Urachal Anomalies and Related Umbilical Disorders

Urachal Anomalies and Related Umbilical Disorders



During bladder development, the urogenital sinus is initially contiguous with the allantois. When the lumen of the allantoic duct becomes obliterated, the urachus remains, connecting the bladder to the umbilicus (Fig. 95.1A and B). It continues to elongate as the fetus grows. The urachus is a muscular tube, with a length ranging from 3 to 10 cm and a diameter of approximately 8 to 10 mm that extends from the dome of the bladder to the umbilicus. It has three distinct tissue layers: (a) an epithelial-lined lumen with cuboidal or transitional epithelium, (b) an intermediate connective tissue layer, and (c) an outer smooth muscle layer. In the adults, the urachus lies between two layers of umbilicovesical fascia along with the umbilical ligaments and the remnants of the obliterated umbilical arteries. This fascial investment tends to contain the spread of urachal disease between the peritoneum and transversalis fascia (Fig. 95.1C).

FIGURE 95.1 A: At 9 weeks of gestational age showing the allantois extending into the body stalk. B: At 3 months’ gestation, the urachus connects to the dome of the bladder. C: The urachus persisting as the median umbilical ligament in the adult.

The urachus normally closes or involutes at approximately 32 weeks’ gestation, and urachal anomalies in general represent an abnormality in the involution process. The anomalies that can result are characterized as patent urachus, urachal cyst, urachal sinus, and urachal diverticulum (Fig. 95.2) (1). Of these anomalies, urachal cysts (45%) and sinuses (37%) are the most commonly identified (2). With the level of detailed imaging available, incidental atretic, cordlike umbilical remnants are also commonly reported.

Apr 24, 2020 | Posted by in UROLOGY | Comments Off on Urachal Anomalies and Related Umbilical Disorders

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