Corpus luteum with ovarian stromal edema is associated with pelvic pain and confusion for ovarian torsion

Pearls and Pitfalls in Imaging of Pelvic Adnexal Torsion: Seven Tips to Tell It's Twisted

Pelvic adnexal torsion is a collective term referring to twisting of an ovary, fallopian tube, or paraovarian cyst on its axis with varying degrees of vascular compromise. Although it is the fifth most common gynecologic emergency, the diagnosis is challenging and often missed due to symptoms, physical examination findings, and imaging features that are nonspecific. Delay in salvage surgery may lead to ovarian or tubal loss, dysfunction, and infertility. The tips shared herein are based on the authors' observations of key clinical and imaging features of torsion, with the intent of heightening radiologists' index of suspicion and diagnostic accuracy in a clear and memorable fashion. Clinically, severe acute pain with a known adnexal mass or of severity to elicit nausea or vomiting should raise concern. At imaging, features of ovarian edema are key to the diagnosis, including asymmetric ovarian enlargement, peripheralized follicles, adjacent free fluid, and foci of stromal hemorrhage. The converse finding of symmetric nonenlarged ovaries in a normal location with any imaging modality has a high negative predictive value for torsion, obviating the need for additional imaging. The whirlpool sign (twisted vascular pedicle), abnormal ovarian location, and uterine tilting are additional key imaging manifestations. The presence of color Doppler flow or contrast enhancement only suggests that an ovary is still viable and should not be used to exclude the diagnosis of torsion. In cases of isolated tubal or paraovarian cyst torsion, the ovaries may appear normal; therefore, recognition of this entity along with appreciation of several key imaging findings may assist with this difficult diagnosis. An invited commentary by Dighe is available online. Online supplemental material is available for this article. ^©RSNA, 2021.

Peripheral hypervascularity of the corpus luteum with ovarian edema (CLOE) may decrease false positive diagnoses of ovarian torsion

INTRODUCTION

In patients with pelvic pain, corpus luteum with associated ovarian edema (CLOE) may be mistaken for ovarian torsion on ultrasound or CECT.

METHODS

This was a multi-reader, blinded, retrospective review performed at a single academic center from 2012 to 2018. Cases of CLOE that were misdiagnosed as torsion and cases of ovarian torsion without a lead-point mass were analyzed. Evaluated ultrasound features included presence of a corpus luteum, ovarian and corpus luteum volume, Color Doppler vascularity of the corpus luteum rim compared to that of the ovarian stroma, peripheral follicular displacement, twisted vascular pedicle, and free fluid. Evaluated CT features included presence of a corpus luteum, ovarian and corpus luteum volume, corpus luteum rim enhancement, twisted vascular pedicle, and free fluid.

RESULTS

39 cases of CLOE and 30 cases of ovarian torsion without lead-point mass were reviewed. A corpus luteum was present in 56.7% of torsed ovaries. In CLOE cases, peripheral hypervascularity of the corpus luteum (manifested as enhancement at CECT or flow signal at Doppler US) was present in 67.7% (21/31) of cases on ultrasound, and in 95.7% (22/23) of cases on CT. No peripheral hypervascularity of the corpus luteum was seen in cases of torsion (p < 0.001). Torsed ovaries were significantly larger than CLOE cases. Other findings were not significantly different between the two groups.

CONCLUSION

Increased blood flow in the periphery of a corpus luteum on color Doppler ultrasound or on CECT is a strong negative predictor for ovarian torsion.