On high-resolution T2 perpendicular to the cervix, measure the tumour, look for parametrial invasion (the dark stromal ring broken), then vagina, pelvic side wall, bladder and rectum, and nodes — FIGO 2018 lets imaging assign the stage.
Orient first
- FIGO 2018 allows imaging and pathology to assign the stage, and made lymph node involvement stage IIIC (pelvic IIIC1, para-aortic IIIC2) — verify against the current FIGO wording.
- Size thresholds (for example 2 and 4 cm within stage IB) matter for fertility-sparing surgery and chemoradiation.
- Parametrial invasion is the key decision: an intact low-signal stromal ring on T2 makes it very unlikely; invasion moves the patient from surgery to chemoradiation.
Acquire the study
- Pelvic MRI with small field-of-view T2 perpendicular and parallel to the cervical canal, sagittal T2, DWI; vaginal gel as local practice; large field-of-view to the renal hila for nodes and hydronephrosis.
The manoeuvre
- Sagittal T2: tumour size in three planes in mm, and extension into the uterine body and vagina (upper two-thirds versus lower third).
- Oblique axial T2 perpendicular to the cervix: integrity of the low-signal stromal ring — a full-thickness break with spiculated tumour into the parametrium indicates invasion.
- Pelvic side wall and ureters: hydronephrosis (stage IIIB).
- Bladder and rectal mucosa on sagittal T2: loss of the fat plane alone is not invasion; mucosal involvement is stage IVA.
- DWI and T2: pelvic and para-aortic nodes, short axis in mm.
What confirms it
- A FIGO 2018 stage with the size and each extension feature stated.
What licenses you to exclude it
- An intact stromal ring on thin-section T2 makes parametrial invasion very unlikely.
The classic misread
- Over-calling parametrial invasion from peritumoural oedema after a biopsy or cone.