Persistence of the processus vaginalis and its related disorders

The processus vaginalis is a blind-ended evagination of the abdominal wall that develops during fetal life and typically undergoes obliteration in early life. Persistence of the processus vaginalis is associated with a number of pathologies including congenital indirect inguinal hernias, communicating hydroceles, funicular and encysted hydroceles, canal of Nuck cysts, and acquired undescended testis. Whilst all are detectable sonographically, there is little educational material relevant to the field of ultrasound with much of the literature directed at surgical and primary care physicians. Furthermore, within the literature there is a lack of consensus on several areas including the anatomy and embryology of the processus vaginalis and the mechanisms behind its obliteration. As such the objective of this paper is to distil the information regarding the persistent processus vaginalis as it is relevant to ultrasound and in doing so address the literature gap for sonographers and sonologists. The anatomy and embryology of the persistent processus vaginalis will be discussed including causative mechanisms for anomalies with their sonographic appearance highlighted.