Abnormal descent of the testis and its complications: A multimodality imaging review.

Cryptorchidism refers to an absence of the testis in the scrotal sac. Testicular descent occurs in two stages: transabdominal and gubernacular. The descent of the testis can be arrested in its usual path of descent (true undescended testis) or can migrate from the usual path of descent (ectopic testis). Localising the missing testis is important for surgical planning, as well as for identification of complications that are more common with cryptorchidism. Ultrasound is the initial imaging modality to visualise, as well as localise the testis in cryptorchidism. However, ultrasound imaging is limited in visualising testes that are not superficial in location. This article highlights various examples of abnormal descent of the testis in usual as well as unusual locations and complications of undescended testes. Further evaluation with computed tomography scan or magnetic resonance imaging is needed in indeterminate cases and for identification of complications. We have highlighted the role of specific modalities with imaging findings in this pictorial review for the appropriate selection of each modality in clinical practice.