Endometriosis (diagrams)

Case contributed by A.Prof Frank Gaillard

Figure 1: etiology

Metastatic Theory

  • Transplantation of endometrial tissue from the uterus to an ectopic location 
  • Most widely accepted mechanism is retrograde menstruation but other theories include lymphovascular spread & iatrogenic implantation
  • Evidence supporting retrograde menstruation:
    • Laparoscopic documentation
    • In vitro growth of shed endometrium in peritoneal fluid
    • In vivo growth of deliberately implanted endometrial cells in subcutaneous fat
    • Anatomic distribution of disease within dependent areas of the pelvis
    • Higher frequency of endometriosis in women with excessive retrograde flow (due to obstructive Mullerian duct anomalies)

Metaplastic Theory

  • Metaplastic differentiation of coelomic epithelium lining the pelvic peritoneum or Mullerian remnant tissue into functioning endometrial cells
  • Proposed mechanism for rectovaginal endometriosis
  • Evidence supporting metaplastic theory
    • Endometriosis in men (rare)
    • Endometriosis in women lacking functional eutopic endometrium (ie Turner’s syndrome, uterine agenesis)

Induction Theory

  • Shed endometrium releases substances that induce undifferentiated mesenchyme to form endometriotic tissue
  • Retroperitoneal endometriosis is thought to be caused by metaplasia of Mullerian remnants located in the rectovaginal septum and is sub-classified into groups according to location. Retroperitoneal disease may be confused by massive disease in the deepest portions of the pouch of Douglas, buried deep to adhesions.

Figure 2: implant morphology

  • retroforniceal implants (65%)
    • typically a small lesion that develops from the posterior fornix toward the rectovaginal septum but not through it
  • hourglass-shaped implants (25%)
    • larger lesions (>3cm) that originate from a retroforniceal location and extend toward the anterior rectal wall
  • rectovaginal septal implants (10%)
    • typically a small lesion, separate from the cervix, located under the peritoneal fold of the cul-de-sac of Douglas

Figure 3: location of implants

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Case information

rID: 9861
Published: 28th May 2010
Last edited: 13th Aug 2019
System: Gynaecology
Inclusion in quiz mode: Excluded

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