Dometriosis of the small intestine N80.5

In 1690, endometriosis was probably described for the first time by the German physician Schroen. The Viennese pathologist von Rokitansky published the first histological description in 1860. In the 1920s, evidence of lymphatic and / or vascular metastasis of endometrial cells was first found by Sampson (Samartzis 2012).

Intestinal endometriosis was first described by de Joselin de Jong in 1913.

Masson was the first to report 35 patients with small bowel endometriosis in 1945 (Kraatz 1977).

Endometriosis is an ectopic proliferation of endometrial glands and interstitium. It is a progressive disease of women of childbearing age (Koyama 2021).

Small bowel endometriosis is considered a benign tumor of the bowel (Herold 2022).

There are numerous classifications of endometriosis. The most common are the following both:

• Clinical intraoperative classification of the American Society for Reproductive Medicine, the rASRM- score:
  • Peritoneum:
    • < 1 cm superficial = 1 point
    • 1 - 3 cm superficial = 2 points
    • > 3 cm superficial = 4 points
    • < 1 cm deep = 2 points
    • 1 - 3 cm deep = 4 points
    • > 3 cm deep = 6 points
  • Ovarian endometriosis:
    • < 1 cm superficial, left or right = 1 point
    • 1 - 3 cm superficial, left or right = 2 points
    • > 3 cm superficial, left or right = 4 points
    • < 1 cm deep, left or right = 4 points
    • 1 - 3 cm deep, left or right = 16 points
    • > 3 cm deep, left or right = 20 points
  • Ovarian adhesions:
    • < 1/3 thin, left or right = 1 point
    • 1/3 - 2/3 thin, left or right = 2 points
    • > 2/3 thin, left or right = 4 points
    • < 1/3 dense, left or right = 4 point
    • 1/3 - 2/3 dense, left or right = 8 points
    • > 2/3 dense, left or right = 16 points
  • Tubal adhesions:
    • < 1/3 thin, left or right = 1 point
    • 1/3 - 2/3 thin, left or right = 2 points
    • > 2/3 thin, left or right = 4 points
    • < 1/3 dense, left or right = 4 point
    • 1/3 - 2/3 dense, left or right = 8 points
    • > 2/3 dense, left or right = 16 points
  • Distal tube occlusion: = 16 points
  • Obliteration of the Douglas space:
    • partial = 4 points
    • complete = 20 points

Score:

- Stage I: 1 - 5 points

- Stage II: 6- 15 points

- Stage III: 16 - 40 points

- Stage IV: > 40 points (Burghaus 2020)

• Clinical classification of endometriosis according to Renner et al:
  • Peritoneal endometriosis
  • Ovarian endometriosis
  • Deep infiltrating endometriosis (e.g. intestine, Douglas, vagina, scar, skin and other rare locations)
  • Adenomyosis uteri (Burghaus 2020)

For further classifications see guideline

Small bowel endometriosis counts as stage IV (extragenital endometriosis [Ebert 2011]).

Benign tumors of the small intestine, which include small bowel endometriosis, occur very rarely at < 5% (Herold 2022).

The prevalence of endometriosis in general in women of reproductive age is between 4 - 10 % , plus asymptomatic patients (Chivia 2020). Thus, endometriosis represents one of the most common gynecological diseases (Burghaus 2020).

Affected are predominantly women between 35 - 44 years. A familial clustering is found, which is why hormonal and genetic aspects probably play a role.

Intestinal endometriosis is found in about 10% of affected patients (Burghaus 2020).

To date, the etiology of endometriosis is unclear. Several theories exist (Mehmood 2021).

The most important hypothesis was proposed by Sampson in 1927. The latter observed that menstrual bleeding refluxed from the fallopian tube during surgery and concluded its implantation in the nearby peritoneum (Koyama 2021).

Risk factors for developing endometriosis are:

- Cycle duration ≤ 27 d

- Period duration

- Number of miscarriages

- Number of pregnancies (Burghaus 2020).

Endometrial tissue reacts to hormones - regardless of the location. It can proliferate into cysts and nodules.

The deposits are usually < 2 cm in size. In the small intestine, endometriosis probably affects the serosa. Chronic inflammation may occur here, which leads to fibrosis as a consequence. This fibrosis can explain the symptoms described below (see "Clinical picture").

(Mehmood 2021).

The small intestine is an unusual site for endometriosis, often causing diagnostic problems.

Affected in the intestine can be:

- Rectosigmoid in 50 - 90 %.

- Small intestine in 2 - 16 %

- appendix in 3 - 18 %

- cecum in 2 - 5 % (Mehmood 2021)

- Lymph node involvement (Koyama 2021)

Small bowel endometriosis can be completely asymptomatic, but it can also lead to the following symptoms:

- intestinal bleeding synchronous with menstruation

- abdominal colicky pain (Herold 2022)

- nausea

- vomiting (Mehmood 2021)

- tenesmus

- flatulence

- Diarrhea and constipation in alternation

- Dyschezia (Burghaus 2020)

The diagnosis is made on the basis of the anamnesis (relation of the complaints to the menstrual calendar) and complex apparative examinations - if necessary also interdisciplinary (Keckstein 2017). Transvaginal sonography, MRI examination and diagnostic operative laparoscopy have proven to be the gold standard (Keckstein 2017).

Transvaginal sonography

This provides good visualization of deeply infiltrated endometriosis including deep rectal involvement. In the latter, the examination shows high specificity and sensitivity (Burghaus 2020).

MRI

MRI of the pelvis should be performed preoperatively because it may visualize lesions that cannot be seen laparoscopically (Hauth 2004). Sensitivity ranges from 77-93% (Mehmood 2021). Burghaus describes the sensitivity with regard to deep infiltration as high, without providing more precise information (2020).

Laparoscopy

Laparoscopy for diagnosis should always be performed in addition to MRI. In a 2004 study by Hauth et al. that included 13 patients with endometriosis, 27 locations could be identified laparoscopically, of which 13 (48%) could not be visualized on MRI.

Colonoscopy

The sensitivity of colonoscopy is only low (Keckstein 2017).

• Patchy infiltration of glands in the muscularis propria and subserosa (Koyama 2021).

• Appendicitis (Kasper 2015)
• Crohn's disease (Chivia 2020)
• ischemic colitis
• inflammatory bowel disease (Mehmood 2021)
• diverticulitis
• intestinal tuberculosis (Koyama 2021)

• Acute intestinal obstruction (Kasper 2ß15)
• Perforation
• intussusception (Koyama 2021)
• recurrent subileus (Herold 2022)
• multiple complications during pregnancy (Zodan 2009)

In the case of superficial endometriosis, symptomatic treatment consists of hormonal treatment, while causal treatment consists of surgical removal of the endometriosis lesions. The form of treatment should always depend on the symptomatology (Keckstein 2017).

For deeply infiltrating symptomatic intestinal endometriosis, the therapy of choice is resection in sano (Burghaus 2020).

Hormone therapy is a symptomatic treatment. It is particularly suitable for small deposits (Mehmood 2021).

The drugs used are:

• Progestin monotherapy
  • Dienogest (first-line substance [Burghaus 2020]), dosage recommendation: 2 mg / d (Leidenberger 2014).
  • z. E.g. Clinovir (medroxyprogesterone acetate), dosage recommendation: 30 - 50 mg / d.
  • Prothil (Medrogeston), dosage recommendation: 50 - 75 mg / d (Ebert 2011).
• GnRH analogues with and without add-back hormone therapy (Gätje 2015).
  • z. E.g. Elagolix, dosage recommendation: 150 mg / d (Ebert 2019)
• Combined oral contraceptives in non-stop administration as off-label use (Ebert 2011).

Treatment should be given for at least 4 - 6 months. Since there is a risk of osteoporosis with GnRH- analogues, the duration of therapy should be limited to a maximum of 6 months (Gätje 2015).

• NSAIDS

The anti-inflammatory and analgesic NSAIDs have been shown to be beneficial in combination with hormone therapy (Mehmood 2021).

The only causal therapy is surgical intervention (Koyama 2021).

In the case of deep infiltrating intestinal endometriosis, surgical removal of the endometrial foci with resection of the affected intestinal segment is the therapy of choice (Burghaus 2020), as well as in the case of large lesions, impending ileus, etc. (Mehmood 2021).

If drug therapy (see below) does not lead to an improvement in symptoms, surgery can be performed electively (Mehmood 2021).

The pain associated with endometriosis can usually be well alleviated by drug therapy (see above). However, the recurrence rate 5 years after the end of therapy is about 50 - 75% (Ebert 2011).

After surgical resection, the recurrence rate is between 5 - 25 % (Burghaus 2020).

If lymph node involvement is evident, follow-up should be performed, as the prognosis in these cases remains unclear (Koyama 2021).

The intra- and postoperative complication rate in the form of anastomotic insufficiency is between 5 - 14 % for resection of the rectal segment. Therefore, deep rectal resection for benign disease is viewed very critically (Burghaus 2020).

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