Construction of a nomogram model to predict technical difficulty in performing laparoscopic sphincter-preserving radical resection for rectal cancer

Table 3 Soft tissue measurement parameters and definitions

Parameter name	Definition
Rectal area (a)	Area of the rectum at the level of the ischial spine
Mesorectal fat area (b)	Area of the mesorectal fat at the level of the ischial spine
Visceral fat area (c)	Area of visceral fat at the level of the umbilicus
Subcutaneous fat area (d)	Area of subcutaneous fat at the level of the umbilicus
Waist circumference (e)	Circumference of the waist at the level of the umbilicus
Anterior-posterior abdominal diameter (RS)	Measurement distance from the umbilicus to the spine-wall intersection in the abdominal plane
Transverse abdominal diameter (TU)	Measurement distance along the horizontal line of the lumbar vertebrae anterior margin at the level of the umblicus