Gender differences in superior hypogastric plexus block via the sacral notch approach for chronic pelvic pain: A retrospective CT-based observational study

Abstract

Chronic pelvic pain is a common and multifactorial clinical syndrome that markedly impairs quality of life in both men and women. Superior hypogastric plexus block (SHGPB) is an effective minimally invasive treatment. The sacral notch approach, a modification of the transdiscal technique, offers a more direct and technically simple puncture pathway. However, sex-related pelvic anatomical differences may affect puncture parameters, and imaging-based evidence remains limited. This study aims to evaluate sex-related differences in key anatomical and technical parameters of SHGPB via the sacral notch approach based on computed tomography imaging and explore the potential clinical value of puncture angle, puncture distance, and the SHGPB index for preoperative assessment and individualized approach selection. This retrospective study analyzed abdominal computed tomography images of 200 patients (100 males and 100 females). Measured parameters included: the angle between the simulated needle trajectory and the sagittal plane; the distance from the skin entry point to the target point; and the SHGPB index, defined as the ratio of the inter-posterior superior iliac spine distance to the transverse diameter of the L5 vertebral body. Parameters were compared between sexes using appropriate statistical tests. The angle between the puncture trajectory and the sagittal plane was 25.33 ± 7.26° (range, 10.70-44.40°) in males and 27.18 ± 8.44° (range, 11.90-52.00°) in females, with no significant difference (P > .05). The puncture distance was 13.43 ± 1.53 cm (range, 10.20-17.60 cm) in males and 13.29 ± 2.39 cm (range, 9.90-32.70 cm) in females, also without significant difference (P > .05). However, the SHGPB index was significantly lower in males (1.75 ± 0.23; range, 1.24-2.33) than in females (1.96 ± 0.24; range, 1.53-2.63; P < .05). The sacral notch approach is characterized by a relatively small puncture angle and a straightforward puncture pathway. Puncture angle and distance remain stable across sexes, whereas the SHGPB index shows significant sex-related differences. The SHGPB index may serve as an important imaging marker for preoperative evaluation of pelvic anatomy and individualized selection of the puncture approach, with potential clinical value in the interventional management of chronic pelvic pain.

Keywords: SHGPB index; chronic pelvic pain; computed tomography; gender differences; sacral notch approach; superior hypogastric plexus block.