Purpose: To introduced our experience with progressive extra-axial hematoma (EAH) in the original frontotemporoparietal (FTP) site after contralateral decompressive surgery (CDS) in traumatic brain injury patients and discuss the risk factors associated with this dangerous situation., Methods: This retrospective study was conducted on 941 patients with moderate or severe TBI treated in Daping Hospital, Army Medical University, Chongqing, China in a period over 5 years (2013-2017). Only patients with bilateral lesion, the contralateral side being the dominant lesion, and decompressive surgery on the contralateral side conducted firstly were included. Patients were exclude if (1) they underwent bilateral decompression or neurosurgery at the original location firstly; (2) although surgery was performed first on the contralateral side, surgery was done again at the contralateral side due to re-bleeding or complications; (3) patients younger than 18 years or older than 80 years; and (4) patients with other significant organ injury or severe disorder or those with abnormal coagulation profiles. Clinical and radiographic variables reviewed were demographic data, trauma mechanisms, neurological condition assessed by Glasgow coma scale (GCS) score at admission, pupil size and reactivity, use of mannitol, time interval from trauma to surgery, Rotterdam CT classification, type and volume of EAH, presence of a skull fracture overlying the EAH, status of basal cistern, size of midline shift, associated brain lesions and types, etc. Patients were followed-up for at least 6 months and the outcome was graded by Glasgow outcome scale (GOS) score as favorable (scores of 4-5) and unfavorable (scores of 1-3). Student's t-test was adopted for quantitative variables while Pearson Chi-squared test or Fisher's exact test for categorical variables. Multivariate logistic regression analysis was also applied to estimate the significance of risk factors., Results: Initially 186 patients (19.8%) with original impact locations at the FTP site and underwent surgery were selected. Among them, 66 met the inclusion and exclusion criteria. But only 50 patients were included because the data of the other 16 patients were incomplete. Progressive EAH developed at the original FTP site in 11 patients after the treatment of, with an incidence of 22%. Therefore the other 39 patients were classified as the control group. Multivariate logistic regression analysis showed that both the volume of the original hematoma and the absence of an apparent midline shift were significant predictors of hematoma progression after decompressive surgery. Patients with fracture at the original impact site had a higher incidence of progressive EAH after CDS, however this factor was not an important predictor in the multivariate model. We also found that patients with progressive EAH had a similar favorable outcome with control group., Conclusion: Progressive EAH is correlated with several variables, such as hematoma volumes ≥10 mL at the original impact location and the absence of an apparent midline shift (<5 mm). Although progressive EAH is devastating, timely diagnosis with computed tomography scans and immediate evacuation of the progressive hematoma can yield a favorable result., Competing Interests: Declaration of Competing Interest There are no conflicts of interest., (Copyright © 2020. Production and hosting by Elsevier B.V.)