Introduction:
Intrarenal reflux (IRR) means the return flow of urine into the kidneys. In this condition, there is an abnormal flow of urine from the renal pelvis back into the renal parenchyma. In the normal urinary system, urine moves from the kidneys to the bladder through the ureters in a single, forward path. However, in the case of intrarenal reflux, the urine goes back to the kidney. In intrarenal reflux, any pathogenic organism present in the bladder urine can reach the renal parenchyma and cause infection or various other complications.
What Is Intrarenal Reflux?
Intrarenal reflux (IRR) is also known as intrarenal backflow or intrarenal vesicoureteral reflux (VUR). This condition is characterized by abnormal flow of urine from the bladder back into the kidneys. This is different from a more common form of renal neuropathy which is called vesicoureteral reflux (VUR). This reflux occurs at the junction where the ureter meets the bladder and may occur because of the position of the ureter in the bladder wall. However, intrarenal reflux usually occurs within the kidney itself and usually occurs as a result of any structural defect or anatomical abnormality in the kidneys.
Intrarenal Reflux Can Be Classified Into Two Types Which Include -
Intralobar Reflux - This type of reflux occurs within the single renal lobe. This is also associated with certain structural abnormalities like calyceal diverticula, which are sac-like structures within the renal calyx.
Interradial Reflux - This reflux means the reflux of urine between adjacent renal lobes and is mostly associated with abnormal communication between the collecting systems of neighboring renal units.
What Is Kidney Reflux and Their Symptoms in Adults?
Kidney reflux, medically known as vesicoureteral reflux (VUR), is a condition where urine flows backward from the bladder into one or both ureters and, in some cases, into the kidneys. Normally, urine flows in one direction from the kidneys to the bladder via the ureters, and the bladder then empties the urine during urination.
Symptoms of Kidney Reflux in Adult:
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Recurrent UTIs can be a common symptom of kidney reflux in adults. These infections might be more frequent or severe due to the backward flow of urine from the bladder to the kidneys.
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A burning feeling when urinating may indicate a urinary tract infection (UTI) or inflammation.
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Fever and chills occur Especially if associated with UTIs or kidney infections.
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Discomfort or pain in the lower back or abdomen can occur, especially during a kidney infection.
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Blood in urine (hematuria) occurs during UTIs or due to kidney irritation caused by the reflux.
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Frequent urges to urinate without producing much urine can also be a symptom.
What Are the Long Terms of Vesicoureteral Reflux?
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Urinary tract infections (UTIs) brought on by urine backing up from the bladder into the kidneys can eventually damage and scar the kidneys. Severe cases of VUR can result in kidney dysfunction or even kidney failure.
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Chronic kidney damage due to VUR can contribute to the development of hypertension (high blood pressure) in some individuals.
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VUR creates an easier pathway for bacteria to reach the kidneys, increasing the risk of recurrent UTIs, which can further damage the urinary system.
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VUR can affect the growth and function of the kidneys, particularly in children whose kidneys are still developing.
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Living with a chronic condition like VUR, especially if it causes repeated health issues or requires ongoing medical management, can impact a person's emotional well-being and quality of life.
What Are the Causes of Intrarenal Reflux?
The exact cause of intrarenal reflux is not always clear, but it can be associated with congenital abnormalities, such as calyceal diverticula (sac-like structures within the renal calyx), ureteral duplication, or other anatomical anomalies within the kidney. These abnormalities can disrupt the normal flow of urine and may lead to reflux, and the primary cause is mostly related to structural abnormalities within the kidney, either congenital or acquired conditions. So, some of the common causes of intrarenal reflux include -
Renal Papillary Necrosis - In this condition, the renal papillae may get damaged or non-functional which are the pointed structures present in the kidney from where urine flows into the ureters. Moreover, renal papillary necrosis can occur as a result of conditions like diabetes, sickle cell disease, analgesic abuse, or urinary tract obstruction. This lead to the formation of necrotic tissue, which can disrupt the normal urine flow and cause intrarenal reflux.
Renal Calculi - Kidney stones or renal calculi can cause obstruction or narrowing of the renal tubules. As the urine flow is obstructed because of the stones, it can lead to increased pressure within the renal pelvis, potentially causing intrarenal reflux.
Ureteropelvic Junction (UPJ) Obstruction - This obstruction refers to the narrowing or blockage of the junction present between the ureter and the renal pelvis (area at the center of the kidneys). The obstruction can cause urine backflow into the renal parenchyma causing intrarenal reflux.
What Are the Clinical Features of Intrarenal Reflux?
As the causes are usually not known for intrarenal reflux, the same goes for its sign and symptoms, as it is not always present with noticeable symptoms, most commonly in mild cases. However, in some cases or severe condition symptoms may occur, which may include -
Pain - Patients with intrarenal reflux may experience pain in the flank region, which is the area on the sides and back of their abdomen, between their lower ribs and hips. The severity of the pain may vary from person to person depending on the underlying cause and the extent of urine backflow.
Hematuria - Hematuria means the presence of blood in the urine, which can be an indication of intrarenal reflux. This may range from the presence of microscopic traces of blood to visible discoloration of urine.
Urinary Tract Infections (UTIs) - Intrarenal reflux can cause a high risk of urinary tract infections due to the backward flow of urine consisting of disease-causing microorganisms. Moreover, recurrent urinary tract infections may be an indication of intrarenal reflux.
How Is Intrarenal Reflux Diagnosed?
Various types of diagnostic tests may be done to diagnose intrarenal reflux, which may include -
Imaging Tests - Renal ultrasound, computed tomography (CT) scan, or magnetic resonance imaging (MRI) can be used to visualize the kidney's anatomy and identify any structural abnormalities or obstructions that may lead to intrarenal reflux.
Voiding Cystourethrogram (VCUG) - This method is most commonly used to diagnose vesicoureteral reflux but can also be used to evaluate the flow of urine within the urinary tract. In this method, X-rays and a contrasting medium are used. The contrasting medium has to be injected into the urinary bladder using a catheter. The flow of the medium is monitored to check for any reflux within the kidneys.
How Is Intrarenal Reflux Treated?
The treatment of intrarenal reflux usually depends upon the underlying condition, the severity of symptoms, and any other complications. Some of the treatment options may include -
Medications - Antibiotics can be prescribed to treat urinary tract infections causing intrarenal reflux. Analgesics or painkillers can also be taken to relieve pain or any discomfort.
Conservative Management - Mild to moderate cases of intrarenal reflux should be managed conservatively by monitoring the symptoms and conducting periodic imaging tests to assess kidney health. This method is done when there are no significant symptoms or complications due to intrarenal reflux.
Surgery - In cases of severe intrarenal reflux, surgeries may have to be done, such as pyeloplasty (to repair ureteropelvic junction obstruction), lithotripsy (to break down kidney stones), or nephrectomy (removal of the affected kidney) may be performed.
Conclusion
Intrarenal reflux is a very rare condition characterized by the abnormal flow of urine within the kidney. This condition can be a challenge to diagnose and treat. To treat this condition, understanding the underlying causes, recognizing the symptoms, and seeking timely medical intervention are crucial for effective treatment. However, with proper care and early diagnosis, this condition can be easily treated and may help in reducing the risk of complications.
