A hernia occurs when an internal organ or tissue protrudes through a weak spot in the surrounding muscle or fascia. While common hernias, such as inguinal or umbilical types, usually involve the intestine or fatty tissue, they rarely affect the urinary system. However, in specific and uncommon scenarios, a hernia can interact with the kidney or its plumbing, potentially leading to significant complications. The risk is specialized and depends heavily on the location and size of the defect.
Anatomical Factors Determining Kidney Risk
The anatomical relationship between the urinary tract and the abdominal wall determines the potential for a hernia to cause kidney issues. The kidneys and ureters are located in the retroperitoneal space, behind the lining of the abdominal cavity. This posterior position generally protects them from most frontal abdominal wall hernias.
Hernias in the flank or lower back (lumbar hernias) pose a more direct risk. A large defect can allow the kidney itself to slip into the hernia sac. More commonly, the ureter can become involved in a type of sliding hernia, particularly in the groin area.
The ureter is dragged along as a part of the hernia sac wall due to its fixed position, known as a ureteroinguinal hernia. A massive incisional hernia may also draw retroperitoneal structures like the ureter into its contents. Any time a urinary tract structure is pulled or compressed, the flow of urine from the kidney is jeopardized.
Mechanisms Leading to Kidney Impairment
The primary process by which a hernia compromises kidney function is through the obstruction of the ureter. When the ureter is pulled, compressed, or kinked by the hernia contents or the defect edges, the flow of urine is blocked. This blockage, which can be partial or complete, is the main cause of long-term damage.
Ureteral obstruction results in hydronephrosis, the swelling of the kidney due to urine backup. Since urine cannot pass the blockage, it accumulates in the collecting system, increasing pressure within the organ. This sustained pressure gradually damages the kidney’s filtering units. Prolonged or complete obstruction carries the highest risk of permanent loss of function.
A hernia containing the kidney itself can also impair function by directly compressing the renal blood vessels. This pressure restricts blood flow to the organ, leading to tissue damage from a lack of oxygen, known as ischemia.
Another pathway involves the herniation of the urinary bladder. If a large part of the bladder protrudes, it can cause stretching or kinking of the urethra or the bladder neck. This prevents the complete emptying of the bladder, causing urine to back up into both ureters and kidneys, resulting in bilateral hydronephrosis and acute kidney injury.
Symptoms and Medical Intervention
If a known hernia begins to affect the urinary system, a patient may experience new onset or worsening pain in the flank or side, corresponding to the affected kidney. Other signs include blood in the urine, a frequent urge to urinate, or a noticeable decrease in urine output.
Systemic signs of obstruction and potential infection, such as fever, chills, and increased urinary tract infections, warrant immediate attention. These urinary symptoms alongside a new or growing hernia mass suggest possible ureteral or bladder involvement. Acute kidney injury, marked by a sudden decline in kidney function, can occur in severe cases of complete obstruction.
Diagnosis requires imaging studies. A physician will order an ultrasound to check for hydronephrosis swelling. A Computed Tomography (CT) scan, particularly with intravenous contrast (CT Urogram), is necessary to visualize the entire urinary tract, identify the entrapped ureter, and confirm the relationship between the hernia and the obstruction.
The definitive treatment for kidney impairment caused by a hernia is surgical repair to relieve the compression or obstruction. The hernia contents, including the ureter or bladder, must be carefully reduced and returned to their proper anatomical position.
Temporary Stabilization Measures
In cases where kidney function is severely compromised, temporary measures may be employed to immediately drain the backed-up urine and stabilize the kidney before the hernia repair is performed. These measures include placing a percutaneous nephrostomy tube or a ureteral stent.