A urachal cyst is a fluid-filled pocket that forms along the urachus, a small tube-like structure left over from fetal development that normally closes before birth and becomes a fibrous cord running between the bladder and the belly button. When part of that tube fails to seal completely, a closed-off section can fill with fluid and sit quietly in the lower abdomen, sometimes for years or even decades, without causing any trouble. Most people who have one never know it. The cyst tends to announce itself only when it becomes infected or grows large enough to press on nearby structures, at which point it can mimic several more common conditions and send patients and doctors down the wrong diagnostic path.
Where a Urachal Cyst Comes From
During early development in the womb, the allantois is a small outpouching that connects the developing bladder to the umbilical cord. Its job is essentially plumbing: it helps route waste away from the growing embryo. The portion of the allantois closest to the body gets folded into what will become the urinary bladder, and the narrow channel running from the bladder up to the navel gradually shrinks.
By roughly ten weeks of gestation, the allantois sits mostly inside the abdominal cavity, and the urachus, which forms from its far end, is on its way to becoming a closed fibrous cord.1PubMed Central. Embryonic and extraembryonic tissues during mammalian development: shifting boundaries in time and space After birth, this cord is retained as a dense strip of tissue called the median umbilical ligament, which you can think of as a biological relic with no remaining function. When the urachus does not fully close, whatever pocket of lining remains can accumulate fluid and form a cyst. Because the urachus runs along the midline of the abdomen, a urachal cyst almost always sits right in the center, between the top of the bladder and the underside of the navel.
How Common Are They
Urachal remnants in general are more common than most people assume, though the vast majority never cause problems. An ultrasound study of nearly 400 children found urachal remnants in about a third of them, with the rate being highest in infants under one year old, where it exceeded 60%.2PubMed. Prevalence of urachal remnants in children according to age and their anatomic variants Most of these remnants are tiny, harmless, and shrink or disappear on their own as the child grows. Among urachal remnants that do become clinically significant, cysts are the single most frequent type. In one pediatric series, urachal cysts made up about half of all diagnosed urachal anomalies.3PubMed Central. Urachal anomalies in children: a single center experience
The condition shows a clear male predominance. A large nationwide study in Japan found a male-to-female ratio of roughly 2.5 to 1 among adults with urachal remnants, with the prevalence peaking in men between 20 and 34 years of age.4PubMed Central. Epidemiology and treatment patterns of urachal remnants in adult patients with omphalitis: a nationwide claims-based study in Japan Why men are affected more often is not entirely clear, but the pattern is consistent across multiple studies and age groups.
What a Urachal Cyst Feels Like
An uncomplicated urachal cyst typically feels like nothing at all. It just sits there. The trouble starts when the cyst becomes infected, which is the most common reason someone ends up in a doctor’s office or emergency room because of one. Once infection takes hold, the symptoms can appear suddenly and vary quite a bit. The most frequent complaint is pain around the belly button or in the lower abdomen, sometimes accompanied by fever, a palpable tender lump in the midline, discharge from the navel, or urinary symptoms like painful urination.5PubMed Central. An infected urachal cyst presenting as acute abdominal pain in a child: A case report In a study of infected urachal anomalies, umbilical pain or discharge was the leading symptom, present in about three-quarters of cases.6International Journal of Surgical Wound Care. Infected Urachal Anomalies: Clinical Features and Bacteriological Studies
In children, the presentation can look dramatic. Case reports describe young children arriving in emergency departments with severe abdominal pain, sometimes with constipation, that initially looks like appendicitis or another surgical emergency.7PubMed Central. Complicated urachal cyst in two pediatric patients: a case report In adults, the picture is similar but the differential diagnosis expands. A case of a 33-year-old woman with pelvic pain and painful urination underscores that infected urachal cysts can present in ways that overlap with urinary tract infections, pelvic inflammatory disease, or other gynecological conditions.8PubMed Central. An Infected Urachal Cyst in an Adult Woman
Why It Gets Misdiagnosed So Often
Urachal cysts have a reputation for fooling clinicians. Because the condition is uncommon and its symptoms overlap with much more prevalent abdominal problems, it often gets mistaken for something else on first evaluation. One report describes an infected urachal cyst that was initially misdiagnosed as an incarcerated umbilical hernia.9PubMed. Infected urachal cyst initially misdiagnosed as an incarcerated umbilical hernia The correct diagnosis is frequently made only when imaging is performed for the suspected condition and reveals the cyst instead.10PubMed Central. The primary considerations and image guided diagnosis of an infected urachal cyst in a pediatric patient
The list of conditions that a urachal cyst can be confused with is long: acute appendicitis, Meckel’s diverticulum, pelvic inflammatory disease, recurrent bladder infections, a perforated bowel, incarcerated umbilical hernia, abdominal abscess, or even a tumor.11Translational Research in Anatomy. Urachal anomalies: A review of pathological conditions, diagnosis, and management This is one of those situations where the diagnosis is straightforward once someone thinks of it but easy to miss when it is not on the radar. Doctors who see a lot of urachal cases generally recommend keeping it on the differential list for any patient with midline lower abdominal pain and signs of infection, particularly when the pain is centered near the navel.12Urology Case Reports. Infected urachal cyst in an adult: A case report
How Urachal Cysts Are Found on Imaging
Ultrasound is usually the first imaging tool used, and in many cases it is enough to identify the cyst. A urachal cyst appears as a fluid-filled pocket sitting in the midline of the lower abdominal wall, typically located near the top of the bladder.13PubMed. Imaging of the Urachus: Anomalies, Complications, and Mimics When the cyst is not infected, it looks like a simple, clear-walled fluid collection. An infected cyst, on the other hand, tends to have thicker walls and more complex internal echoes, which can make it harder to interpret.14PubMed. Urachal remnant diseases: spectrum of CT and US findings
Ultrasound has decent sensitivity for identifying urachal remnants in children, correctly picking up about four out of five cases in one study, but its ability to tell exactly what type of remnant is present is not perfect.15PubMed. The impact of preoperative ultrasound on correct diagnosis of urachal remnants in children For cases where the diagnosis is uncertain or the clinical picture is complicated, CT scanning and sometimes MRI provide more detailed views. CT is particularly useful for evaluating the extent of infection, mapping the cyst’s relationship to the bladder, and ruling out other conditions. One of the challenging aspects of imaging is that both infected urachal cysts and the rare urachal cancer can look similar on both ultrasound and CT, with thick walls and mixed internal contents.16PubMed. Urachal remnant diseases: spectrum of CT and US findings When there is any suspicion of malignancy, additional imaging and ultimately tissue sampling become necessary.
What Bacteria Are Involved When a Cyst Gets Infected
The infections that develop in urachal cysts tend to involve a mix of bacterial species rather than a single culprit. Bacteriological studies have shown that anaerobic bacteria are commonly involved. Among the organisms isolated, the most frequently cultured were Prevotella and Bacteroides species, followed by Staphylococcus, Streptococcus, and Corynebacterium species.17International Journal of Surgical Wound Care. Infected Urachal Anomalies: Clinical Features and Bacteriological Studies The presence of anaerobes matters clinically because it influences the choice of antibiotics. Standard empiric antibiotic regimens that do not cover anaerobes may not fully control the infection, which is one reason some infected urachal cysts prove stubborn to treat with antibiotics alone and eventually require drainage.
Treatment in Children and When Surgery Can Wait
The management of urachal cysts in children has shifted over the past couple of decades. Older surgical teaching held that any urachal remnant found should be removed to prevent future infection or, in theory, malignant transformation. Current evidence supports a more conservative approach, especially in young children.
Urachal remnants in babies under six months are likely to resolve on their own without any intervention.18PubMed. Management of urachal remnants in early childhood Even in older children, many urachal cysts that are discovered incidentally remain asymptomatic and do not grow or cause problems. A recent retrospective study found that many non-excised cysts stayed quiet and some shrank or disappeared entirely over time, suggesting that watchful waiting is appropriate for asymptomatic children.19PubMed Central. Management of urachal anomalies in children: insights from a retrospective cohort study Observation with periodic ultrasound monitoring allows clinicians to track any changes and intervene only if symptoms develop.
Even some symptomatic cases can be managed without a full surgical excision. One study concluded that nonoperative management is a reasonable option and can be extended to infected urachal cysts after initial drainage, since drained infected cysts sometimes close up on their own over time.20PubMed. Nonoperative management of symptomatic urachal anomalies That said, the recurrence rate for infected cysts managed with drainage alone has been reported at around 30%, so some of those patients do eventually need surgery.21Journal of Pediatric Surgery Case Reports. To excise or not to excise infected urachal cysts: A case report and review of the literature
Surgical Approaches for Cysts That Need Removal
When surgery is indicated, whether because the cyst keeps getting infected, is causing persistent symptoms, or raises concern about its nature, complete excision of the cyst along with the urachal remnant is the standard treatment. Some surgeons also remove a small cuff of the bladder dome where the urachus attaches, particularly when there is any worry about abnormal tissue.
The big debate in recent years has been between open surgery and laparoscopic (keyhole) surgery. Both achieve the same goal, and operative times and blood loss are similar between the two approaches. Where laparoscopy pulls ahead is in recovery. A comparative study of adults found that patients treated laparoscopically had a shorter hospital stay and a faster return to full activity, with full recovery taking roughly 11 days versus about 16 days for the open approach.22PubMed Central. Umbilicus-sparing laparoscopic versus open approach for treating symptomatic urachal remnants in adults A pediatric series similarly showed laparoscopic excision to be safe and effective, with operating times averaging around 50 minutes and hospital stays of two to four days.23PubMed Central. Laparoscopic management of urachal cysts Some newer laparoscopic techniques are designed to preserve the navel’s appearance, which matters cosmetically since the surgical field is right at the belly button.
Handling an Infected Cyst Before Surgery
Operating on a urachal cyst in the middle of an active infection carries higher risks. Evidence consistently supports a two-stage approach for infected cysts: first, treat the infection with antibiotics and drain the abscess, and then go back weeks later for the definitive surgical excision once inflammation has settled. One early series reported complications in every patient who had the cyst removed during an active infection, while no complications occurred in those managed with the two-stage approach.24PubMed. The infected urachal cyst: primary excision versus a staged approach
Later work reinforced this pattern, showing that the two-stage approach was associated with shorter hospitalizations and fewer wound-related problems compared to immediate excision.25PubMed Central. Surgical management for an infected urachal cyst in an adult: Case report and literature review The staged strategy is especially recommended when infection has spread significantly, such as cases with abscess formation, rupture into surrounding tissues, or signs of sepsis.26PubMed Central. Treatment of infected urachal cysts For milder infections where the inflammation is well contained, some surgeons feel comfortable with single-stage excision, but the available data is limited and the sample sizes in the studies comparing the two strategies are small.
The Cancer Question
One of the fears that historically drove aggressive surgical removal of urachal remnants was the possibility of malignant transformation. Urachal cancer does exist, and it is overwhelmingly adenocarcinoma, a type of glandular cancer. Case reports have documented adenocarcinoma arising within a urachal cyst.27PubMed Central. Malignant transformation of a urachal cyst—a case report and literature review A pathological study of urachal cancers found that most of the tumors were associated with urachal remnants, and in a majority of those cases the remnant lining already showed precancerous changes.28PubMed Central. Urachal carcinoma: a clinicopathologic analysis of 24 cases with outcome correlation
That sounds alarming, but context matters. Urachal cancer is extremely rare, accounting for a tiny fraction of all bladder cancers, and the absolute risk of any individual urachal cyst turning malignant is very low. The cancer question becomes relevant mainly in two scenarios: when imaging of a cyst shows atypical features such as solid components, calcification, or thick irregular walls, and when a patient is older. Urachal cancers tend to present in middle-aged adults rather than children. This is part of why the current pediatric approach favors observation over preemptive surgery: removing every incidentally discovered cyst in a child to prevent a cancer that is vanishingly uncommon and decades away does not make clinical sense. In adults, however, a cyst that looks unusual on imaging or keeps recurring warrants a lower threshold for excision and pathological examination of the tissue.
What Gets Confused for a Urachal Cyst on Imaging
Radiologists have their own differential diagnosis to sort through when they spot a midline cystic structure in the lower abdomen. A non-infected urachal cyst can resemble a bladder diverticulum, which is an outpouching of the bladder wall, or a mesenteric cyst, which arises from the lining of the abdominal cavity rather than from the urachus.29European Society of Radiology. Urachal remnant pathologies: A pictoral essay The key distinguishing feature is location: a urachal cyst sits strictly in the midline between the bladder dome and the navel, whereas other cystic structures in the abdomen tend to arise from different anatomical landmarks. CT and MRI can trace the connection between the cyst and the bladder dome, which clinches the diagnosis when ultrasound alone is ambiguous.30PubMed Central. The urachus revisited: multimodal imaging of benign & malignant urachal pathology
Living With a Known Urachal Cyst
If you have been told you have a urachal cyst that was discovered incidentally on imaging done for another reason, the practical question is what to do about it. For a small, asymptomatic cyst in an otherwise healthy person, many specialists now recommend watchful waiting with periodic imaging rather than immediate surgery. The cyst may never cause a problem. The triggers for reconsidering surgery are the development of symptoms such as pain, fever, or umbilical discharge; growth of the cyst on follow-up imaging; or the appearance of features suggesting something other than a simple benign cyst.
There is no proven way to prevent a urachal cyst from becoming infected, and no medication that makes it go away. If you notice new-onset pain centered around your navel, especially if it comes with fever or redness, it is worth mentioning your known cyst to whatever doctor you see, since that history can save valuable time reaching the correct diagnosis. Carrying a note of the finding in your medical records or on your phone ensures that information is available even if you end up in an unfamiliar emergency room. The condition is uncommon enough that many emergency physicians may not think of it without a prompt, and a quick mention can steer the workup in the right direction from the start.