title: Pneumomediastinum and pneumoperitoneum on computed tomography after peroral endoscopic myotomy (POEM): postoperative changes or complications?
abstract: BACKGROUND
  Many of the acute alterations after peroral endoscopic myotomy (POEM) may be of little clinical significance, while others may herald major clinical problems. The question whether pneumomediastinum/pneumoperitoneum is a normal postoperative finding after POEM, or should be regarded as a sign of a complication needs to be evaluated. Familiarity with these findings in computed tomography (CT) is essential for radiologists.
  
  
  OBJECTIVE
  To evaluate whether or not pneumomediastinum/pneumoperitoneum detected by chest CT is a sign of a complication after POEM using CO2 insufflation for esophageal achalasia.
  
  
  METHODS
  One hundred and eight patients with esophageal achalasia who underwent chest CT within 30 hours after POEM were included. CT findings were retrospectively reviewed by two radiologists in consensus. The correlation between pneumomediastinum and/or pneumoperitoneum shown on CT and the development of complications was analyzed.
  
  
  RESULTS
  Abnormal findings were identified on post-treatment CT, including pneumomediastinum and/or pneumoperitoneum (53.7%, 58/108), pneumothorax (0.9%, 1/108), subcutaneous emphysema (29.6%, 32/108), pleural effusion (69.4%, 75/108), segmental atelectasis of lung tissue (29.6%, 32/108), minor inflammation of lungs (69.4%, 75/108), and ascites (0.9%, 1/108). Pneumomediastinum and pneumoperitoneum were observed simultaneously in 29 cases. The incidence rate of mild complications was high (79.6%, 86/108), while the rate of severe complications was low (2.8%, 3/108). There was no significant correlation between the occurrence of pneumomediastinum and/or pneumoperitoneum on CT and the development of complications (P = 0.542), or the development of severe complications including delayed hemorrhage, esophageal perforation, and retroperitoneal abscess.
  
  
  CONCLUSIONS
  Pneumomediastinum and pneumoperitoneum detected by CT occur frequently after POEM and may be regarded as normal postoperative changes.
authors.affiliation: Department of Radiology, Zhongshan Hospital, Fudan University; Shanghai Institute of Medical Imaging; Department of Medical Imaging, Shanghai Medical College, Fudan Unversity, Shanghai, PR China.
authors.forename: Shan
authors.initials: S
authors.lastname: Yang
authors.affiliation: Department of Radiology, Zhongshan Hospital, Fudan University; Shanghai Institute of Medical Imaging; Department of Medical Imaging, Shanghai Medical College, Fudan Unversity, Shanghai, PR China.
authors.forename: Meng-Su
authors.initials: MS
authors.lastname: Zeng
authors.affiliation: Department of Radiology, Zhongshan Hospital, Fudan University; Shanghai Institute of Medical Imaging; Department of Medical Imaging, Shanghai Medical College, Fudan Unversity, Shanghai, PR China.
authors.forename: Zhi-Yong
authors.initials: ZY
authors.lastname: Zhang
authors.affiliation: Department of Radiology, Zhongshan Hospital, Fudan University; Shanghai Institute of Medical Imaging; Department of Medical Imaging, Shanghai Medical College, Fudan Unversity, Shanghai, PR China.
authors.forename: Hao-Ling
authors.initials: HL
authors.lastname: Zhang
authors.affiliation: Department of Radiology, Zhongshan Hospital, Fudan University; Shanghai Institute of Medical Imaging; Department of Medical Imaging, Shanghai Medical College, Fudan Unversity, Shanghai, PR China.
authors.forename: Liang
authors.initials: L
authors.lastname: Liang
authors.affiliation: Department of Radiology, Zhongshan Hospital, Fudan University; Shanghai Institute of Medical Imaging; Department of Medical Imaging, Shanghai Medical College, Fudan Unversity, Shanghai, PR China ys11206@163.com.
authors.forename: Xing-Wei
authors.initials: XW
authors.lastname: Zhang
mesh_terms: D000328:Adult; D000368:Aged; D004562:Electrocardiography; D004931:Esophageal Achalasia / Q000601:surgery*; D004945:Esophagoscopy; D005260:Female; D006801:Humans; D008297:Male; D008478:Mediastinal Emphysema / Q000000981:diagnostic imaging* / Q000209:etiology*; D008875:Middle Aged; D057605:Natural Orifice Endoscopic Surgery; D011027:Pneumoperitoneum / Q000000981:diagnostic imaging / Q000209:etiology*; D011183:Postoperative Complications / Q000000981:diagnostic imaging*; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed / Q000379:methods*
keywords: Computed tomography (CT); Esophageal achalasia; X-ray; complications; peroral endoscopic myotomy (POEM)