulmonary embolism, which can be life threatening.

Here are some frequently asked questions people have about OVT.

How common is pulmonary embolism in people with OVT?

In 13% to 25% of people with OVT, pulmonary embolism is a complication. This a serious risk since PE is life threatening and may not have any symptoms.

What should I do if I suspect I may have ovarian vein thrombosis?

OVT is a medical emergency that requires prompt medical attention. It’s important to visit a doctor right away if you have potential OVT symptoms, especially if you’ve recently given birth.

Is ovarian vein thrombosis more common after vaginal birth or cesarean section?

OVT occurs more often after cesarean delivery than vaginal birth. It’s a complication of cesarean delivery in about 1 in 800 births and vaginal delivery in 1 in 9,000 births.

OVT is a rare condition characterized by a blood clot in the veins that lead from your ovaries to the main blood vessel in your abdomen called the vena cava. It can cause life threatening complications and requires immediate treatment.

Doctors treat OVT with a combination of medications and surgical options. Medical health professionals are still investigating the best way to treat it.