It is important to know the embryological development and anatomy of the urachus to understand its pathological spectrum.

Patent urachus or urachal fistula, secondary to complete failure of allantoic duct regression, is the most frequent congenital urachal anomaly, followed by urachal cyst, sinus and diverticulum. Radiological diagnosis may be incidental and is usually easy to achieve.

Infection is commonly secondary to prior urachal anomalies, although it can also appear due to a nearby inflammatory condition, mainly Crohn disease. The clinical picture, along with certain imaging findings should lead to diagnosis.

Urachal metastatic malignancies (most frequently in the context of peritoneal carcinomatosis) are more frequent than primary tumors, the most common of which are mucinous cystoadenocarcinomas. They characteristically arise in the lower segment of the urachus and associate bladder involvement, making distinction from primary bladder urothelial carcinoma difficult. A novel staging system for urachal carcinoma has been recently proposed, with specific therapeutic recommendations for each situation.