Background

During the first stages of intrauterine life, the urachus connects the bladder to the allantois sac through the umbilicus. Toward the end of gestation, the urachus obliterates and becomes a fibrous band, forming the umbilical ligament between the peritoneum and fascia. Abnormalities of the urachus include the patent urachus, cysts, sinus, and fistula. Each of these entities represents a failure of complete obliteration of the urachus. Contrary to other urachus anomalies, urachal cysts are usually small and silent unless they are infected. The diagnosis is often made during childhood. Infection is the usual mode of presentation among adult cases, otherwise the condition usually remains asymptomatic. Benign noninfected urachal cysts discovered in adulthood is a rare condition considered.

Case presentation

We present the cases of two patients with benign noninfected urachal cysts manifested in adulthood. The first case is a 26-year-old Tunisian white man who presented with complaints of clear fluid draining from the base of the umbilicus evolving for a week, with no other associated symptoms. He had no prior history of a lower abdominal mass and no voiding complaints. The physical examination revealed an outcome of clear fluid from the umbilicus with no signs of inflammation or a palpable mass, associated with a noncomplicated umbilical hernia. The results of all blood tests were normal. A subsequent urine culture was negative. We completed abdominal sonography that showed a small peri vesical hypoechogenic cystic formation reminiscent of a urachal cyst (Fig. 1). The patient was then operated on: he had a laparoscopic excision of the cyst and was cured of an umbilical hernia in the same surgery (Fig. 2). The diagnosis of a benign noninfected urachal cyst was confirmed histologically. No adverse event was noted and the patient was discharged on day 1 after surgery.

Fig. 1
figure 1

Abdominal ultrasonographic finding of a urachal cyst. Arrow indicating the urachal cyst

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Fig. 2
figure 2

Urachal cyst after laparoscopic excision

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The second case had similar clinical presentations. The patient was a 27-year-old Tunisian white woman who was referred to the surgery department with a history of intermittent draining of clear fluid from the umbilicus evolving for a year, with no other associated symptoms. The patient was treated with antibiotics, but recurrence of the symptomatology was noted. Blood and urine tests were normal. Abdominal sonography combined with a computed tomography (CT) scan identified a urachal cyst of 3 cm. the patient underwent surgery and had a laparoscopic excision of the urachal cyst with no intraoperative incidents. The postoperative course was simple. Pathologic examination revealed the urachal cysts without any unusual features.

For both patients, no recurrence of the symptoms was noted in the subsequent clinical follow-up.

Discussion

The urachus is an embryologic structure that communicates between the apex of the bladder and the umbilicus. It normally closes by birth. If any portion of this embryologic structure remains patent, a urachal abnormality results. Various types of remnants have been described, including cysts, sinus, diverticulum, and a patent urachus. It is a rare congenital anomaly, with an incidence of 1:300,000 in infants and 1:5000 in adults [1].

Infection is the most common complication [1].

Urachal remnants, most commonly cysts, require intervention when they become infected or symptomatic.

As in the two reported cases, periumbilical drainage is the most common presentation of urachal cyst in adults and it is not necessarily associated with infection. Diagnosis is facilitated by imaging, especially ultrasound, which shows the cyst in the majority of cases. Otherwise, this examination can be replaced by a CT scan, especially in case of complications.

In Tables 1 and 2 we have summarized all the cases of benign noninfected urachal cyst in adult patients that have been reported in the literature so far.

Table 1 Case reports of benign noninfected urachal cysts in adult until December 2021
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Table 2 Series of urachal remnants in adult patient and cases of benign noninfected urachal cysts
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Asymptomatic, noninfected urachal cysts can be approached with watchful waiting, while infected urachal cysts almost require treatment that includes antibiotics, percutaneous drainage, or surgical removal. The therapeutic option depends on the presenting signs and symptoms, in addition to the individual operability and eventual surgical complications. There are two possible treatment modalities of this entity: either percutaneous drainage followed by surgical removal or one-stage open, laparoscopic, or robotic removal; the decision depends on the surgeon’s expertise and technologies involved in each surgical approach and the unique characteristics of the urachal cystic lesion being evaluated [20].

The nonoperative management of symptomatic urachal cyst is an acceptable approach and can be applied to infected urachal cysts after initial drainage. Infected cysts drained adequately may obliterate progressively and spontaneously. Ultrasonography is very useful for follow-up.

With regards to complications, Cutting et al, [21] reported peri-umbilical bleeding after surgery. Active umbilical bleeding was controlled laparoscopically in the repeat intervention. The blood supply at the umbilicus is from the branch artery of the inferior epigastric artery not from umbilical ligaments [22]. Wide circular resection of the fascia around the umbilicus should be avoided since it can risk injury to this branch. Omphalitis secondary to symptomatic urachal remnants often necessitates simultaneous resection of the umbilicus.

Furthermore, incomplete resection can lead to recurrence; therefore, appropriate debridement of the infected tissue is required [23, 24].

Conclusion

Although it normally disappears to birth, part of the urachus may persist in few people. Urachal cysts can develop at any age. Urachal cysts are often not associated with any signs or symptoms; however, there are complications such as infection. In these cases, symptoms may include abdominal pain, fever, pain with urination, and/or hematuria. A laparoscopic approach is best to treat these abnormalities, with less comorbidity and undesirable events.