# Anatomical Shifts of the Bowel During Positioning: Relevance to Prone Lateral Access Surgery

## TL;DR

This study shows that the bowel shifts backward in the prone position, which is important for lateral spine surgery planning.

## Contribution

The study quantifies bowel positional changes in prone versus supine positions for lateral lumbar surgery.

## Key findings

- Bowel displacement was consistently posterior in the prone position at L2/3, L3/4, and L4/5 levels.
- Female sex and prior abdominal surgery were linked to reduced bowel mobility at L3/4 and L4/5.
- The abdominal aorta showed minimal positional change between postures.

## Abstract

This radiographic analysis aimed to evaluate the differences in the anatomical position of the bowel relative to the lateral surgical corridor and the spine between prone and supine positions. Retroperitoneal transpsoas lateral lumbar interbody fusion can be performed in the prone position, allowing simultaneous lateral and posterior spinal access without repositioning; however, bowel positional changes associated with this approach have not been well characterized. From January 2020 to December 2024, 13 patients who underwent computed tomography (CT)-guided biopsy in the prone position with imaging spanning L2-L5 were retrospectively analyzed. Patient factors, including age, sex, body mass index, history of abdominal surgery, and malignancy, were recorded. Supine and prone CT scans obtained within one month were used to measure the distances from the posterior vertebral line to the bowel and abdominal aorta at the L2/3, L3/4, and L4/5 levels, and positional differences between postures were calculated. The cohort consisted of eight men and five women with a mean age of 60.2 years and a mean body mass index of 20.8; six patients had a history of abdominal surgery, and 11 had a history of cancer. Posterior bowel displacement was observed at all levels in the prone position, with mean changes of -0.6 mm at L2/3, -3.5 mm at L3/4, and -5.1 mm at L4/5, whereas the position of the abdominal aorta showed minimal change. Regression analysis identified female sex and prior abdominal surgery as significant factors which were statistically associated with bowel displacement at L3/4 and prior abdominal surgery and malignancy as significant factors at L4/5. Our data indicate consistent posterior bowel displacement in the prone position and suggest that female sex, malignancy, and prior abdominal surgery are associated with reduced bowel mobility, which has important implications for prone lateral lumbar surgical approaches.