TULAA combines the laparoscopic and open technique and is considered to be a safe, fast and cost-effective procedure. On the other hand, preparation is limited due to the single instrument, especially in complicated appendicitis. In this study we analyze the outcome of our TULAA patients, focusing on conversion and complication rates. We performed a retrospective study including all patients treated with TULAA in our department between 2006 and 2016. We analyzed patient data, operative data, costs, complications, and conversion rate to standard laparoscopic or open appendectomy. 1275 children and adolescents were enrolled. Mean age was 10.2 years. TULAA was completed in 88% of cases. The overall mean operative time was 33min. The overall complication rate was 5.7%. The most common complications were wound infection (2.7%), seroma (1.7%) and wound abscess (1.4%). Both the conversion rate and the complication rate were significantly higher in complicated appendicitis. Furthermore, the conversion rate is higher in overweight or obese patients. TULAA is a safe, quick and cost-effective treatment option for acute appendicitis in children and adolescents. The complication rate and conversion rate are significantly correlated with the degree of appendiceal inflammation and comparable other surgical procedures.