Ovarian Vein Thrombosis: Clinical Features, Risk Factors, and Outcomes
Authors: Assal Amer , Kaner Justin D , Danda Neeraja , Billett Henny H 
Published: October 2019

Abstract
Whether a complication of gynecologic surgeries or a peripartum event, ovarian vein thrombosis (OVT) remains poorly understood, with no consensus regarding its importance or treatment. In an effort to better understand the significance of OVT, we investigated the incidence, clinical features, predisposing factors, future thrombotic complications, and therapeutic patterns of this condition.
Methods : We collected cases of OVT in adult women encountered over the 10 years. Data mining software was used to search the text of imaging reports for the terms ovarian or gonadal located within 5 words of the terms thrombus, thrombosis or thrombosed. Records were reviewed to confirm diagnosis and collect demographic data, presentation and features of OVT at baseline, past medical and surgical history, and future venous thromboembolism (VTE) events. Follow up period was defined as date of last EMR entry. All chart review were conducted by study authors and discrepancies reviewed by at least two authors. Data were analyzed using Chi-squared, t-testing for unpaired samples, and ANOVA.
Results : 223 cases of confirmed OVT were identified and included in the analysis. Average follow-up time was 1163 (±977) days. The majority of cases were identified on computed tomography (CT) imaging (n=219). Mean age was 55 years (range 20 - 89 years). History of VTE was noted in 22 patients, diabetes in 44 patients and cancer in 134 patients, 64.3% of which were gynecologic. In a majority of patients, OVT was associated with a history of abdominal surgery; 60.5% of these were gynecologic procedures and 83.7% of those included a hysterectomy. Only 36.6% were noted to have otherwise unexplained abdominal pain. Chemotherapy was administered to 99 (44.4%) patients, 57 (57.6%) of which developed OVT during chemotherapy. Taxol was used in 61 patients (61.6%); 43 (70.5%) of which developed OVT during Taxol therapy.
The incidence of right (R) or left (L) OVT was similar (44.6% vs. 41.4% respectively) with a high percentage of bilateral (B) thrombi (14%). Peripartum state was associated with an increase in ROVT (60.0% versus 43.1%, p=0.033); cancer patients had a higher incidence of LOVT and BOVT compared to non-cancer patients (46.6% and 18.8% vs. 33.7% and 6.7% respectively, p=0.0005). Gynecologic surgery was also associated with an increase in LOVT and B OVT (44.0% and 18.7% versus 37.5% and 6.8% p=0.007).
Our cohort experienced 26 (11.7%) recurrent VTE events, 20 DVTs and 6 PEs (Table 1). Average time to recurrence was 393.5 (±400) days. Past VTE was associated with a higher risk of future DVT but not PE (22.0% and 0%, p=0.046 for VTE). No recurrent VTE events were noted in the peripartum group, however this did not reach statistical significance (p=0.089). Even when peripartum patients were excluded, LOVT and BOVT were associated with a higher VTE recurrence rate than ROVT (16.3% and 19.4%, p=0.01). Patients with cancer tended to have a higher VTE recurrence rate than non-cancer patients, but this did not reach statistical significance (14.2% versus 7.9%, p=0.15). However, recurrence was associated with greater mortality (p=0.002). Anticoagulation was initiated at the time of OVT diagnosis in only 21 (9.4%) patients, with 4 VTE recurrent events.
Conclusion: This is the largest OVT study to date. We demonstrate that OVT can occur within either ovarian vein, but occurs predominantly on the right in peripartum patients. We show increased recurrent events in our cohort and an association of recurrence with mortality, which argues against a benign' nature of OVT in post-hysterectomy patients. We were not able to detect increased VTE recurrence in cancer patients, in the peripartum, in diabetics, or in patients with a history of VTE. Anticoagulation initiated at the time of OVT was not associated with decreased recurrence rates but this may be due to selection bias. This study provides evidence that a prospective study of patients is needed to determine the utility of therapy for OVT.
Table 1 Subgroup analysis of the risk of future thrombotic events Variable (N) Recurrent VTE N (%) P Value Total (223) 26 (11.7%) Peripartum (20) 0 (0%) 0.089 Cancer (134) 19 (14.2%) 0.15 History of VTE (22) 5 (22.7%) 0.088 Laterality BOVT (31) 6 (19.4%) 0.07 LOVT (92) 15 (16.3%) ROVT (99) 5 (5.1%) Extension Present (17) 3 (17.6%) 0.42 Absent (206) 23 (11.2%) During chemotherapy (57) 9 (15.8) 0.65 Anticoagulated for OVT (21) 4 (19.0) 0.27

Disclosures
No relevant conflicts of interest to declare.