Accuracy of imaging modalities for adnexal torsion: a systematic review and meta-analysis

Background: Adnexal torsion (AT), a serious gynaecological emergency, often presents with non-specific symptoms leading to delayed diagnosis.

Objective: To compare the test accuracy of ultrasound, computed tomography (CT) and magnetic resonance imaging (MRI) to diagnose AT.

Search strategy: We searched EMBASE, MEDLINE and Cochrane CENTRAL until December 2019.

Selection criteria: Studies reporting on the accuracy of any imaging modality (Index Test) in female patients (paediatric and adult) suspected of AT compared with surgical diagnosis and/or standard clinical/radiological follow-up period until resolution of symptoms (Reference Standard).

Data collection and analysis: We assessed study quality using QUADAS-2. We conducted test accuracy meta-analysis using a univariate model or a hierarchical model.

Main results: We screened 3836 citations, included 18 studies (1654 women, 665 cases), and included 15 in the meta-analyses. Ultrasound pooled sensitivity (n = 12, 1187 women) was 0.79 (95% CI 0.63-0.92) and specificity was 0.76 (95% CI 0.54-0.93), with negative and positive likelihood ratios of 0.29 (95% CI 0.13-0.66) and 4.35 (95% CI 2.03-9.32), respectively. Using Doppler with ultrasound (n = 7, 845 women) yielded similar sensitivity (0.80, 95% CI 0.67-0.93) and specificity (0.88, 95% CI 0.72-1.00). For MRI (n = 3, 99 women), the pooled sensitivity was 0.81 (95% CI 0.63-0.91) and specificity was 0.91 (95% CI 0.80-0.96). A meta-analysis for CT was not possible with two case-control studies and one cohort study (n = 3, 232 women). Its sensitivity range was 0.74-0.95 and specificity was 0.80-0.90.

Conclusions: Ultrasound has good performance as a first-line diagnostic test for suspected AT. Magnetic resonance imaging could offer improved specificity to investigate complex ovarian morphology, but more evidence is needed.

Tweetable abstract: To investigate adnexal torsion, ultrasound is a good first-line diagnostic test with a pooled sensitivity of 0.79 and specificity of 0.76.