Assessment of liver volume reduction after preoperative acute weight loss for bariatric surgery: A prospective computed tomography-based study

Background: Patients with a BMI ≥50 kg/m2 face increased perioperative risks due to hepatomegaly, excessive adiposity, and severe comorbidities. Most guidelines recommend preoperative weight loss to reduce these risks by decreasing liver volume and improving co-morbid conditions. This study aimed to evaluate the efficacy of preoperative acute weight loss (AWL) in reducing liver volume, as assessed by paired non-contrast computed tomography (CT) scans. Methods: This prospective study was conducted between March and September 2019 at a university hospital. Patients with a BMI ≥50 kg/m2 undergoing bariatric surgery were included. They followed an 800 kcal/day diet for two weeks before surgery. Baseline characteristics and metabolic parameters were collected. Liver volume was measured using non-contrast CT scans before and after AWL. Data were analyzed for changes in liver volume and associated parameters. Results: A total of 12 patients (6 males and 6 females; mean age 35.8 ± 10.7 years) successfully completed the two-week preoperative AWL without complications. All patients subsequently underwent Roux-en-Y gastric bypass (RYGB). The mean body weight decreased from 154.8 ± 20.3 kg to 141.2 ± 19.9 kg (8.6 ± 6.5 %, p ≤ 0.01), and BMI decreased from 55.3 ± 4.5 kg/m2 to 50.6 ± 6.3 kg/m2 (8.6 ± 6.5 %, p ≤ 0.01). Liver volume was significantly reduced by 24.6 ± 9.6 % (p ≤ 0.001). Fasting blood sugar and systolic blood pressure decreased by 12.7 ± 14.2 % (p < 0.05) and 10.1 ± 6.6 % (p ≤ 0.001), respectively, while abdominal wall thickness was reduced by 4.9 ± 2.9 % (p ≤ 0.001). The mean operative time was 140 min, with no conversions to open surgery or perioperative complications. Conclusions: Preoperative AWL is an effective strategy for reducing liver volume, body weight and metabolic parameters in patients with BMI ≥50 kg/m2 undergoing bariatric surgery. These reductions may facilitate safer laparoscopic procedures by improving surgical access and reducing perioperative risks. Given its feasibility and safety, AWL should be considered an essential component of preoperative preparation for bariatric surgery.