Bladder Endometriosis: What do we know and what is left to find out? A narrative review

Bladder endometriosis accounts for 70-85% of urinary tract endometriosis cases. Urinary tract endometriosis occurs in approximately 1% of those living with endometriosis. Underlying aetiology and pathogenesis are not fully understood, but there are several plausible theories. As well as the typical pain symptoms, those with bladder endometriosis can experience several urinary tract symptoms. The manifestation of these symptoms can have complex pathways and processes. Imaging is accurate in the diagnosis of bladder endometriosis and clinicians should be mindful of the risk of silent kidney loss. Management should be guided by symptoms; both medical and surgical options are feasible. Surgical management offers potentially definitive treatment. Excisional surgery via bladder shave or partial cystectomy offers good improvement in symptoms with relatively low rates of serious complications and recurrence.

Accuracy of Transvaginal Ultrasound Compared to Cystoscopy in the Diagnosis of Bladder Endometriosis Nodules

OBJECTIVES

To evaluate the accuracy of transvaginal ultrasound (TVUS) in predicting detrusor infiltration and ureteral meatus involvement in patients with bladder endometriosis (BE) to select which cystoscopic procedures could be avoided and, secondarily, to assess the relationship between symptoms and the characteristics of nodules and the association of BE with other forms of endometriosis.

METHODS

Patients with BE diagnosed by TVUS were classified according to detrusor infiltration: BE with partial involvement of the muscular layer (group 1) and total muscular layer involvement with bladder protrusion (group 2). We analyzed the accuracy of TVUS compared with subsequently performed cystoscopy, the correlation with symptoms, and the association with other forms of endometriosis.

RESULTS

Among the 22 patients included, TVUS showed 9 patients with BE nodules partially affecting the detrusor (group 1) with normal cystoscopic findings (TVUS negative predictive value, 100%). Transvaginal ultrasound detected 13 nodules with total involvement, all visible by cystoscopy (TVUS positive predictive value, 100%). Transvaginal ultrasound also identified ureteral orifices that were free of involvement at greater than 10 mm from the BE nodule in 21 of 22 women (TVUS sensitivity, 95%). Ultrasound criteria for adenomyosis and endometriosis in other locations were present in 20 of 22 patients.

CONCLUSIONS

Transvaginal ultrasound can identify the infiltration of BE nodules in the bladder wall and predict cystoscopic findings with great accuracy. Nodules that partially affect the muscular layer have normal cystoscopic findings, thereby obviating the need for this procedure. Bladder endometriosis nodules are commonly associated with other forms of endometriosis and do not usually affect the ureteral meatus.

Early-life factors, in-utero exposures and endometriosis risk: a meta-analysis

This meta-analysis aimed to offer a general picture of the available data on the effects of early-life factors on the risk of developing endometriosis in adult life. An advanced, systematic search of the online medical databases PubMed, EMBASE and CINAHL was limited to full-length manuscripts published in English in peer-reviewed journals up to February 2019. Log of relative risk (RR) was employed to calculate the pooled effect sizes using both fixed and random effects modelling and I-squared tests to assess heterogeneity. Funnel plots were used to investigation publication bias. The meta-analysis was registered in PROSPERO (ID CRD42019138668). Six studies that included a total of 2360 women affected by endometriosis were analysed. The pooled results showed that the risk of developing endometriosis in adult life was significantly increased by being born prematurely (logRR 0.21, 95% CI -0.03 to 0.40), having a low birthweight (logRR 0.35, 95% CI -0.15 to 0.54), being formula-fed (logRR 0.65, 95% CI -0.35 to 0.95) and having been exposed to diethylstilbestrol (DES) in utero (logRR 0.65, 95% CI 0.26 to 1.04. Among intrauterine and early neonatal exposures, prematurity, birthweight, formula feeding and DES were risk factors for the development of endometriosis in adult life.

Peculiar Aspects of Endometriosis in Adolescents

Although documented rates of endometriosis in adolescent patients undergoing laparoscopy for chronic pelvic pain range from about 25% to 45%, adolescent endometriosis has received limited attention in terms of research activity and follow-up studies. In this manuscript, distinctive characteristics of adolescent and young endometriosis have been considered in order to define pathogenetic and scientific concepts that might be useful in clarifying some aspects of the adult disease as well. Some highlights relative to the cellular origin of the disease can be derived from reported cases before menarche, from the appearance of endometriotic lesions in teenagers (mostly stage I-II endometriosis), and from the relative infrequency of ovarian endometriotic cysts in this population. Adolescents and young patients might be also particularly useful for studying the natural course of the disease. To this end, clinical manifestations and recurrence patterns of the disease in adolescent patients need to be elucidated. Differences in clinical aspects of the disease between the adult and young populations are presented. Risk of recurrence and potential risk factors involved in the reappearance of the disease in teenagers are completely unknown. (Journal of Endometriosis 2010; 2: 19–25)

Bladder Endometriosis: A Systematic Review of Pathogenesis, Diagnosis, Treatment, Impact on Fertility, and Risk of Malignant Transformation

CONTEXT

The bladder is the most common site affected in urinary tract endometriosis. There is controversy regarding the pathogenesis, clinical management (diagnosis and treatment), impact on fertility, and risk of malignant transformation of bladder endometriosis (BE).

OBJECTIVE

To systematically evaluate evidence regarding the pathogenesis, diagnosis, medical and surgical treatment, impact on female fertility, and risk of malignant transformation of BE.

EVIDENCE ACQUISITION

A systematic review of PubMed/Medline from inception until October 2016 was performed in accordance with the Preferred Reporting Items for Systematic Review and Meta-analysis (PRISMA) statement and was registered in the PROSPERO registry (www.crd.york.ac.uk/prospero; CRD42016039281). Eighty-seven articles were selected for inclusion in this analysis.

EVIDENCE SYNTHESIS

BE is defined as the presence of endometrial glands and stroma in the detrusor muscle. Ultrasonography is the first-line technique for assessment of BE owing to its accuracy, safety, and cost. Clinical management can be conservative, using hormonal therapies, or surgical. When conservative treatment is preferred, estrogen-progestogen combinations and progestogens should be chosen because of their favorable profile that allows long-term therapy. Surgery should guarantee complete removal of the bladder nodule to minimize recurrence, so transurethral surgery alone should be avoided in favor of segmental bladder resection. There is not a strong rationale for hypothesizing a detrimental impact of BE per se on fertility. Furthermore, current evidence does not support the removal of bladder endometriotic lesions because of the potential risk of malignant transformation since this phenomenon is exceedingly rare.

CONCLUSIONS

BE is a challenging condition, and the common coexistence of other types of endometriosis means that clinical management of BE should involve collaboration between gynecologists and urologists.

PATIENT SUMMARY

In this article we review available knowledge on bladder endometriosis. The review provides a useful tool to guide physicians in the management of this complex condition.

Replication and meta-analysis of previous genome-wide association studies confirm vezatin as the locus with the strongest evidence for association with endometriosis

STUDY QUESTION

Is it possible to replicate the genetic association of single nucleotide polymorphisms (SNPs) rs13394619, rs4141819, rs7739264, rs17694933 and rs10859871 in five genetic loci previously identified as associated with endometriosis in an Italian Caucasian population?

SUMMARY ANSWER

SNP rs10859871 near the vezatin (VEZT) gene was found to be significantly associated with endometriosis in general while SNPs rs17694933 and rs4141819 were associated with Stage III/IV and ovarian disease, respectively.

WHAT IS KNOWN ALREADY

Endometriosis represents a complex disease in which the phenotypic manifestations are influenced by both genetic and environmental factors. Recent genome-wide association studies (GWASs) have allowed to identify some SNPs associated with the predisposition to the disease. A meta-analysis published in 2014 combined results from GWAS and replication studies showing that of the nine loci found to be associated with the disease in at least one of the studies, six (rs7521902, rs1270667, rs13394619, rs7739264, rs1537377 and rs10859871) remained genome-wide significant while two others (rs1250248 and rs4141819) showed borderline genome-wide significant association with more severe disease.

STUDY DESIGN, SIZE, DURATION

Allele frequencies of selected SNPs (rs13394619, rs4141819, rs7739264, rs17694933 and rs10859871) were investigated in 305 women with laparoscopically proven endometriosis, 285 laparoscopic controls and 2425 healthy, blood donor controls from the general population. A meta-analysis with previous data was also conducted.

PARTICIPANTS/MATERIALS, SETTING, METHODS

A total of 590 women who underwent endoscopic surgery were enrolled in the study and a blood sample was collected. After DNA extraction, genotype was obtained using Taq-Man pre-designed assay. Genotype data from healthy blood donor women were obtained from an existing genotype bank.

MAIN RESULTS AND THE ROLE OF CHANCE

A statistically significant association with endometriosis was found for SNP rs10859871, close to the VEZT gene, compared with both general population [odds ratio (OR) = 1.43, 95% confidence interval (CI): 1.20-1.71, P = 6.9 × 10(-5)] and laparoscopic controls (OR = 1.58, 95% CI: 1.24-2.02, P = 2.1 × 10(-4)). Meta-analysis with previous data confirmed the rs10859871 SNP as that with the strongest evidence for association with endometriosis (OR = 1.19, 95% CI: 1.15-1.24, P = 7.9 × 10(-20)). A further meta-analysis conducted using data from Stage III-IV endometriosis resulted in stronger genome-wide significant effect sizes for four out of the five SNPs tested.

LIMITATIONS, REASONS FOR CAUTION

The inability to confirm all previous demonstrated associations considering all stages of endometriosis may be due to a lack of statistical power and differences in the definition of cases included.

WIDER IMPLICATIONS OF THE FINDINGS

The associations with the SNPs identified so far have been obtained with a relatively small sample size supporting a limited heterogeneity across the various datasets. This represents an important advance in the identification of genetic markers of this disease.

STUDY FINDING/COMPETING INTERESTS

No funding to declare. The authors have no competing financial interests in relation to the content of this research paper.

Postoperative medical therapy after surgical treatment of endometriosis: from adjuvant therapy to tertiary prevention

The high rate of disease recurrence after surgery is critical and frustrating for women with endometriosis. Adjuvant treatments using a 3- to 6-months course of hormone therapy after surgery have been extensively investigated during the last 2 decades; however, results have been unsatisfactory, primarily because the benefits of hormone therapy rapidly vanish once treatment is discontinued. The protective effect is limited to the period of use. Accordingly, it is recognized that suppressive hormone therapy after surgery markedly prevents recurrent episodes only if given over the long term. The emerging view is that estroprogestins do not ameliorate the effects of surgery but demonstrate tertiary prevention of the disease. They prevent ovulation and reduce retrograde menstrual flow, two crucial events in the pathogenesis of endometriosis. The available literature strongly supports the benefits of prolonged administration of estroprogestins after surgery in preventing recurrence of endometriomas and dysmenorrhea. In contrast, data on dyspareunia and nonmenstrual pelvic pain remain scanty and unconvincing, and there is no information about recurrence of other forms of endometriosis such as peritoneal implants and adhesions. Overall, estroprogestin therapy after surgery to treat endometriosis should be recommended in women who do not seek to become pregnant. Further evidence is warranted to better delineate the beneficial effects of this emerging but convincing strategy.

Unravelling the Ovarian Endometrioma Pathogenesis: “The Long and Winding Road” across the Various Theories

Controversy exists regarding the pathogenesis of endometriotic ovarian cysts. Different and complex theories have been proposed over the years since the description of chocolate cysts by Sampson in 1921. We have herein reviewed findings in support and against the most widely accepted theories. According to the theory of Hughesdson and Brosens, a prerequisite for endometrioma formation seems to be the inversion and progressive invagination of the ovarian cortex after the accumulation of menstrual debris derived from bleeding of superficial endometriotic implants, which are located on the ovarian surface and adherent to the peritoneum. Disproving the metaplasia hypothesis put forward by Donnez and coworkers and supporting the involvement of the ovulation process in the development of ovarian endometriosis, Vercellini and colleagues have recently demonstrated that a cystic corpus luteum may be a transitory step toward endometrioma formation. As these theories are not able to explain the various aspects of endometrioma formation fully, the possibility that the coelomic metaplasia of the ovarian mesothelium with changes into typical endometrial glands and stroma might be responsible for the endometrioma formation cannot be totally ruled out. Further research is needed to clearly elucidate the pathogenetic aspects of endometriotic ovarian cysts.

Endometriosis in a rural remote setting: a cross-sectional study

Women in Western nations are exposed to an "unnatural" high number of menstrual cycles and this has been claimed to favour the development of endometriosis. If so, the prevalence of the disease should be low in remote rural settings characterized by high fertility rate, frequent teen-age pregnancy and protracted breast-feeding. To verify this hypothesis, we investigated the prevalence of endometriosis among women referring to the District Hospital of Aber, Northern Uganda for gynecological complaints. Subjects were considered affected if they had a history of surgery for endometriosis or if they had a positive clinical or ultrasound examination. Overall, a total of 528 gynecological consultancies were performed during the one year study period. Endometriosis was recorded in only one case. The frequency of the disease in the whole cohort of referred cases was thus 0.2% (95% confidence intervals (CI): 0.01-0.9%). When focusing on non-pregnant women in their reproductive age, it was 0.3% (95% CI: 0.01-1.3%). When considering women complaining symptoms suggestive for endometriosis, it was 0.4% (95% CI: 0.02-1.9%). In conclusion, endometriosis is rare in a community characterized by high fertility rate, frequent teen-age pregnancy and protracted breast-feeding, supporting the idea that the reproductive pattern plays a crucial role in the pathogenesis of the disease.

Inflammation: a link between endometriosis and preterm birth

Endometriosis is a chronic inflammatory disease affecting women's health. Pain and infertility are the major symptoms caused by a hormonal/immunological dysfunction, which causes an endometrial impairment. The same pathogenetic mechanisms are also associated with preterm birth: hormones, cytokines, neurohormones, and growth factors interact in modulating extracellular matrix and prostaglandin secretion, thus activating the inflammatory process in placental membranes and myometrium. An overlap of molecules and mechanisms may explain the evidence that preterm birth is a common outcome in pregnant patients with endometriosis.

MicroRNAs and the pathogenesis of endometriosis

Micro RNAs (miRNAs) are small non-coding RNAs which regulate numerous cellular processes at the posttranscriptional and translational level. In endometriosis, expression of miRNAs is frequently dysregulated. miRNAs are predicted to modulate several relevant processes involved in the pathogenesis of endometriosis, including cell proliferation, apoptosis, cell migration and invasiveness, angiogenesis, and inflammation, as well as stem cell properties. miRNA expression has been studied by microarray profiling and quantitative real-time PCR, enabling the identification of specific miRNAs as potential novel diagnostic markers for endometriosis. The future application of locked-nucleic acid miRNA inhibitors, miRNA decoys, and synergistic approaches involving conventional therapeutics may open up promising new perspectives in endometriosis therapy.

Recurrent endometrioma and ovarian reserve: biological connection or surgical paradox?

OBJECTIVE

Cumulative evidence supports the view that ovarian endometriomas originate from ovulatory events and that the ovarian reserve is reduced following surgery. On these bases, we have hypothesized that the risk of recurrence may be related to the residual ovarian reserve of the operated ovary.

STUDY DESIGN

We retrospectively selected 45 women scheduled for in vitro fertilization who previously underwent surgical excision of monolateral endometriomas and compared ovarian responsiveness in those who did (n = 24) and did not (n = 21) have a recurrent endometrioma.

RESULTS

In the intact ovaries, the mean ± SD number of codominant follicles in women with and without recurrences was 3.5 ± 1.7 and 3.7 ± 2.2, respectively (P = NS). In the affected ovaries, the mean ± SD number of follicles in gonads with and without recurrences was 2.5 ± 2.3 and 1.1 ± 1.5, respectively (P < .05).

CONCLUSION

Ovarian responsiveness is higher in gonads that developed recurrent endometriomas.

Perinatal environment and endometriosis

BACKGROUND/AIMS

Perinatal environmental exposure may affect fetal development and reprogram the developing organism for adult-onset disease. In this case-control study, we aimed at assessing this pathogenetic model in endometriosis.

METHODS

Consecutive patients with a first laparoscopic diagnosis of endometriosis were selected as cases. Controls were women who underwent laparoscopy during the same study period, but who were found to be free of the disease. Selected women and their mothers were interviewed.

RESULTS

Ninety-one women with endometriosis and 82 controls were selected. Handedness, a variable believed to be determined prenatally by hormonal environment in utero significantly differed between the study groups. Women with the disease were less likely to be left- or mixed-handed (adjusted OR: 0.24, 95% CI: 0.08-0.71). In contrast, we failed to detect any association with birth order, maternal age, smoking, nausea, weight gain, prematurity, birth weight and breast-feeding.

CONCLUSIONS

Our results generally do not support the view that in utero exposure may play a major role in the pathogenesis of endometriosis. The association with handedness, however, is intriguing in this regard and deserves further investigation.