Gastrointestinal and Urinary Tract Endometriosis: A Review on the Commonest Locations of Extrapelvic Endometriosis

Extrapelvic endometriosis is a rare entity that presents serious challenges to researchers and clinicians. Endometriotic lesions have been reported in every part of the female human body and in some instances in males. Organs that are close to the uterus are more often affected than distant locations. Extrapelvic endometriosis affects a slightly older population of women than pelvic endometriosis. This might lead to the assumption that it takes several years for pelvic endometriosis to "metastasize" outside the pelvis. All current theories of the pathophysiology of endometriosis apply to some extent to the different types of extrapelvic endometriosis. The gastrointestinal tract is the most common location of extrapelvic endometriosis with the urinary system being the second one. However, since sigmoid colon, rectum, and bladder are pelvic organs, extragenital pelvic endometriosis may be a more suitable definition for endometriotic implants related to these organs than extrapelvic endometriosis. The sigmoid colon is the most commonly involved, followed by the rectum, ileum, appendix, and caecum. Most lesions are confined in the serosal layer; however, deeper lesion can alter bowel function and cause symptoms. Bladder and ureteral involvement are the most common sites concerning the urinary system. Unfortunately, ureteral endometriosis is often asymptomatic leading to silent obstructive uropathy and renal failure. Surgical excision of the endometriotic tissue is the ideal treatment for all types of extrapelvic endometriosis. Adjunctive treatment might be useful in selected cases.

Choosing the right surgical technique for deep endometriosis: shaving, disc excision, or bowel resection?

Deep endometriosis (DE) remains the most difficult endometriotic entity to treat. Medical treatment for DE can reduce symptoms but does not cure the disease, and surgical removal of the lesion is required when lesions are symptomatic, impairing bowel, urinary, sexual, and reproductive functions. Although several surgical techniques such as laparoscopic bowel resection, disc excision, and rectal shaving have been described, there is no consensus regarding the choice of technique or the timing of surgery. Our review of publications reporting results and complications of surgery for rectovaginal DE reveals a relatively higher complication rate after bowel resection compared with shaving and disc excision, especially for rectovaginal fistulas, anastomotic leakage, delayed hemorrhage, and long-term bladder catheterization. Data show that shaving is feasible even in advanced disease. The risk of immediate complications after shaving and disc excision is probably lower than after colorectal resection, allowing for better functional outcomes. The presumed higher risk of recurrence related to shaving has not been demonstrated. For these reasons, surgeons should consider rectal shaving as a first-line surgical treatment of rectovaginal DE, regardless of nodule size or association with other digestive localizations. When the result of rectal shaving is unsatisfactory (rare cases), disc excision may be performed either exclusively by laparoscopy or by using transanal staplers. Segmental resection may ultimately be reserved for advanced lesions responsible for major stenosis or for several cases of multiple nodules infiltrating the rectosigmoid junction or sigmoid colon.

Patterns of Bowel Invisible Microscopic Endometriosis Reveal the Goal of Surgery: Removal of Visual Lesions Only

STUDY OBJECTIVE

To document the presence of bowel invisible microscopic endometriosis implants and their relationship with deep endometriosis macronodule infiltrating the bowel.

DESIGN

A series of consecutive patients with deep endometriosis infiltrating the rectum and/or sigmoid colon (Canadian Task Force classification II-2).

SETTINGS

A university referral center.

PATIENTS

Ten patients managed by colorectal resection.

INTERVENTIONS

A microscopic study of endometriotic foci of the bowel involving 3272 microsection slides was established using a unique method of step serial sections using combined transverse and longitudinal macrosection. Two-dimensional reconstruction based on slide scanning highlighted the presence and localization of the deep endometriosis macronodule in contrast with bowel invisible microscopic endometriosis microimplants.

MEASUREMENTS AND MAIN RESULTS

The distance separating the microimplants and the nodule and their histologic characteristics. The mean length of the colorectal specimens was 91 ± 19 mm. The maximum distance between the farthest microimplants was 7.2 cm. The maximum distance from the macroscopic nodule limit to the farthest microimplant was 31 mm. Bowel invisible microscopic endometriosis microimplants presented with similar features independently of the type of spread. They had an active appearance including stroma and glands, were sometimes decidualized, and were free of fibrosis. They were found on the distal/rectal limit of the specimen in 3 patients and on both limits (distal/rectal and proximal/sigmoid colon) in 1 patient.

CONCLUSION

Invisible microscopic endometriosis implants surround the bowel macroscopic endometriosis nodule at variable distances, suggesting that complete surgical microscopic removal may be a challenging goal. These results may help to reconsider the principles and feasibility of the surgical management of bowel endometriosis.

[Bowel endometriosis and infertility: Do we need to operate?]

Endometriosis is a benign chronic inflammatory disease, whose pathogenesis is still unclear. Endometriosis is responsible for infertility and/or pelvic pain. One of the most important features of the disease is the heterogeneity (clinical and anatomical: superficial peritoneal, ovarian and/or deep infiltrating lesions). Bowel involvement constitutes one particularly severe form of the disease, affecting 8-12% of women with deep endometriosis. In case of associated infertility, bowel endometriosis constitutes a real therapeutic challenge for gynecologists. Indeed, while complete resection of the lesions alleviates pain and seems to improve spontaneous fertility, surgery remains technically challenging and may cause severe complications. Reverting to assisted Reproductive Technology (ART) is another valuable therapeutic option regarding pregnancy rates. Thus, the choice between surgical management or ART is still debated. Benefits and risks of these two options should be considered and discussed before planning treatment. In the present study, we aimed to answer the question: Bowel endometriosis and infertility: do we need to operate?

Preoperative assessment of factors associated with difficulty in performing total laparoscopic hysterectomy

AIM

Our objective was to determine the preoperative factors associated with difficulty in total laparoscopic hysterectomy (TLH).

METHODS

This retrospective clinical study included 157 patients who underwent TLH for leiomyoma or adenomyosis between 2009 and 2013. All patients underwent magnetic resonance imaging (MRI) before surgery. We categorized patients as 'difficult' if the operation time was > 243 min, if total blood loss was > 500 mL, or if conversion to laparotomy was necessary. Preoperative information, including MRI findings, was compared between the difficult and 'other' patients. Stepwise logistic regression analysis was used to control for covariates that were significant on univariate analysis (P < 0.05).

RESULTS

The presence of an endometrioma, a previous cesarean section (CS), a wide uterus, and a high body mass index were independent risk factors for being a difficult patient. For adenomyosis patients, the presence of an endometrioma, a prior CS, subtype II adenomyosis, and high body mass index were independent risk factors for being a difficult patient. For leiomyoma patients, the presence of an endometrioma, a prior CS, and having at least seven leiomyomas were independent risk factors for being a difficult patient. All laparotomy conversion patients had multiple risk factors.

CONCLUSION

We have elucidated the factors associated with difficult TLH patients using patients' background and preoperative MRI findings. Awareness of these predictive factors may enable surgeons to prepare for the operation, minimize complications, or choose another more appropriate route of hysterectomy than TLH.

Surgery for endometriosis: beyond medical therapies

Endometriosis-associated pelvic pain and subfertility may be managed medically in many cases; however, the surgical management of this insidious disease remains a necessary part of the treatment algorithm. Laparoscopy for diagnosis alone is rarely indicated with the advancements in preoperative imaging. When surgery is performed, the ideal goal would be a therapeutic and effective surgical intervention based on the preoperative evaluation. Surgery for women with pain due to endometriosis may be indicated in patients who cannot or do not wish to take medical therapies; acute surgical or pain events; deep endometriosis; during concomitant management of other gynecologic disorders; and patients seeking fertility with pain. The role of surgery for endometriosis-related subfertility may be considered in those with hydrosalpinges undergoing IVF; management of ovarian endometriomas in specific circumstances; and when a patient requests surgery as an alternative to assisted reproductive technology (ART). Surgery for ovarian endometriomas requires special attention due to the risk of potential harm on future fertility. Finally, a combined approach of surgery followed by postoperative medical therapy offers the best long-term outcomes for recurrence of disease and symptoms. A patient-centered approach and a goal-oriented approach are essential when determining the options for care in this population.

Research Priorities for Endometriosis

The 3rd International Consensus Workshop on Research Priorities in Endometriosis was held in São Paulo on May 4, 2014, following the 12th World Congress on Endometriosis. The workshop was attended by 60 participants from 19 countries and was divided into 5 main sessions covering pathogenesis/pathophysiology, symptoms, diagnosis/classification/prognosis, disease/symptom management, and research policy. This research priorities consensus statement builds on earlier efforts to develop research directions for endometriosis. Of the 56 research recommendations from the 2011 meeting in Montpellier, a total of 41 remained unchanged, 13 were updated, and 2 were deemed to be completed. Fifty-three new research recommendations were made at the 2014 meeting in Sao Paulo, which in addition to the 13 updated recommendations resulted in a total of 66 new recommendations for research. The research recommendations published herein, as well as those from the 2 previous papers from international consensus workshops, are an attempt to promote high-quality research in endometriosis by identifying and agreeing on key issues that require investigation. New areas included in the 2014 recommendations include infertility, patient stratification, and research in emerging nations, in addition to an increased focus on translational research. A revised and updated set of research priorities that builds on this document will be developed at the 13th World Congress on Endometriosis to be held on May 17-20, 2017, in Vancouver, British Columbia, Canada.

New developments in the medical treatment of endometriosis

Endometriosis affects 1 in 10 women of reproductive-age. The current treatments are surgical and hormonal but have limitations, including the risk of recurrence, side effects, contraceptive action for women who desire pregnancy, and cost. New treatments include gonadotropin-releasing hormone analogues, selective progesterone (or estrogen) receptor modulators, aromatase inhibitors, immunomodulators, and antiangiogenic agents. Further research is needed into central sensitization, local neurogenesis, and the genetics of endometriosis to identify additional treatment targets. A wider range of medical options allows for the possibility of precision health and a more personalized treatment approach for women with endometriosis.

Local upregulation of transient receptor potential ankyrin 1 and transient receptor potential vanilloid 1 ion channels in rectosigmoid deep infiltrating endometriosis

Transient Receptor Potential Vanilloid 1 (TRPV1) and Transient Receptor Potential Ankyrin 1 (TRPA1) expressed mainly by primary sensory neurons function as major nociceptive integrators. They are also present on the rat endometrium in an oestrogen-regulated manner. TRPV1 is upregulated in peritoneal and ovarian endometriosis patients, but there is no information about TRPA1 and their pathophysiological significances. In this study, patients undergoing laparoscopic surgery were investigated: severe dysmenorrhoea due to rectosigmoid deep infiltrating endometriosis ( n = 15), uterine fibroid-induced moderate dysmenorrhoea ( n = 7) and tubal infertility with no pain ( n = 6). TRPA1 and TRPV1 mRNA and protein expressions were determined by quantitative polymerase chain reaction and semi-quantitative immunohistochemistry from the endometrium samples taken by curettage. Results were correlated with the clinical characteristics including pain intensity. TRPA1 and TRPV1 receptors were expressed in the healthy human endometrium at mRNA and protein levels. Sparse, scattered cytoplasmic TRPA1 and TRPV1 immunopositivities were found in the stroma and epithelial layers. We detected upregulated mRNA levels in deep infiltrating endometriosis lesions, and TRPV1 gene expression was also elevated in autocontrol endometrium of deep infiltrating endometriosis patients. Histological scoring revealed significant TRPA1 and TRPV1 difference between deep infiltrating endometriosis stroma and epithelium, and in deep infiltrating endometriosis epithelium compared to control samples. Besides, we measured elevated stromal TRPV1 immunopositivity in deep infiltrating endometriosis. Stromal TRPA1 and TRPV1 immunoreactivities strongly correlated with dysmenorrhoea severity, as well TRPV1 expression on ectopic epithelial cells and macrophages with dyspareunia. Epithelial TRPA1 and stromal TRPV1 immunopositivity also positively correlated with dyschezia severity. We provide the first evidence for the presence of non-neuronal TRPA1 receptor in the healthy human endometrium and confirm the expression of TRPV1 channels. Their upregulations in rectosigmoid deep infiltrating endometriosis lesions and correlations with pain intensity suggest potential roles in pathophysiological mechanisms of the disease.

Long-term functional outcomes following colorectal resection versus shaving for rectal endometriosis

BACKGROUND

Two surgical approaches usually are used in the surgical management of deep infiltrating endometriosis of the rectum: the radical approach that mainly is based on colorectal resection and the conservative or symptom-guided approach that prioritizes conservation of the rectum. There are no data available that compare long-term functional digestive outcomes of 1 approach to the other.

OBJECTIVE

The purpose of this study was to compare long-term digestive outcomes in women who were treated by either rectal shaving or colorectal resection for deep endometriosis infiltrating the rectum.

STUDY DESIGN

A retrospective comparative study was performed. All women who were treated with surgery for deep endometriosis infiltrating the rectum by either shaving or colorectal resection at the University Hospital of Rouen from January 2005 to January 2010 were enrolled. Follow-up evaluation was carried out for a minimum of 5 years. Postoperative evaluation of digestive symptoms was performed by 4 standardized gastrointestinal questionnaires: the Gastrointestinal Quality of Life Index, the Knowles-Eccersley-Scott-Symptom score for constipation, the Wexner score for anal continence, and the Bristol Stool Score. Symptoms that were related to endometriosis, fertility, and disease recurrence were obtained from a specific questionnaire.

RESULTS

A total of 77 women were included. Three women were lost to follow up (3.9%), and 3 were treated by disc excision (3.9%). The mean follow-up time was 80±19 months. Forty-six women underwent conservative rectal shaving, and 25 women underwent colorectal resection. Patient characteristics and the severity of the disease were comparable in both groups. Patients who were treated by rectal shaving had significantly better Gastrointestinal Quality of Life Index values, lower Knowles-Eccersley-Scott-Symptom scores for postoperative constipation, and better anal continence. No statistically significant differences were revealed for postoperative pelvic pain. Rectal recurrence occurred in 8.7% of patients who were treated by conservative surgery: 4.3% underwent secondary colorectal resection and 4.3% were treated secondarily by rectal shaving. Consequently, avoiding a recurrence for merely 1 patient would have required 11 patients to undergo colorectal resection instead of shaving.

CONCLUSION

Our data suggest that, in patients who are treated for rectal endometriosis, colorectal resection does not improve long-term postoperative functional outcomes when compared with rectal shaving.

Surgical treatment of deep infiltrating rectal endometriosis: in favor of less aggressive surgery

Deep infiltrating endometriosis of the rectum is a severe disease concerning young women of reproductive age. Because it is a benign condition, aggressive surgical treatment and subsequent complications are not always accepted by young patients. Two surgical approaches exist: the radical approach, employing colorectal resection; and the conservative approach, based on rectal shaving or full-thickness disc excision. At present, the majority of patients with rectal endometriosis worldwide are managed by the radical approach. Conversely, as high as 66% of patients with colorectal endometriosis can be managed by either rectal shaving or full-thickness disc excision. Most arguments that used to support the large use of the radical approach may now be disputed. The presumed higher risk of recurrence related to conservative surgery can be balanced by a supposed higher risk of postoperative bowel dysfunction related to the radical approach. Bowel occult microscopic endometriosis renders debatable the hypothesis that more aggressive surgery can definitively cure endometriosis. Although most surgeons consider that radical surgery is unavoidable in patients with rectal nodules responsible for digestive stenosis, conservative surgery can be successfully performed in a majority of cases. In multifocal bowel endometriosis, multiple conservative procedures may be proposed, provided that the nodules are separated by segments of healthy bowel of longer than 5 cm. Attempting conservation of a maximum length of rectum may reduce the risk of postoperative anterior rectal resection syndrome and subsequent debilitating bowel dysfunction and impaired quality of life. Promotion of less aggressive surgery with an aim to better spare organ function has become a general tendency in both oncologic and benign pathologies; thus the management of deep colorectal endometriosis should logically be concerned, too.

Urocortin and corticotrophin-releasing hormone receptor type 2 mRNA are highly expressed in deep infiltrating endometriotic lesions

Ovarian endometrioma (OMA) and deep infiltrating endometriosis (DIE) are the most severe forms of endometriosis, but different pathogenetic mechanisms and clinical symptoms distinguish these two forms. Corticotrophin-releasing hormone (CRH) and urocortin (Ucn) are endometrial neuropeptides involved in tissue differentiation and inflammation. The expression of CRH, Ucn, Ucn2, CRH-receptors (type-1 and type-2) and inflammatory enzymes phospholipase-A2 group IIA (PLA2G2A) and cycloxygenase-2 (COX2) were evaluated in OMA (n = 22) and DIE (n = 26). The effect of CRH or Ucn on COX2 mRNA expression was evaluated in cultured human endometrial stromal cells. In DIE lesions, CRH, Ucn and CRH-R2 mRNA levels were significantly higher than in OMA (P < 0.01, P < 0.001 and P < 0.05, respectively); DIE lesions showed a higher expression of COX2 (P < 0.01) and PLA2G2A (P < 0.05) mRNA than OMA, which was positively correlated with CRH-R2 mRNA expression (P < 0.05). Intense immunostaining for CRH and Ucn was shown in DIE. Treatment of cultured endometrial stromal cells with Ucn significantly increased COX2 mRNA expression (P < 0.01); this effect was reversed by the CRH-R2 antagonist astressin-2B. In DIE, DIE lesions highly express neuropeptide and enzyme mRNAs, supporting a strong activation of inflammatory pathways.

Postoperative hormonal therapy after surgical excision of deep endometriosis

The clinical management of women with deep peritoneal endometriosis remains controversial. The debate focuses mainly on the precise role of hormonal medical treatment and surgery and on the most suitable surgical technique to be used. In particular, considering the risks of second-line surgery, prevention of recurrences after first-line surgery is a priority in this context. Post-surgical medical therapy has been advocated to improve the effectiveness of surgery and prevent recurrences. However, adjuvant therapy, i.e. a short course of 3-6 months of hormonal therapy after surgery, has been proven to be of limited or no benefit for endometriosis in general and for deep peritoneal endometriosis in particular. On the other hand, two cohort studies suggest a beneficial effect of prolonged hormonal therapy after surgery for deep endometriosis. Even if this evidence is too weak to confidently advocate systematic administration of prolonged medical therapy after surgery, we argue in favour of this approach because of the strong association of deep endometriosis with other disease forms. In fact, women operated on for deep endometriosis may also face recurrences of endometriomas, superficial peritoneal lesions and pelvic pain in general. The demonstrated high effectiveness of prolonged postoperative therapy for the prevention of endometriomas' formation and dysmenorrhea recurrence should thus receive utmost consideration in the decision-making process.

Kinase signalling pathways in endometriosis: potential targets for non-hormonal therapeutics

BACKGROUND

Endometriosis, the growth of endometrial tissue outside the uterine cavity, is associated with chronic pelvic pain, subfertility and an increased risk of ovarian cancer. Current treatments include the surgical removal of the lesions or the induction of a hypoestrogenic state. However, a reappearance of the lesion after surgery is common and a hypoestrogenic state is less than optimal for women of reproductive age. Additional approaches are required. Endometriosis lesions exist in a unique microenvironment characterized by increased concentrations of hormones, inflammation, oxidative stress and iron. This environment influences cell survival through the binding of membrane receptors and a subsequent cascading activation of intracellular kinases that stimulate a cellular response. Many of these kinase signalling pathways are constitutively activated in endometriosis. These pathways are being investigated as therapeutic targets in other diseases and thus may also represent a target for endometriosis treatment.

METHODS

To identify relevant English language studies published up to 2015 on kinase signalling pathways in endometriosis, we searched the Pubmed database using the following search terms in various combinations; 'endometriosis', 'inflammation', 'oxidative stress', 'iron', 'kinase', 'NF kappa', 'mTOR', 'MAPK' 'p38', 'JNK', 'ERK' 'estrogen' and progesterone'. Further citing references were identified using the Scopus database and finally current clinical trials were searched on the clinicaltrials.gov trial registry.

RESULTS

The current literature on intracellular kinases activated by the endometriotic environment can be summarized into three main pathways that could be targeted for treatments: the canonical IKKβ/NFκB pathway, the MAPK pathways (ERK1/2, p38 and JNK) and the PI3K/AKT/mTOR pathway. A number of pharmaceutical compounds that target these pathways have been successfully trialled in in vitro and animal models of endometriosis, although they have not yet proceeded to clinical trials. The current generation of kinase inhibitors carry a potential for adverse side effects.

CONCLUSIONS

Kinase signalling pathways represent viable targets for endometriosis treatment. At present, however, further improvements in clinical efficacy and the profile of adverse effects are required before these compounds can be useful for long-term endometriosis treatment. A better understanding of the molecular activity of these kinases, including the specific extracellular compounds that lead to their activation in endometriotic cells specifically should facilitate their improvement and could potentially lead to new, non-hormonal treatments of endometriosis.

Neuromodulation for the Treatment of Endometriosis-Related Symptoms

Sacral and pudendal neuromodulation have been advocated for the treatment of refractory pelvic pain, urinary urgency and retention, as well as fecal incontinence or constipation, all of which are commonly related to endometriosis and/or its surgical treatment.

In this review, the mechanisms of action and different routes of neuromodulation will be detailed, as well as all the studied applications of neuromodulation on ameliorating symptoms related to endometriosis and/or its treatment.

Dienogest Treatment Improves Quality of Life in Women with Endometriosis

Background

The aim of this study was to assess the efficacy of dienogest treatment in improving quality of life in women with endometriosis.

Methods

This was a prospective observational multicenter study at the universities of Siena, Milano, Cagliari, Perugia, Busto Arstizio, Pisa, Padova, Palermo, Foggia, Roma, Pescara and Catanzaro, including 142 patients with a diagnosis of endometriosis who received dienogest 2 mg once daily, for up to 90 days. Each patient underwent an evaluation of pelvic pain measured by visual analogue scale (VAS) from 0 to 10 points, and of quality of life measured by a mental and physical index before and after treatment.

Results

The mean ± SD of VAS was 8.2 ± 1.6 in women with endometriosis, and this progressively and significantly decreased to 5.9 ± 2.6 at the end of the study. Mental index score values increased from 39.0 ± 9.8 to 46.0 ± 9.1 (p<0.001); likewise, the physical index increased from 39.6 ± 9.6 to 47.7 ± 8.5 (p<0.001). During the treatment period, the most frequent adverse events (AEs) were headache (30.8%), followed by bleeding (29.4%), depression (26.6%), breast tenderness (23.8%) and acne (2.0%), but these were transitory, and none led to withdrawal from the study.

Conclusions

The present prospective study showed that dienogest is an effective and well-tolerated treatment improving the quality of life in endometriotic women.

Computed tomography-based virtual colonoscopy in the assessment of bowel endometriosis: The surgeon's point of view

OBJECTIVE

To discuss the role of computed tomography-based virtual colonoscopy (CTC) in preoperative assessment of bowel endometriosis.

METHODS

Retrospective study using data prospectively recorded, including 127 patients with colorectal endometriosis, having undergone CTC for bowel endometriosis. The study was conducted in a tertiary referral center during 38 consecutive months. Preoperative assessment included CTC, magnetic resonance imaging (MRI), endorectal ultrasound (ERUS) and clinical examination. Information concerning identification of deep infiltrating endometriosis (DIE) of the bowel, the length and height of colorectal involvement, stenosis of digestive lumen and associated digestive localizations were compared with intraoperative findings.

RESULTS

Sensitivity and specificity of CTC for DIE of the rectum, the sigmoid colon, associated digestive localizations, and stenosis of the digestive lumen were respectively 97% and 84%, 93% and 88%, 84% and 97%, 96% and 96%. Intraoperative estimation of the length of digestive tract involved by DIE was closer to that provided by CTC than those provided by MRI and ERUS. When CTC revealed stenosis of digestive lumen, higher rates of colorectal resection (63% vs. 9.6%, < 0.001) and disc excision (25.9% vs. 11%, 0.03) were recorded.

DISCUSSION

For those surgeons using various procedures for management of bowel endometriosis, accurate information on the length and height of bowel involvement, as well as the existence of bowel stenosis enables informed decision regarding the feasibility of conservative techniques versus bowel resection. Preoperative identification of associated localizations above the sigmoid colon is another major advantage related to CTC.

CONCLUSIONS

CTC provides accurate data on the length and height of colorectal involvement by DIE, stenosis of digestive lumen and associated lesions of digestive tract, which impact on the choice of surgical procedure.

Pathogenetic Mechanisms of Deep Infiltrating Endometriosis

Endometriosis is a benign gynecologic disease, affecting women of reproductive age associated with chronic pelvic pain, dysmenorrhea, dyspareunia and infertility. Ovarian endometrioma (OMA), superficial peritoneal endometriosis (SPE), and deep infiltrating endometriosis (DIE) are, till now, recognized as major phenotypes. The discussion is to know whether they share the same pathogenetic mechanisms. Till today, DIE is recognized as the most severe clinical form of endometriosis and has a complex clinical management. The DIE lesions have been considered in the present article, without distinguishing between the anterior (bladder) or the posterior (vagina, uterosacral ligaments, rectum, and ureter) compartment. The present knowledge indicates that hormonal function (estrogen and progesterone receptors) and immunological factors, such as peritoneal macrophages, natural killer cells, and lymphocytes, are critically altered in DIE. The aggressive behavior of DIE may be explained by the highly decreased apoptosis (nuclear factor kappa-light-chain-enhancer of activated B cells [NF-kB], B-cell lymphoma 2 [Blc-2], and anti-Mullerian hormone) and by the increased proliferation activity related to oxidative stress (NF-kB, reactive oxygen species, extracellular regulated kinase (ERK), advanced oxidation protein product). Invasive mechanisms are more expressed (matrix metalloproteinases and activins) in DIE in comparison to the OMA and SPE. Correlated with the increased invasiveness are the data on very high expression of neuroangiogenesis (nerve growth factor, vascular endothelial growth factor, and intercellular adhesion molecule) genes in DIE. Therefore, at the present time, several of the DIE pathogenetic features result specific in comparison to other endometriosis phenotypes, pleading for the existence of a specific entity. These evidence of specific pathogenetic features of DIE may explain the more severe symptomatology related to this form of endometriosis and suggest possible future target medical treatments.