OBJECTIVE: CLOVES syndrome (CLO: congenital lipomatous overgrowth, V: vascular anomalies E: epidermal nevi S: spinal anomalies) is a rare, non-heritable sporadic overgrowth disorder with serious morbidity. Previous anecdotal reports indicate that CLOVES patients are at risk for serious thromboembolic events in the perioperative period. The purpose of this study is to systematically determine the adverse events associated with anesthesia and diagnostic or interventional procedures for CLOVES patients, so appropriate assessment of risk can be performed and adequate precautions can be taken in the future to prevent complications. METHODS: We selected our study cohort by gathering patients in the Vascular Anomalies Center (VAC) database with the diagnosis of CLOVES syndrome. Our primary group of interest was patients that were anesthetized at Boston Children's Hospital (BCH) since 2005. All patients having the diagnosis of CLOVES were included. IRB approval was obtained prior to patient selection. Data was collected from BCH electronic medical records. Patient age, gender, ASA level, estimated amount of blood loss (EBL), surgery status, MRI status, complication(s), type of complication if any, and medical history was recorded in a Microsoft Excel document on a password-protected computer. Data analysis was carried out with no statistical analysis beyond simple incidence and prevalence of certain characteristics due to the extremely small patient population. RESULTS: We found that out of the 38 patients in our cohort, 15 (or 39%) suffered from complications during the perioperative period. A total of 23 (or 61%) did not have any complications. Results further showed that pulmonary emboli, respiratory issues, and hypo/hypertension were the most prevalent complications. In addition we found that there was no correlation between substantial EBL and complication occurrence in this cohort. CONCLUSION: In comparison to preliminary studies of Alomari, 2008 and Sapp et al., 2007, we report a lower occurrence of thromboembolic events in CLOVES patients. We hypothesize that this is because patients at BCH were treated aggressively with various prophylactic methods to help minimize the risk of such events. We recommend that early prophylactic anticoagulation methods are applied to future patients. Additionally, we recommend that CLOVES patients be followed by a hematologist and care team that are familiar with the condition throughout their stay at the hospital to reduce the risk of thromboembolic events.