The urachus is an embryonic remnant of the cloaca and the allantois which is present after birth as a midline fibrous cord extending from the anterior dome of the urinary bladder to the umbilicus [1
]. If the obliteration of the urachal patency does not proceed normally after birth, the persistent urachal remnant may result in various clinical problems. The congenital urachal anomalies are more common in males and have 4 types including patent urachus (about 50% of cases), urachal cyst (about 30%), urachal sinus (about 15%), and urachal diverticulum (about 5%) [2
]. The incidence of urachal anomalies in infancy and childhood has been reported at about 1 in 5,000 with 3:1 male to female ratio [3
]. Because urachal disease is usually detected in infancy and childhood, it is rare in adults. Yiee et al. [4
] reported that there were approximately two cases of urachal abnormality per 100,000 hospital admissions in adults.
Clinical presentation is usually associated with superadded infection of the urachal cyst. Infected urachal cysts present with various symptoms; low abdominal mass, umbilical discharge, tenderness with erythema, fever, urinary tract infection, hematuria, and peritonitis. Infected urachal cyst can occasionally lead to urachal abscess and can develop to systemic septic condition. With a severe urachal cyst infection, pyourachus can form a fistula with bladder, bowel or umbilicus. Abscess rupture due to expansion of infected urachal cyst can cause acute abdomen requiring emergency operation [5
Diagnosis of urachal cyst is usually made with either ultrasonography or computed tomography. Cystography or cystoscopy can be useful to define the full extent of the cyst wall and delineate the urachal sinus [6
]. Initial administering of IV antibiotics and definitive surgical excision is recommended in the treatment of urachal abscess. Simple drainage of the cyst is not recommended due to high recurrence rates (approximately 30%) [7
]. If the patient has a huge size of abscess with poor general condition, it is better to perform percutaneous drainage of the urachal abscess before surgical excision [8
]. Because of the high recurrence rate and possibility of developing carcinoma in the urachal remnant, it is a key point to complete resection of the cyst wall throughout its length during operation [9
]. Operation may include removal of cuff of the bladder if there is communication between the urachal cyst and the bladder. Open excision has been performed as the treatment of choice, traditionally. However, recently, the laparoscopic method has been accepted as an alternative option because of faster recovery, less postoperative pain and better cosmetic results [10
In summary, urachal abscess is rare in adulthood but should be considered as differential diagnosis of abdominal pain, because it may require emergency surgical management. This case demonstrates that urachal abscesses are a rare but critical disease presenting with abdominal pain in adults.