Imaging of the umbilicus.

The umbilicus is a scar of the umbilical cord containing various embryonic remnants that can lead to postnatal diseases. It is the collection point for blood and lymphatic flow and other structures. Hence, various diseases and conditions can occur. In this review, we aimed to categorize umbilical diseases based on the embryonic remnants, including urachal remnants, omphalomesenteric duct anomalies, and complications of the umbilical arteries and veins. The urachus, formed from the allantois, can result in anomalies such as patent urachus and urachal cysts, with infections being the most common complication. Radiologists must note that urachal carcinoma is a rare complication presenting with characteristic imaging findings. The omphalomesenteric duct can lead to Meckel's diverticulum, the most prevalent gastrointestinal anomaly. In addition, obliterated umbilical arteries and veins can cause various conditions, including hernias and abscesses. This review also summarizes the umbilical ring lesions, such as gastroschisis and omphalocele, and iatrogenic lesions associated with laparoscopic procedures and catheter placement. Imaging techniques such as ultrasound, computed tomography, and magnetic resonance imaging are crucial for diagnosing and managing these conditions. Understanding the embryological basis and imaging features of umbilical diseases is vital for timely diagnosis and treatment.