Clinical overview
Staging systems for endometriosis exist because the disease is heterogeneous: from a tiny peritoneal implant in an asymptomatic woman to a frozen pelvis with bowel and bladder involvement. A single name — "endometriosis" — does too much work. Staging exists to: (1) communicate disease burden between clinicians; (2) guide surgical planning; (3) provide a research substrate; and (4) predict fertility outcome (though imperfectly).
The registrar must know the rASRM (revised American Society for Reproductive Medicine) system in detail because it is used in nearly every operation note and theatre summary in South Africa. You should also know the newer ENZIAN classification (for deep infiltrating endometriosis) and the EFI (Endometriosis Fertility Index) because they capture what rASRM misses: bowel/bladder depth, ureteric involvement, and the fertility prognosis.
Adenomyosis lacks a universally accepted staging system. The MUSA (Morphological Uterus Sonographic Assessment) features and the more recent grading systems based on depth of myometrial involvement (focal vs diffuse, anterior vs posterior wall, percentage of myometrium involved) are the current pragmatic tools.
The chapter explains each system, what it measures and what it doesn't, and how to apply them in the South African public-sector context where MRI access is uneven and most staging happens at laparoscopy or by skilled ultrasound.
Core knowledge
rASRM staging of endometriosis (1996)
rASRM stage rises with endometrioma burden, adhesions and pouch of Douglas obliteration, not pain severity.
A point-based system applied at laparoscopy. Points are awarded for:
- Peritoneal implants — number, size, depth (superficial vs deep).
- Ovarian endometriomas — size, side.
- Adhesions — film vs dense, surface area of involvement.
- Pouch of Douglas obliteration — partial or complete.
Total points produce a stage:
- Stage I (minimal): 1–5 points. Few superficial implants; no significant adhesions; no endometriomas.
- Stage II (mild): 6–15 points. More implants; some superficial peritoneal disease; minor adhesions.
- Stage III (moderate): 16–40 points. Endometrioma(s) >1 cm, multiple deeper implants, significant adhesions.
- Stage IV (severe): >40 points. Large endometriomas (often bilateral), dense adhesions, often partial or complete obliteration of pouch of Douglas, bowel or bladder involvement.
rASRM strengths: widely used, simple, allows comparison between surgeons. rASRM weaknesses: poor correlation with pain (a small implant on a sacral nerve can be devastating; large lesions can be silent); poor correlation with fertility outcome; does not account for deep infiltrating disease beyond simple "deep" designation; does not capture extrapelvic disease.