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Ureteropelvic junction (UPJ) obstruction

Ureteropelvic junction obstruction

UPJ (Ureteropelvic Junction) obstruction is a medical condition that involves a partial or complete blockage at the point where the renal pelvis (the top part of the ureter) connects to the ureter. This junction is responsible for draining urine from the kidney to the ureter, which then carries it to the bladder. When there is an obstruction at the UPJ, it can disrupt the normal flow of urine, leading to various symptoms and potential complications.


The causes of UPJ obstruction can vary and may include:

  1. Congenital Anomalies: Many cases of UPJ obstruction are congenital, meaning individuals are born with this condition. Congenital UPJ obstruction occurs due to an abnormality in the development of the ureter and renal pelvis during fetal growth. The most common congenital cause is an abnormal blood vessel overlying the UPJ or an intrinsic narrowing of the junction.

  2. Abnormal Blood Vessels: Some people may have an aberrant blood vessel, often an artery, that lies over the UPJ or compresses it. This vascular compression can hinder urine flow and lead to UPJ obstruction.

  3. Kidney Stones: Kidney stones that become lodged at or near the UPJ can obstruct urine flow. These stones may form within the renal pelvis or migrate from other parts of the urinary system.

  4. Scar Tissue (Stricture): Scar tissue can develop at the UPJ due to various factors, including previous surgical procedures, kidney stones, or infections. The formation of scar tissue can cause narrowing or partial blockage.

  5. Tumors: Rarely, tumors in or around the UPJ area can obstruct urine flow. These tumors may be benign or malignant and require treatment.

  6. Inflammation or Infection: Infections, such as pyelonephritis (kidney infection), can lead to inflammation and scarring near the UPJ. This scarring can potentially result in obstruction.

It's important to note that congenital UPJ obstruction is the most common type and is typically identified in children or young adults. This condition may not become symptomatic until later in life when urine flow becomes more substantial.



The severity of symptoms can vary depending on the extent of the obstruction. Common symptoms of UPJ obstruction may include:

  1. Flank Pain: The most common symptom of UPJ obstruction is persistent or recurrent pain in the flank (the area between the lower ribs and the hip). The pain is typically felt on the side of the affected kidney and may be described as a dull ache, discomfort, or sharp pain. The pain may come and go, but it often worsens when the kidney is working harder, such as after drinking fluids.

  2. Renal Colic: Some individuals with UPJ obstruction may experience episodes of renal colic, which are intense, cramp-like pain in the flank or lower back. This can be similar to the pain caused by kidney stones.

  3. Urinary Tract Infections (UTIs): UPJ obstruction can lead to recurrent UTIs, as urine may not flow freely from the affected kidney. UTI symptoms may include frequent urination, painful urination, cloudy urine, and fever.

  4. Hematuria: Blood in the urine (hematuria) may occur in individuals with UPJ obstruction. This can be visible as pink, red, or brown urine or may be detected only through microscopic analysis of the urine.

  5. Nausea and Vomiting: Some people with UPJ obstruction may experience nausea and vomiting, especially during episodes of severe pain.

  6. Abdominal Pain: In addition to flank pain, individuals with UPJ obstruction may experience abdominal pain or discomfort, which can radiate to the lower abdomen.

  7. Hydronephrosis: In cases of UPJ obstruction, the affected kidney may become swollen due to the buildup of urine (hydronephrosis). This swelling can sometimes be visible or palpable in the abdominal area.

It's important to note that the severity and presence of these symptoms can vary from person to person. In some cases, UPJ obstruction may be asymptomatic and only detected incidentally during medical imaging for other reasons. However, when symptoms are present, they often result from increased pressure in the renal pelvis and renal parenchyma, as urine cannot freely flow from the kidney to the ureter.
If you or someone you know is experiencing symptoms suggestive of UPJ obstruction, it is important to consult with a healthcare provider for a proper evaluation and diagnosis. Diagnostic tests, such as ultrasound, CT scans, or intravenous pyelography, may be needed to confirm the presence and severity of the condition. Early diagnosis and appropriate treatment can help preserve kidney function and alleviate symptoms.


The diagnosis of Ureteropelvic Junction (UPJ) obstruction typically involves a series of medical evaluations and imaging studies to assess the condition and its severity. Here are the common diagnostic steps and tests used to confirm UPJ obstruction:

  1. Medical History and Physical Examination: The healthcare provider will begin by taking a detailed medical history and conducting a physical examination. They will inquire about symptoms, such as flank pain, urinary tract infections, hematuria, and other relevant information.

  2. Blood and Urine Tests: Blood tests, such as a complete blood count (CBC) and a basic metabolic panel (BMP), may be performed to assess kidney function and the presence of infection. Urinalysis can help identify any blood or signs of infection in the urine.

  3. Imaging Studies:

    • Ultrasound: A renal ultrasound is a non-invasive imaging test that can provide initial information about the kidneys and the presence of hydronephrosis (swelling of the kidney) indicative of UPJ obstruction.

    • CT Scan: A contrast-enhanced CT scan is often used to provide detailed images of the urinary system, including the renal pelvis, ureter, and UPJ. It can help confirm the diagnosis and assess the severity of the obstruction.

    • Intravenous Pyelography (IVP): An IVP is a specialized X-ray procedure that involves injecting a contrast dye into the bloodstream to highlight the urinary tract structures. It can provide dynamic images of the kidney and the flow of contrast through the ureter and may reveal the site of obstruction.

    • Magnetic Resonance Urography (MRU): MRU is an imaging technique that uses MRI to visualize the urinary tract and can provide information about UPJ obstruction and its impact on kidney function.

  4. Renal Scintigraphy: A renal nuclear scan may be used to assess the function of each kidney and determine if there is reduced function in the affected kidney due to UPJ obstruction.

  5. Cystoscopy: In some cases, a cystoscopy may be performed to examine the bladder and lower urinary tract to rule out other possible causes of symptoms.

Once UPJ obstruction is confirmed, the healthcare provider will assess the severity of the condition to determine the most appropriate treatment approach. Treatment options may include observation and monitoring, surgical intervention (pyeloplasty) to repair the obstruction, or other minimally invasive procedures, depending on the specific circumstances and the patient's overall health.
If you suspect UPJ obstruction or have symptoms suggestive of this condition, it is essential to seek medical evaluation and diagnosis by a healthcare provider or urologist. Early diagnosis and appropriate treatment can help preserve kidney function and alleviate symptoms.


The treatment of Ureteropelvic Junction (UPJ) obstruction typically involves surgical intervention to alleviate the blockage and restore normal urine flow. The choice of treatment approach depends on the severity of the obstruction, the patient's overall health, and the specific circumstances. Here are the common treatment options for UPJ obstruction:

  1. Pyeloplasty: Pyeloplasty is the most common and effective surgical procedure for UPJ obstruction. It involves the reconstruction or repair of the UPJ area to create a wider and unobstructed passage for urine to flow freely from the renal pelvis to the ureter. There are several types of pyeloplasty:

    • Open Pyeloplasty: In an open pyeloplasty, a surgical incision is made in the abdomen or flank to access the kidney and UPJ area. This approach allows the surgeon to directly repair the obstruction.

    • Laparoscopic or Robot-Assisted Laparoscopic Pyeloplasty: Minimally invasive procedures can be performed using small incisions and specialized instruments. This approach often results in shorter hospital stays and quicker recovery times compared to open surgery.

  2. Endopyelotomy: In some cases, particularly for less severe UPJ obstructions, an endopyelotomy may be performed. This minimally invasive procedure involves using a flexible, thin instrument (ureteroscope) to access the UPJ and make incisions or remove obstructive tissue.

  3. Stent Placement: In emergency situations or for patients who are not candidates for surgery, a temporary or permanent stent may be placed to maintain urine flow. However, stents are not typically considered a definitive treatment and may be associated with complications.

  4. Nephrectomy: In rare and severe cases where the affected kidney is nonfunctional, causing significant health problems, or if there are severe complications, surgical removal of the kidney (nephrectomy) may be necessary.

The choice of treatment is made on an individual basis, taking into consideration the patient's overall health, the severity of the obstruction, and the potential for preserving kidney function. Pyeloplasty is considered the gold standard for treating UPJ obstruction because it directly addresses the underlying problem and typically results in improved urine flow and relief of symptoms.
After surgical intervention, individuals will be closely monitored to assess kidney function and ensure that urine flow has been restored. Most people experience significant relief from symptoms and improved kidney function after treatment.
It's important to consult with a urologist or healthcare provider to determine the most appropriate treatment approach for UPJ obstruction. Early diagnosis and intervention are essential to prevent complications and preserve kidney health.


The complications of Ureteropelvic Junction (UPJ) stenosis can be significant if the condition is not treated in a timely manner. UPJ stenosis refers to a narrowing or blockage at the junction where the ureter meets the renal pelvis, impeding the normal flow of urine from the kidney to the bladder. Here are some potential complications associated with UPJ stenosis:

  1. Hydronephrosis: This is the swelling of the kidney due to the buildup of urine. It occurs because the urine cannot flow normally through the obstructed UPJ. Over time, hydronephrosis can lead to kidney damage.

  2. Kidney Damage: Prolonged obstruction can result in damage to the kidney tissues. In severe cases, this can lead to loss of kidney function in the affected kidney, known as renal atrophy.

  3. Urinary Tract Infections (UTIs): The stasis of urine due to UPJ stenosis can lead to an increased risk of infections in the urinary tract. Recurrent UTIs are common in individuals with untreated UPJ obstruction.

  4. Kidney Stones: The reduced urine flow and stasis can also create an environment conducive to the formation of kidney stones, which can be painful and may require additional treatment.

  5. Pain: UPJ stenosis can cause flank pain or pain in the back, which can range from mild to severe. The pain is often related to the buildup of urine and increased pressure in the kidney.

  6. Hypertension: In some cases, chronic obstruction at the UPJ can lead to elevated blood pressure, although the exact mechanism is not fully understood.

  7. Decreased Kidney Function: If left untreated, UPJ stenosis can lead to a progressive decline in the overall function of the affected kidney.

  8. Urinary Leakage or Fistula Formation: In rare cases, prolonged high pressure in the kidney due to severe UPJ stenosis can lead to the formation of abnormal connections (fistulas) or leakage of urine.

  9. Psychological Impact: Chronic pain and recurrent urinary problems can have a significant impact on quality of life, leading to psychological stress or depression in some individuals.

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