Background: Use of rigid instruments via transvaginal (TV) route has been proposed as a practical alternative to natural orifice translumenal endoscopic surgery (NOTES) using flexible devices. However, its safety has not been fully evaluated for each abdominal organ with different positional relationship to the vagina. The aim of this study is to obtain baseline anatomical data necessary for safer use of rigid TV instruments, by three-dimensional (3-D) radiologic measurements. Patients and methods: A retrospective study was conducted on 51 consecutive female Japanese patients with aortic aneurysm who underwent whole-body multidetector computed tomography as preoperative evaluation. The gallbladder (GB), esophagogastric junction (EGJ), and spleen were located on 3-D images, and the following were obtained: (1) the distance from the vagina, (2) the transverse deviation from the midline, and (3) the sagittal deviation from the "vagina-promontory (V-P)" line. Results: The median distance from the vagina was 26.1 cm for GB, 30.6 cm for EGJ, and 31.1 cm for spleen. The transverse deviation from the midline was 17.7 for GB, 7.0 for EGJ, and 12.9 for spleen. The sagittal deviation from the V-P line was 7.6 degrees for GB, -7.0 for EGJ, and -10.3 for spleen. The percentage of "negative angle" cases, which means that the target is located "below" the V-P line, was only 9.8 % for GB versus 88 % for EGJ and spleen. Conclusions: The intra-abdominal length of TV instruments should be more than 35 cm in Japanese population. GB is widely deviated from the midline and therefore can be safely approached even with rigid/straight instruments. Access to more midline and distant targets may suffer from interference by the sacral promontory, and be potentially dangerous in terms of risk of compression injury by rigid and straight instruments.
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