Endometriosis for USMLE Step 2

Already subscribed? Log in »

Endometriosis for the USMLE Step 2 Exam

Definition and Pathophysiology

Endometriosis is a chronic condition where endometrial-like tissue grows outside the uterus, most commonly on the ovaries, fallopian tubes, and peritoneal surfaces.

Retrograde Menstruation: The backward flow of menstrual blood through the fallopian tubes into the pelvic cavity is the leading theory.
Coelomic Metaplasia: Peritoneal cells can transform into endometrial cells under certain hormonal and inflammatory conditions.
Immune Dysfunction: Ineffective immune clearance allows ectopic endometrial cells to persist and proliferate.
Estrogen Dependence: Endometrial implants are estrogen-sensitive, leading to cyclical growth and inflammation.

Risk Factors

Genetics: Positive family history increases the risk.
Menstrual Factors: Early menarche, short menstrual cycles, and heavy bleeding increase estrogen exposure, raising risk.
Low BMI: Leaner body types have a higher incidence.
Nulliparity: Women without previous pregnancies show a higher likelihood of developing endometriosis.

Clinical Manifestations

Dyspareunia: Pain during deep sexual intercourse, often due to pelvic adhesions.

Dyschezia: Painful defecation, especially during menstruation, linked to lesions on or near the rectum.

Infertility: Up to 50% of women with endometriosis experience infertility due to structural distortion and inflammatory changes affecting reproductive organs.

Diagnosis

Assessment based on symptoms such as dysmenorrhea, dyspareunia, and chronic pelvic pain.
Pelvic exam findings may include tenderness, adnexal masses, or nodularity in the posterior vaginal fornix.

Transvaginal Ultrasound: Primary imaging for suspected ovarian endometriomas, often showing a “ground-glass” appearance.
MRI: Useful for visualizing deep infiltrative endometriosis, guiding treatment plans.

Gold Standard: Allows direct visualization, biopsy, and staging of endometriotic lesions.
Can also be used therapeutically to excise or ablate endometrial implants and adhesions.

Differential Diagnosis

Pelvic Inflammatory Disease (PID): Typically includes fever and leukocytosis, differentiating it from endometriosis.
Irritable Bowel Syndrome (IBS): Characterized by bowel symptoms without physical evidence of pelvic lesions.
Interstitial Cystitis: Bladder pain syndrome with urinary frequency and urgency, typically not related to menstruation.

Management

Combined Oral Contraceptives (COCs): Reduce pain by suppressing ovulation and reducing menstrual flow.
Progestins: Inhibit endometrial growth, administered as oral, injectable, or intrauterine (LNG-IUD).
Gonadotropin-Releasing Hormone (GnRH) Agonists: Reduce estrogen levels, leading to a hypoestrogenic state to minimize lesion growth.

Laparoscopic Excision or Ablation: Recommended in cases resistant to medical therapy or when fertility preservation is a concern.
Definitive Surgery: Hysterectomy with or without bilateral salpingo-oophorectomy may be considered in severe, refractory cases not requiring fertility.

Key Points

Endometriosis involves the growth of endometrial-like tissue outside the uterus, causing chronic pelvic pain, dysmenorrhea, dyspareunia, and infertility.
Pathophysiology: Primarily due to retrograde menstruation, coelomic metaplasia, immune dysfunction, and estrogen dependence.
Risk Factors: Family history, early menarche, short cycles, low BMI, and nulliparity.
Diagnosis: Based on symptoms, physical exam findings, ultrasound for endometriomas, and laparoscopy for confirmation and treatment.
Management:

NSAIDs for pain relief.
Hormonal therapies such as COCs, progestins, and GnRH agonists to reduce estrogen-driven lesion growth.
Surgical options like laparoscopy for excision and definitive surgery for refractory cases.