PID is clinical; imaging is for the patient who looks unwell or has a mass — to find the thick-walled, fluid-filled tube (cogwheel), the tubo-ovarian complex or abscess, and the size that decides drainage.
Orient first
- Progression: salpingitis → pyosalpinx → tubo-ovarian complex (structures still recognisable) → tubo-ovarian abscess.
- Abscesses larger than ~7–8 cm often need drainage (verify local practice).
- Mimics: appendicitis, endometrioma, torsion, ectopic pregnancy.
Acquire the study
- Transvaginal probe; transverse and longitudinal planes of each adnexa; colour Doppler.
The manoeuvre
- Tube: tubular fluid-filled structure with thick walls; cogwheel sign in cross-section.
- Ovary: recognisable (complex) vs not (abscess); measure the collection in cm.
- Colour Doppler: hyperaemia of the wall.
- Free fluid with debris; tenderness on probe pressure.
What confirms it
- Thick-walled tubal or adnexal collection with a compatible clinical picture.
What licenses you to exclude it
- Normal adnexa do not exclude PID — it remains a clinical diagnosis.
The classic misread
- A hydrosalpinx (thin wall, incomplete septa) called pyosalpinx.