Purpose: Uterine leiomyomas (fibroids) are extremely common, seen in up to 70% of women by the age of 50 years [1,2,4]. MR imaging of fibroids has increased with pre-procedural planning (pre-embolization or myomectomy). Incidental findings of dilated lymphatics or an unusual engorged appearance of the ovary may be seen, which can trigger concern for pelvic pathology (ie, an underlying ovarian mass or ovarian torsion). This can lead to an unnecessary additional or more emergent intervention such as oophorectomy. The goal of this investigation was to determine the incidence of findings in asymptomatic patients which were suggestive of outflow obstruction (venous or lymphatic) as evidenced by dilated lymphatics and ovarian engorgement/signs of massive ovarian edema and to correlate these findings with the size of the fibroid uterus as compared to an age matched control population without fibroids.

Methods: After IRB approval, we performed a retrospective review of our institution’s radiologic database for all contrast-enhanced pelvic MRI from 2007-2015 with the key words “fibroid uterus” and “ovarian edema”, “dilated lymphatics”, “loculated pelvic fluid.” The search yielded 923 cases of which 864 cases were excluded: absence of fibroids or small fibroid uteri (< 100 cc uterine volume [3]) (397 cases), normal ovaries (302), no loculated collection (38), presence of endometrioma/endometriosis (61), images not available from archive (13), redundant (51), ovarian neoplasm (4), and findings suggestive of leiomyosarcoma (3). We identified 54 asymptomatic patients (without clinical symptoms suggestive of ovarian torsion) with contrast enhanced MRI findings that included fibroid uterus with either ovarian abnormality or abnormal pelvic fluid collections. We compared these findings to 54 asymptomatic patients without fibroids. The cases were retrospectively reviewed and analyzed by two blinded abdominal radiologists (fellow and attending) for the following findings: uterine volume, location of abnormal ovary/fluid collection (if ovary is abnormal, we evaluated for the presence of ovarian enlargement, T2 hyperintensity, and enhancement), and predominant fibroid type adjacent to the abnormality. Statistical analysis was performed using the Student’s t-tests.

Results: The average uterine volume in the 54 patients with fibroid uteri and with signs of lymphatic obstruction (ovarian edema/lymphatic dilatation) was 1046 cc (range 132-6192 cc). The average uterine volume in the 54 control patients was 602 cc (range 115-3293 cc). Ovarian edema and/or lymphatic dilatation was noted with increased frequency in asymptomatic patients imaged for fibroid uterus over asymptomatic female patients without a fibroid uterus imaged for other causes (p< 0.0001). Massive ovarian edema (defined by prior criteria, including increased size with peripheral distribution of follicles, not in the setting of PCOS) was noted in 11/54 asymptomatic fibroid patients; there was a signification association with increasing uterine volume as compared to controls (p<0.01) and as compared to patients with lymphatic obstruction alone (p<0.05). There were no patients in the control group with massive ovarian edema (p<0.0001). Asymptomatic patients without a fibroid uterus often had high T2 signal in the ovary that contained a corpus luteum (13/54), but without peripheral distribution of follicles and without significant enlargement relative to the contralateral ovary. There were 29/54 patients with only lymphatic obstruction associated with fibroid uterus. There were 25/54 with ovarian edema (of which 11/24 had signs of massive ovarian edema and 16/24 also had lymphatic obstruction). Of the 11 patients with massive ovarian edema, 3 of these patients went to the operating room, where a viable ovary was seen.

Discussion: Signs of outflow (venous or lymphatic) obstruction by enlarged fibroid uteri can be ovarian engorgement and lymphatic dilatation. Massive ovarian edema, thought to result from intermittent or partial ovarian torsion in a symptomatic patient, has been mistaken for a solid malignant neoplasm and treated with oophorectomy [5]. However, the condition is theorized to be caused by partial venous and lymphatic obstruction, accounting for its imaging appearance [6]. Conservative management of massive ovarian edema has been successful when it is suggested/suspected prospectively [5]. Our results indicate that massive ovarian edema and lymphatic obstruction are benign findings present in patients with large fibroid uteri, for which non-operative management is appropriate. To our knowledge, this is first study investigating this phenomenon in the presence of fibroid uterus.

Conclusion: Ovarian edema and/or dilated lymphatics in the setting of large fibroid uteri may be due to vascular congestion or lymphatic obstruction. In the absence of pain and symptoms concerning for ovarian torsion, we postulate that these are incidental findings and recommend conservative management as opposed to immediate surgical exploration.