Ovarian vein thrombosis is an uncommon but potentially serious disorder that is associated with a variety of pelvic conditions—most notably, recent childbirth, but also pelvic inflammatory disease, malignancies, and pelvic surgery. Recognition and treatment of this condition is needed to avoid the morbidity and mortality that are related both to the thrombosis and to any associated infection/sepsis. [1, 2, 3, 4, 5] See the images below.
Ovarian vein thrombosis arises out of the coincident conditions of venous stasis and hypercoagulability, which are commonly present in the recently postpartum patient. Other conditions that are associated with hypercoagulability, such as recent surgery, malignancy, and Crohn disease,  also increase the patient's risk for ovarian vein thrombosis.
Some clinicians believe septic pelvic thrombophlebitis is part of a continuum of related illnesses that is distinguished mainly by the presenting manifestations of fever without pain. Both ovarian vein thrombosis and septic pelvic thrombophlebitis are influenced by the Virchow triad of vessel wall injury, stasis, and hypercoagulability. 
Ovarian vein thrombosis occurs in 0.02-0.18% of pregnancies and is diagnosed on the right side in 80-90% of the affected postpartum patients.
The typical patient with ovarian vein thrombosis (ie, thrombophlebitis) presents with pelvic pain, fever, and a right-sided abdominal mass.  The combination of anticoagulant and intravenous (IV) antibiotic therapy is the treatment of choice. In cases of clinically significant thrombosis, inferior vena cava (IVC) filter placement should be considered. (Note that patients who have undergone total abdominal hysterectomy and bilateral salpingo-oophorectomy with retroperitoneal lymph node dissection can incidentally demonstrate ovarian vein thrombosis on contrast-enhanced computed tomography [CT] scanning.  )
Ultrasound (US), magnetic resonance imaging (MRI), and CT scanning are the best radiologic modalities for making the diagnosis of ovarian vein thrombosis. US can provide a quick and inexpensive initial examination, without risk to the patient. However, US is frequently limited by overlying bowel gas. [9, 10, 11, 12, 13] MRI allows the examiner to avoid the use of ionizing radiation and IV iodinated contrast material. CT scanning can be obtained more easily than MRI at most institutions. However, although these 2 cross-sectional modalities are more sensitive and specific than US,  they are more time consuming and expensive. [15, 16, 17, 18]
US is useful for the initial study and follow-up imaging of ovarian vein thrombosis; however, the limitations of US include obscuration of the gonadal/ovarian vein by overlying bowel gas. Furthermore, operator dependence is always a concern when using US for any diagnosis. Color Doppler US is a helpful tool for the assessment of blood flow in the imaged vessels.
CT scanning and MRI findings usually allow a definitive diagnosis of ovarian vein thrombosis and the exclusion of other clinical diagnostic possibilities.
CT scanning demonstrates an enlarged ovarian vein with central hypodensity—representing thrombosis—a sharply defined vessel wall, and perivascular inflammatory stranding. See the images below.
Ovarian vein thrombosis can be diagnosed only with IV contrast. Spiral CT scanning is the preferred technique. When the classic image is present, the degree of confidence in the diagnosis is high. CT scanning can also exclude other conditions, although US is preferred for many of the gynecologic differential diagnostic possibilities.
The primary limitation is achieving sufficient contrast enhancement. The timing of the contrast administration must be such that the contrast is in the venous phase. If contraindications to IV contrast exist (eg, allergy), CT scanning becomes a more limited and perhaps inadequate modality.
Magnetic Resonance Imaging
For optimal MRI imaging, obtain axial T1-weighted, spin-echo images and axial fat-saturated, T2-weighted, fast spin-echo images with a body coil.
MR angiography (MRA) is performed with patient breath holding and 2-dimensional time-of-flight techniques, with flow compensation (gradient moment nulling). A spatial saturation pulse is placed superiorly to obtain selective venograms. Maximum intensity projections can be created from MRA acquisitions in different angles. Findings demonstrate a flow void where thrombosis is present.
MRI sensitivity and specificity are high. A positive finding virtually always means that ovarian vein thrombosis is present.
US may be limited by the presence of overlying bowel gas. If clinical suspicion of ovarian vein thrombosis persists after a negative or equivocal US, CT scanning or MRI is recommended as the next examination.
Ovarian vein thrombosis can be confused with appendicitis, hydroureter, lymphadenopathy, a dilated fallopian tube, and a thrombosed inferior mesenteric vein. US can readily image many of the other differential diagnostic possibilities.
Nuclear medicine is not commonly performed to evaluate a patient for ovarian vein thrombosis. A variety of approaches have been attempted that have provided only limited results.
A positive finding on venography is the presence of a filling defect that is consistent with a clot within the ovarian vein.
Angiography can help to make the diagnosis of ovarian vein thrombosis, but this technique is not usually performed because of the availability of noninvasive, cross-sectional imaging methods.