Mean velocity and peak systolic velocity can help determine ischaemic and non-ischaemic priapism

To determine the threshold waveform characteristics at Doppler ultrasound (DUS) to differentiate between ischaemic and non-ischaemic priapism.

Fifty-two patients were categorised into "ischaemic" and "non-ischaemic" types based on clinical and blood-gas findings: 10 patients with non-ischaemic priapism; 20 with ischaemic priapism before surgical shunt placement and 22 with ischaemic priapism after surgical shunt placement. DUS traces were analysed: peak systolic velocity (PSV) and mean velocity (MV) were calculated. Histological samples were obtained at the time of surgery. Three clinical outcome groups were defined: (1) normal, (2) regular use of pharmacostimulation, and (3) refractory dysfunction/penile implant.

All non-ischaemic priapism cases had a PSV >50 cm/s and all but one had an MV of >6.5 cm/s. In pre-surgery ischaemic cases, all men had a PSV <50 cm/s and MV <6.5 cm/s. Two flow patterns were observed in this group: PSV <25 cm/s in all men scanned before needle aspiration; and in 6/14 after needle aspiration, a high velocity/high resistance (low net inflow) pattern, with peak systolic flows >22 cm/s but diastolic reversal. In post-surgery ischaemic priapism, flow parameters overlapped with the non-ischaemic group. PSV/MV did not predict clinical outcome or histology.

In the present cohort, PSV <50 cm/s and MV <6.5 cm/s were predictive of ischaemic priapism (pre-shunt; p<0.01). Patients with ischaemic priapism may show PSV >22 cm/s, but have diastolic reversal and therefore low net perfusion. Post-shunt, DUS findings were extremely variable and did not predict histology or clinical outcome.