Urachal cyst is a malformation of embryonic development, in which a closed cavity containing serous fluid is formed in the urinary duct. Small cysts may not manifest any symptoms for a long time, tumors of considerable size are characterized by abdominal pain due to compression of the intestine, palpable swelling of the abdominal wall, urination disorders. Diagnostics may include ultrasound of the urinary organs, cystoscopy, with a cyst with the formation of a fistula canal ‒ fistulography. Treatment in adults is exclusively operative, active surveillance tactics are possible in children.
ICD 10
Q64.4 Urinary duct anomaly [urachus]
Meaning
Urachal cyst is a urological pathology, which is 2 times more often registered in newborn boys. The share of this embryonic defect accounts for 42% of all anomalies in the development of the urinary canal. About a third of people at birth have one or another pathology of the urachus, which is not always detected during life, but is confirmed by the results of autopsies. In adults, the neoplasm is more often diagnosed accidentally during imaging studies or during surgical interventions. The clinic develops with complications: cyst perforation, fistula canal formation, infection. In women, pathology is rare, sometimes symptoms manifest during pregnancy as the fetus grows.
Causes
It is not known for certain what causes a violation of the reduction of the urinary duct. Studies have shown that in people with Down syndrome, Beckwith-Wiedemann, trisomy 13 and 18, defects of the embryonic urinary canal are more common. It has been noted that newborns with low body weight may develop therapy-resistant omphalitis associated with a rudimentary duct cyst or with congenital complete or incomplete fistula. Predisposing factors include:
- Genetic pathology. Sometimes embryonic defects are the result of a genetic mutation. In this case, the pathology of urachus is often combined with other serious developmental defects, sometimes incompatible with life. Hereditary disease is transmitted to the child from the father and / or mother, but sometimes mutations leading to malformations of the genitourinary system occur spontaneously.
- Exogenous effects. Some medications, alcohol, drugs and other environmental factors have a teratogenic effect on the fetus, resulting in various defects in the development of the urogenital tract. Diseases suffered by the mother at a critical time for the development of the fetus are also considered as a possible cause of a violation of the structure of the organs of the genitourinary system.
Pathogenesis
The role of urachus is the discharge of fetal urine into amniotic fluid during embryogenesis. This duct is a derivative of the allantois stem and is formed by 2-3 months of pregnancy. The closure of the urachus begins with the fifth month of gestation. By the time of birth, normally, the embryonic canal in most children is completely closed, transforming into the median vesico-umbilical ligament.
With the development of ultrasound diagnostics, it was found that a small hole in the rudimentary process can be preserved in healthy children. The opinion of practitioners is divided – this is a pathology or a variant of the norm. Urachal cyst is formed due to non-obliteration of the duct in the middle part and can persist throughout life. The epithelium of the canal in adults produces fluid that promotes cyst growth, in children the cystic cavity may also contain mucus, meconium masses, urine. There are observations when the growth of the embryonic duct occurred independently by the age of 1.5 years.
Classification
The cyst of the excretory duct can have different sizes, its volume is variable – from 5-10 ml to 100-150 ml. There are giant cystic cavities that cause compression of neighboring organs. There are complicated and uncomplicated urachal cyst. The urinary duct is conventionally divided into three parts: proximal, median and distal. When regression processes are disrupted, four known defects occur in various parts of this embryonic formation, including urachal cyst (some authors include an alternating sinus defect in the classification, when the cyst is drained alternately through the navel and into the bladder):
- Umbilical fistula (incomplete). The absence of obliteration preserves the communication with the navel (distal non-infection), leads to the formation of a fistula, or sinus (this name is often used in English literature). It occurs in 36.5% of cases.
- Vesico-umbilical fistula (complete). Urine from the bladder through the navel comes out, since the embryonic duct is completely open. It is diagnosed in 20% of cases from all pathologies of urachus.
- Diverticulum. Its formation is caused by the non-filling of the duct in the area of the tip of the bladder (proximal section). The frequency of detection of diverticula is 1.6%.
- Urachal cyst. The isolation of the cyst from the navel and bladder is characteristic, i.e., the distal and proximal ends of the urinary passage are closed. Cystic formations are located more often in the middle, but can be localized at any level of the urachus. This pathology is registered most often – in 42% of cases.
Symptoms
With a small size of the formation, symptoms are absent for a long time; they appear with the growth of the cyst and the secondary attachment of the infection. The patient complains of pain in the lower abdomen, in the navel area, discomfort and frequent urination. The feeling of incomplete emptying after urination occurs due to an obstacle to the outflow of urine. If the cyst has a compressive effect on the intestines, flatulence, constipation, spasms are added. With a palpatory examination of the abdomen below the navel, a tightly elastic rounded formation can be determined, painful when pressed. Hyperemia of the skin above it and sharp soreness indicate infection.
When a fistula is formed, serous fluid is released from the navel (when infected, a purulent discharge with an unpleasant odor, blood). Excessive maceration leads to the development of dermatitis. The breakthrough of the cyst deep into the bladder is manifested by the clinic of acute cystitis: pain with frequent urination, fever, change in the nature of the urine secreted (fetid odor, admixture of blood and pus). In adults, urachal cyst is often diagnosed during an examination conducted for macrohematuria. Dyspareunia (pain and discomfort during and after sexual contact) is registered less frequently.
Complications
The embryonic cyst of urachus is complicated by infection, fistula formation. In newborns, the risk of cyst suppuration is higher, since the child’s own immune system is still imperfect. In adults, a potential malignancy of the embryonic canal is dangerous, adenocarcinoma develops in 90%. It is proved that the risk of neoplastic process increases with age. According to literature analysis, 10-30% of cases of bladder cancer originate from the mouth of the urinary duct.
Relatively rarely, stone formation occurs in the cyst with persistent inflammation, pain syndrome, perforation. One of the life-threatening complications is peritonitis, which develops when an infected cystic formation ruptures with the outpouring of purulent contents into the abdominal cavity. There are references to purulent fasciitis and sepsis in the literature.
Diagnostics
The diagnosis is established by a urologist, based on complaints, anamnesis, physical examination and the results of an instrumental examination. A complicated cyst of the rudimentary duct can be suspected if there is urinary or purulent discharge from the umbilical canal. Laboratory tests for this pathology are nonspecific and can be useful for assessing the degree of concomitant purulent-inflammatory process. The algorithm of instrumental diagnostics:
- Ultrasound examination. Ultrasound of the bladder and structures of the anterior abdominal wall is the main way to visualize the cystic formation of the embryonic duct. The diagnostic accuracy is close to 100%. The urachal cyst on sonograms is located as a rounded delimited cavity with smooth edges. Its dimensions are variable. In case of inflammation, the contents are inhomogeneous, there is swelling of the surrounding tissues, when the sensor is pressed, pain is typically increased.
- Additional diagnostic methods. With a complicated cyst, fistulography is performed, which can show a fistulous course in the wall of the bladder or inside the navel. The message of a cyst with a bladder is visible during cystoscopy, the features of the fistula canal are shown by cystography. MRI is used more often in adults with suspected neoplastic transformation of the rudiment, and CT of the urinary system – with stone formation. With symptoms of peritonitis, laparoscopy is performed.
A rudimentary canal cyst implies differential diagnosis with acute omphalitis (inflammation of the navel), umbilical hernia, hernia of the white line of the abdomen. Defects of the urinary duct differentiate among themselves. Similar to an opened cyst, manifestations may be in the vesicolabular and umbilical fistula, diverticula.
Treatment
In childhood, even if a rudimentary cyst is complicated by fistula formation, dynamic observation is possible. As a result of the postnatal evolution of the urinary tract, complete obliteration of the urachus can occur even with concomitant inflammatory process. To stop it, antibacterial therapy is carried out taking into account sensitivity and assess the dynamics of treatment. Given the potential complications with a high risk of mortality, surgical tactics in practical urology remains a priority:
- Percutaneous puncture. Aspiration of the contents with subsequent sclerosing of the walls can be performed with an aseptic uncomplicated cyst of the urinary tract. Percutaneous puncture drainage is a minimally invasive intervention, but the likelihood of relapses does not allow it to be considered as the main treatment.
- A one-step operation. The intervention is resorted to with recurrent omphalitis or the re-formation of a cyst six months after its percutaneous puncture. Treatment can be performed in an open and laparoscopic manner. The scope of the operation involves draining and excision of the cyst at a time. The tactic is applicable in the absence of pronounced inflammation.
- Two-stage operation. This type of surgery is preferable for complicated forms. Initially, the cyst is drained with the subsequent appointment of antibacterial therapy. At the second stage, the urachus is excised together with the median fold of the peritoneum from the navel to the bladder, in most cases partial cystectomy is performed.
Prognosis and prevention
The prognosis with timely surgical treatment is favorable, because it avoids complications. No preventive measures with proven effectiveness have been developed. Taking into account the potential teratogenic effects of alcohol, nicotine and narcotic drugs on the woman’s body and the fetus, it is necessary to adhere to a healthy lifestyle not only during pregnancy, but also throughout life. During gestation, contact with poisons, chemicals, ionizing radiation is unacceptable. Preventive intake of multivitamin complexes, pre-gravidar preparation, early examination of a couple helps to reduce the likelihood of a child with malformations, including the urogenital tract.
