Differences in Uterine Innervation in Patients Undergoing Hysterectomy for Chronic Pelvic Pain

Introduction. Difficult intrapartum episodes may be associated with damage to structures on the lateral pelvic side wall in some patients with chronic pelvic pain (Quinn, 2000). Several patterns of damage to the levator ani have been described with axial magnetic resonance imaging of the lower pelvis in patients with CPP. Damage sufficient to avulse the levator ani from its origin over the arcus tendineus levator ani (LAd II) may also be associated with interruption of the nerve supply to the lower pelvis. This study has been performed to investigate the innervation of the uterus in parous subjects undergoing hysterectomy for chronic pelvic pain (CPP).
Patients & Methods. Retrospective review of the pathology archive identified 26 patients undergoing hysterectomy for chronic pelvic pain (Group I, mean age 42.3 years, range 29-52 years; parity 2.1, range 0-7). Their histology reports included nine patients (9/26) with a diagnosis of adenomyosis, 12/26 were “histologically normal” and 5/26 had predominantly leiomyomata. Eight nulliparous subjects undergoing hysterectomy were also identified by retrospective review of archived material (Group II, mean age 40 years, range 30-52). Twenty four multiparous subjects (Group III, mean age 43.4 years, range 32-53 years; parity 2.0 children; range 1-4) were similarly identified.

All tissue blocks contained the endometrial-myometrial interface in the region of the uterine isthmus and were stained with PGP 9.5 (Novocastra Laboratories Ltd, Newcastle upon Tyne, UK) using a standard immunohistochemical regimen. Visualisation of the binding of the antibodies was achieved by incubating the sections with the Universal Elite ABC Kit (Vector Laboratories, Peterborough, UK) and chromogenic visualisation was achieved using Liquid 3,3’-diaminobenzidine (DAB) in chromogen solution (Dako Ltd, Ely, UK). Sections of pancreas were used as positive controls and incubated on all slides throughout the staining procedures. Sections were reviewed by two observers (MDH and MJQ).

Results. Three different patterns of innervation were identified in the patients with chronic pelvic pain (group I). Precise definitions and criteria for each pattern of staining were adopted by both observers:

4/26 demonstrated relatively normal patterns of innervation (normal, pattern A).

13/26 showed a marked increase in small diameter nerve fibers running through the myometrial stroma in haphazard coursesremote from vascular structures (proliferative, pattern B, Figure 1). This pattern was frequently observed in association

With collateral sprouting of nerve fibers from major nerve bundles. 9/26 showed a marked reduction in uterine innervation across the tissue section with absence of nerve fibers in most neurovascular bundles (denervatory, pattern C, Figure 2). Two

None of the nulliparous subjects showed marked variations in their staining patterns (0/8, Group II). Six multiparous subjects undergoing hysterectomy for a variety of presentations (6/24, group III) demonstrated a proliferative pattern of nerve staining (pattern B).
Conclusions. (1)Variations in uterine innervation have been identified in patients undergoing hysterectomy for chronic pelvic pain. (2) These variations include marked proliferation of small-diameter nerve fibers in the myometrium in some subjects and large areas of denervation of the myometrium in other subjects.