We use transumbilical laparoscopic-assisted appendectomy (TULAA) with a lifting retractor as the surgical technique of first choice for acute appendicitis. Although this technique provides excellent cosmetic results and contributes to reducing medical costs, it is less advantageous in difficult-to-complete cases that require conversion to pneumoperitoneum or additional ports. We retrospectively reviewed the records of 76 patients who underwent laparoscopic appendectomy between June 2020 and March 2023 (43 in a TULAA group and 33 in a pneumoperitoneal conversion group) to identify preoperative factors associated with pneumoperitoneal conversion. Univariate analysis showed significant differences for preoperative C-reactive protein (CRP) level, age, and body mass index. Logistic regression analysis identified preoperative CRP level and age as significant risk factors for pneumoperitoneal conversion. The pneumoperitoneal conversion rate was 12.5%, 48.2%, and 68% for patients with 0, 1, and 2 preoperative risk factors, respectively, indicating patients with 2 risk factors were more likely to undergo pneumoperitoneal conversion. These data may inform the selection of the surgical technique and the decision to convert to pneumoperitoneum.