A urachal cyst is a sinus

Sinus (anatomy)

Sinus is Latin for "bay", "pocket", "curve", or "bosom". In anatomy, the term is used in various contexts.A sinus is a sack or cavity in any organ or tissue, or an abnormal cavity or passage caused by the destruction of tissue...

 remaining from the allantois

Allantois

Allantois is a part of a developing animal conceptus . It helps the embryo exchange gases and handle liquid waste....

 during embryogenesis

Embryogenesis

Embryogenesis is the process by which the embryo is formed and develops, until it develops into a fetus.Embryogenesis starts with the fertilization of the ovum by sperm. The fertilized ovum is referred to as a zygote...

. It is a cyst which occurs in the remnants between the umbilicus

Navel

The navel is a scar on the abdomen caused when the umbilical cord is removed from a newborn baby...

 and bladder

Bladder

Bladder usually refers to an anatomical hollow organBladder may also refer to:-Biology:* Urinary bladder in humans** Urinary bladder ** Bladder control; see Urinary incontinence** Artificial urinary bladder, in humans...

. This is a type of cyst occurring in a persistent portion of the urachus

Urachus

The urachus is a fibrous remnant of the allantois, a canal that drains the urinary bladder of the fetus that joins and runs within the umbilical cord...

, presenting as an extraperitoneal mass in the umbilical

Navel

The navel is a scar on the abdomen caused when the umbilical cord is removed from a newborn baby...

 region. It is characterized by abdominal pain, and fever if infected. It may rupture, leading to peritonitis

Peritonitis

Peritonitis is an inflammation of the peritoneum, the serous membrane that lines part of the abdominal cavity and viscera. Peritonitis may be localised or generalised, and may result from infection or from a non-infectious process.-Abdominal pain and tenderness:The main manifestations of...

, or it may drain through the umbilicus. Urachal cysts are usually silent clinically until infection, calculi or adenocarcinoma

Adenocarcinoma

Adenocarcinoma is a cancer of an epithelium that originates in glandular tissue. Epithelial tissue includes, but is not limited to, the surface layer of skin, glands and a variety of other tissue that lines the cavities and organs of the body. Epithelium can be derived embryologically from...

 develop.

Symptoms

• Lower abdominal pain
• Pain on urination
• Persistent umbilical discharge
• Fever
• UTI (Urinary Tract Infection
  Urinary tract infection
  A urinary tract infection is a bacterial infection that affects any part of the urinary tract. Symptoms include frequent feeling and/or need to urinate, pain during urination, and cloudy urine. The main causal agent is Escherichia coli...
  
  )
• Lump
• Hematuria
  Hematuria
  In medicine, hematuria, or haematuria, is the presence of red blood cells in the urine. It may be idiopathic and/or benign, or it can be a sign that there is a kidney stone or a tumor in the urinary tract , ranging from trivial to lethal...