We reported the case of a 79-year-old woman who presented to the emergency after four days of progressively worsening periumbilical pain. Laboratory tests revealed a slight leukocytosis. Physical examination revealed a non-reducible umbilical mass protruding through the abdominal wall which was diagnosed as an incarcerated umbilical hernia.
An ultrasound (figure 1) was performed and revealed a hypoechoic periumbilical lesion with internal echoes protruding through the rectus abdominus muscle. Abdominal computed tomography (CT) scan with intravenous contrast was ordered to further elucidate the findings. The CT scan (figure 2) demonstrated a well-defined low-attenuation lesion with 10x9x6 cm in the umbilical region which was herniating through the umbilical defect. There was a thin and linear connection to the bladder, suggestive of an infected urachal cyst.
The urachus is a ductal remnant that arises embryologically, originating from the involution of the allantois and cloaca, and extending between the bladder dome and the umbilicus.  
Urachal anomalies are extremely rare in adults and the incidence is largely unknown in this age group. 
Cysts often remain clinically silent, and may never require medical treatment unless infected.  
The difficulty in accurately identifying these entities is largely a result of their myriad of presentations. 
The delay in diagnosis and treatment can lead to various complications with nonspecific clinical findings such as the formation of complex fistulas and abscesses, with the attendant risk of potential intraperitoneal rupture causing peritonitis and sepsis.   
Our case was clinically misidentified as incarcerated umbilical hernia until imaging techniques revealed a herniated infected urachal cyst. So, the patient received intravenous antibiotic therapy and was taken to the operating room, where she underwent percutaneous drainage of the cyst. A two-week outpatient follow-up confirmed an uneventful recovery.
Urachal anomalies in older adults are rare and rarest when presenting as an umbilical herniation. In conclusion, this condition can mimic other causes of low abdominal pain and the diagnosis may remain presumptive until clearly confirmed by imaging findings.
 Parada VC, Adam SZ, Nikolaidis P, et al. Imaging of the urachus: Anomalies, complications, and mimics. Radiographics. 2016;36(7):2049–63.
 Ash A, Gujral R, Raio C. Infected urachal cyst initially misdiagnosed as an incarcerated umbilical hernia. J Emerg Med. 2012;42(2):171–3.
 Seo IY, Han DY, Oh SJ, et al. Laparoscopic excision of a urachal cyst containing large stones in an adult. Yonsei Med J. 2008;49(5):869–71.
 Jayakumar S, Darlington D. Acute Presentation of Urachal Cyst: A Case Report. Cureus. 2020;12(5).
 Elkbuli A, Kinslow K, Ehrhardt JD, et al. Surgical management for an infected urachal cyst in an adult: Case report and literature review. Int J Surg Case Rep. 2019;57:130–3.
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