Objective: This study intended to investigate the reproducibility of the Waters' view for maxillary sinusitis and to define its place in clinical practice.
Materials and method: Radiographs of 80 maxillary sinuses of patients with suspected acute sinusitis were read by 6 radiologists, 6 ENT surgeons, 6 general practitioners (GPs). Interobserver agreement was calculated using the kappa statistic.
Results: Agreement was good (kappa = 0.63; 95% CI 0.58-0.68) between radiologists when the criteria used to define acute sinusitis were "important mucosal swelling, air-fluid level or complete opacity". When the criteria "air-fluid level or complete opacity" were used, agreement was fair (kappa 0.39; 95% CI 0.35-0.44). Between ENT-surgeons kappas were respectively 0.58 (95% CI 0.53-0.63) and 0.37 (95% CI 0.32-0.42). Between GPs kappas were respectively 0.30 (95% CI 0.25-0.35) and 0.28 (95% CI 0.23-0.33).
Conclusion: The reproducibility of Waters' views of the maxillary sinuses is best when the interpretation is performed by radiologists or ENT surgeons, and when criteria for sinusitis are: important mucosal swelling, air fluid level or complete opacity. The good interobserver agreement combined with the known high negative predictive value of these diagnostic criteria makes the Waters' view only useful for ruling out acute sinusitis.