Fig. 3From: Postoperative results of ventilation tube insertion: a retrospective multicenter study for suggestion of grading system of otitis media with effusionComparison of ventilation tube retaining duration. Duration of ventilation tube retention after ventilation tube insertion surgery was significantly different when compared between two groups: grade I-IV was 10.8 (±6.4) and grade V was 9.6 (±5.8) (p = 0.019)Back to article page