Which morphological investigations and how to interpret them to make the diagnosis of PCOS?

The need for a calibrated imaging of polycystic ovaries (PCO) is now stronger than ever since the consensus conference held in Rotterdam in 2003. However, imaging PCO is not an easy procedure and it requires a thorough technical and medical background. The two-dimensional (2-D) ultrasonography (U/S) remains the standard for imaging PCO and the current consensus definition of PCO determined at the joint ASRM/ESHRE consensus meeting on PCOS rests on this technique: either 12 or more follicles measuring 2 to 9mm in diameter and/or increased ovarian volume (>10cm(3)). However, these thresholds need being revisited with the use of the new machines that have better spatial resolution and with the advent of the 3-D U/S. Doppler study and magnetic resonance imaging (MRI) are seldom useful for diagnosis but may be interesting for clinical research.