An urachal cyst is a cyst formed in the urachus, a primordial canal that links the bladder to the umbilical cord at the first stages of fetal development.
Patients with an urachal cyst typically display no symptomatology, unless the cyst has been subject to complications. One of the frequent complications is an infection, in which case symptoms include fever, abdominal pain, hematuria and pain during urination, alongside an abdominal mass that can be palpated during a physical exam [9].
Should the patient's symptoms raise suspicion about the presence of an urachal cyst, the following procedures may be performed in order to establish a definitive diagnosis [9]:
Other pathologies producing symptoms imitating those of an urachal cyst include abscesses, hernias, hematomas and any type of malignant masses of the abdominal wall or urachus. A CT scan provides the optimal sensitivity for an urachal cyst, even though it cannot accurately differentiate between malignant and non-malignant masses. Various degrees of calcification are strong indicators of cancer [10]. Approximately 57% of the patients who were found to have a cancerous tumor and not an urachal cyst also displayed calcifications on the CT scan [10] [11].
Urachal cyst symptomatology is solely exhibited upon complications, commonly infection. In such a case, antibiotic treatment and total surgical excision of the urachal remnants are mandatory, for fear of malignant development on urachal grounds [9] [12]. This is traditionally done with open surgery, which, however does increase morbidity, as well as the time a patient requires in order to post-surgically recover. The cyst is removed with our without the bladder's cuff and the umbilicus remains intact as there is not need for it to be resected. There have also been reports of infected urachal cysts that have healed without any intervention; due to a potential malignancy, however, upon the diagnosis of an urachal remnant, the whole structure is excised.
A partial or radical cystectomy is performed in cases where urachal cancer is diagnosed. The procedure can be carried out either laparoscopically or in an open fashion, depending on the surgeon's experience and the specific circumstances of each condition [13].
Patients diagnosed with an urachal cyst exhibit excellent prognosis. Surgical drainage of the cyst and complete removal of the urachal remnants are a necessity, as the structure evinces a slight tendency towards neoplastic differentiation. No need for frequent patient monitoring is required after the procedure is performed.
The urachus constitutes the primordial channel connecting the bladder to the umbilical cord in a fetus, which mediates the excretion of waste from its body, before the stage of full development is reached. The urachus normally disappears after birth, but under undetermined circumstances it may fail to do so, leading to the formation of urachal abnormalities, one of which is the urachal cyst. Urachal cysts are most of the times independent developmental anomalies.
Urachal abnormalities are observed rarely in the population. They are mostly identified during the time of infancy or childhood, and seldom in the adult population [3] [4]. Even though the structure of the urachus is normally expected to disappear prior to birth, some newborn children still exhibit urachal remnants. The latter, when diagnosed before the completion of 6 months of age typically do not require treatment as they resolve automatically [2].
It is estimated that 0.02% of the children present with urachal abnormalities, 1/3 of which were affected with an urachal cyst [5] [6], a fact that illustrates the rarity of the urachal cyst in the general population. Adults, on the other side, exhibit a prevalence of 0,01% regarding urachal developmental defects [5]. Data was collected from necrotomy studies.
Urachal cysts and other abnormalities show a predilection for men, affecting them at a rate of 3:1 when compared to women [7]. As far as potential complications are concerned, urachal adenocarcinoma accounts for 51% of them, while urachal cyst for 35% of the observed complications [1].
The urachus is a primordial structure that develops during the fourth month of fetal development. It is a canal connecting the bladder and umbilicus, shaped as the bladder descends into the pelvic region. Its precise anatomical location is between the retropubic space and the transversalis fascia.
As far as histology is concerned, the urachus, an extension of the allantois, features 3 layers. These are, inner to outer, the transitional epithelial layer, a layer of fibroconnective tissue and a smooth muscle layer. Almost in the majority of the people (98%), the urachus regresses prior to birth, leaving a remnant known as the median umbilical ligament [8]. Independent developmental defects lead to the formation of various types of urachal abnormalities that usually go asymptomatic, unless complications such as infection or cancer arise. Such abnormalities include the urachal cyst, patent urachus, urachal diverticulum, urachal sinus and alternating sinus.
Since urachal cysts are developmental defects and not associated with underlying conditions and risk factors, no preventive measures can be assumed.
The urachus is a primitive canal, which provides a connection between the bladder and umbilical cord in the early stages of development of the fetus. Although it typically regresses prior to birth, defective processes lead to the occlusion of its terminal parts, leaving the central part open; as a result, a cyst is formed [1].
Urachal cysts are most common among children, although they can also be observed in the adult population. It is a diagnostically challenging abnormality, as the cysts remain asymptomatic unless complicated. Typical complications primarily include infections; secondarily, rupture with subsequent peritonitis and adenocarcinomas may also arise. In cases of infection, symptoms include fever and abdominal pain, for which a plethora of other conditions could also account. Upon diagnosis, cysts are surgically drained and removed [1] [2].
An urachal cyst is only one of the 5 types of the defects associated with the urachus and its failure to disappear after the development of a fetus is completed. Other urachal defects include the patent urachus, alternating sinus, vesicourachal diverticulum and urachal sinus.
An urachal cyst is a cyst located at the urachus, a primitive structure that exists before a baby is born and connects the bladder with the umbilicus. The existence of the urachus is vital for the survival of the fetus: since the body is not fully developed yet, this channel helps the fetus to excrete liquid waste from its system.The urachus typically vanishes right before birth.
What are the causes of a urachal cyst?
In some cases, it may remain even after a child is born, for reasons that cannot be accurately pinpointed. It is however important to keep in mind that certain developmental defects can happen on their own, namely unconnected with other diseases and syndromes. An individual with an urachus that has persisted even after birth runs no other danger of developing a condition.
An urachal cyst is one of the abnormalities observed in the persisting urachus: both the sides of the urachal channel collapse and its central part remains open, thus creating a pouch-like structure.
These cysts are mainly observed in children; adults however can also develop a cyst on the grounds of an existing urachus. In the adult population these cysts may provide fertile grounds for cancer to develop.
Signs and symptoms of urachal cyst
An urachal cyst typically produces no symptoms and most people are unaware of its presence. If complications arise, like infection and urachal cancer, characteristic symptoms that may be observed include painful sensation in the lower abdomen, fever, a lump that can be felt in the vicinity of the umbilicus and, possibly, discharge from the umbilicus. Other signs of complications are bloody urine and pain while urinating, which indicate a possible urinary tract infection.
The condition is mainly diagnosed during childhood. A child may exhibit discharge from the umbilicus, fever, pain while urinating and general discomfort. A pediatric urologist will carry out the necessary diagnostic tests (ultrasound, CT scan) in order to confirm the presence of an inflamed urachal cyst.
An infected urachal cyst can be further complicated if it ruptures. This is a dangerous complication that should at all costs be avoided. The ruptured cyst will unleash bacteria and other toxic substances into the abdominal cavity, causing peritonitis, at the same time exerting pressure on organs found in the vicinity and increasing the risk for internal bleeding. Internal bleeding is also a potentially fatal condition if not treated with immediate surgery.
How to treat a urachal cyst?
Urachal cysts are usually diagnosed when they are inflamed due to infection. A patient with an infected urachal cyst first receives antibiotics to treat the inflammation and then has the cyst surgically excised. If the inflammation has spread to surrounding tissues and those are also dead, the resection will involve those parts as well.
In case a person is diagnosed with urachal cancer, a surgical procedure called cystectomy will be performed. Cystectomy means removal of the bladder; this procedure can be done with incisions on the skin (open) and laparoscopically. A surgeon will decide which way will achieve the best results for each patient.