Design: Prospective observational study using preoperative color doppler 2D transabdominal ultrasound to measure abdominal wall thickness and distance from skin to aorta, inferior vena cava and superior mesenteric artery.

Setting: Complex gynecology and gynecology oncology practice at tertiary hospital

Patients or Participants: Female patients (n=187) undergoing laparoscopic gynecologic procedure between January 2021 and March 2024.

Interventions: Preoperative transabdominal ultrasound

Measurements and Main Results:
Normal BMI (n=83), overweight BMI (n=57) and obese BMI class I - III (n=53) were included. For the entire cohort, mean (SD) abdominal wall thickness 2.59 cm (1.12), maximum periumbilical abdominal wall thickness 8.6cm, and distance (centimeters) from skin to aorta 3.20 (1.67), IVC 3.20 (1.80) and SMA 1.83(1.11) were measured. Abdominal wall thickness was significantly less for normal weight women compared to overweight and obese women (1.82 vs 2.57 vs 3.69, p<0.001). Compared to normal and overweight women, skin to vessel distance in obese patients was significantly larger for aorta (4.50 vs 5.69 vs 7.89, p<0.001), IVC (4.47 vs 5.76 vs 7.84, p<0.001), and SMA (3.45 vs 4.55 vs 5.70, p<0.001), respectively. When controlling for age, parity, and previous laparotomy or laparoscopic surgery, every per unit increase in BMI reduced the risk of falling in the lowest quartile of skin to vessel distance for aorta (aOR 0.73 95%CI 0.64-0.0.83, p<0.001) and IVC (aOR 0.71, 95%CI 0.62-0.82, p<0.001) and SMA (aOR 0.74, 95%CI 0.66-0.83, p<0.001).

Conclusion: 2D color doppler transabdominal ultrasound is feasible and useful in evaluating the abdominal wall thickness and distance to major retroperitoneal periumbilical vessels. Normal BMI patients have a significantly shorter distance to retroperitoneal vessels than overweight and obese patients. When choosing length of entry device, surgeons must remain mindful of the short distance to vessels regardless of BMI.