Joseph Junewick, MD FACR
over 7 years ago
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Inflamed Urachal Remnant
Joseph Junewick, MD FACR
|Diagnostic Category: Developmental or Congenital
|Created: over 6 years ago
|Updated: over 6 years ago
11 year old with right lower quadrant pain and fever.
Inflamed Urachal Remant
US – Heterogeneous lesion arising form anterior dome of the urinary bladder with cordlike extension to umbilicus. Note calcifications within the lesion.
The urachus, or median umbilical ligament, extends upward in the midline from the anterior dome of the bladder toward the umbilicus. It is a vestigial remnant of the cloaca ( the cephalic extension of the urogenital sinus and a precursor of the fetal bladder) and the allantois (a derivative of the yolk sac). The fetal urachus is tubular and persists postnatally as a fibrous band with no known function. Varying degrees of urachal patency can give rise to various clinical problems, not only in infants and children but also in adults.
Congenital urachal anomalies are twice as common in males compared to females. There are four types of congenital urachal anomalies: 1) patent urachus, 2) umbilical-urachal sinus, 3) vesicourachal diverticulum, and 4) urachal cyst. A patent urachus accounts for about 50% of all cases of urachal anomalies. A patent urachus is commonly seen in patients with bladder outlet obstruction (posterior urethral valves). An umbilical-urachal sinus accounts for about 15% of cases. Umbilical-urachal sinus consists of blind dilatation of the urachus at the umbilical end. A small opening into the umbilicus is generally present. Vesicourachal diverticulum accounts for about 3%–5% of urachal anomalies. In vesicourachal diverticulum, the urachus communicates only with the bladder dome. This condition results when the vesical end of the urachus fails to close. Vesicourachal diverticulum is asymptomatic in most cases and is usually discovered incidentally on imaging. Urachal cysts for about 30% of urachal remnants. A urachal cyst develops if the urachus closes at both the umbilicus and the bladder. It occurs primarily in the lower one-third of the urachus. Urachal cysts are usually small but if they enlarge they can become symptomatic. Occasionally the urachus may close normally but then reopen as a result of other pathologic conditions.
The majority of patients with urachal abnormalities are asymptomatic. Patients with patent urachus present with fluid discharge from the umbilicus; urachal-umbilical fistulas have periodic umbilical drainage. Infection is a common presenting symptom. Benign urachal neoplasms including adenomas, fibromas, fibroadenomas, fibromyomas, and hamartomas are extremely rare. Malignant urachal neoplasms are rare, representing less than 0.5% of all bladder cancers.
Yu JS, et al. Urachal Remnant Diseases: Spectrum of CT and US Findings. Radiographics (2001); 21:451-461.
Kim Dombrowski RDMS