Teaching Case

23-year-old male patient presented with fever and severe abdominal pain for 1 week and swelling in the umbilical region for 3 weeks. On physical examination, a purulent umbilical discharge with surrounding erythema and tenderness was noted. USG of the abdomen was documented as normal. CECT of the abdomen and pelvis was performed subsequently.

Axial contrast enhanced CT of the abdomen shows a thin tubular channel extending from anterosuperior aspect of urinary bladder to the umbilicus (Fig. 1a-s; 2a,b). The umbilical portion of the tubular channel is distended with a small amount of fluid collection and air loculi just below the umbilicus, suggestive of an infected patent urachus (Fig. 1d,e; 2b, c). Scout image of the abdomen shows no obvious abnormality (Fig. 2d). Schematic representation of the various types of urachal abnormalities (Fig. 2e).

The urachus (median umbilical ligament) is a normal embryonic remnant of the primitive bladder dome [1, 2, 4]. Normally in adults, it exists as a fibrous cord that results from descent of the bladder into the pelvis forming a canal, which extends from the dome of the bladder to the umbilicus [2, 4]. The urachus is developmentally the upper part of the bladder, both of which arise from the ventral part of the cloaca [3].
Urachal diseases can be congenital or acquired. Congenital anomalies occur when the urachus fails to obliterate [2, 4].
Five types of urachal abnormalities have been defined as follows with schematic representation in Figure 2e:
1) Patent urachus, in which the tubular structure fails to close.
2) Urachal cyst, with an open central portion with closed ends.
3) Urachal sinus, which drains proximally into the umbilicus.
4) Vesicourachal diverticulum, where the distal communication to the bladder persists.
5) Alternating sinus, which can drain to either bladder or umbilicus [1, 4].
The incidence of a patent urachus in adults is unknown but rare. It is more common in men than women [1]. The clinical presentation is highly variable which makes diagnosis difficult, however, this patient presented with fever and the impression of acute abdomen.
The presence of the triad of symptoms including a tender midline infraumbilical mass, umbilical discharge and sepsis should raise suspicion of infected patent urachus or urachal cyst. In this case, ultrasound was not specific but the CT showed the characteristic tubular channel, which is seen in patent urachal abnormality.
Other complications include uracho-colonic fistula, stone formation and neoplastic transformation which were absent in this patient.
The management of symptomatic infected patent urachus includes antiobiotic therapy followed by complete surgical resection after draining abscess if present [1, 4]. A laparascopic approach may also be considered as it provides easier access and good long-term cosmetic results [1].