Differences in uterine innervation at hysterectomy

Association of Uterine Tissue Innervation and Peripheral Nerve Density with Adenomyosis Related Pain. A Systematic Review

Adenomyosis is associated with dysmenorrhea and chronic pelvic pain; however, the triggering mechanisms of painful stimuli and the role of uterine nerve fibers in the manifestation of pain remain poorly understood. The objective of this study was to systematically review the role of uterine nerve fibers' presence and density in the occurrence of pain in patients with adenomyosis. An electronic search was performed using the Embase, PubMed/Medline, and Cochrane databases. We included all studies from inception to November 2023. A total of ten studies that compared uterine biopsies samples of women with and without adenomyosis were included. The biomarker antiprotein gene product 9.5 was decreased or absent in the endometrium of most included women with adenomyosis. None of the included studies observed a difference in neurofilament (NF) staining between the adenomyosis and non-adenomyosis groups. Studies that assessed nerve growth factor (NGF) staining were heterogeneous in design. One study reported no difference in immunohistochemistry staining in any endometrial layer between the adenomyosis and non-adenomyosis groups, while another reported increased staining in the adenomyosis functional endometrial layer, and a third study reported overexpression of NGF, synaptophysin (SYN), and microtubule-associated protein 2 mRNA in focal adenomyosis alone. Preliminary data from poor-quality studies suggest an increase in the uterine density of nerve fibers in patients with adenomyosis. Well-designed studies are essential to assess the cause-and-effect relationship between uterine nerve fibers and pain in patients with adenomyosis.

Advanced Insights into Human Uterine Innervation: Implications for Endometriosis and Pelvic Pain

(1) Background: Understanding uterine innervation, an essential aspect of female reproductive biology, has often been overlooked. Nevertheless, the complex architecture of uterine innervation plays a significant role in conditions such as endometriosis. Recently, advances in histological techniques have provided unprecedented details about uterine innervation, highlighting its intricate structure, distribution, and density. The intricate nature of uterine innervation and its influence on pathologies such as endometriosis has garnered increasing attention. (2) Objectives: This review aims to compile, analyze, and summarize the existing research on uterine innervation, and investigate its implications for the pathogenesis of endometriosis and associated pain. (3) Methods: A systematic review was conducted in line with PRISMA guidelines. Using the PubMed database, we searched relevant keywords such as "uterine innervation", "endometriosis", and "pain association". (4) Results: The initial literature search yielded a total of 3300 potential studies. Of these, 45 studies met our inclusion criteria and were included in the final review. The analyzed studies consistently demonstrated that the majority of studies focused on macroscopic dissection of uterine innervation for surgical purposes. Fewer studies focused on micro-innervation for uterine innervation. For endometriosis, few studies focused on neural pain pathways whereas many studies underlined an increase in nerve fiber density within ectopic endometrial tissue. This heightened innervation is suggested as a key contributor to the chronic pain experienced by endometriosis patients. (5) Conclusions: The understanding of uterine innervation, and its alterations in endometriosis, offer promising avenues for research and potential treatment.

Outcomes After Surgery at an Interdisciplinary Centre of Expertise for Endometriosis and Pelvic Pain in Canada: A Prospective Cohort Study

OBJECTIVES

To prospectively evaluate pain-related quality-of-life (Endometriosis Health Profile-30 [EHP-30] pain subscale) after surgery at an interdisciplinary centre of expertise for endometriosis and pelvic pain.

METHODS

A prospective cohort study was completed of persons undergoing surgical management for pelvic pain between December 2013 and July 2016 at an interdisciplinary tertiary referral centre for pelvic pain and endometriosis. We compared the change in EHP-30 scores for the following scenarios: (1) type of surgery (conservative surgery vs. hysterectomy), (2) stage of endometriosis (stage I/II vs. III/IV), and (3) age (age <40 vs. age ≥40 years). We used mixed-effects models to evaluate changes in pain during follow-up after surgery.

RESULTS

Overall, 595 individuals met our inclusion criteria; the follow-up rate was 65.9% (392/595). In total, 436 (73.3%) underwent conservative surgery, while 159 (26.7%) underwent hysterectomy. Improvements in pain-related quality-of-life were seen for both conservative surgery and hysterectomy but greater improvements were seen with hysterectomy (P < 0.001). For conservative surgery, similar improvements in quality-of-life were observed regardless of endometriosis stage (I/II vs. III/IV) (P = 0.84) or age (<40 or ≥40 years old) (P = 0.87). We also observed similar improvements in quality-of-life regardless of stage (P = 0.24) or age (P = 0.71) after hysterectomy.

CONCLUSIONS

At an interdisciplinary centre of expertise, there were significant improvements in quality-of-life after endometriosis surgery. These improvements were seen for both conservative surgery and hysterectomy (although greater improvement with the latter), for early and advanced stage disease, and younger and older patients.

Anatomic and functional mapping of human uterine innervation

OBJECTIVE

To better understand the physiology of pain in pelvic pain pathological conditions, such as endometriosis, in which alterations of uterine innervation have been highlighted, we performed an anatomic and functional mapping of the macro- and microinnervation of the human uterus. Our aim was to provide a 3-dimensional reconstruction model of uterine innervation.

DESIGN

This was an experimental study. We dissected the pelvises of 4 human female fetuses into serial sections, and treated them with hematoxylin and eosin staining before immunostaining.

SETTING

Academic Research Unit.

PATIENTS

None.

INTERVENTIONS

None.

MAIN OUTCOME MEASURES

Detection of nerves (S100 +) and characterization of the types of nerves. The slices obtained were aligned to construct a 3-dimensional model.

RESULTS

A 3-dimensional model of uterine innervation was constructed. The nerve fibers appeared to have a centripetal path from the uterine serosa to the endometrium. Within the myometrium, innervation was dense. Endometrial innervation was sparse but present in the functional layer of the endometrium. Overall innervation was richest in the supravaginal cervix and rarer in the body of the uterus. Innervation was rich particularly laterally to the cervix next to the parametrium and paracervix. Four types of nerve fibers were identified: autonomic sympathetic (TH+), parasympathetic (VIP+), and sensitive (NPY+, CGRP1+ and VIP+). They were found in the 3 portions and the 3 layers of the uterus.

CONCLUSIONS

We constructed a 3-dimensional model of the human uterine innervation. This model could provide a solid base for studying uterine innervation in pathologic situations, in order to find new therapeutic approaches.

Assessment of Pain at Different Steps of Diagnostic Hysteroscopy Using Room Temperature Normal Saline versus Warmed Normal Saline Solution as Distension Medium: A Randomized Controlled Trial

Objectives

Compare pain intensity at entry into the cervical os, during uterine distension and 15 min after the procedure, in patients undergoing diagnostic hysteroscopy with room temperature normal saline versus that with saline warmed to 38-40°C, using visual analog scale (VAS) score. Furthermore, compare the time taken and failed procedures between them.

Materials and Methods

This was a randomized controlled, prospective study conducted at a Tertiary Care Center on 100 patients planned for diagnostic hysteroscopy with a 4 mm 30° hysteroscope using vaginoscopy technique. They were divided into two groups of 50 each, with control undergoing the procedure using normal saline at room temperature and the test with saline warmed to 38-40°C as distension medium. Primary outcomes were VAS at the point of entry into the internal os (T0), 1 min later (T1), and 15 min after the procedure (T15). Secondary outcomes were procedural acceptance, time taken, and failed procedures.

Results

The mean VAS in the control group at T0, T1, T15 was 3.31 (1.461;‒0.870-0.245), 2.46 (1.398;‒0.539-0.498), 0.75 (0.911;‒0.379-0.338), respectively, as compared to the test group of 3.62 (1.282;‒0.870-0.245), 2.48 (1.148;‒0.540-0.498), 0.77 (0.911;‒0.379-0.379), respectively. About 73.5% of controls and 68.8% in the test group were willing to undergo the procedure again. About 93.9% of controls would recommend it further as against 93.8% among the test controls. The time taken and number of failed procedures showed no statistical difference.

Conclusion

No significant difference was noted in terms of outcomes measured by warming the distension medium.

Neural plasticity of the uterus: New targets for endometrial cancer?

Endometrial carcinoma is the most common gynecological malignancy in Western countries and is expected to increase in the following years because of the high index of obesity in the population. Recently, neural signaling has been recognized as part of the tumor microenvironment, playing an active role in tumor progression and invasion of different solid tumor types. The uterus stands out for the physiological plasticity of its peripheral nerves due to cyclic remodeling brought on by estrogen and progesterone hormones throughout the reproductive cycle. Therefore, a precise understanding of nerve-cancer crosstalk and the contribution of the organ-intrinsic neuroplasticity, mediated by estrogen and progesterone, of the uterine is urgently needed. The development of new and innovative medicines for patients with endometrial cancer would increase their quality of life and health. This review compiles information on the architecture and function of autonomous uterine neural innervations and the influence of hormone-dependent nerves in normal uterus and tumor progression. It also explores new therapeutic possibilities for endometrial cancer using these endocrine and neural advantages.

Comparative transcriptome analysis between patient and endometrial cancer cell lines to determine common signaling pathways and markers linked to cancer progression

The rising incidence and mortality of endometrial cancer (EC) in the United States calls for an improved understanding of the disease's progression. Current methodologies for diagnosis and treatment rely on the use of cell lines as models for tumor biology. However, due to inherent heterogeneity and differential growing environments between cell lines and tumors, these comparative studies have found little parallels in molecular signatures. As a consequence, the development and discovery of preclinical models and reliable drug targets are delayed. In this study, we established transcriptome parallels between cell lines and tumors from The Cancer Genome Atlas (TCGA) with the use of optimized normalization methods. We identified genes and signaling pathways associated with regulating the transformation and progression of EC. Specifically, the LXR/RXR activation, neuroprotective role for THOP1 in Alzheimer's disease, and glutamate receptor signaling pathways were observed to be mostly downregulated in advanced cancer stage. While some of these highlighted markers and signaling pathways are commonly found in the central nervous system (CNS), our results suggest a novel function of these genes in the periphery. Finally, our study underscores the value of implementing appropriate normalization methods in comparative studies to improve the identification of accurate and reliable markers.

Intraoperative local injection of uterosacral ligaments with ropivacaine during uterine surgery: A systematic review and meta-analysis of randomized controlled trials

AIM

To perform a systematic review and meta-analysis of all randomized controlled trials that examined the efficacy of intraoperative local injection of the uterosacral ligaments with ropivacaine on postoperative pain and opioids consumption in patients undergoing uterine surgery for hysterectomy/myomectomy.

METHODS

PubMed, Scopus, Web of Science and Cochrane Library databases were screened from inception to September 5th, 2020. We appraised the risk of bias using the Cochrane's risk of bias tool. Resting postoperative pain scores and cumulative consumption of postoperative opioids were regarded as continuous data, analyzed using the inverse variance method and reported as standardized mean difference (SMD) and weighted mean difference (MD), respectively, with 95 % confidence intervals (95 % CIs).

RESULTS

Five studies met the inclusion criteria comprising 230 patients (117 and 113 patients received ropivacaine and placebo, respectively). The studies had an overall low risk of bias. Resting postoperative pain scores were not significantly different between both groups at 2 h (SMD = -0.30, 95 % CI [-0.70, 0.11], p = 0.15), 12 h (SMD = 0.04, 95 % CI [-0.26, 0.37], p = 0.81) and 24 h (SMD = -0.06, 95 % CI [-0.32, 0.20], p = 0.68). However, the ropivacaine group had significantly reduced cumulative opioid consumption during the first 24 h postoperatively (MD = -9.07, 95 % CI [-14.47, -3.66], p = 0.001).

CONCLUSION

Intraoperative local infiltration of uterosacral ligaments with ropivacaine is technically feasible and significantly reduces postoperative opioid consumption in women undergoing gynecologic surgery of the uterus.

Role of para-cervical block in reducing immediate postoperative pain after total laparoscopic hysterectomy: a prospective randomized placebo-controlled trial

Objective

To study the efficacy and safety of 0.5% bupivacaine in paracervical block to reduce immediate postoperative pain after total laparoscopic hysterectomy.

Methods

A prospective, randomized, double-blind, placebo-controlled study was conducted at a tertiary referral center involving thirty women each in the treatment and placebo groups. Paracervical block with 10 mL of 0.5% bupivacaine (treatment group) or 0.9% saline (placebo group) was administered following general anesthesia and prior to proceeding with total laparoscopic hysterectomy. Visual analogue scale (VAS) scores at 30 and 60 minutes post extubation and mean VAS score (average VAS score at 30 and 60 minutes) were compared. Adequate pain control was defined as mean VAS score ≤5. Additional postoperative opioid requirement, hospital stay, and readmissions were also compared.

Results

Baseline variables such as age, previous history of cesarean section, operating time, and weight of the specimen were comparable in both groups. VAS scores at 30 (5.0±2.8 vs. 7.0±1.4) and 60 minutes (5.2±2.8 vs. 7.0±0.8) and the mean VAS score (5.1±2.7 vs. 6.8±0.9) were significantly lower in the treatment group. Adequate pain control (mean VAS score ≤5) was 57% higher and additional opioid consumption was 47% lower in the treatment group. No significant difference was found in the duration of hospital stay and readmission rate.

Conclusion

Paracervical block with bupivacaine was useful in reducing immediate postoperative pain with a 25% reduction in mean VAS score and a 47% reduction in opioid consumption in the first hour after total laparoscopic hysterectomy.

Evaluation and ranking of different interventions for pain relief during outpatient hysteroscopy: A systematic review and network meta-analysis

AIM

To identify the highest-ranked pharmacological and nonpharmacological interventions for pain relief during outpatient hysteroscopy.

METHODS

We conducted an online bibliographic search in different databases from inception till July 2019. We included randomized controlled trials assessing effect of pharmacological and nonpharmacological interventions on pain relief during outpatient hysteroscopy. Our main outcomes were pain scores at different endpoints of the procedure. We applied this network meta-analysis based on the frequentist approach using statistical package 'netmeta' (version 1.0-1) in R.

RESULTS

The review included 39 randomized controlled trials (Women n = 3964). Misoprostol plus intracervical block anesthesia (mean difference [MD] = -3.32, 95% confidence interval [CI] [-6.06, -0.59]), misoprostol (MD = -1.92, 95% CI [-3.04, -0.81]) and IV analgesia (MD = -2.01, 95% CI [-3.27, -0.25]) were effective in reducing pain during the procedure compared to placebo. Ranking probability showed that misoprostol plus intracervical block anesthesia was the highest ranked pharmacological treatment for pain relief during the procedure (P score = 0.92) followed by misoprostol alone (P score = 0.78), and IV analgesia (P score = 0.76). Regarding nonpharmacological treatments, transcutaneous electrical nerve stimulation (TENS) showed a significant pain reduction compared to placebo (MD = -1.80, 95% CI [-3.31, -0.29]). TENS ranked as the best nonpharmacological treatment (P score = 0.80) followed by CO₂ distention (P score = 0.65) and bladder distention (P score = 0.60).

CONCLUSION

Combination of misoprostol plus local anesthesia appears to be the most effective pharmacological approach for pain reduction during and after outpatient hysteroscopy. Nonpharmacological approaches as TENS and bladder distention showed considerable efficacy but should be further investigated.

The Autonomic Innervation and Uterine Telocyte Interplay in Leiomyoma Formation

The autonomic innervation of the uterus is involved in multiple pathophysiological processes in both humans and animals. Pathological conditions such as adenomyosis or inflammatory pelvic disease are usually accompanied by significant alterations in uterine innervation. In the current study, we focused on autonomic innervation of uterine fibroids, the identification of recently described interstitial cells, telocytes, and the possible interplay between these structures. In this work, uterine telocytes were identified by immunopositivity for c-kit, CD34, and PDGFRα. Nerves were revealed by immunolabeling for neuronal markers: protein gene product PGP 9.5, inducible nitric oxide synthase (iNOS), choline acetyltransferase (ChAT), and tyrosine hydroxylase (TH). The gross organization of myometrial tissue has been analyzed by routine histology. The results demonstrated that the density of iNOS and ChAT-immunopositive neurons in the uterine fibroids was higher than that in the control samples. The density of telocytes in the fibrosis foci was lower than that in the normal myometrium. Our results suggest that autonomic innervation and telocytes are involved in the microenvironment imbalance characteristic of uterine leiomyoma. Since NOS-positive nerves play an important role in oxidative stress modulation, they might lead to a decrease in the number of telocytes, which are crucial components in the pathogenesis of leiomyoma formation.

Comparison of Nerve Fiber Density between Patients with Uterine Leiomyoma with and without Pain: a Prospective Clinical Study

Introduction

We aimed to compare the presence and the amount of nerve fibers in endometrial, myometrial and leiomyoma tissues using protein gene product 9.5 (PGP 9.5) and neurofilament (NF) immunohistochemical staining in uterine leiomyoma patients with and without pain complaint.

Methods

Patients undergoing hysterectomy for uterine leiomyoma were prospectively enrolled in the study. Twenty-five uterine leiomyoma patients without pelvic pain complaint (visual analog scale (VAS) < 5) were assigned to Group 1; 23 uterine leiomyoma patients with pelvic pain complaint (VAS ≥ 5) were assigned to Group 2. Endometrial, myometrial and leiomyoma tissues obtained from hysterectomy specimens were stained immunohistochemically using PGP 9.5 and NF dyes. The presence and density of nerve fibers were compared between the two groups.

Results

None of the endometrial samples in either groups stained with PGP 9.5 and NF dyes. There was no statistically significant difference in the number of nerve fibers in myometrial and leiomyoma tissues between the two groups with either of the stains (PGP 9.5: p = 0.39 and p = 0.29; NF: p = 0.83 and p = 0.65, respectively). There was agreement between PGP 9.5 and NF immunohistochemical staining for nerve fiber detection in myometrial and leiomyoma tissues (p < 0.05/κ = 0.622 and p < 0.05/κ = 0.388, respectively).

Conclusion

This study demonstrates that the quantity and density of nerve fibers in myometrial and leiomyoma tissue in patients with pain were similar to that in patients without pain.

A Review and Reconsideration of Nonneoplastic Myometrial Pathology

From 1861 to 1962, clinicopathologic research tried to explain the association of abnormal uterine bleeding with uterine enlargement. The etiology was theorized as metropathy, suggesting that myometrial dysfunction may predispose to abnormal uterine bleeding. Research reached a nadir in 1962, when a major review dismissed myometrial hypertrophy as a plausible explanation after prior rejections of the theories of chronic myometritis, fibrosis uteri, and subinvolution as causes of bleeding. Subsequent to this arose a crusade against unnecessary hysterectomies in the 1970s. Although myometrial hyperplasia was proposed in 1868, it is only in the past 25 years that tangible evidence has supported that idea. It now appears that clinically enlarged uteri are due to globoid outward bulging of the uterus, caused by increased intramural pressure—often unrelated to either uterine weight or myometrial thickness. Abnormal (dysfunctional) uterine bleeding may often be due to spontaneous rupture of thrombosed dilated endometrial vessels, due to the combined effects of obstructed venous drainage by increased intramural pressure, and Virchow’s triad. Despite a century-old known association of parity with naturally occurring outer wall myometrial scars (fibrosis uteri with elastosis), it was not previously suggested that these may reflect healing reactions to muscle tears during labor and delivery. We now suggest that smaller, similar inner wall elastotic scars in the nerve-rich inner myometrium may explain many cases of pelvic pain. This review suggests that diverse pressure-related lesions may be present in clinically abnormal uteri that have been called “normal” since the crusade against unnecessary hysterectomy.

Postablation neuroma of the myometrium-a report of 5 cases

When hysterectomy is performed for chronic pelvic pain, routine pathology examination often provides no explanation. However, analysis of small uterine nerves using immunostains may help to address this deficiency. Small uterine nerves tend to be sparse or absent in wide areas of normal myometrium. Some studies of uterine nerves have suggested that endometriosis, adenomyosis, and fibroids are not inherently painful, with increased small nerves in the inner uterine wall associated with the history of pelvic pain. Although such areas may appear normal on hematoxylin and eosin (H&E), we have found a subtle inner wall lesion termed inner myometrial elastosis, best detected with trichrome or elastic stains, which may be a reaction to microscopic tears of inner myometrium. Such tears may induce increased inner wall innervation via the generation of nerve growth factor in granulation tissue. In the course of studying uterine nerves with immunostains, we found 5 cases with florid nerve proliferation, after deep endometrial ablation for abnormal uterine bleeding led to increased pelvic pain. We suggest that immunostains for postablation neuromas should be done in hysterectomies when pelvic pain increases after endometrial ablation. This may offer gynecologists and their patients an objective finding with a rational, scientific explanation for the pelvic pain.

Nerve fibers and endometriotic lesions: partners in crime in inflicting pains in women with endometriosis

One of major objectives in treating endometriosis is to alleviate pain since dysmenorrhea and other types of pain top the list of complaints from women with endometriosis who seek medical attention. Indeed, endometriosis-associated pain (EAP) is the most debilitating of the disease that negatively impacts on the quality of life in affected women, contributing significantly to the burden of disease and adding to the substantial personal and societal costs. Unfortunately, the mechanisms underlying the EAP are still poorly understood. In the last two decades, one active research field in endometriosis is the investigation on the distribution and genesis of nerve fibers in eutopic and ectopic endometrium, and the attempt to use endometrial nerve fiber density for diagnostic purpose. Since EAP presumably starts with the terminal sensory nerves, in or around endometriotic lesions, that transduce noxious mediators to the central nervous system (CNS) which ultimately perceives pain, this field of research holds the promise to elucidate the molecular mechanisms underlying the EAP, thus opening new avenues for novel diagnostics and therapeutics. In this review, we shall first briefly provide some basic facts on nerve fibers, and then provide an overview of some major findings in this filed while also note some conflicting results and expose areas in need of further research. We point out that since recently accumulated evidence suggests that endometriotic lesions are wounds undergoing repeated tissue injury and repair, the relationship between endometriotic lesions and nerve fibers is not simply unidirectional, i.e. lesions promote hyperinnervations. Rather, it is bidirectional, i.e. endometriotic lesions and nerve fibers engage active cross-talks, resulting in the development of endometriosis and pain. That is, nerve fibers and endometriotic lesions are actually partners in crime in inflicting pains in women with endometriosis, aided and abetted possibly by other culprits, some yet to be identified. We provide a list of possible perpetrators likely to be involved in this crime. Finally, we discuss possible implications when viewing the relationship from this vista.

Are endometrial nerve fibres unique to endometriosis? A prospective case-control study of endometrial biopsy as a diagnostic test for endometriosis in women with pelvic pain

STUDY QUESTION

Can the presence of endometrial nerve fibres be used as a diagnostic test for endometriosis in women with pelvic pain?

SUMMARY ANSWER

Endometrial fine nerve fibres were seen in the endometrium of women both with and without endometriosis, making their detection a poor diagnostic tool for endometriosis.

WHAT IS KNOWN ALREADY

Laparoscopy and biopsy are currently the gold standard for making a diagnosis of endometriosis. It has been reported that small density nerve fibres in the functional layer of the endometrium are unique to women with endometriosis and hence nerve fibre detection could function as a less invasive diagnostic test of endometriosis. However, it may be that other painful conditions of the pelvis are also associated with these nerve fibres. We therefore focused this prospective study on women with pelvic pain to examine the efficacy of endometrial nerve fibre detection as a diagnostic test for endometriosis.

STUDY DESIGN, SIZE, DURATION

This prospective case-control study conducted between July 2009 and July 2013 included 44 women with pelvic pain undergoing laparoscopic examination for the diagnosis of endometriosis. Immunohistochemical nerve fibre detection in endometrial curettings and biopsies using anti-protein gene product 9.5 was compared with surgical diagnosis.

PARTICIPANTS/MATERIALS, SETTINGS, METHODS

Paired endometrial biopsies and curettings were taken from patients with (n = 22, study group) and without (n = 22, control group) endometriosis. Tissue was analysed by immunohistochemistry and nerve fibres were counted whenever they were present in the functional layer of the endometrium.

MAIN RESULTS AND THE ROLE OF CHANCE

Fine nerve fibres were present in the eutopic endometrium of patients both with and without endometriosis. The presence of nerve fibres in curettings was not effective for either diagnosing or excluding endometriosis; sensitivity and specificity were 31.8 and 45.5% respectively, positive predictive value was 36.8% and negative predictive value was 40.0%. Few endometrial biopsy specimens were found to have nerve fibres present; sensitivity and specificity for endometrial biopsy were 13.6 and 68.2% respectively, positive predictive value was 30.0% and negative predictive value was 44.1%.

LIMITATIONS, REASONS FOR CAUTION

This was a relatively small sample size and studies like this are subject to the heterogeneous nature of the patient population and tissue samples, despite our best efforts to regulate these parameters.

WIDER IMPLICATIONS OF THE FINDINGS

Our results demonstrate that fine nerve fibres are present in women with and without endometriosis. Future work should focus on the function of endometrial nerves and whether these nerves are involved with the subfertility or pain that endometriosis sufferers experience. Our study does not support the detection of endometrial nerve fibres as a non-invasive diagnostic test of endometriosis in women with pelvic pain.

A combined ultrasound and histologic approach for analysis of uterine fibroid pseudocapsule thickness

Authors investigated 75 patients with uterine myomas, appraising whether fibroid pseudocapsule (FP) thickness varies depending on fibroid location, by a prospective cohort trial (level of evidence II-2) settled in University-affiliated Hospitals. Uteri were scanned via bidimensional and power Doppler ultrasound (US) to map the fibroids and record the FP thickness, prior to hysterectomy for symptomatic uterine fibroids. After hysterectomy, FP specimens were sampled and analyzed by pathologists. Ultrasound and histology data were matched. Pseudocapsule thickness of 108 fibroids was measured: subserosal fibroids (SSFs), intramural fibroids (IMFs), and fibroids near the endometrial cavity (FEC). The FEC's pseudocapsules were considerably thicker than those of IMF and SSF measured by US and histology (P = .001). A clear cutoff existed between FEC pseudocapsule thickness and all other pseudocapsules, with significant differences observed at 2 mm (P = .001). Similarity between histological and US measurements was observed only with IMF pseudocapsules, whereas FEC or SSF showed significant differences. The pseudocapsule of fibroids is considerably thicker near the endometrial cavity when compared to those of both IMFs and SSFs. Since fibroids closest to the endometrial cavity are the most involved in fertility and infertility and FP is considerably thicker near the endometrial cavity, it is possible to hypothesize an involvement of FP of fibroid near the endometrium since FP contains many neuropeptides and neurotransmitters that are physiologically active, even if these data may take on a broader meaning in a study on a larger number of patients.

The brain-uterus connection: brain derived neurotrophic factor (BDNF) and its receptor (Ntrk2) are conserved in the mammalian uterus

The neurotrophins are neuropeptides that are potent regulators of neurite growth and survival. Although mainly studied in the brain and nervous system, recent reports have shown that neurotrophins are expressed in multiple target tissues and cell types throughout the body. Additionally, dysregulation of neurotrophins has been linked to several disease conditions including Alzheimer's, Parkinson's, Huntington's, psychiatric disorders, and cancer. Brain derived neurotrophic factor (BDNF) is a member of the neurotrophin family that elicits its actions through the neurotrophic tyrosine receptor kinase type 2 (Ntrk2). Together BDNF and Ntrk2 are capable of activating the adhesion, angiogenesis, apoptosis, and proliferation pathways. These pathways are prominently involved in reproductive physiology, yet a cross-species examination of BDNF and Ntrk2 expression in the mammalian uterus is lacking. Herein we demonstrated the conserved nature of BDNF and Ntrk2 across several mammalian species by mRNA and protein sequence alignment, isolated BDNF and Ntrk2 transcripts in the uterus by Real-Time PCR, localized both proteins to the glandular and luminal epithelium, vascular smooth muscle, and myometrium of the uterus, determined that the major isoforms expressed in the human endometrium were pro-BDNF, and truncated Ntrk2, and finally demonstrated antibody specificity. Our findings suggest that BDNF and Ntrk2 are transcribed, translated, and conserved across mammalian species including human, mouse, rat, pig, horse, and the bat.

Expression of neuronal markers in the endometrium of women with and those without endometriosis

STUDY QUESTION

How do the expression patterns of neuronal markers differ in the endometrium of women with and without endometriosis?

SUMMARY ANSWER

The neuronal markers, PGP9.5, NGFp75 and VR1, are expressed in the endometrium at levels that do not differ between women with and without endometriosis.

WHAT IS KNOWN ALREADY

Aberrant neuronal growth within the uterus may contribute to abnormal fertility and uterine dysfunction. However, controversy still exists as to whether aberrant innervation in the endometrium is associated with gynaecological pathology such as endometriosis. This may reflect the use of subjective methods such as histology to assess the innervation of the endometrium. We, therefore, employed a quantitative method, western blotting, to study markers of endometrial innervation in the presence and absence of endometriosis.

STUDY DESIGN, SIZE, DURATION

This study included 45 women undergoing laparoscopic examination for the diagnosis of endometriosis. Endometrial samples were analysed by western blot for the expression of neuronal and neurotrophic markers, PGP9.5, VR1 and NGFp75.

PARTICIPANTS/MATERIALS, SETTINGS, METHODS

Endometrial pipelle biopsies were obtained from patients with (n = 20, study group) and without (n = 25, control group) endometriosis. Tissue was analysed by immunohistochemistry and western blot analysis for the expression of pan-neuronal marker, PGP9.5, sensory nociceptive marker, TPVR1, and low-affinity neurotrophic growth factor receptor, NGFRp75.

MAIN RESULTS AND THE ROLE OF CHANCE

PGP9.5, NGFp75 and VR1 were expressed in the endometrium of women, independent of the presence of endometriosis. Furthermore, the expression level of PGP9.5, VR1 and NGFp75 did not alter between the two cohorts of women.

LIMITATIONS, REASONS FOR CAUTION

Studies of this nature are subject to the heterogeneous nature of patient population and tissue samples despite attempts to standardize these parameters. Hence, further studies using similar methodology will be required to confirm our results.

WIDER IMPLICATIONS OF THE FINDINGS

Our results highlight that sensory neuronal markers are present in women with and without endometriosis. Future work will assess what the targets of the endometrial nerves are and investigate their function, their impact on endometrial biology and, in particular, whether aberrant neuronal function, rather than the mere presence of neuronal function, could be the root cause of subfertility and/or pain affecting many endometriosis sufferers. Our results do not, however, confirm the previous paradigm of increased innervation in the endometrium of women with endometriosis, nor the use of nerve cell detection from pipelle biopsies to diagnose endometriosis.

Chronic pelvic pain in endometriosis: an overview

Chronic pelvic pain (CPP) could be considered nowadays a deep health problem that challenges physicians all over the world. This because its aetiology is still unclear, the course of the disease could vary a lot among different patients and through time in the same patient, and the response to treatments is not every time successful. Among women who underwent laparoscopy for CPP, endometriosis is found in about 1/3 of the cases, while only 25% of women with histological confirmed endometriosis are asymptomatic. A wide range of variables may exert their influence on the resulting pain syndrome in endometriosis; for example, score according to American society for reproductive medicine (rASRM), size of the sub-peritoneal and pelvic wall implants, Douglas obliteration, previous surgery. It is widely accepted nowadays that central nervous system (CNS) and peripheral nervous system (PNS) seems to influence each other and this interconnection play a key role in pain modulation. Moreover, the phenomena induced by endometriosis in the pelvis, including the breakdown of peritoneal homeostasis and the induction of the production of proinflammatory and proangiogenic cytokines, are responsible of altered innervations and modulation of pain pathways in these patients. There are many proposed medical and surgical approach to treat this painful syndrome, although there is necessity of more efforts to create new non-invasive strategies that set a more accurate diagnosis of the causes of endometriotic-related CPP, and therefore facilitate its eradication.

The ON-Q pain management system in elective gynecology oncologic surgery: Management of postoperative surgical site pain compared to intravenous patient-controlled analgesia

Objective

The goal of this study was to compare postoperative surgical site pain in gynecologic cancer patients who underwent elective extended lower midline laparotomy and managed their pain with either the ON-Q pain management system (surgical incision site pain relief system, ON-Q pump) or an intravenous patient-controlled analgesia pump (IV PCA).

Methods

Twenty gynecologic cancer patients who underwent elective extended lower midline laparotomy were divided into two groups. One group received a 72-hour continuous wound perfusion of the local anesthetic ropivacaine (0.5%, study group) into the supraperitoneal layer of the abdominal incision through the ON-Q pump. The other group received intravenous infusion pump of patient-controlled analgesia (fentanyl citrate 20 mg/mL · kg+ondansetron hydrochloride 16 mg/8 mL+normal saline). Postoperative pain was assessed immediately and at 6, 24, 48, 72, and 96 hours after surgery using the visual analogue scale.

Results

Postoperative surgical site pain scores at 24, 48, and 72 hours after surgery were lower in the ON-Q group than the IV PCA group. Pain scores at 24 hours and 48 hours after surgery were significantly different between the two groups (P=0.023, P<0.001). Overall painkiller administration was higher in the ON-Q group but this difference was not statistically significant (5.1 vs. 4.3, P=0.481).

Conclusion

This study revealed that the ON-Q pain management system is a more effective approach than IV PCA for acute postoperative surgical site pain relief after extended lower midline laparotomy in gynecologic cancer patients.

Intrauterine anesthesia for gynecologic procedures: a systematic review

OBJECTIVE

To assess the effectiveness of intrauterine local anesthesia in reducing pain associated with outpatient gynecologic procedures.

DATA SOURCES

We searched online databases PubMed or MEDLINE, Embase, Google Scholar, and Clinicaltrials.gov and hand-searched reference lists from reviews evaluating pain-control methods for gynecologic office procedures. We identified randomized controlled trials using intrauterine local anesthetic in gynecologic procedures.

METHODS

Titles and abstracts were screened for 1,236 articles. We identified 45 potential articles for inclusion. We excluded 22 of these studies because: 1) they were not randomized controlled trials; 2) they did not describe a quantifiable dose of medication used in the study; 3) they did not investigate an intrauterine anesthetic; 4) they did not study a potentially awake, outpatient procedure; and 5) they did not clearly report results or represented duplicate publication. Twenty-three articles were ultimately included for review.

TABULATION, INTEGRATION, AND RESULTS

Two authors independently reviewed full search results and assessed eligibility for inclusion and independently abstracted data from all articles that met criteria for inclusion. Disagreements regarding eligibility or abstraction data were adjudicated by a third independent person. Our primary end point was the reported effect of intrauterine local anesthesia on patient-reported pain scores. As a result of heterogeneity in study methods, outcome measures, and reporting of outcomes, results could not be combined in a meta-analysis. Good evidence supports use of intrauterine anesthesia in endometrial biopsy and curettage, because five good-quality studies reported reduced pain scores, whereas only one good-quality study reported negative results. We found moderate evidence to support intrauterine anesthesia in hysteroscopy, because one good-quality study and two fair or poor quality studies reported reduced pain scores, whereas two good-quality studies had negative results. Good evidence suggests that intrauterine anesthesia is not effective in hysterosalpingography; three good-quality studies reported that pain scores were not reduced, and no good quality studies showed a beneficial effect in that procedure. Evidence was insufficient concerning first-trimester abortion, saline-infusion ultrasonogram, tubal sterilization, and intrauterine device insertion.

CONCLUSION

Intrauterine local anesthesia can reduce pain in several gynecologic procedures including endometrial biopsy, curettage, and hysteroscopy and may be effective in other procedures as well.

The Endometrium in Adenomyosis

Eutopic and ectopic endometria of women with adenomyosis show a series of metabolic and molecular abnormalities that increase angiogenesis and proliferation, decrease apoptosis, allow local production of estrogens, create progesterone resistance, and impair cytokine expression. These changes enhance the ability of the endometrium to infiltrate the junctional zone myometrium and the growth of ectopic tissue. In addition, in these subjects several immunological abnormalities have been observed, together with an increased production of ‘free radicals’ leading to excessive growth of endometrial stromal cells that may facilitate the establishment of adenomyosis. A limiting factor is that these studies have been performed on hysterectomy specimens representing final stages of the disease. This increased knowledge has created new therapeutic options, including the block of local aromatase production through the use of selective estrogen receptor modulators, estrogen-progestin combinations and gonadotropin-releasing hormone super agonists. Also promising are investigations into the mechanism of dysmenorrhea and abnormal uterine bleeding.

Abdominal and urogenital diseases can often be the cause of lower back pain and sciatic-like symptoms

SUMMARY The treatment of lower back pain and sciatic-type symptoms are often not related to spinal cord infringement, but are due to other factors such as urogenital irritation and piriformis syndrome. Other factors can exist and it behooves the physician to make a definitive diagnosis in order to prevent treating with medicines and treatments that often do not work. Medicines in high doses can lead to dependence or addiction. A normal MRI test is often a flag to the physician that something other than spinal problems may be the cause. A complete workup must be performed including imaging procedures, diagnostic testing and specialized physical examinations if initial diagnosis and treatments do not produce an amelioration of symptoms. There are many causes of chronic lower back pain and sciatica-type symptoms and if the problems and symptoms persist, they should be investigated.

Surgical management of neurovascular bundle in uterine fibroid pseudocapsule

The uterine fibroid pseudocapsule is a fibro-neurovascular structure surrounding a leiomyoma, separating it from normal peripheral myometrium. The fibroid pseudocapsule is composed of a neurovascular network rich in neurofibers similar to the neurovascular bundle surrounding a prostate. The nerve-sparing radical prostatectomy has several intriguing parallels to myomectomy. It may serve either as a useful model in modern fibroid surgical removal, or it may accelerate our understanding of the role of the fibrovascular bundle and neurotransmitters in the healing and restoration of reproductive potential after intracapsular myomectomy. Surgical innovations, such as laparoscopic or robotic myomectomy applied to the intracapsular technique with magnification of the fibroid pseudocapsule surrounding a leiomyoma, originated from the radical prostatectomy method that highlighted a careful dissection of the neurovascular bundle to preserve sexual functioning after prostatectomy. Gentle uterine leiomyoma detachment from the pseudocapsule neurovascular bundle has allowed a reduction in uterine bleeding and uterine musculature trauma with sparing of the pseudocapsule neuropeptide fibers. This technique has had a favorable impact on functionality in reproduction and has improved fertility outcomes. Further research should determine the role of the myoma pseudocapsule neurovascular bundle in the formation, growth, and pathophysiological consequences of fibroids, including pain, infertility, and reproductive outcomes.

Neurovascular bundle in fibroid pseudocapsule and its neuroendocrinologic implications

The myoma pseudocapsule is a surgical-anatomical entity surrounding the fibroid that separates the myoma from normal uterine tissue. The myoma pseudocapsule has a delicate vascular network rich with neurotransmitters analogous to the neurovascular bundle surrounding the prostate. The pseudocapsule neurovascular bundle is extremely important during myomectomy to promote uterine myometrial healing and, consequently, for uterine reproductive function. New advancements in surgery, including the use of laparoscopic myomectomy by an intracapsular technique and magnification of the myoma pseudocapsule to enhance visualization are comparable to the dissection during a radical prostatectomy. Fibroid detachment occurring inside the pseudocapsule causes less bleeding, spares the neurovascular bundle and promotes better uterine healing. The maintenance of myometrial integrity after laparoscopic myomectomy maintains uterine function and therefore improves reproductive outcomes, including labor.

Chronic pelvic pain and endometriosis: translational evidence of the relationship and implications

BACKGROUND

Many clinicians and patients believe that endometriosis-associated pain is due to the lesions. Yet causality remains an enigma, because pain symptoms attributed to endometriosis occur in women without endometriosis and because pain symptoms and severity correlate poorly with lesion characteristics. Most research and reviews focus on the lesions, not the pain. This review starts with the recognition that the experience of pain is determined by the central nervous system (CNS) and focuses on the pain symptoms.

METHODS

Comprehensive searches of Pubmed, Medline and Embase were conducted for current basic and clinical research on chronic pelvic pain and endometriosis. The information was mutually interpreted by a basic scientist and a clinical researcher, both in the field of endometriosis. The goal was to develop new ways to conceptualize how endometriosis contributes to pain symptoms in the context of current treatments and the reproductive tract.

RESULTS

Endometriotic lesions can develop their own nerve supply, thereby creating a direct and two-way interaction between lesions and the CNS. This engagement provides a mechanism by which the dynamic and hormonally responsive nervous system is brought directly into play to produce a variety of individual differences in pain that can, in some women, become independent of the disease itself.

CONCLUSIONS

Major advances in improving understanding and alleviating pain in endometriosis will likely occur if the focus changes from lesions to pain. In turn, how endometriosis affects the CNS would be best examined in the context of mechanisms underlying other chronic pain conditions.

Autonomic denervation and the origins of chronic Western diseases

Many chronic Western diseases result from lifestyles that include refined diets, poor bowel habits, limited physical exercise and suboptimal patterns of childbirth. Western diets result in reduced stool weights, increased bowel transit times and persistent physical efforts during defaecation. Prolonged physical efforts during defaecation and childbirth cause latent, or direct, injuries to branches of the cardiac (thorax), coeliac (abdomen) and hypogastric (pelvis) plexi. Injuries to autonomic nerves result in impaired visceral function including visceral dysmotility, tissue hypoplasia and hyperplasia, increased susceptibility to infection, and, aberrant reinnervation with sensitisation of the central nervous system (CNS). These unrecognised injuries are vulnerable to the long list of causes of autonomic Dysfunction, e.g. stress, alcohol, drugs, infection, trauma, cancer, etc. Specific injuries at different anatomical locations in midline autonomic pathways give rise to a wide range of Western diseases from infancy to old age, through diverse and cumulative mechanisms.

Endometriosis: the elusive epiphenomenon

The denervation-reinnervation view proposes that retrograde menstruation results from loss of normal, fundocervical polarity caused by injuries to uterine nerves. Injuries may be sporadic (following vaginal delivery) or recurrent (after persistent straining during defaecation) creating very different appearances at laparoscopy. Clinical symptoms of pelvic pain, menstrual problems, dyspareunia, and dysmenorrhoea result from aberrant reinnervation that may occur with, or without deposits of pelvic endometriosis. Endometrium, delivered by retrograde menstruation, adheres to any injured tissues in the lower pelvis. Classical 'endometriosis' is largely an epiphenomenon to underlying processes of denervation and reinnervation.

Perivascular nerve fibre proliferation: The consequence of prolonged straining

Four clinical cases are described in which a history of straining to achieve defaecation over many years, was associated with prolonged pelvic pain and the neuro-immunohistochemical observation of perivascular nerve fibre proliferation (PVNFP). Specimens of uterus, vagina, vulva and bladder have all demonstrated this novel histological feature. In three of the four cases, treatment with gonadotrophin releasing hormone agonists was associated with temporary improvement of the pain.

Uterine innervation in fibroids: A qualitative study

This study describes the innervation of uterine fibroids in a retrospective survey of archived material. A total of 24 uteri containing fibroids were identified; four nulliparous uteri with single large fundal fibroids (200 - 320 g) and 20 multiparous uteri with one, or more, fibroids (80 - 230 g). Tissue blocks from the uterine isthmus and the fibroids, were identified, sectioned and stained for nerves with anti-S100 using a standard immunohistochemical regimen. Normal uterine innervation includes concentrations of nerves in the subserosal layer and at the endometrial-myometrial interface with sparse neurovascular bundles distributed throughout the myometrial stroma. Nulliparous uteri with single large fibroids demonstrated relatively normal patterns of innervation with nerves distributed throughout the stroma of the fibroid. In multiparous uteri with fibroids, there were no nerves detectable in the substance of the fibroids. Increased numbers of nerve fibres were observed in the pseudo-capsule of some fibroids and may reflect compression of normal myometrial tissue and their contained nerves, or, a minor degree of nerve fibre proliferation. This study demonstrates that fibroids in multiparous uteri do not contain nerves. Single, large nulliparous fibroids situated at the uterine fundus appear to contain relatively normal patterns of innervation.

The inferior hypogastric plexus: A different view

The morphology of the inferior hypogastric plexus has been demonstrated in a series of dissections of nulliparous cadavers. Each cadaver was embalmed in a solution containing a significant proportion of methanol which preserved the pliability of the tissues enabling the nerve plexi to be clearly demonstrated. These structures are not normally encountered during general gynaecological surgery and clinicians are often unaware of the possible consequences of injury during vaginal delivery or sustained constipation. Denervation of pelvic organs, with subsequent reinnervation over the medium term, may account for a variety of obstetric and gynaecological syndromes.

Medical, surgical and alternative treatments for chronic pelvic pain in women: a descriptive review

Several causes of chronic pelvic pain (CPP) are recognised, but in many women a definite diagnosis cannot be made. Few randomised controlled trials on treatment of CPP have been conducted. In a Cochrane systematic review, only medroxy-progesterone acetate, counselling, a multidisciplinary approach and lysis of deep adhesions had a proven benefit. The aim of this descriptive review is to describe the management of CPP, which can focus on treating the pain itself, the underlying cause, or both. Combination drug therapy with medications with different mechanisms of action may improve therapeutic results. Pelvic denervating procedures should be indicated in selected circumstances, as the magnitude of the effect is undefined. Several alternative non-invasive treatments have been proposed including exercise programmes, cognitive and behavioural medicine, physical therapy, dietary modification, massage and acupuncture. When the woman has completed her family and particularly when pelvic varices have been demonstrated, hysterectomy can be considered after a careful pre-operative assessment. However, substantial pain relief may be achieved in no more than 60-70% of the cases. A minority of patients (3-5%) will experience worsening of pain or will develop new symptoms after surgery. Treatment of CPP, generally, requires acceptance of the concept of managing rather than curing symptoms.

Injuries to the levator ani in unexplained, chronic pelvic pain

Patterns of injury to the levator ani in parous women with laparoscopy-negative, chronic pelvic pain (CPP) are described. A consecutive series of 26 parous women with laparoscopy-negative CPP, had magnetic resonance imaging (MRI) in axial, coronal and sagittal planes. Similar imaging studies were performed in 32 parous women having MRI scans for other clinical indications and 20 asymptomatic, nulliparous women. Three patterns of injury/defect to the levator ani (LAd) were observed in 20/26 patients with unexplained pelvic pain: avulsion of the pubococcygeus from its origin at the pubis (LAd I, 3/20), avulsion of the pubococcygeus from its origin at the arcus tendineus levator ani (LAd II, 14/20), and, loss of shape and form of the pubococcygeus (LAd III, 6/20). Three patterns of injury to the levator ani have been described with MR imaging in parous women with unexplained CPP.