Penile Doppler ultrasound study in priapism: A systematic review

Background: Penile Doppler ultrasound (PDU) is suggested to be an alternative to blood gas analysis (BGA) from the corpora cavernosa in differentiating between high- and low-flow priapisms, with limited supportive evidence.

Aim: To compare penile Doppler ultrasound study and blood gas analysis in the diagnosis of priapism, through a systematic review of the literature.

Methods: Studies were identified by literature search of Medline, Scopus, Cochrane and ClinicalTrials.Gov. Studies were included if their participants had priapism evaluated by Penile Doppler ultrasound, and reported data on the blood gas analysis or pudendal artery angiography (PAA). Two authors independently extracted the articles using predetermined datasets, including indicators of quality.

Outcomes: Correlation of penile Doppler ultrasound with blood gas analysis and pudendal artery angiography.

Results: Twelve studies were included. Three studies compared Penile Doppler ultrasound to blood gas analysis and pudendal artery angiography. Penile Doppler ultrasound was used as adjunctive to blood gas analysis to differentiate low flow from high flow priapism, guidance for embolization, etiological diagnosis in three studies. Compared to pudendal artery angiography, penile Doppler ultrasound had a sensitivity of 40-100% and a specificity of 73%, to localize vascular injury and anatomical abnormalities (two studies). Penile Doppler ultrasound was also used for the follow-up after the treatment of priapism (two studies). No study reported an impact on functional results or a delay of management due to penile Doppler ultrasound use.

Clinical translation: We reviewed evidence on penile Doppler ultrasound study in priapism. Penile Doppler ultrasound study performance was comparable to blood gas from corpus cavernosum. It is recommended to use doppler as an alternative diagnostic tool.

Strengths & limitations: Our systematic review had limitations. Firstly, the number of cases in the included studies was small. Secondly, these studies were all retrospective. Lastly, few data were reported with regards to hemodynamic parameters of penile Doppler ultrasound, and the majority of studies did not describe these in detail.

Conclusions: Evidence supports that penile Doppler ultrasound is a reliable way for differentiating high-flow and low-flow priapism. We recommend penile Doppler ultrasound study as an alternative of blood gas analysis from corpus cavernosum, especially when the latter is not available.

Level of evidence: 3.