BACKGROUND Bleeding, ulceration and cardiac failure can occur in rapidly involuting congenital hemangioma (RICH). Bleeding intensity ranges from superficial to life-threatening. OBJECTIVE To determine whether there are sonographic criteria associated with an increased risk of bleeding, ulceration or cardiac failure in RICH in order to identify children who need close monitoring or prophylactic treatment. MATERIALS AND METHODS This retrospective single-center study included RICH patients over a period of 13 years. We evaluated sonographic features of RICH on B-mode and Doppler ultrasound. We correlated the occurrence of bleeding, ulceration and cardiac failure with four sonographic findings: (1) visible vessel, (2) venous ectasia, (3) venous lake and (4) arteriovenous shunting. RESULTS We included 24 patients. Ulceration occurred in five cases, bleeding in four cases, one of which was life-threatening. Cardiac failure was observed more frequently in RICH with venous lakes (P=0.028). Bleeding and ulceration appeared more frequently in RICH with venous ectasia and venous lakes. Cardiac failure was associated with the presence of venous ectasia. All children with cardiac failure or ulceration had arteriovenous shunts. CONCLUSION RICH with venous lakes on ultrasound is prone to develop bleeding, cardiac failure and ulceration. This association was only significant for cardiac failure.