Endometriosis for USMLE Step 1
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Endometriosis for the USMLE Step 1 Exam
Definition and Pathophysiology
- Definition
- Endometriosis is a disorder involving ectopic implantation of endometrial-like tissue outside the uterine cavity, commonly affecting the ovaries, fallopian tubes, and peritoneum.
- Pathophysiology
- Retrograde Menstruation: Endometrial cells are thought to reflux through the fallopian tubes into the pelvic cavity.
- Coelomic Metaplasia: Peritoneal cells may transform into endometrial-like cells due to inflammatory stimuli.
- Immune Dysfunction: Impaired immune clearance allows ectopic endometrial cells to implant and grow.
- Hormonal Factors: Estrogen dependency of endometrial cells promotes growth of ectopic lesions, exacerbating symptoms.
Risk Factors
- Family History: Increased risk in first-degree relatives of women with endometriosis.
- Early Menarche and Short Menstrual Cycles: Associated with increased exposure to estrogen.
- Nulliparity: Higher incidence observed in women who have not had children.
- Low BMI: Lower body mass index is a noted risk factor.
Clinical Manifestations
- Pelvic Pain:
- Chronic pelvic pain that often worsens during menstruation (dysmenorrhea).
- May also present as noncyclical pain.
- Dyspareunia: Pain during deep sexual intercourse, often due to adhesions and inflammatory reactions in the pelvis.
- Dyschezia: Painful bowel movements, especially if lesions are near or on the bowel.
- Infertility: A common complication, likely related to pelvic adhesions and altered anatomy.
Diagnosis
- Clinical Evaluation:
- Based on symptoms of chronic pelvic pain, dysmenorrhea, dyspareunia, and infertility.
- Physical exam may reveal tenderness and, occasionally, nodularity on the uterosacral ligaments.
- Imaging:
- Transvaginal Ultrasound: Preferred initial imaging to detect ovarian endometriomas, which appear as "ground-glass" cysts.
- MRI: Sometimes used to evaluate deeper lesions or complex cases.
- Laparoscopy:
- Gold Standard: Allows direct visualization of lesions and biopsies.
- Can be used to assess severity and treat endometrial implants and adhesions.
Differential Diagnosis
- Pelvic Inflammatory Disease (PID): Presents with pelvic pain and may be accompanied by fever, distinguishing it from endometriosis.
- Irritable Bowel Syndrome (IBS): Presents with abdominal pain and altered bowel habits but lacks physical findings of endometrial lesions.
- Interstitial Cystitis: Characterized by bladder pain and urinary symptoms, typically without menstrual correlation.
Management
- NSAIDs: First-line treatment to manage pain symptoms.
- Hormonal Therapy:
- Combined Oral Contraceptives (COCs): Suppress ovulation and reduce menstrual flow, alleviating pain.
- Progestins: Inhibit endometrial tissue growth.
- Gonadotropin-Releasing Hormone (GnRH) Agonists: Reduce estrogen production, inducing a hypoestrogenic state to decrease lesion size.
- Surgical Therapy:
- Laparoscopic Excision: Recommended for symptom relief and fertility preservation in more severe cases.
- Hysterectomy: Considered in refractory cases but generally avoided in young patients desiring fertility.
Key Points
- Endometriosis is defined by ectopic endometrial-like tissue outside the uterus, causing chronic pelvic pain, infertility, and dysmenorrhea.
- Pathophysiology involves retrograde menstruation, coelomic metaplasia, immune dysfunction, and estrogen-driven tissue growth.
- Risk Factors: Family history, early menarche, short cycles, low BMI, and nulliparity increase risk.
- Symptoms include chronic pelvic pain, dysmenorrhea, dyspareunia, dyschezia, and infertility.
- Diagnosis relies on clinical assessment, imaging (ultrasound for endometriomas), and laparoscopy for definitive diagnosis.
- Treatment:
- NSAIDs for pain management.
- Hormonal therapies such as COCs, progestins, and GnRH agonists.
- Surgical options, including laparoscopy for excision and hysterectomy for refractory cases.