Introduction and aim of the study: Evacuation proctography (EP) has been regarded as the gold standard for the diagnosis of posterior pelvic floor disorders. Magnetic Resonance Imaging (MRI), transperineal ultrasound (TPUS) and endovaginal Ultrasound (EVUS) are less invasive, avoid ionizing radiation and provide a three compartment assessment. Our aim was to establish the accuracy of four imaging techniques and determine if ultrasound/MRI could substitute EP.
Materials and methods: Prospectively, 131 women with symptoms of obstructed defecation syndrome underwent all four imaging techniques. Target conditions under evaluation were rectocele, enterocele, intussusception, anismus and pelvic floor descent. Findings were dichotomised into present or absent. Images were assessed independently by two observers blinded to clinical and other imaging findings. Discrepancies were resolved by a tertiary observer. EP was assumed to be an imperfect gold standard. Latent Class Analysis was used as is regarded the best statistical test in the absence of a gold standard [
[1]
].Results: MRI and TPUS were better in diagnosing rectocele compared to EP (sensitivity 1.00; 0.92 vs. 0.50). All four were equally good in diagnosing enterocele (sensitivity 0.43;0.38; 0.47;0.79). EP was best in diagnosing intussusception (sensitivity 0.67 vs. 0.14;0.07;0.34). EVUS was best in diagnosing anismus (sensitivity 1.00 vs. 0.33;0.34;0.61). MRI and EP were equally good in diagnosing pelvic floor descent (sensitivity 0.95;0.92 vs. 0.35;0.20).
Interpretation of results: MRI could substitute EP for the diagnosis of rectocele, enterocele and pelvic floor descent, due to its excellent tissue discrimination. EP remains the preferred technique to diagnose intussusception. EVUS is a valuable tool for diagnosis of animus.
Conclusions: This is the first study to assess the accuracy of four imaging techniques, showing EP is no longer the best available. MRI and ultrasound could to substitute EP for specific conditions and therefore the best imaging modality for each patient should be selected based on symptoms and suspected condition.
Reference
- Evaluation of diagnostic tests when there is no gold standard. A review of methods.Health Technol Assess. 2007; 11 (iii,ix-51)
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© 2017 Published by Elsevier Inc.
