A cyst with a reticular "lace" or retracting-clot pattern and no internal colour flow is a haemorrhagic corpus luteum; echogenic free fluid in the pelvis and Morison pouch means it has ruptured.
Orient first
- A functional cyst of reproductive age: it evolves and resolves over one to two cycles.
- The clot retracts to a concave-edged, avascular component — the feature that separates it from a solid nodule.
- Ruptured haemorrhagic cysts are a cause of haemoperitoneum; a positive pregnancy test changes the question to ectopic pregnancy.
Acquire the study
- Transvaginal ultrasound with colour and power Doppler at low scale; transabdominal view of the upper abdomen (Morison pouch) for free fluid.
The manoeuvre
- Measure the cyst in three planes in cm and describe the internal echo pattern: fine reticular (lace), retracting clot with concave margins, fluid level.
- Colour and power Doppler on every internal component: no internal flow; peripheral "ring" flow in the wall is expected.
- Pelvic free fluid: anechoic vs echogenic (blood), volume estimate, clot near the ovary (sentinel clot).
- Transabdominal: Morison pouch and paracolic gutters for haemoperitoneum extent.
- Pregnancy status stated; if positive, examine the adnexa for an extra-ovarian mass.
What confirms it
- Typical lace or retracting-clot pattern with no internal colour flow in a premenopausal woman; resolution on follow-up ultrasound at 6–12 weeks.
What licenses you to exclude it
- Any internal colour flow in a solid-looking component excludes a simple haemorrhagic cyst — manage as a solid adnexal lesion (O-RADS).
The classic misread
- Calling a retracting clot a solid nodule — it has concave margins and no flow.
- Missing an ectopic pregnancy by not stating pregnancy status.
- Recommending follow-up of a classic haemorrhagic cyst under 5 cm in a premenopausal woman — O-RADS usually needs none (verify the version your department uses).