In general, the diagnosis of urachal anomalies requires clinical suspicion and a thorough physical examination. Further evaluation in patients with periumbilical drainage should include a sinogram, and those with a periumbilical mass should undergo ultrasonographic imaging. A voiding cystourethrogram may be required in selected patients (2,3).

Complete failure of the urachal lumen to close results in an open connection between the bladder and the umbilicus. Patients present with umbilical leakage of urine and often a protruding tissue mass (Fig. 95.3). The leakage may be more obvious during times of increased intra-abdominal pressure such as crying, coughing, or straining. The fluid may be analyzed for urea and creatinine to confirm its urinary quality. Two factors thought to contribute to a persistent patent urachus are bladder outlet obstruction and failure of the bladder to descend into the pelvis (4,5). With regard to bladder outlet obstruction, distal urinary obstruction is thought not to be the only causative factor because normally, the urachus closes developmentally before the urethra becomes tubularized (6). In addition, only 14% of patients with patent urachus demonstrate bladder outlet obstruction clinically, and it is uncommon
for a patent urachus to be associated with posterior urethral valves. Alternatively, it can be seen with urethral atresia, as in prune belly syndrome. The diagnosis may be confirmed with a sonogram, although a voiding cystourethrogram may be more useful because it may rule out bladder outlet obstruction concurrently. Alternatively, methylene blue or indigo carmine may be instilled in either the bladder or the umbilical opening and detected in the umbilicus or bladder, respectively. The differential diagnosis for patent urachus includes patent omphalomesenteric duct, urachal sinus, omphalitis, granulation of a healing umbilical stump or umbilical granuloma, and infected umbilical vessel. An umbilical granuloma may be associated with a small amount of serous drainage and may appear similar to a patent urachus. It may have a smooth or irregular surface and may appear pedunculated. Normal imaging studies in these patients suggest the diagnosis of umbilical granuloma.

Segmental or incomplete closure of the urachal lumen may result in the formation of a urachal cyst (Fig. 95.4). The cyst usually forms in the proximal or lower third of the urachal remnant near the bladder (7). Usually, the cyst is lined with transitional epithelium and filled with serous fluid, but mucinous contents have been described. In general, urachal cysts are small and asymptomatic. Symptoms such as pain, erythema with localized swelling, and tenderness below the umbilicus may occur with infection and may be accompanied by chills, fever, irritative voiding symptoms, hematuria, and pyuria. Alternatively, symptoms may arise as the result of mass effect due to a large urachal cyst. These patients present with a sensation of abdominal fullness or pain, a mass, or irritative voiding symptoms due to compression of the bladder. Diagnosis is most easily confirmed by ultrasound or computerized tomography (CT).