The anthropometric definition of the rectum is highly variable

Area of Science:

• Anatomy
• Colorectal Surgery
• Surgical Oncology

Background:

• Accurate localization of colorectal pathology relies on precise definitions of the rectum.
• Current definitions of rectal landmarks are often imprecise, leading to challenges in surgical planning and pathology identification.

Purpose of the Study:

• To establish anthropometric definitions for common pelvic landmarks.
• To evaluate the relationship between these landmark distances and patient characteristics such as sex and weight.

Main Methods:

• Intra-operative measurements of pelvic landmarks from the anal verge were taken in 71 patients undergoing open proctectomy.
• Patient characteristics were recorded and analyzed.
• Statistical analyses included Spearman correlation and Wilcoxon rank sum tests.

Main Results:

• Significant variability was observed in distances to all measured landmarks (dentate line, puborectalis muscle, anterior peritoneal reflection, sacral promontory, confluence of taenia).
• Men exhibited longer mean distances to the dentate line, puborectalis muscle, and anterior peritoneal reflection compared to women.
• Patient weight correlated with distances to most landmarks, except the confluence of taenia.

Conclusions:

• Pelvic landmark locations demonstrate considerable inter-individual variability.
• Relying on fixed, absolute measurements from the anal verge for rectal pathology localization is inaccurate due to patient variability.