Identification and injury to the inferior hypogastric plexus in nerve-sparing radical hysterectomy

Abstract

Waterjet dissection of the inferior hypogastric plexus (IHP) resulted in a more rapid return of normal urodynamics than blunt dissection (control group) in patients who received laparoscopic nerve-sparing radical hysterectomy (NSRH) in a randomized controlled study. However, the definite reasons for these results were unknown. This subgroup analysis compared the neural areas and impairment in the IHP uterine branches harvested during NSRH as an alternative to the IHP vesical branches between the waterjet and control groups. This study included samples from 30 eligible patients in each group of the trial NCT03020238. At least one specimen from each side of the IHP uterine branches was resected. The tissues were scanned, images were captured, and the neural component areas were calculated using the image segmentation method. Immunohistochemical staining was used to evaluate neural impairment. The control and waterjet groups had similar areas of whole tissues sent for evaluation. However, the control group had significantly fewer areas (median 272158 versus 200439 μm², p = 0.044) and a lower percentage (median 4.9% versus 3.0%, p = 0.011) of neural tissues. No significant changes in immunohistochemical staining were found between the two groups. For patients with residual urine ≤100 and >100 ml at 14 days after NSRH (42 and 18 patients, respectively), there were significantly different percentages of neural tissues in the resected samples (p < 0.001). Hence, Due to the accurate identification of IHP during NSRH, the waterjet dissection technique achieved better urodynamic results.

Figure 1

Flow diagram of the study. IHP, inferior hypogastric plexus. NSRH, nerve-sparing radical hysterectomy.

Figure 2

Illustration of the right parametrium. (A) The drainage of the inferior vesical vein (IVV) and middle vesical vein (MVV) to the deep uterine vein (DUV), an anatomic landmark of the cardinal ligament, is displayed. (B) After removal of the vessels, the inferior hypogastric plexus (IHP) with its vesical and uterine branches were displayed. In our study, the uterine branches of the IHP were resected for pathological evaluation, and the vesical branches were deliberately reserved.

Figure 3

An illustration of quantitative analysis of the neural tissue proportion in a cross section of uterine branches of the inferior hypogastric plexus (×20). The indigo circles denote the neural tissue captured by the image segmentation method. A more detailed description is provided in Supplement 1.

Figure 4

Images of specific staining for nerve tissues. (A) Normal myelin in luxol fast blue (LFB) staining. (B) Mild myelin decrease in LFB staining. (C) Normal expression of myelin basic protein (MBP). (D) Mild myelin decrease in MBP expression. (E) Normal expression of neurofilament (NF). (F) Mild decrease of NF expression.