Methods
We performed a randomized controlled trial (ESPRESSO trial) in which we analyzed the aspiration samples in two groups. Women were allocated either to saline contrast sonohysterography and subsequent endometrial sampling (SCSH-Sampling group) or to the opposite order (Sampling-SCSH group). Dedicated gyneco-pathologists retrospectively assessed the specimens and recorded the type (blood, mucus, epithelium, intact glands, stroma and tissue context) and quantity (on a scale of 0–3) of material that was found in the specimens.