Definition

Hydronephrosis is a condition characterized by the swelling and widening of the kidney due to the accumulation of urine. This condition can affect individuals of all ages, both male and female and may occur in one or both kidneys. Hydronephrosis can also manifest in babies still in the womb, a condition known as antenatal hydronephrosis. Hydronephrosis typically serves as a symptom of an underlying condition that existed previously.

Causes

Hydronephrosis is typically caused by a blockage in the urinary system, which disrupts the flow of urine from the body. The urinary system consists of the kidney, ureter, bladder, and urethra. If there is a blockage in any part of this system, urine may not be expelled properly or could even flow back into the kidney. As a result, urine accumulates in the kidney, leading to swelling and enlargement. Hydronephrosis more commonly affects one kidney, but it is possible for it to occur in both kidneys.

In adults, several diseases and conditions can lead to hydronephrosis, including:

• Kidney stones: Small stones may obstruct the ureter, impeding the flow of urine.
• Prostate enlargement: Common in older men, an enlarged prostate gland can press against the urethra, leading to urinary obstruction.
• Uterine enlargement: Enlargement of the uterus, often during pregnancy, can exert pressure on the ureter, causing obstruction.
• Ureteral narrowing: This condition may result from injury, surgery, or infection in the ureter, leading to a restricted urine flow.
• Nerve damage affecting the urinary system: Nerve damage, particularly in the bladder, can disrupt the normal process of emptying the bladder efficiently.
• Cancer or tumors: Tumors in the ureter or bladder can obstruct urine flow.
• Blood clots: Blood clots that block blood vessels may lead to impaired kidney function.
• Ovarian cysts: Cysts in the ovaries can exert pressure on the ureter, causing obstruction and subsequent hydronephrosis.

Antenatal hydronephrosis occurs in babies in the womb, and the exact cause is sometimes unknown. This condition can be detected during prenatal ultrasound examinations. Some possible causes of antenatal hydronephrosis include:

• Increased fetal urine production late in pregnancy.
• Transient dilation or temporary widening of the ureter due to the influence of pregnancy hormones. This condition typically resolves after the baby is born.
• Vesicoureteral reflux: This occurs when urine flows back from the bladder into the ureter due to malfunctioning valves, potentially leading to urine refluxing back into the kidneys.
• Anatomical abnormalities.

Risk factor

Based on its causes, it can be concluded that hydronephrosis often arises due to specific diseases. Consequently, the risk factors for hydronephrosis increase in conditions where these diseases are not well managed. Some diseases that can cause hydronephrosis include:

• Kidney stones
• History of previous kidney surgery or injury
• Presence of tumors or cancer in the bladder, cervix, large intestine, or prostate
• Prostate enlargement
• Pregnancy
• Urinary tract infections
• Congenital or birth-related obstructions
• Blood clots

Symptoms

The symptoms of hydronephrosis vary depending on the primary causes. However, in antenatal hydronephrosis, the causes are often unknown. Symptoms of hydronephrosis in adults include:

• Pain in the lower back or flank on one side: The pain may occur suddenly and be severe, or it may be mild but recurrent. It may worsen after drinking a lot of water, especially in cases of kidney stone obstruction
• Nausea and vomiting
• Problems with urination: This may include pain during urination, increased frequency of urination, or decreased urine output
• Presence of blood in the urine or hematuria
• Fever
• Delayed growth and development in children

Diagnosis

Diagnosis of hydronephrosis is established after the doctor conducts a medical interview about the symptoms, followed by physical examinations and diagnostic tests to determine the underlying causes. During the physical examination, the doctor may palpate the kidneys externally, and in cases of severe hydronephrosis, the kidney may be palpable. Some diagnostic tests include:

• Ultrasonography (USG): This imaging technique uses sound waves to create images of the inside of the body, particularly the kidneys. Swelling in the kidney indicative of hydronephrosis can be visualized.
• Blood tests: These tests help confirm infections, assess kidney function, and measure urea levels in the body.
• Urine tests or urinalysis: These tests are performed to detect infections or kidney stone minerals in the urine.
• Intravenous urography (IVU): This examination involves the injection of a contrast agent or dye into the bloodstream, followed by X-rays of the kidneys. Contrast helps visualize urine flow along the urinary tract and identify any obstructions.
• CT scan: This test is performed if the kidneys are not adequately visualized on ultrasound or intravenous urography.

In babies with antenatal hydronephrosis, the diagnosis is made during the mother's pregnancy. Antenatal hydronephrosis is detected through ultrasound examinations after the 20th week of pregnancy. Subsequent ultrasound examinations are routinely performed to monitor the progression (severity) of the condition. Further examinations are conducted after the baby is born.

Management

Treatment of hydronephrosis is tailored to the specific condition and severity of the disease. In adults, the treatment principles include:

• Expelling accumulated urine and reducing kidney pressure.
• Preventing permanent kidney damage.
• Managing the underlying causes of the disease.

Following these management principles, several steps are typically taken in cases of hydronephrosis:

• Drainage of urine from the body: This is often achieved through catheterization, which can alleviate pain and prevent further kidney damage. Catheterization involves inserting a small tube through the urethra into the bladder. If obstruction prevents this, a suprapubic catheter may be inserted through the abdominal wall.
• Addressing the underlying causes of the disease: Hydronephrosis can result from various conditions that must be treated first, such as:
• Kidney stones: Treatment may involve shock wave lithotripsy or specific surgical procedures to remove the stones.
• Prostate enlargement: Management options include medication or prostate removal surgery.
• Ureteral narrowing: This can be addressed using stents or short tubes to widen the narrowed ureter.
• Cancer: Treatment may involve chemotherapy, radiotherapy, or surgical removal of cancerous tissue.
• Urinary tract infections: These are typically treated with antibiotics and pain medication.

Antenatal hydronephrosis in babies usually does not require specific treatment. The condition typically improves after birth and over the following months, with no risk to the mother or baby. However, the baby may require follow-up examinations several weeks after birth to monitor disease progression, typically through ultrasound examinations. Before considering the baby's recovery from hydronephrosis, the doctor may prescribe antibiotics to reduce the risk of urinary tract infections.

Complications

The most common complication in cases of hydronephrosis is urinary tract infection (UTI). Urine retention can create an environment conducive to bacterial growth, increasing the risk of infection. UTIs may ascend to the kidneys, causing pyelonephritis (kidney infection), or spread to the bloodstream, leading to sepsis. Untreated hydronephrosis can result in permanent kidney damage. However, kidney failure is rare because the kidneys can still function adequately even if one of them is not working properly. Conversely, antenatal hydronephrosis typically does not lead to serious complications. 

Prevention

Preventing hydronephrosis involves addressing the prevention of its underlying conditions. Here are some preventive measures that can be taken at home:

• Stay adequately hydrated.
• Maintain personal hygiene, especially in the genital area.
• Avoid delaying urination when you feel the urge to go.
• Reduce consumption of high-sodium foods.
• Seek prompt medical evaluation and treatment if you experience symptoms of prostate enlargement.
• Undergo regular medical check-ups if you have a family history of cancer to detect any potential issues early on.

When to see a doctor?

Seek medical attention if you experience any of the symptoms mentioned or have a history of the mentioned conditions. Hydronephrosis can be effectively managed when its underlying cause is identified. Some warning signs to watch out for include severe pain in the lower back or abdomen, severe vomiting, and a fever above 39°C. Seek immediate medical care at the nearest healthcare facility for prompt treatment.

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