The kidneys are constantly filtering the blood and producing urine in varying quantities. Once sufficient urine fills the bladder, the urge to urinate prompts a person to expel the urine. However, various blockages can disrupt the kidney’s function of producing urine. This can cause serious consequences as the retained wastes in the blood can adversely affect the body. It can even lead to life-threatening complications.
What is a blocked kidney?
The term ‘blocked kidney’ usually refers to a condition that impairs drainage of urine from the kidney. The blockage may be within the kidney, like in the case of a large kidney stone within the kidney that blocks the output of kidney. However, the blockage can be further down the urinary tract, like within the ureter or bladder. Urine can then accumulate within the kidney thereby causing it to swell and can even damage the kidney. This is known as hydronephrosis.
Read more on hydronephrosis.
Since a ‘blocked kidney’ is not a medical term, it can also sometimes be loosely used to refer to blockages of the artery and vein that supply the kidney. A narrowing of the kidney artery is known as renal artery stenosis. Sometimes a blood clot can block the already narrowed renal artery. Renal vein thrombosis is where a blood clot forms in the kidney vein. It can then obstruct the blood flowing out of the kidney. These two blood vessel conditions can affect kidney function but the blockage is in the blood circulation to the kidney and not in the kidney itself.
Causes of a Blocked Kidney
Since a blocked kidney is primarily understood to refer to an obstruction of urine flow, problems within the kidney and urinary tract are considered as possible causes. Renal artery stenosis an renal vein thrombosis as well as other circulatory problems with the kidney are not considered further as possible causes of a blocked kidney.
Within the Kidney
There are three possible causes of an obstruction within the kidney that obstructs the outflow of urine. The obstruction would lie in the renal pelvis or where the kidney continues to the ureter (ureteropelvic junction). It may also lie in the renal calyx but this often does not completely obstruct urine outflow.
- Kidney stone, usually a large stone that cannot pass into the ureter and remains within the kiney.
- Blood clots, usually a large clot that may obstruct the ureteropelvic junction (UPJ).
- Tumors, either benign (non-cancerous) or malignant (cancerous).
Within the Urinary Tract
If there is an obstruction within the urinary tract then urine will back up and even block the outflow of urine from the kidney. This can occur with one or more of the following conditions.
- Urinary stones which are either stones that form in the kidney and are small enough to pass into the ureter or stones that form in the bladder (bladder stones).
- Ureteral stricture which is a narrowing of the ureter. This is more likely to arise from injury to the ureter that can lead to the formation of scar tissue.
- Neurogenic bladder where damage or dysfunction of the nerves supplying the bladder can hamper urination thereby causing urine to become backed up.
It is important to note that masses outsie of the urinary tract can compress the ureter in particular thereby causing an obstruction. In men, prostate conditions can compress the urethra that passes through it. This includes benign prostate hypertrophy (BPH), prostatitis and prostate cancer. Large abdominal tumors can compress the ureter from the outside of it but it is more common with pregnancy when the enlarged uterus compresses the ureter.
Signs and Symptoms
The signs and symptoms of a blocked kidney can vary to some degree depending on the underlying cause. However, with the obstruction of the passage of urine, there are some common urinary symptoms in all of these conditions.
- Reduced urine output (oliguria) or no urine (anuria).
- Pain in the upper flank (kidney problems), along the flank (ureteral conditions) or pelvis (bladder conditions).
- Pain when urinating or attempting to urinate.
- Blood in the urine (hemturia) when urination is possible.
- Nausea and vomiting, particularly when urine output persists for days or longer.
- Leg swelling which is a sign of kidney damage.
It is important to note that most of these symptoms arise with common urinary conditions, such as a urinary tract infection (UTI) and urinary stones, even though urine is able to pass out of the kidney. It can therefore be difficult to differentiate between these other more common conditions (like UTIs and urinary stones) and hyponephrosis at the outset.
Treatment of Blocked Kidney
The exact cause of urine outflow from the kidney needs to be identified. This may require various diagnostic investigations. It is also important to confirm whether hydronephrosis is present. The choice of treatment for a blocked kidney can therefore vary depending on the underlying cause. Some of the treatment options may include:
- Medication like allopurinol to dissolve stones or and diuretics to prevent stones from forming.
- Non-invasive therapy such as extracorporeal shock wave lithotripsy (ESWL) to break up stones with sound waves.
- Surgery like percutaneous nephrolithotomy to surgically remove kidney stones from the urinary tract.
The treatments mentioned above are specifically for kidney stones that cause a blocked kidney. Dietary and lifestyle changes may also be helpful in some of these cases. If urine is accumulating within the kidney (hydronephrosis) then other procedures may be necessary. This includes a nephrostomy to drain urine out of the body or a stent in the ureter to widen it and allow urine to flow into the bladder.
Complications of a Blocked Kidney
If hydronephrosis is not treated or does not resolve then it can cause kidney damage. Initially the urine accumulation reduces kidney function and can even lead to kidney failure. If both kidneys are affected simultaneously then this can lead to serious consequences and even culminate in death.
Hydronephrosis also increases the risk of kidney infections which may also lead to other equally serious complications. However, early diagnosis and treatment of a blocked kidney can drastically reduce the risk of complications but there is a risk of recurrence in some of the possible causes of a hydronephrosis.