PURPOSEThe aim of this study was to describe in detail the characteristics and accreditation compliance of laboratories in the United States applying for Intersocietal Accreditation Commission (IAC) transcranial Doppler (TCD) accreditation. METHODSThis was a retrospective study of all applicant laboratories from 2012 to 2015. We used the IAC database to extract laboratory characteristics and guideline compliance metrics. RESULTSEvaluation of 97 laboratories demonstrated that 67% were hospital-based and located in the South (43.3%), corresponding to the location of Stroke Belt states. Cases from 186 interpreting physicians, of which 110 (59%) were neurologists, were evaluated during the accreditation process. Established practice was the most common training pathway (54.8%), and a majority had not obtained an additional vascular interpretation credential (72.6%). From 318 case studies, the most frequent indications were subarachnoid hemorrhage (31.0%), stroke (17.0%), and carotid stenosis (14.3%). Although most laboratories had been previously accredited, accreditation was delayed for 77.3% due to incomplete studies (33.0%), discrepant findings between the report and the laboratory's diagnostic criteria (23.7%), and discrepant findings between the report and the waveforms/images (17.5%). CONCLUSIONSThe results suggest that there are significant differences between IAC applicant laboratories and laboratories represented by Centers for Medicaid and Medicare Services (CMS) claims data. In addition, accurate study reporting, physician training, and ongoing quality improvement activities may not be optimized in laboratories applying for accreditation. With the information learned from this study, educational strategies by professional organizations, including the IAC, can be tailored to help improve TCD practice.