Prevalence of Pulmonary Bullae and Blebs in Postmortem CT Imaging With Potential Implications for Diving Medicine

Background: Pulmonary bullae and blebs can result in a pneumothorax. Their prevalence in the normal population is currently unknown. Postmortem CT (PMCT) images from a forensic database were used to determine the prevalence of pulmonary bullae/blebs in the normal Dutch adult population and its consequence for diving medicine, as bullae and blebs are often considered a contraindication for diving. Methods: Forensic PMCT scans of 130 adults were analyzed for the presence of bullae and/or blebs in a cross-section of the Dutch population without pulmonary disorders. The lungs had to be unharmed, expanded, and without signs of illnesses. Normal early-stage postmortem changes in the lungs were accepted. Results: Analysis was performed per decade. Group I (aged 21-30 years) included 26 patients. Blebs were observed in four persons; one exhibited blebs and bullae. Group II (aged 31-40 years) included 28 patients; blebs were observed in nine individuals, one with bullae. Group III (aged 41-50 years) included 27 patients; blebs were noted in nine individuals, bullae in one, and bullae and blebs in four. Group IV (aged 51-60 years) included 28 patients; blebs were noted in seven individuals and two with bullae and blebs. Group V (aged 61-70 years) included 21 patients; blebs were noted in three persons, bullae and blebs in two, and isolated bullae in one. On average, most bullae/blebs were < 10 mm, and none exceeded 20 mm. Conclusions: By reassessing pulmonary PMCT scans, we found a surprisingly high incidence of small bullae and/or blebs in one-third (33.8%; 95% CI, 25.7-41.9) of the general population without underlying lung disease. This finding can have potential implications for diving medicine.