# Small Intestine Length Measurement Using 3D CT Volumetry and in Vivo Laparoscopic Measurement Using Pre-marked Graspers: A Comparative Study

## TL;DR

This study compares 3D CT volumetry and laparoscopic methods for measuring small intestine length in bariatric surgery, finding that 3D CT is reliable and saves time.

## Contribution

The study demonstrates that 3D CT volumetry is a reliable and time-saving alternative to intraoperative bowel length measurement in bariatric surgery.

## Key findings

- 3D CT volumetry showed no significant difference in total bowel length compared to intraoperative measurements.
- The average intraoperative measurement time was 19 minutes, which could be reduced using 3D CT.
- 3D CT volumetry provides acceptable consistency for preoperative planning in bariatric surgeries.

## Abstract

The method for assessing the bowel length is debatable but crucial in bariatric surgeries, especially revisional ones. It may be linked to improved weight loss and reducing nutritional deficiencies; however, it can be time-consuming, increasing the likelihood of complications during and after the surgery. 3D CT volumetry could offer a non-invasive, time-saving alternative for accurate Total Bowel Length (TBL) measurement, potentially reducing operative time and associated risks.

This study compares small bowel length using 3D CT volumetry versus in vivo laparoscopic measurement with pre-marked graspers, and assesses the time consumed intra-operatively for TBL measurement in cases of revisional bariatric surgery.

This cross-sectional study included 34 bariatric surgery candidates undergoing revisional or conversion bariatric surgery requiring bowel length estimation. Surgeries included Roux-en-Y gastric bypass (RYGB), single anastomosis duodeno-ileal bypass with sleeve gastrectomy (SADI-S), one-anastomosis gastric bypass (OAGB), banded Roux-en-Y gastric bypass (banded RYGB), and distalization. Pre-operatively, 3D CT volumetry-based bowel length measurements were performed and interpreted by the same radiologist, and compared with intraoperative bowel measurements, which were estimated in vivo laparoscopically using pre-marked graspers. A single surgeon did all the surgical procedures.

The participants had an average age of 42.0 years and a mean BMI of 40.4 ± 7.6 kg/m². The cohort was predominantly female (73.5%). The bowel length estimation took an average of 19 ± 4 min intra-operatively. A comparison of radiographic and intraoperative measurements showed no significant differences for TBL (P = 0.264). The intraclass correlation (ICC) for radiographic and intraoperative measurements showed that radiographic TBL shows acceptable consistency (P = 0.007).

3D CT volumetry can be considered a reliable and safe method for TBL assessment. It aids in accurate preoperative planning, reduces operative time, and avoids the risks encountered during intraoperative bowel measurements in bariatric surgery.

• An ideal bowel length should achieve effective weight loss while minimizing nutritional deficiencies.

• Estimation of total bowel length using 3D CT volumetry shows reliable results compared to intraoperative measurements.

• Estimation of total bowel length using 3D CT volumetry minimizes operative time.

The online version contains supplementary material available at 10.1007/s11695-025-08446-8.