Mumtu Lalla, M4
The Article: Budhram, et al. “A Case-Control Study of Sonographic Maximum Ovarian Diameter as a Predictor of Ovarian Torsion in Emergency Department Females With Pelvic Pain.” Academic Emergency Medicine 2019; 152-159.
The Idea: Ovarian torsion is a diagnosis that often presents atypically and has significant complications if missed. Color and power Doppler ultrasound are often used in the evaluation of ovarian torsion, but are unreliable. Subsequent examination by radiologist is also time-consuming, expensive and low-yield. Because normal-sized ovaries are unlikely to cause torsion, this study examines the use of mean ovarian diameter (MOD) as a screening test in the emergency department.
The Study: This study was a retrospective case-control study from January 2000 to December 2014 at a single, large tertiary care ED.
● Inclusion Criteria: Female patients ages 2-100 that presented to the ED within the study period with a chief complaint of “pelvic pain” or “lower abdominal pain” and who received a radiology department transvaginal and/or transabdominal pelvic ultrasound with an indication of “rule-out torsion”
● Exclusion Criteria: Patients whose both ovaries were not completely visualized and measured by ultrasound, if no ultrasound report was available or if ovarian torsion was diagnosed by CT. Patients were also excluded from the torsion group if manual chart review did not confirm torsion via operative findings. Patients were excluded from the control group if torsion was identified on subsequent visits within 3 months, and these patients were included in the torsion group.
● 3,605 patients with a suspicion of ovarian torsion were identified as a base cohort. 121 patients from that cohort were diagnosed by the ED as having ovarian torsion. 92 of those cases were identified with both surgically-confirmed ovarian torsion and an ultrasound report. Ninety-two age-matched control patients were selected from the remainder cohort who received a pelvic ultrasound to rule out torsion, but in whom torsion was not diagnosed.
● Primary Endpoints: the association between ovarian torsion and a MOD of >3 or >5 cm as assessed by ultrasound in postmenarchal subjects.
● Secondary Endpoints: the association between ovarian torsion and a MOD of >3 or >5 cm as assessed by ultrasound in premenarchal patients.
Results:
Zero patients in the postmenarchal torsion group had a MOD < 3 cm, while seven of 81 (8.6%) had MOD ≤5 cm. Among patients with torsion, 30 of 77 (39%) had normal arterial and venous Doppler signal. In postmenarchal patients, the sensitivity for a 3-cm threshold value was 100%, but the specificity was 30% (95% CI =20.8%–41.1%). Sensitivity decreased to 91% using a 5-cm MOD and specificity increased to 92%.
In regards to the secondary outcome, no premenarchal patients were also found to have torsion with largest ovarian diameter < 3 cm. In the premenarchal group, though, torsion tended to occur within a smaller range of ovarian diameter, between 4 and 7 cm.
The Takeaway: This paper reveals several important points. First, that screening decisions for patients with lower abdominal pain should be based on ovarian size rather than Doppler findings given the poor sensitivity of Doppler in ruling out torsion. Assessment of arterial and venous blood flow in the ovaries can be technically difficult due to body size, interposed bowel gas, or because torsion is intermittent. The paper also discusses how increasing the threshold value for MOD from 3-cm to 5-cm decreases sensitivity but increases specificity, excluding torsion in an increased number of patients.
Limitations of this study: 1. Single-centered study 2. Does not account for user operability in finding and measuring ovarian diameter