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Urachal Cyst – What It Is, Causes, Symptoms, Diagnosis, Treatment & Prevention

What is Urachal Cyst?

A urachal cyst is a fluid‑filled sac that forms in the urachus, a vestigial tube that connects the fetal bladder to the umbilical cord. In most people the urachus closes and becomes a fibrous cord called the median umbilical ligament. When this canal fails to close completely, a segment in the middle can remain patent and fill with mucus or fluid, creating a cystic mass.

Urachal cysts are usually congenital (present from birth) but often remain unnoticed until childhood, adolescence, or even adulthood when they become symptomatic or are discovered incidentally on imaging.

Common Causes

Because a urachal cyst is fundamentally a developmental anomaly, the “causes” relate to factors that prevent normal involution of the urachus. The following conditions or circumstances are most frequently associated with the formation or complication of urachal cysts:

• Incomplete obliteration of the urachal lumen during fetal development.
• Persistence of a mid‑portion urachal remnant (isolated cyst) while the proximal and distal ends close.
• Infection of a pre‑existing urachal cyst by skin flora (e.g., Staphylococcus aureus) or gut bacteria.
• Trauma or iatrogenic injury to the lower abdomen (e.g., surgery, laparoscopic ports) that disrupts the median umbilical ligament.
• Obstruction of cyst outflow due to mucus plug or debris.
• Secondary inflammation from adjacent intra‑abdominal pathologies such as diverticulitis or appendicitis.
• Neoplastic transformation (rare) – adenocarcinoma arising in a urachal remnant.
• Congenital anomalies that accompany urachal defects, such as omphalomesenteric duct remnants.
• Immune‑compromised states that predispose to infection (e.g., diabetes, HIV).
• Persistent urachal sinus or fistula that can evolve into a cystic configuration.

Associated Symptoms

Many urachal cysts are asymptomatic and discovered incidentally. When symptoms do appear, they typically result from infection, mass effect, or, rarely, malignant change.

• Pain or tenderness in the lower abdomen or suprapubic region.
• A palpable, firm midline lump** near the umbilicus.
• Redness, warmth, or swelling of the overlying skin – signs of infection.
• Fever, chills, or malaise accompanying an infected cyst.
• Urinary symptoms (frequency, dysuria) if the cyst presses on the bladder.
• Discharge or foul odor from the umbilicus if a sinus tract is present.
• Gastrointestinal upset (nausea, loss of appetite) in severe infection.
• Rarely, hematuria or painless abdominal mass when a malignant lesion develops.

Most patients notice a gradual increase in size rather than sudden onset, unless the cyst becomes infected, which can cause rapid swelling and pain.

When to See a Doctor

Because the condition can progress to infection or, in rare cases, cancer, you should schedule a medical evaluation promptly if you experience any of the following:

• Persistent or worsening lower‑abdominal pain, especially if it’s localized to the midline.
• A growing lump near the belly button that does not resolve within a few weeks.
• Redness, heat, or drainage from the umbilicus.
• Fever ≥ 100.4 °F (38 °C) with abdominal discomfort.
• Difficulty urinating, urinary urgency, or blood in the urine.
• Unexplained weight loss, night sweats, or fatigue.
• Any sudden change in size of a known abdominal mass.

Early assessment can prevent complications such as abscess formation, rupture, or spread of infection to the peritoneal cavity.

Diagnosis

Diagnosis is made through a combination of history, physical examination, and imaging studies. The typical diagnostic pathway includes:

1. Clinical Examination

• Inspection of the umbilical area for swelling, discharge, or skin changes.
• Palpation of a midline mass – cysts are usually non‑pulsatile and may feel fluctuant.

2. Laboratory Tests (if infection is suspected)

• Complete blood count (CBC) – elevated white blood cells suggest infection.
• C‑reactive protein (CRP) or erythrocyte sedimentation rate (ESR) – markers of inflammation.
• Urine analysis – to rule out concurrent urinary tract infection.
• Culture of any pus or drainage to guide antibiotic therapy.

3. Imaging Modalities

• Ultrasound – first‑line, non‑invasive; shows a well‑defined anechoic or hypoechoic cystic structure anterior to the bladder.
• CT scan (contrast‑enhanced) – provides detailed anatomy, assesses for surrounding inflammation, abscess, or involvement of the bowel.
• MRI – useful for soft‑tissue characterization and when radiation exposure is a concern (e.g., in children).
• Fistulography – may be performed if a sinus tract is suspected.

4. Histopathology (when removed)

Excised tissue is examined to confirm a benign cystic lining (often columnar or stratified epithelium) and to rule out malignant transformation.

Reliable information on diagnosis can be found in sources such as the Mayo Clinic and the National Institutes of Health (NIH) Urachal Anomalies review.

Treatment Options

Treatment depends on whether the cyst is symptomatic, infected, or suspected to be malignant.

1. Conservative Management (Uncomplicated Cysts)

• Observation with periodic ultrasound every 6–12 months.
• Patient education on signs of infection.

2. Medical Therapy (Infected Cyst)

• Antibiotics – broad‑spectrum agents targeting skin flora and gram‑negative bacilli (e.g., amoxicillin‑clavulanate, cefazolin, or a fluoroquinolone if resistant organisms are suspected). Therapy usually lasts 7–14 days.
• Pain control – acetaminophen or ibuprofen as needed.
• Close follow‑up; if no improvement within 48–72 hours, proceed to drainage.

3. Procedural Intervention

• Image‑guided needle aspiration – can relieve symptoms and provide culture material. Often a bridge to definitive surgery.
• Incision and drainage (I&D) – performed in the emergency department for abscess formation.

4. Surgical Excision (Definitive Treatment)

Complete removal of the cyst and the urachal tract is the gold‑standard to prevent recurrence or malignant change.

• Laparoscopic excision – minimally invasive, shorter recovery, and low complication rates.
• Open midline or Pfannenstiel incision – preferred for large cysts, extensive inflammation, or suspicion of cancer.
• In cases of suspected carcinoma, a en‑bloc cystectomy with partial cystectomy and lymph node sampling may be required.

Post‑operative care includes wound monitoring, short course antibiotics, and activity restriction for 2–4 weeks.

5. Home Care After Treatment

• Keep the incision clean and dry; change dressings as instructed.
• Monitor for increasing redness, swelling, or fever.
• Gradually resume normal activities; avoid heavy lifting for at least 4 weeks.

Prevention Tips

Because a urachal cyst is a congenital anomaly, true primary prevention is limited. However, several strategies can reduce the risk of complications:

• Prompt treatment of any abdominal or umbilical infections to avoid spread to a latent cyst.
• Maintain good skin hygiene around the navel, especially in children and individuals with obesity.
• Seek medical evaluation for any new midline abdominal lump, even if painless.
• For patients with known urachal remnants, schedule routine imaging as advised by a urologist.
• Control chronic conditions (diabetes, immunosuppression) that increase infection susceptibility.
• Avoid unnecessary abdominal trauma (e.g., harsh sports without protective gear).

Emergency Warning Signs

• Sudden, severe abdominal pain with a rigid or board‑like abdomen.
• High fever (≥ 102 °F / 38.9 °C) combined with chills and vomiting.
• Rapid expansion of the midline mass or signs of rupture (e.g., sudden drainage of pus or foul fluid).
• Severe urinary retention or inability to pass urine.
• Signs of septic shock: low blood pressure, rapid heart rate, confusion, or dizziness.
• Visible blood in urine or persistent gross hematuria.

If any of these arise, seek emergency medical care immediately.

Key Takeaways

A urachal cyst is a rare, usually congenital, fluid‑filled remnant of the fetal urachus. While many remain silent, infection or growth can cause pain, fever, and a palpable abdominal mass. Diagnosis relies on physical exam and imaging, and definitive treatment is surgical excision. Early recognition of infection or red‑flag symptoms is essential to avoid serious complications such as abscess, peritonitis, or, albeit seldom, cancer.

For more detailed information, consult reputable sources such as:

• Mayo Clinic – Urachal Anomaly
• Cleveland Clinic – Urachal Cyst
• National Institutes of Health (NIH) – Urachal Anomalies
• World Health Organization (WHO) – Surgical safety guidelines (relevant to operative management).

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