Assessing the clinical utility of color Doppler ultrasound for ovarian torsion in the setting of a negative contrast-enhanced CT scan of the abdomen and pelvis.

PURPOSE: The purpose of this study is to evaluate the utility of color Doppler ultrasound (CDU) in the assessment of ovarian torsion following a negative contrast-enhanced computed tomography (CT) examination.

METHODS: This is a retrospective study of women who presented to the ED with abdominal pain and received both a contrast-enhanced CT and CDU within a 24-h period. The abdominal/pelvic CT examinations were evaluated for findings specific to torsion, including ovarian size greater than 5 cm, the presence of free fluid, uterine deviation, fallopian tube thickening, ovarian fat stranding, smooth wall thickening, the presence of the "twisted pedicle" sign, and abnormal ovarian enhancement. The results were compared to the presence or absence of ovarian torsion on the concurrent US.

RESULTS: The initial query yielded 834 cases among 789 women. Of those 834 cases, 283 cases in 261 women received both imaging modalities within a 24-h period. The CT examinations demonstrated 48 cases with an ovarian size greater than 5 cm. 84 cases showed the presence of free fluid. Three cases of fallopian tube thickening were identified. One case of smooth wall thickening and a "twisted pedicle" sign were noted. Fifteen cases demonstrated stranding of the peri-ovarian fat. Twenty nine cases showed abnormal ovarian enhancement. A total of 111 cases showed at least one positive finding. Fourteen positive cases were identified on the CDU studies. Of the 14 positive cases, 11 had ovarian size greater than 5 cm. Twelve cases demonstrated the presence of free fluid. There was no uterine deviation or smooth wall thickening. One twisted pedicle was noted. Seven cases showed peri-ovarian fat stranding. Ten cases showed abnormal enhancement. Abnormalities on CT were noted in all cases suspicious for ovarian torsion on CDU. No negative CT examinations were associated with a positive CDU. In this small sample size, the negative predictive value of a negative CT examination was 100%.

CONCLUSION: A negative contrast-enhanced CT examination of the abdomen and pelvis is sufficient to rule out ovarian torsion. Therefore, there is no utility in the addition of CDU specifically to evaluate for ovarian torsion following a negative contrast-enhanced CT scan of the abdomen and pelvis.