What is a urachal cyst?

What is a Urachal Cyst?

A urachal cyst is a congenital anomaly resulting from incomplete obliteration of the urachus—the embryological remnant of the allantois that normally connects the bladder apex to the umbilicus during fetal development and should obliterate into a fibrous band (the median umbilical ligament) by birth. 1, 2

Embryology and Pathophysiology

• The urachus is a tubular structure that extends from the dome of the bladder to the umbilicus and represents an allantoic and cloacal remnant that normally obliterates into a fibrous band by late fetal development 3
• When obliteration fails to occur completely, various urachal anomalies can develop depending on the location and degree of incomplete closure 4
• Urachal cysts are the most common urachal anomaly in the pediatric population, occurring in approximately 1 out of 5,000 live births, though they are only clinically relevant in about 1 out of 150,000 of the population 1, 2

Clinical Presentation

• Urachal cysts are typically asymptomatic and often discovered incidentally until infection or other complications develop 1, 2
• When infected, these cysts can mimic a wide variety of intra-abdominal and pelvic disorders, leading to delayed or missed diagnosis 5, 2
• Children commonly present with umbilical discharge, while adults more frequently present with hematuria 2
• Physical examination may reveal a tender, palpable mass in the umbilical or infraumbilical region, particularly when infected 3

Diagnostic Approach

• Ultrasound and computed tomography (CT) are the imaging modalities ideally suited for demonstrating urachal remnant diseases 2
• Infected urachal cysts typically display increased echogenicity on ultrasound and appear as thick-walled cystic or mixed attenuation lesions on CT 2
• Ultrasound can reveal a long tubular structure coursing from the dome of the bladder anteriorly and superiorly to the subumbilical region, which may be fluid-filled with internal echoes suggestive of infection or abscess formation 3
• Additional imaging studies such as umbilical fistulogram and voiding cystourethrogram can support the diagnosis in complex cases 4

Critical Management Considerations

• Complete surgical excision of the urachal cyst with bladder cuff resection is the definitive treatment recommended by the National Comprehensive Cancer Network to prevent recurrent infection and malignant transformation 6
• The surgical approach should include en-bloc resection of the entire urachal ligament with umbilicus and bladder cuff excision 6
• Incomplete excision must be avoided, as retained urachal remnants carry a risk of malignant transformation into urachal carcinoma 6
• In cases of acute infection with sepsis, initial antibiotic therapy should be administered prior to surgical intervention 4

Surgical Technique Options

• Laparoscopic excision represents a safe and effective minimally invasive alternative to traditional open approaches (semicircular infraumbilical incision or lower midline laparotomy) 1, 5
• Laparoscopic management offers comparable surgical results with advantages including shorter operative times (average 50 minutes versus 63 minutes for open), shorter hospital stays (2-4 days), very low morbidity, minimal risk of recurrence, and excellent cosmesis 1, 5
• Complete excision via laparoscopy is particularly useful when clinical suspicion exists despite lack of radiological evidence 1