Deep infiltrating endometriosis (DIE) represents the most severe form of endometriosis and is present in 20-35% of all women suffering from the disease. Intestinal nodules are observed in 3% to 37% of endometriosis patients. In cases of colorectal DIE, adequate therapy depends on the depth of infiltration and the size of the lesion as well as the woman's quality of life. Removal of the specimen after segmental bowel resection can be performed by either mini-laparotomy or by the natural orifice specimen extraction (NOSE) technique .

The assessment of the quality of life and fertility outcome of the patients was done by using electronic questionnaires before and after surgery.

Endometriosis is an enigmatic disease affecting 6-10% of women of reproductive age or 176 millions of women worldwide (1). Endometriosis is defined as the presence of endometrial-like tissue outside the uterus and it induces a chronic inflammatory reaction (2). Deep infiltrating endometriosis (DIE) represents the most severe form of endometriosis (described by the invasion of anatomical structures and organs deeper than 5 mm beyond the peritoneum) and is present in 20-35% of all women suffering from the disease (3). Intestinal deep infiltrating endometriosis is known as lesions infiltrating at least the muscular layer of the bowel wall and most commonly affects the rectum, sigmoid colon and the rectovaginal septum. (4).

Even if bowel endometriosis may be totally asymptomatic, in many patients intestinal wall DIE alters significantly quality of life by provoking constipation, diarrhea, hematochezia, intestinal cramping, abdominal bloating, intestinal stenosis or obstruction and pain of defecation (5, 6). Rectal fixation to adjacent structures results in angulation of the rectum and subsequent defecatory pain and constipation. Fibrosis of nodules can lead to rectal constriction and stenosis, cyclical inflammation of the rectal wall may lead to changes in bowel habit (usually diarrhoea) with or without rectal bleeding (7).

Although the surgical laparoscopic management of endometriosis is widely accepted, the optimal type of resection, whether conservative approach (shaving, disc resection) or radical technique (involves limited resection of the bowel wall with preservation of all adjacent structures-autonomic pelvic plexus, rectal vascular supply- known as "nerve-vessel sparing limited segmental resection"), is under discussion for treatment of deep endometriosis infiltrating the rectum.

In cases of colorectal DIE, adequate therapy depends on the precise location, extent of the nodule and depth of invasion, as well as the woman's quality of life (3). Removal of the specimen after segmental bowel resection can be performed by either mini-laparotomy (conventional method) or by the natural orifice specimen extraction (NOSE) technique. (8).

The conventional method raises concerns because this could disrupt the integrity of the abdominal wall. Moreover, extraction site laparotomy is associated with higher postoperative pain scores. The occurrence of particular complications such as incisional hernias and wound infections is also higher than after conventional laparoscopic procedures (8).

In order to avoid these complications, NOSE technique has been introduced. During NOSE colectomy the specimen is extracted through a natural orifice and an intracorporeal anastomosis is performed (8).

Several studies have demonstrated a significant drop in pain scores and amelioration of impaired sexual functioning and improved pregnancy rates in women following surgical resection of colorectal endometriosis (9).

The aim of this study is to report the short, medium and long-term bowel functional outcomes and improvement of infertility, quality of life in women undergoing conventional and NOSE segmental bowel resection for endometriosis at our institution using validated questionnaires.

Functional and psychological outcomes will be assessed using different questionnaires at baseline and postoperative follow-up moments.

• Endometriosis Health Profile, EHP 30 (10)
• Gastrointestinal Quality of Life Index, GIQLI (11)
• Low Anterior Resection Syndrome score, LARS (12)
• Assessment of endometriosis related pain: Visual Analog Scale (13)
• Psychological questionnaires: Pain catastrophizing Scale (14), Self-Efficacy for Managing Chronic Disease 6-item Scale (15).

Inclusion criteria:

• Age: 18 - 45 years (both inclusive)

• Complaining of infertility and/or pain

• Deep endometriosis infiltrating the rectum on at least one imaging technique or confirmed by previous surgery

  • up to 15 cm from the anus
  • Involving at least the muscularis layer in depth

Exclusion criteria

A potential subject who meets any of the following criteria will be excluded from participation in this study:

• Suspected pelvic malignancy
• Pregnancy
• Patients without bowel resection

Hundred and fifty (n=150) premenopausal women with deep infiltrating endometriosis of the rectum who are scheduled for surgical treatment for DIE in our institution during the time will be included in the study.

All women with suspicion of a deep endometriosis will be examined (gynecological examination) by a surgeon experienced in endometriosis. For further mapping of the endometriosis following imaging techniques will be used:

• Transvaginal ultrasound using the IDEA terminology to describe the endometriotic lesions found (17)
• Complementary examinations can be needed depending on the lesions that are found. For example, MR examination, or intravenous pyelogram in women with associated involvement of the urine tract.

Will individual participant data will be available (including datadictionaires)? Individual participant data will be available. What data in particular will be shared? Individual participant data that underline the results reported in the article after deidentification (text, tables, figures and appendices) will be shared.

What other documents will be available? Study protocol, statistical analysis plan, analytic code will be available as well.

When will data be available (start and end dates)? Data will be available from 3 months to 5 years after the publication of the article.

With whom? The data will be shared with researchers who provide a methodologically sound proposal.

For what types of analysis? To achieve aims in the approved proposal. By what mechanism will data be made available? Proposals should be directed to attila.z.bokor@gmail.com. To gain access, data requestors will need to sign a data access agreement. Data are available for 5 years.

5 years after study closure

Any researcher intersted in the study