Endometriosis — SAQ

Stem

A 30-year-old nulliparous woman presents with a 3-year history of progressively worsening dysmenorrhoea that begins two days before her menses, deep dyspareunia, chronic non-cyclical pelvic pain, and a 12-month history of involuntary infertility. She has no significant past medical or surgical history and takes no regular medications. On pelvic examination there is tender nodularity in the posterior vaginal fornix, a fixed retroverted uterus, and left adnexal tenderness. Transvaginal ultrasound shows a 5 cm left adnexal mass with homogeneous ground-glass low-level internal echogenicity, a thick wall, no papillary projections and no internal Doppler flow.

Questions

a) What is the most likely diagnosis, and list three clinical features from the stem that support it? (2 marks)

Endometriosis with a left ovarian endometrioma. Supporting features: (i) the symptom triad of secondary, progressive dysmenorrhoea (premenstrual onset), deep dyspareunia and chronic pelvic pain with infertility; (ii) tender nodularity in the posterior vaginal fornix and a fixed retroverted uterus (deep infiltrating endometriosis); (iii) the ground-glass echogenic adnexal mass with no papillary projections — the pathognomonic transvaginal ultrasound appearance of an ovarian endometrioma.

b) Outline the pathophysiology, naming the leading theory of origin and two molecular hallmarks. (3 marks)

The leading theory of origin is Sampson's retrograde menstruation — menstrual debris refluxes through the tubes into the pelvic cavity where viable endometrial fragments implant; this is necessary but not sufficient (occurs in up to 90 per cent of women, yet only ~10 per cent develop disease), so additional defects in immune clearance, attachment and angiogenesis are required. Two molecular hallmarks: (1) oestrogen dependence — implants overexpress aromatase and 17-beta-HSD type 1, synthesising their own oestradiol and overexpressing oestrogen receptor beta; and (2) progesterone resistance — reduced PR-B and failure to induce 17-beta-HSD type 2, leaving implants oestrogen-dominant and contributing to infertility via defective implantation. (A third is chronic inflammation: macrophage release of IL-1, IL-6, IL-8, TNF-alpha and PGE2 drives pain and adhesions.)

c) Describe the stepwise definitive management for this patient's pain, naming drugs, doses and routes. (3 marks)

As she does not desire immediate fertility: Step 1 — NSAIDs (ibuprofen 400 mg PO TDS or naproxen 500 mg PO BD) plus a continuous combined oral contraceptive (ethinylestradiol 30 to 35 micrograms + progestogen, daily). Step 2 — a progestogen if Step 1 fails: dienogest 2 mg PO once daily, a levonorgestrel intrauterine system (Mirena), or DMPA 150 mg IM every 3 months. Step 3 — a GnRH agonist with add-back: goserelin 3.6 mg SC every 4 weeks plus tibolone 2.5 mg PO once daily (add-back permits longer treatment by countering hypo-oestrogenic bone loss). An alternative modern option is the oral GnRH antagonist relugolix combination (relugolix 40 mg + estradiol 1 mg + norethisterone acetate 0.5 mg PO once daily). Surgical management is indicated for the 5 cm endometrioma and any deep disease — laparoscopic ovarian cystectomy (stripping) for the endometrioma (lower recurrence than drainage/ablation, with counselling on ovarian-reserve loss) and excision for deep infiltrating disease; post-operative hormonal suppression (LNG-IUS or COC) reduces recurrence.

d) List four complications of endometriosis. (2 marks)

(1) Infertility — via anatomic distortion, ovulatory dysfunction, peritoneal inflammation, impaired oocyte quality and defective implantation; (2) chronic pelvic pain with central sensitisation and reduced quality of life/work productivity; (3) a small but real risk of malignant transformation to ovarian clear-cell or endometrioid carcinoma; (4) surgical complications — loss of ovarian reserve after cystectomy, ureteric/bowel/bladder injury in DIE surgery, adhesion formation — and medical side effects such as hypo-oestrogenic bone loss with GnRH analogues.