• Endometriosis results from the presence of endometrial tissue (glands or stroma) implanted outside of the uterus which may result in pelvic pain or infertility
  • Affects approximately 5% to 10% of reproductive-aged women, with a reported annual incidence in women aged 15 to 49 years of 0.1% 
  • Risk factors include
    • Early menarche (<10 years old)
    • Menstrual cycle <28 days 
    • Menstrual flow ≥5-6 days 
    • Reproductive tract anomalies
    • Nulliparity 
    • White race 
  • The most common location is the ovaries; other locations include the peritoneum, uterosacral ligaments, and retrouterine pouch
  • Chronic pelvic pain and subfertility associated with endometriosis may be due to the estrogen-stimulated inflammatory response of the lesions
  • Patients with history of endometriosis may have slight increased risk of ovarian cancer, but this risk may be reduced with >10 years of oral contraceptive use


  • Cause unknown but likely multifactorial  
  • Most common theory is retrograde menstruation resulting in implantation of refluxed menstrual tissue on pelvic structures  


  • Ectopic tissue outside uterus triggers chronic, estrogen-stimulated inflammatory response  
  • Pain likely due to overproduction of cytokines, prostaglandins, and inflammatory substances which sensitizes central nervous system and triggers pain response
  • Subfertility may be due to
    • Inflammation of endometriotic lesions, impairing tuboovarian function, and leading to distorted ovum release and poor ovarian reserve/quality 
    • Estrogen promoting chronic persistence/growth of lesions 
  • Infertility can occur due to
    • Mechanical obstruction by pelvic adhesions 
    • Dysfunctional interactions between sperm/fallopian tube epithelium 
    • Tubal damage 
    • Increased cytokine levels that inhibit folliculogenesis and spermatozoa transportation/transplantation
    • Altered hormonal levels, resulting in extended follicular phase and abnormalities in luteinizing hormone secretion 
    • Genetic polymorphisms

History and Physical Examination

Chief concern (CC) 
  • Possibly asymptomatic; symptoms can be variable and be related to other conditions
  • Pain most commonly presents as
    • Dysmenorrhea (most common) 
    • Dyspareunia
    • Postcoital bleeding 
    • Dysuria 
    • Dyschezia
    • Irregular menstrual cycle 
    • Lower back/abdominal discomfort 
    • Chronic pelvic pain  
History of present illness (HPI) 
  • Average 7 to 12 years between symptom onset and diagnosis
  • Ask about menstrual history
    • Average time between menstrual cycles (<28 days may indicate endometriosis) 
    • Average length of menses (≥5-6 days may indicate endometriosis) 
    • Age at menarche (early menarche may be associated with endometriosis) 
  • Pain characterization; pain with endometriosis may be strongest premenstrually and subside postmenses  
Medical history
  • Ask about  
  • Obstetrical history including time intervals between pregnancies 
  • Problems with infertility/subfertility 
  • History of gynecologic cancers 

Family and social history  
  • Ask about
    • First-degree relatives with endometriosis
    • Family history of gynecologic cancers
    • Missed school/work, impact on quality of life
    • Desire for fertility 
  • If pelvic exam is not feasible, perform abdominal exam to rule out abdominal mass (although normal abdominal exam does not exclude diagnosis) 
  • Pelvic exam: signs that may suggest endometriosis include
    • Decreased uterine/adnexal mobility
    • Uterine/adnexal enlargement 
    • Tender adnexal masses due to endometriomas 
  • Other findings may include
    • Visible vaginal endometriotic lesions 
    • Tender posterior vaginal fornix 
    • Cervical motion tenderness 
  • Rectovaginal exam may show tenderness or nodularity of uterosacral ligaments
  • Pelvic exam findings may be normal; this does not exclude endometriosis
  • Exam during menses may improve detection of deeply infiltrating nodules  

Differential Diagnosis 

  • Alternative causes of pelvic pain
    • Dysmenorrhea due to
      • Adenomyosis 
      • Myoma 
      • Infection 
      • Cervical stenosis 
    • Dyspareunia due to
      • Diminished/insufficient vaginal lubrication 
      • Infection 
      • Musculoskeletal causes  
      • Pelvic vascular congestion 
      • Urinary causes 
    • Generalized pelvic pain due to
    • Acute pelvic pain due to
      • Ovarian torsion 
      • Acute appendicitis 
  • Other causes of infertility
    • Anovulation 
    • Cervical factors 
    • Luteal phase deficiency 
    • Male factor infertility 
    • Tubal disease or infection
  • Endosalpingiosis: rare, benign condition with tubal epithelium development outside the fallopian tube

Making the Diagnosis 

  • Suspect diagnosis in women of reproductive age with history of pelvic pain, likely with pelvic tenderness and nodularity on palpation of uterosacral ligament and rectovaginal fascia on physical exam    
  • Obtain imaging to establish diagnosis
    • Ultrasound is the first-line test for evaluation
      • Transvaginal ultrasound should be considered even if pelvic and/or abdominal exams are normal 
      • Transabdominal ultrasound of pelvis if transvaginal scan is inappropriate
      • Findings may be normal
    • Magnetic resonance imaging
      • Findings may be normal
      • May be helpful for detecting endometrial cysts and deeply infiltrating bowel or rectovaginal septal endometriosis  
  • Definitive diagnosis made by laparoscopic visualization of endometrial lesions with biopsy/histologic confirmation
    • Laparoscopy should be considered even if ultrasound is normal 
    • Biopsy should be obtained to confirm diagnosis of endometriosis (although negative result does not exclude endometriosis) and exclude malignancy
    • Consider treatment during diagnostic laparoscopy for either
      • Peritoneal endometriosis not involving bowel, bladder, or ureter 
      • Uncomplicated ovarian endometriosis 
    • Lesion characteristics
      • Classic lesions resemble endometrium, with blue or blue-black powder-burn appearance (may be associated with hemosiderin deposits) 
      • Nonclassic lesions may be white, or clear and red flame-like lesions 
      • Endometrioma are pseudocysts (also called chocolate cysts) and may contain dense, dark brown fluid (also called chocolate fluid)
  • If laparoscopy is normal, endometriosis is excluded and alternative management should be offered 

Management Overview

  • Medical management of endometriosis-related pain aimed at alleviating symptoms
  • Surgical management
    • Reserved for patients with pain refractory to medical treatment, have uncertain diagnosis, have acute pelvic findings, or desire pregnancy in near future  
    • Conservative options for patients who wish to preserve fertility/want to avoid early menopause
    • Definitive surgical management with hysterectomy with bilateral salpingo-oophorectomy for patients with endometriosis refractory to medical treatment who do not desire future fertility  
    • Consider postsurgical hormonal suppression
  • Endometriosis-related subfertility
    • Surgical management
      • Laparoscopic treatment of minimal or mild endometriosis
      • Excision/ablation plus adhesiolysis for endometriosis not involving bowel, bladder, or ureter 
      • Laparoscopic ovarian cystectomy with cyst wall excision for endometriomas 
      • For bowel endometriosis, laparoscopic removal of endometriosis plus bowel resection
    • Alternative treatments
  • Follow-up
    • Long-term surveillance recommended due to chronic, recurring nature of condition 
    • Outpatient follow-up needed for patients with confirmed endometriosis, particularly if they refuse surgical management, if they have
      • Deep endometriosis involving bowel, bladder, or ureter 
      • ≥1 endometrioma >3 cm 


  • Infertility  
  • Pregnancy-related complications 
  • Bowel complications 
  • Urological complications 


  • May be chronic, relapsing, and progressive
  • May self-stabilize or resolve without treatment  
  • Ovarian cancer occurs in <1% of women with endometriosis
  • Surgical treatment of lesions associated with long-term pain management in up to 50%
  • Recurrence of endometriosis postoperatively reported to be reduced with postoperative long-term hormone therapy  

Kendra Church, MS, PA-C, is a physician assistant at Dana-Faber Cancer Institute/Brigham & Women’s Hospital and is also an Associate Deputy Editor for DynaMed, an evidence-based point-of-care database.


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  2. Schrager S, Falleroni J, Edgoose J. Evaluation and treatment of endometriosis. Am Fam Physician. 2013;87(2):107-113.
  3. Vercellini P, Viganò P, Somigliana E, Fedele L. Endometriosis: pathogenesis and treatment. Nat Rev Endocrinol. 2014;10(5):261-275.
  4. Brown R, Byrne D, Curran N, et al. Endometriosis: diagnosis and management. NICE guideline NG73. National Institute for Health and Care Excellence; 2017.
  5. American College of Obstetricians and Gynecologists (ACOG). Practice bulletin no. 114: management of endometriosis. Obstet Gynecol. 2010;116(1):223-236, reaffirmed 2018

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