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Impact of surgery on fertility among patients with deep infiltrating endometriosis

  • Author Footnotes
    1 Joint first authorship.
    Maja Raos
    Footnotes
    1 Joint first authorship.
    Affiliations
    Department of Clinical Medicine, Aarhus University, Incuba Skejby, Building 2, Palle Juul-Jensens Boulevard 82, 8200 Aarhus N, Denmark

    Department of Urology, Aarhus University Hospital, Palle Juul-Jensens Boulevard 99, 8200 Aarhus N, Denmark
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  • Author Footnotes
    1 Joint first authorship.
    Mie Mathiasen
    Correspondence
    Corresponding author at: Department of Urology, Aarhus University Hospital, Palle Juul-Jensens Boulevard 99, 8200 Aarhus N, Denmark.
    Footnotes
    1 Joint first authorship.
    Affiliations
    Department of Urology, Aarhus University Hospital, Palle Juul-Jensens Boulevard 99, 8200 Aarhus N, Denmark
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  • Mikkel Seyer-Hansen
    Affiliations
    Department of Clinical Medicine, Aarhus University, Incuba Skejby, Building 2, Palle Juul-Jensens Boulevard 82, 8200 Aarhus N, Denmark

    Department of Obstetrics and Gynecology, Aarhus University Hospital, Palle Juul-Jensens Boulevard 99, 8200 Aarhus N, Denmark
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  • Author Footnotes
    1 Joint first authorship.
Open AccessPublished:December 06, 2022DOI:https://doi.org/10.1016/j.ejogrb.2022.12.004

      Highlights

      • Pregnancy rate after surgery for bowel endometriosis is 60.6%.
      • Complications do not seem to affect live birth rate or time to pregnancy.
      • Pregnancy rate after surgery and expectant management are comparable.

      Abstract

      Objective

      The aim of the study was to investigate pregnancy and live birth rate after surgical resection of rectosigmoid deep infiltrating endometriosis (DIE), and study if complications affect these rates.

      Study design

      Historical case series. 193 patients with rectosigmoid DIE and pregnancy intention undergoing a rectosigmoid resection for DIE from January 2009 to May 2019. All operations were performed at the Department of Obstetrics and Gynecology, Aarhus University Hospital, Denmark. Surgical and fertility outcome data were obtained through patient files. Anonymized data was analyzed statistically. Normally distributed continuous variables are stated as means, categorical data as percentages and time to pregnancy as Kaplan-Meier failure function. Live birth rates stratified on complications were tested with chi2 test.

      Results

      117 patients became pregnant postoperatively with a pregnancy and live birth rate of 60.6% and 53.9%, respectively. 39 patients (20.2%) became pregnant spontaneously and 78 patients (40.4%) by intrauterine insemination or assisted reproductive technologies. Median time to pregnancy after surgery was 12.4 months (range: 0.4–58). Clavien-Dindo complication grade III (none grade IV) was registered among 16.6%. These patients had pregnancy and live birth rates of 50%, not statistically significantly different from those without complications.

      Conclusions

      Postoperative pregnancy and live birth rates after resection of rectosigmoid endometriosis in this study are in line with conservative treatment, when comparing with the literature. Interestingly, complications (Clavien-Dindo grade III) did not affect live birth rate or time to pregnancy.

      Abbreviations:

      ART (Assisted reproductive technologies), DIE (Deep infiltrating endometriosis)

      Keywords

      Introduction

      Endometriosis is a common benign gynecological condition defined as ectopic presence of endometrium-like tissue with an estrogen-dependent and local inflammatory component [
      • Ahn S.H.
      • Khalaj K.
      • Young S.L.
      • Lessey B.A.
      • Koti M.
      • Tayade C.
      Immune-inflammation gene signatures in endometriosis patients.
      ]. Deep infiltrating endometriosis (DIE) is defined as endometriotic subperitoneal invasion exceeding 5 mm in depth and can be located uterosacrally, in the intestine, vagina, bladder and ureter (most to least frequent) [
      • Chapron C.
      • Chopin N.
      • Borghese B.
      • Foulot H.
      • Dousset B.
      • Vacher-Lavenu M.C.
      • et al.
      Deeply infiltrating endometriosis: pathogenetic implications of the anatomical distribution.
      ]. Rectosigmoid endometriosis can be associated with severe pain and infertility. Especially, at severe endometriosis stages very few are expected to become pregnant with an expectant approach [
      • Olive D.L.
      • Stohs G.F.
      • Metzger D.A.
      • Franklin R.R.
      Expectant management and hydrotubations in the treatment of endometriosis-associated infertility.
      ]. Due to the benign nature of endometriosis, treatment is based on the patient’s symptoms and pregnancy wish.
      Primary treatment of endometriosis and especially pain symptoms is hormonal therapy [
      • Dunselman G.A.
      • Vermeulen N.
      • Becker C.
      • Calhaz-Jorge C.
      • D'Hooghe T.
      • De Bie B.
      • et al.
      ESHRE guideline: management of women with endometriosis.
      ]. This includes oral contraceptives, progestogen and gestagen intrauterine device [
      • Vercellini P.
      • Buggio L.
      • Frattaruolo M.P.
      • Borghi A.
      • Dridi D.
      • Somigliana E.
      Medical treatment of endometriosis-related pain.
      ]. However, besides gonadotropin-releasing hormone (GnRH) agonist in relation to fertility treatment, hormonal therapy has no place for patients with pregnancy intention, because of the contraceptive effect.
      Assisted reproductive technologies (ART) is generally accepted as infertility treatment among women with endometriosis, and shows similar live births rates to women without endometriosis undergoing ART [
      • Qu H.
      • Du Y.
      • Yu Y.
      • Wang M.
      • Han T.
      • Yan L.
      The effect of endometriosis on IVF/ICSI and perinatal outcome: A systematic review and meta-analysis.
      ,
      • Kheil M.H.
      • Sharara F.I.
      • Ayoubi J.M.
      • Rahman S.
      • Moawad G.
      Endometrioma and assisted reproductive technology: a review.
      ]. However, the impact of ART on pain is still discussed, as studies disagree if it possibly worsens endometriosis symptoms [
      • Mathiasen M.
      • Egekvist A.G.
      • Kesmodel U.S.
      • Knudsen U.B.
      • Seyer-Hansen M.
      Similar evolution of pain symptoms and quality of life in women with and without endometriosis undergoing assisted reproductive technology (ART).
      ,
      • Seyer-Hansen M.
      • Egekvist A.
      • Forman A.
      • Riiskjaer M.
      Risk of bowel obstruction during in vitro fertilization treatment of patients with deep infiltrating endometriosis.
      ]. On the contrary, bowel resection for DIE (segmental or disc excision) improves symptoms [
      • Roman H.
      • Bubenheim M.
      • Huet E.
      • Bridoux V.
      • Zacharopoulou C.
      • Darai E.
      • et al.
      Conservative surgery versus colorectal resection in deep endometriosis infiltrating the rectum: a randomized trial.
      ], but it is widely discussed in the literature whether surgery has a place in improving fertility [
      • Rocha A.M.
      • Albuquerque M.M.
      • Schmidt E.M.
      • Freitas C.D.
      • Farias J.P.
      • Bedin F.
      Late Impact of the Laparoscopic Treatment of Deep Infiltrating Endometriosis with Segmental Colorectal Resection.
      ,
      • Blanc M.
      • von Theobald P.
      Fertility after surgery for deep infiltrating endometriosis.
      ,
      • Hudelist G.
      • Aas-Eng M.K.
      • Birsan T.
      • Berger F.
      • Sevelda U.
      • Kirchner L.
      • et al.
      Pain and fertility outcomes of nerve-sparing, full-thickness disk or segmental bowel resection for deep infiltrating endometriosis-A prospective cohort study.
      ]. This discussion also includes the not neglectable perioperative complication rate of up to 11–13%, including anastomotic leakage, ureteral lesion, rectovaginal fistula and pelvic abscess [
      • Abo C.
      • Moatassim S.
      • Marty N.
      • Saint Ghislain M.
      • Huet E.
      • Bridoux V.
      • et al.
      Postoperative complications after bowel endometriosis surgery by shaving, disc excision, or segmental resection: a three-arm comparative analysis of 364 consecutive cases.
      ,
      • Iversen M.L.
      • Seyer-Hansen M.
      • Forman A.
      Does surgery for deep infiltrating bowel endometriosis improve fertility? A systematic review.
      ], as well as if complications affect pregnancy and live birth rate.
      The aim of this study was to evaluate pregnancy and live birth rates after surgical treatment for colorectal DIE as well as if they are affected by complications.

      Material and methods

      Study design

      Single-center 10-year experience involving 193 patients who had surgery for DIE and pregnancy intention from 1st of January 2009 to 31st of May 2019. The study was conducted at Department of Obstetrics and Gynecology at Aarhus University Hospital (AUH), one of two tertial referral centers for DIE in Denmark. Primary outcome was live birth rate according to Harbin consensus [
      • Hodgson R.M.
      • Lee H.L.
      • Wang R.
      • Mol B.W.
      • Johnson N.
      Interventions for endometriosis-related infertility: a systematic review and network meta-analysis.
      ] and pregnancy rate, not including miscarriages. Rates were stratified after conception mode. Pregnancy was defined as ongoing clinical pregnancy by positive pregnancy test or live fetus in gestational week six to eight visualized by ultrasound. Secondary outcomes were time to pregnancy, postoperative complications, and stoma.

      Procedure

      Surgery was performed as minimally invasive laparoscopy with rectosigmoid segment or disc resection, depending on size and accessibility of the infiltration. Endometriosis in other locations was surgically excised as well. Surgery was performed as joined venture between a gynecologist and general surgeon. During the study period, the specialized team consisted of four gynecologist and seven colorectal surgeons. Postoperative follow-up was scheduled at four months, one and two years after surgery. Follow-ups reviewed pain and fertility status and were carried out at the outpatient clinic or by phone.

      Study population

      The patients were identified by The Danish Civil Registration System (CPR). Inclusion criteria were ICD-10 code for rectosigmoid endometriosis (DN805C) and procedure code for laparoscopic rectosigmoid resection (KJGB01). Exclusion criteria were no postoperative pregnancy intention and age above 41 years at date of surgery, as this is the age limit for publicly funded fertility treatment in Denmark.

      Data collection and management

      Data were obtained from patient files and included the following: Demographic information, previous surgery, perioperative surgical information, complications, hospitalization time, magnetic resonance imaging (MRI) information on the extend of the bowel infiltrate and other locations of endometriosis as well as pre- and postoperative pregnancy and fertility. For each patient an electronic case report form (eCRF) was created in the secure web-based database platform REDCap® [
      • Harris P.A.
      • Taylor R.
      • Thielke R.
      • Payne J.
      • Gonzalez N.
      • Conde J.G.
      Research electronic data capture (REDCap)–a metadata-driven methodology and workflow process for providing translational research informatics support.
      ]. This platform provides an audit trail of all activities regarding all eCRF. Data entry was maintained by two of the authors (MM and MR).

      Ethical approval

      Permission to carry out this study and review patient files has been granted by Central Region Denmark (no. 1–16-02–345-16, 8th June 2016) and the Danish Patient Safety Authority (no. 3–3013-2894/1, 21st March 2019). No permission from the Committee on Health Research Ethics was necessary due to study design.

      Calculation

      Prior to statistical analysis, data were anonymized. Normally distributed continuous variables are stated as means with standard deviation (SD) or 95% confidence intervals (95% CI). Data, not normally distributed, were presented as median and range. Categorical data are shown as percentages. Kaplan-Meier failure function illustrates time to pregnancy. Time to pregnancy limit was set at five years for patients not obtaining pregnancy. Pregnancy and livebirths rates stratified on complications were tested with Chi2 test according assumptions related to populations size in each cell. Statistical analyses were performed in Stata 16 (StataCorp, College Station, TX, USA).

      Results

      The final study population for analysis consisted of 193 patients (Fig. 1). If evaluation of ovaries and salpinges during surgery indicated possibility for spontaneous pregnancy, patients were encouraged to try for spontaneous conception. Some patients, however, decided to continue directly to ART.
      Figure thumbnail gr1
      Fig. 1Flow chart of study population. DIE = deep infiltrating endometriosis, IUI = intrauterine insemination, ART = assisted reproductive technologies.
      Table 1 presents baseline characteristics of study population. The department’s guideline requires a preoperative BMI of 30 or lower as a preventative measure to decrease risk of peri- and postoperative complications. Nevertheless, 14 patients had surgery with above BMI 30, and three of them had a postoperative complication. The majority, 107 patients, were in the normal BMI range. “Other” infertility reasons were single civil status (three patients), polycystic ovary syndrome (one patient), uterus didelphys (one patient) and previous bilateral salpingo-oophorectomy (one patient). Six patients had combined decreased tubal passage and male factor infertility. Five patients had one ovary.
      Table 1Baseline characteristics.
      NResults
      Age, mean in years (SD)19331.7 (3.7)
      BMI
      Body Mass Index = weight (kg) / height2 (m).
      , mean in kg/m2 (SD)
      187
      6 missing.
      24.2 (3.8)
      Infertility duration, median in months (range)107
      86 missing.
      24 (6 – 72)
      Parity (%)
      • Nullipara
      • Primipara
      • Multipara


      148

      38

      7


      76.7

      19.7

      3.6
      Infertility cause in addition to endometriosis (%)
      • Decreased tubal passage
      • Male factor
      • Other


      11

      25

      6


      5.7

      13.0

      3.1
      Previous ART
      Assisted Reproductive Technologies.
      (%)
      10755.4
      Previous surgery with endometriosis as indication (%)
      • 0 surgeries
      • 1 surgery
      • 2 surgeries
      • 3 or 4 surgeries


      118

      53

      15

      7


      61.1

      27.5

      7.8

      3.6
      a Body Mass Index = weight (kg) / height2 (m).
      b 6 missing.
      c 86 missing.
      d Assisted Reproductive Technologies.
      MRI was the primary imaging modality for DIE diagnosis and surgical planning (Table 2). Only five patients did not get an MRI scan prior to surgery. Not all MRIs are stated with exact measurements but just with the statement, that a rectosigmoid nodule is present.
      Table 2Magnetic resonance imaging (MRI) findings.
      NResult
      Size of rectosigmoid nodule, median in mm (range)
      • Length
      • Depth


      160

      147


      30 (8 – 90)

      11 (4 – 23)
      Distance from anal verge, median in cm (range)16811 (6 – 20)
      Two rectosigmoid nodules (%)2010.4
      Adenomyosis (%)2814.5
      Endometrioma (%)
      • Unilateral
      • Bilateral


      57

      44


      29.5

      22.8
      Hydronephrosis (%)
      • Unilateral
      • Bilateral


      17

      5


      8.8

      2.6
      The main part, 188 (97.4%) surgeries were performed laparoscopically. Segmental resection was performed among 149 patients (77.2%) and the remaining 22.8% had a disc excision. No patients were treated with shaving only. Median duration of operation was 178 min (range: 35 – 454), and median hospitalization time was 6 days (range: 2 – 35).
      Live birth rate was 53.9% (104/193), and the majority (61.5%) obtained pregnancy after ART. Table 3 provides information on conception mode and pregnancy. Specific information on the number of patients who intended spontaneous conception postoperatively prior to ART is not available, but 126 patients were treated with ART, 67.5% of whom got pregnant. 88.9% of all pregnancies resulted in live birth. Pregnancy rate for women with MR-verified adenomyosis was 64.3% (18/28).
      Table 3Postoperative fertility and pregnancy characteristics.
      NResult
      Pregnancy rate (%)11760.6
      Time to pregnancy, median in months (range)11712.2 (0.4 – 58)
      Twin pregnancies (%)94.7
      Pregnancy rate in relation to mode of conception (%)
      • Spontaneous
      • IUI
        Intrauterine Insemination.
      • ART
        Assisted Reproductive Technologies.


      39

      2

      76


      33.3

      1.7

      65.0
      Live birth rate in relation to mode of conception (%)
      • Spontaneous
      • IUI
        Intrauterine Insemination.
      • ART
        Assisted Reproductive Technologies.


      38

      2

      64


      36.5

      1.9

      61.5
      a Intrauterine Insemination.
      b Assisted Reproductive Technologies.
      Women with primary infertility preoperatively (n = 148) had a postoperative pregnancy rate of 64.9% with 34.4% as spontaneous pregnancies. Patients with secondary infertility prior to surgery (parity of one or two, n = 45) had a postoperative pregnancy rate of 46.7% with 28.6% as spontaneous pregnancies. Mean age of nullipara and multipara was 31.4 years (95% CI: 30.8 – 32.0) and 32.7 years (95% CI: 31.7 – 33.8), respectively.
      Time to pregnancy is shown in Fig. 2, Fig. 3. Median time to spontaneous pregnancy was 9.8 months (range: 0.4 – 44) and 12.6 months (range: 1.8 – 58) for ART pregnancies. After operation 67 patients got medical intervention with median duration time of 7 months (range: 1 – 53). 59.7% (40/67) became pregnant, 72.5% by ART, 16.7 months (range: 3.8 – 49.5) after treatment termination.
      Figure thumbnail gr2
      Fig. 2Time to pregnancy (all patients in the study population). Kaplan-Meier failure estimate of time to pregnancy of all patients in the study population.
      Figure thumbnail gr3
      Fig. 3Time to pregnancy (based on mode of pregnancy). Kaplan-Meier failure estimate of time to pregnancy of patients who became pregnant postoperatively.

      Complications

      Postoperative complications occurred for 38 patients (19.7%). Five had two simultaneous complications after surgery. Specific types of complications are shown in Table 4. One “Other” complication was rotation of stoma. Eleven patients (5.7%) had Clavien-Dindo Classification [
      • Clavien P.A.
      • Barkun J.
      • de Oliveira M.L.
      • Vauthey J.N.
      • Dindo D.
      • Schulick R.D.
      • et al.
      The Clavien-Dindo classification of surgical complications: five-year experience.
      ] grade III anastomotic leakage with need of surgical intervention. Complication rates were 15.9% (7/44) and 16.8% (25/149) for disc and segmental resection, respectively. Forty-one patients (21.2%) got a temporary stoma, either during primary surgery or secondary in relation to a complication. One patient (0.5%) got a permanent stoma.
      Table 4Postoperative complications.
      NResult
      Types of complications (all Clavien-Dindo grades) (%)
      • Anastomotic leakage
      • Ureteral leakage
      • Pelvic absces
      • Rectovaginal fistula
      • Ureteral obstruction
      • Ureterovaginal fistula
      • Bladder perforation
      • Other
      38

      13

      12

      5

      2

      3

      1

      1

      1
      19.7

      6.7

      6.2

      2.6

      1.0

      1.6

      0.5

      0.5

      0.5
      Complication grade in regard to the Clavien-Dindo Classification:
      • Grade III
      • Grade IV-V


      32

      0


      16.6

      0
      Days until diagnosis of complication, median (range)385.5 (0 – 49)
      Stoma (%)
      • During primary surgery
      • During secondary surgery


      30

      11


      15.5

      5.7
      Days until reversed stoma, median (range)39110 (25 – 913)
      Among patients with one or two postoperative complications 16 patients (50%) became pregnant, seven by spontaneous conception and nine by ART. Median time to pregnancy 10.7 months (range: 2.6 – 58.0) for Clavien-Dindo III. Complications did not statistically significantly affect pregnancy and live birth rates (Table 5).
      Table 5Pregnancy and live birth rate related to complications.
      Pregnancy ratep-valueLive birth rate
      Three missing.
      p-value
      No complication63% (97/155)61.8% (94/152)
      Complications

      Clavien-Dindo III
      50% (16/32)0.1950% (16/32)0.21
      * Three missing.

      Discussion

      In this study, we found a pregnancy rate of 60.6% and a live birth rate of 53.9% after surgical treatment for colorectal DIE. This was, interestingly, not affected by complications, neither did it prolong time to pregnancy.
      Our study reports a high live birth rate, which could be explained by exclusion of early miscarriage before gestational age of 12 weeks. In spite of this, when looking at study population size and the extent of the surgery, our pregnancy rate is comparable to similar studies. Other studies with complete DIE surgery show great variation in overall postoperative pregnancy rates from 42.9% to 81% [
      • Blanc M.
      • von Theobald P.
      Fertility after surgery for deep infiltrating endometriosis.
      ,
      • Hudelist G.
      • Aas-Eng M.K.
      • Birsan T.
      • Berger F.
      • Sevelda U.
      • Kirchner L.
      • et al.
      Pain and fertility outcomes of nerve-sparing, full-thickness disk or segmental bowel resection for deep infiltrating endometriosis-A prospective cohort study.
      ,
      • Roman H.
      • Chanavaz-Lacheray I.
      • Ballester M.
      • Bendifallah S.
      • Touleimat S.
      • Tuech J.J.
      • et al.
      High postoperative fertility rate following surgical management of colorectal endometriosis.
      ]. The high pregnancy rate of 81% may be explained by fewer patients included compared to our study and a longer follow-up for all patients. A review by Cohen et al. found a pregnancy rate of 46.9% for patients surgically treated for bowel endometriosis [
      • Cohen J.
      • Thomin A.
      • Mathieu D'Argent E.
      • Laas E.
      • Canlorbe G.
      • Zilberman S.
      • et al.
      Fertility before and after surgery for deep infiltrating endometriosis with and without bowel involvement: a literature review.
      ].
      Regarding spontaneous pregnancy, this study found a live birth rate of 19.7% and pregnancy rate of 20.2%. To compare, spontaneous pregnancy rate with expectant management is found to be 21–36% [
      • Stepniewska A.
      • Pomini P.
      • Bruni F.
      • Mereu L.
      • Ruffo G.
      • Ceccaroni M.
      • et al.
      Laparoscopic treatment of bowel endometriosis in infertile women.
      ,
      • Vercellini P.
      • Pietropaolo G.
      • De Giorgi O.
      • Daguati R.
      • Pasin R.
      • Crosignani P.G.
      Reproductive performance in infertile women with rectovaginal endometriosis: is surgery worthwhile?.
      ,
      • Ferrero S.
      • Scala C.
      • Biscaldi E.
      • Racca A.
      • Leone Roberti Maggiore U.
      • Barra F.
      Fertility in patients with untreated rectosigmoid endometriosis.
      ], and 39.7% after ART [
      • Ferrero S.
      • Scala C.
      • Biscaldi E.
      • Racca A.
      • Leone Roberti Maggiore U.
      • Barra F.
      Fertility in patients with untreated rectosigmoid endometriosis.
      ]. Vidal F et al [
      • Vidal F.
      • Guerby P.
      • Simon C.
      • Lesourd F.
      • Cartron G.
      • Parinaud J.
      • et al.
      Spontaneous pregnancy rate following surgery for deep infiltrating endometriosis in infertile women: The impact of the learning curve.
      ] reported a live birth rate of 44% after surgery for DIE, but the study population was smaller (n = 25) and only 17 had bowel endometriosis (six underwent segment resection and 11 rectal shaving). A review found a postoperative spontaneous pregnancy rate of 31.4% [
      • Darai E.
      • Cohen J.
      • Ballester M.
      Colorectal endometriosis and fertility.
      ]. Hence, segmental resection of bowel endometriosis does not seem to affect spontaneous pregnancy significantly.
      Our results are comparable with expectant management, even though it is close to the lower end of the interval. Explanations could be, that 21.8% of our population had an additional cause of infertility, which made spontaneous conception impossible. Hence, these confounding infertility etiologies suggest that ART as well as surgery could be the reason for pregnancy. Patients who previously underwent ART, went directly into ART postoperatively instead of intending spontaneous conception. Furthermore, focus on motivating and encouraging the patients, who were candidates for spontaneous conception, to try for at least 12 months prior to ART have not been routine practice throughout all 10 years. Eight patients were not able to obtain pregnancy with ART preoperatively but got pregnant postoperatively. This relatively small number is not sufficient to state, that surgery for DIE improves fertility in itself.
      According to cumulative pregnancy rate in Fig. 3, spontaneous pregnancies seem to be achieved quicker compared to ART pregnancies, which is in accordance with Roman et al. [
      • Roman H.
      • Chanavaz-Lacheray I.
      • Ballester M.
      • Bendifallah S.
      • Touleimat S.
      • Tuech J.J.
      • et al.
      High postoperative fertility rate following surgical management of colorectal endometriosis.
      ]. This could possibly be due to latency related to ART referral and downregulation as part of ART.
      Some patients needed medical therapy to manage DIE postoperatively. This group had a median time to pregnancy of 16.7 months after treatment cessation, indicating a delay. This could be due to a delay in obtaining a regular menstrual cycle after medical endometriosis treatment with anticontraceptive.
      A Clavien-Dindo grade III complication rate of 16.6% is higher than we expected. It reflects the complicated nature of these operations. It might also represent a learning curve phenomenon during the study period. But according to Vidal F el. al., the surgeons experience does not seem to affect fertility outcome [
      • Vidal F.
      • Guerby P.
      • Simon C.
      • Lesourd F.
      • Cartron G.
      • Parinaud J.
      • et al.
      Spontaneous pregnancy rate following surgery for deep infiltrating endometriosis in infertile women: The impact of the learning curve.
      ].
      We know that the first five study years were associated with more segmental resections and a higher percentage of stomas at primary surgery. Additionally, unpublished data from our latest DIE surgeries, after the study period, reveal a lower complication rate regarding anastomotic leakage and ureter lesions. The majority had a segmental resection, which indicates a severe degree of bowel involvement. To compare, disc excision was related to smaller infiltrates and lower complication rates. This is in line with existing literature describing fewer complications with a more conservative surgical approach [
      • Marty N.
      • Touleimat S.
      • Moatassim-Drissa S.
      • Millochau J.C.
      • Vallee A.
      • Stochino Loi E.
      • et al.
      Rectal shaving using plasma energy in deep infiltrating endometriosis of the rectum: four years of experience.
      ]. On the other hand, Roman et al. showed no significant difference in complication risk between conservative surgical approach and segmental colorectal resection, apart from increased risk of bowel stenosis after resection [
      • Roman H.
      • Bubenheim M.
      • Huet E.
      • Bridoux V.
      • Zacharopoulou C.
      • Darai E.
      • et al.
      Conservative surgery versus colorectal resection in deep endometriosis infiltrating the rectum: a randomized trial.
      ].

      Strengths and limitations

      The strengths of our study include the single-center specialized setting. The endometriosis team at our department is highly experienced in treatment of DIE. Furthermore, our study population is large compared to other retrospective and prospective studies [
      • Iversen M.L.
      • Seyer-Hansen M.
      • Forman A.
      Does surgery for deep infiltrating bowel endometriosis improve fertility? A systematic review.
      ]. Due to the great availability of public fertility treatment in Denmark, medical records regarding ART were easily obtainable for the majority of patients included in our study, hence securing sufficient data.
      Our study is limited by the retrospective design not having a reference group. Additionally, it is a single center study which affects generalizability. At referral, the patients were severely affected by pain symptoms related to DIE. Therefore, it would not have been ethically acceptable not to offer these patients surgery and await spontaneous pregnancy instead.
      Information on pain and other endometriosis-associated symptoms would have been valuable. A previous study from our department showed significant improvement in pain and quality of life among 175 women one year after bowel resection for rectosigmoid endometriosis [
      • Riiskjaer M.
      • Forman A.
      • Kesmodel U.S.
      • Andersen L.M.
      • Ljungmann K.
      • Seyer-Hansen M.
      Pelvic pain and quality of life before and after laparoscopic bowel resection for rectosigmoid endometriosis: A prospective.
      ]. Smoking habits and alcohol consumption is missing and would have been beneficial, as these factors can impact disease and fertility status as well as surgical complications.

      Conclusions

      Informing patients with bowel endometriosis and pregnancy intention regarding treatment choice is not easy. But our results indicate that the risk of complications does not seem to affect either chance of pregnancy, live birth or time to pregnancy. Hence, this implies that patients suffering from bowel endometriosis should not stay away from surgery because of fear of complications affecting their chances of pregnancy. However, it is always important to inform these patients thoroughly preoperatively and take into account every patient’s individual preference and priority in order for her to give informed consent on a solid basis. To elicit definitively whether surgery for bowel endometriosis improves fertility, RCT is needed and this is in progress at present.

      Declaration of Competing Interest

      The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

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