Article: Mashiach R, Melamed N, Gilad N, Ben-Shitrit G, Meizner I. Sonographic diagnosis of ovarian torsion: accuracy and predictive factors. J Ultrasound Med. 2011;30(9):1205-1210. doi:10.7863/jum.2011.30.9.1205
Background: Ovarian torsion is the fifth most common gynecologic surgical emergency, affecting around 3% of women. It is important to diagnose this early to prevent loss of the adnexa or ovary and more rarely, potentially fatal thrombophlebitis or peritonitis. Due to the variable clinical presentation of ovarian torsion, diagnosis can be challenging. Conventional sonographic findings and Doppler flow studies may assist in reaching the diagnosis of torsion. However, the accuracy of this diagnostic method is controversial as studies have shown a correct diagnosis is only made in 23%-66% of cases before surgery.
Goal: This study sought to determine the accuracy of sonographic diagnosis of ovarian torsion and the predictive value of sonographic signs associated with ovarian torsion.
Study Design:
Inclusion criteria: Women attending the ultrasound unit at the department of obstetrics and gynecology at a university-affiliated tertiary medical center between 2002 through 2008 for whom sonographic findings raised a suspicion of ovarian torsion. From this dataset, the women who underwent diagnostic laparoscopy following the sonographic examination were included in the study. Data on 8 torsion-related sonographic parameters were obtained from medical records and the combinations that provided the highest diagnostic accuracy in each category were included. These parameters included ovarian edema, ipsilateral ovarian enlargement, ovarian cyst, abnormal ovarian location, abnormal ovarian blood flow, free fluid around the ovary or in the Douglas pouch, distended fallopian tube, and bleeding within the affected ovary. This resulted in sixty-three women meeting the study criteria.
Methodology: Multivariate stepwise logistic regression analysis was used to determine which sonographic factors best predicted ovarian torsion as well as to assess the effect of other factors including sonographic approach, side of torsion, and ultrasound operator.
Results: Overall accuracy of sonographic diagnosis of Ovarian Torsion was identified at 74.6%, as Ovarian torsion was identified laparoscopically in 47 of the 63 women.
The most common finding in cases with no ovarian torsion on laparoscopy was hemorrhagic corpus luteum. Four women (6.3%) had no abnormal findings on laparoscopy.
The most frequent sonographic signs in cases of ovarian torsion were ovarian edema, abnormal ovarian blood flow, ipsilateral enlargement of the affected ovary, and presence of free fluid around the ovary or in the Douglas pouch.
A substantial number of women had ovarian torsion despite the presence of normal ovarian blood flow (13%), lack of ipsilateral ovarian enlargement (13%), and no evidence of ovarian cyst or mass on sonography (60%).
The most diagnostically accurate and statistically significant sonographic signs were abnormal ovarian blood flow and presence of free fluid around the affected ovary or in the Douglas pouch.
The sensitivity of individual sonographic signs ranged from 36.2% to 85.1%, and the specificity ranged from 18.8% to 87.5%. Ovarian edema, abnormal ovarian blood flow, and ipsilateral ovarian enlargement were associated with high sensitivity, whereas free fluid around the ovary, ovarian cyst, and abnormal ovarian location were associated with higher specificity.
A combination of 2 or more sonographic signs was associated with a higher specificity and PPV for ovarian torsion, up to 100% for most combinations.
The diagnostic accuracy of ovarian torsion was unrelated to the side of torsion or the sonographic approach. There was considerable variability in the accuracy of the sonographic diagnosis among operators, however the differences did not reach statistical significance.
Limitations: This study was limited by the small sample size and retrospective design, in addition to use of data obtained from various different ultrasound operators. In addition, there was no evidence on false-negative sonographic studies, since not all women with pelvic pain undergo laparoscopy.
Conclusion: This study found that sonographic diagnosis of ovarian torsion is accurate, given that it is usually the first imaging modality for women presenting with pelvic or lower abdominal pain, and it can be useful in detecting cases of ovarian torsion. However, ovarian torsion should still be considered if the clinical presentation is suggestive of ovarian torsion, even if the typical sonographic signs are absent. In situations where the clinical presentation is indeterminate, the specificity of the sonographic diagnosis can be increased by using combinations of sonographic signs and Doppler evaluation in the assessment.
Post by Alexandra Myers, MS4