What Is Urinoma?
The urinary system is a crucial organ of the human body. It contains organs that filter the blood, form urine, and maintain the fluid and electrolyte levels of the body. The urinary system can be divided into two parts, the upper and the lower. The upper part contains the kidneys and the ureters, whereas the lower part consists of the urethra and the urinary bladder. The organs of the upper urinary tract, mainly the kidneys, are a part of the retroperitoneal space.
As the name suggests, the retroperitoneal space is present behind the peritoneum of the abdominal cavity. The perirenal space is the largest part of the retroperitoneum and comprises the kidneys, their tubules, and the adrenal glands. Under normal conditions, the urine flows from the kidneys to the ureters and outside the body through the urethra. However, if the urinary tract is damaged due to trauma or other conditions, the urine leaks into the perirenal space and gets collected there, resulting in a condition known as urinoma.
What Are the Causes of Urinoma?
Urinoma, or the abnormal collection of urine in the perirenal space, results from damage to the kidneys or their parts. When the urine enters the retroperitoneal or perirenal space, the fat present in this space breaks down, resulting in the encapsulation of urine. The main cause of urinoma are described below:
-
Kidney Stones - The minerals and salts present in the urine crystallize and clump together to form kidney stones. They restrict the flow of urine and damage the kidneys. The stones not only remain confined to the kidneys but can travel down the ureters. Sometimes, these stones cause rupture of the walls of the ureters resulting in urine leakage and urinoma.
-
Ureteropelvic Junction Obstruction - The junction where the urine is transferred from the kidneys to the ureters is known as the ureteropelvic junction. If it gets obstructed, the urine backflows and accumulates, increasing pressure on the kidneys. The pressure increases to the extent that the walls of the kidneys get ruptured, resulting in the leakage of urine in the space outside the kidneys.
-
Retroperitoneal Fibrosis - Retroperitoneal fibrosis is a condition in which extra tissue or fibers form in the space behind the stomach. These tissues form mass and block the ureters. As a result, the urine flows back to the kidneys, and they swell. The swelling might increase the pressure on the kidneys and cause their rupture resulting in urine leakage.
-
Renal Trauma - Renal or kidney trauma is one of the most common causes of urinoma. The kidneys might get injured due to an accident, stab wound, or other causes. As a result of trauma, the walls of the kidneys are damaged, and the urine might leak into the surrounding space.
-
Bladder Outlet Obstruction - Bladder outlet obstruction is the blockage of the flow of urine from the bladder to the urethra. It is commonly seen in men. When the urine does not flow through the bladder, it flows back to the ureters and the kidneys. As a result, the pressure on the kidneys increases resulting in their rupture and urine leakage.
-
Pelvic Surgery - The pelvis is an important organ of the human body present between the legs and the abdomen. It supports the organs of the urinary tract. Pelvic surgery needs to be done when the pelvis gets damaged due to trauma. After the surgery, the most common complication is ureteral injuries. When the ureters are injured, the urine either leaks into the space outside or flows back to the kidneys.
-
Ureteroscopy - It is a procedure in which a small telescope-like instrument known as the ureteroscope is inserted into the urinary system through the urethra. If the procedure is not performed under proper training, there is a risk of ureteral perforation.
-
Pregnancy - During pregnancy, the baby grows in the uterus or womb. As the baby grows further, pressure on the urinary bladder increases resulting in the leakage of urine. The urine might also leak into the retroperitoneal space resulting in urinoma.
What Are the Symptoms of Urinoma?
The patient usually experiences the following symptoms:
-
Severe pain in the abdomen, lower back, and the sides (flank pain).
-
The patient feels sick and tired throughout the day and is unable to concentrate on his work.
-
Presence of a lump or mass near the abdomen.
-
The urine does not get eliminated and remains within the body. Therefore, it increases the risk of urinary tract infections. Sometimes the infection is accompanied by fever.
-
The person might lose weight as he does not feel like eating anything due to the pain.
What Methods Are Used to Diagnose Urinoma?
The diagnosis of urinoma is based on medical history, physical examination, and laboratory and imaging tests. Medical history and physical examination provide an idea about the general health of the patient. Laboratory and imaging tests help to confirm the diagnosis. The methods used to diagnose urinoma have been described below:
-
Medical History - The medical history gives an idea about the symptoms of the condition, the time of their onset, other conditions the patient is suffering from, the medications being taken, the family history, and if the patient has undergone any major surgery in the past.
-
Physical Examination - The doctor palpates the abdominal and lower back region to check if it is paining or not. The vitals of the patient are also checked to rule out other diseases.
-
Laboratory Tests - The following laboratory tests are usually recommended:
-
Blood Test - The doctor recommends the patient undergo a blood test to check the levels of creatinine and white blood cells. Creatinine is a waste product formed after muscle activity. It is eliminated from the blood by the kidneys. If the kidneys are damaged, the levels of creatinine are high.
-
Urinalysis - The urine sample obtained from the patient is sent to the laboratory for examination under a microscope. The presence of white blood cells and blood in urine is indicative of infection.
-
-
Imaging Tests - The following imaging tests are usually recommended:
-
Intravenous Pyelogram - It is an imaging technique in which X-ray images of the urinary system are obtained. The patient is laid on a table, and the X-rays are taken. A dye is injected into the urinary system through the veins, and the X-rays are taken as the dye flows through the urinary bladder and the kidneys. The patient is asked to urinate, and again an X-ray of the empty bladder is obtained. In the case of urinoma, the dye collects outside the urinary system in the perirenal space.
-
Ultrasound - In this procedure, sound waves are sent to the body with the help of a device known as a transducer. The patient is laid on a table, and the doctor moves a transducer over the abdomen. Ultrasound shows the presence of a mass near the kidneys formed due to urinoma (urine leakage).
-
Computerized Tomography (CT) Scans - It is the diagnostic method of choice in urinoma. The patient lies on a table that slides into a tunnel-like device where the X-rays are taken. A contrast material is usually injected to have a better view of the internal organs. It also helps to detect the problems present in the kidneys and other organs.
-
How Is a Urinoma Managed?
The treatment of urinoma depends upon the severity. If the urinoma is small, it will reabsorb, and no drainage of the urine is required. If the urinoma is large and the patient experiences fever along with infection, the following treatment procedure is followed.
-
Percutaneous Drainage - It is a procedure in which a tube known as a catheter is inserted into the urinary system through the urethra. The catheter is usually inserted under the guidance of ultrasound or computerized tomography (CT) scans. A guidewire is usually inserted prior to the catheter insertion. The urinoma reduces in volume after the catheter is inserted. If this does not happen, the following procedure is usually performed.
-
Percutaneous Nephrostomy - This procedure is done under general anesthesia in which the patient is made to fall asleep. An incision is made in the lower back region, and a catheter is inserted to reduce pressure on the urinary system. It also helps to reduce the size of the mass formed by urinoma and facilitates the drainage of urine. A tube known as a ureteral stent is left in place for a few days to allow the urine to pass easily.
What Are the Complications of Urinoma?
Urinoma is a mass formed due to the leakage of urine in the retroperitoneal space. If left untreated for long, retroperitoneal abscess develops, which might rupture and cause complications. An abscess is a pus-filled mass that can form in any body part. If it forms in the space behind the abdomen, it is known as a retroperitoneal abscess. The patient presents with fever, pain, nausea, and weight loss. It mainly occurs when the bacteria enters the urinary tract or the abdomen and causes infections. If the abscess is small, antibiotics are usually recommended. On the contrary, surgical intervention is required if the abscess is large and has ruptured.
Conclusion:
Urinoma is a condition in which a mass forms in the space outside the kidneys due to the leakage of urine. If the kidneys or their internal structures are damaged, the urine leaks into the perirenal space and gets encapsulated there. Urinoma is not a life-threatening condition but requires treatment at the earliest. It is because if the urine forms an abscess in the retroperitoneal space, it becomes difficult to treat it. The patient presents with fever, abdominal pain, and enlargement of the lower back due to a mass. It is important to consult the doctor as soon as these symptoms are noted. If the urinoma is in the early stage, it will reabsorb itself, but surgery needs to be done if the urinoma persists for long.
