Hydronephrosis: Symptoms, Types, Causes and Treatment

Hydronephrosis is a medical condition characterized by abnormal dilation or swelling of the kidney’s collecting system due to impaired drainage of urine. This can affect one or both kidneys, and the presentation, underlying causes, and management strategies can vary widely depending on age, severity, and etiology. Early detection and appropriate intervention are essential to prevent permanent kidney damage. In this comprehensive article, we will explore the symptoms, types, causes, and treatment options for hydronephrosis, synthesizing current evidence and clinical perspectives.

Symptoms of Hydronephrosis

Hydronephrosis can be a silent condition, especially when mild or detected early through routine imaging. However, as the severity increases or if the obstruction persists, symptoms can develop. Recognizing these symptoms is crucial for timely diagnosis and intervention.

Symptom	Description	Age Group	Source
Flank/Abdominal Pain	Intermittent or persistent pain in side or abdomen	Children, Adults	1 2 9
Abdominal Mass	Palpable swelling in the abdomen/flank	Infants, Children	1 2
Hematuria	Blood in the urine, visible or microscopic	All Ages	1 9
Nausea/Vomiting	Gastrointestinal discomfort, sometimes with pain	All Ages	1 2
Urinary Tract Infection (UTI)	Fever, dysuria, pyelonephritis	Children	2 9
Kidney Stones	Pain, urinary symptoms, possible infection	All Ages	1 9 12
Growth Retardation/Anemia	Impaired growth or anemia due to chronic disease	Children	2
Hypertension	Elevated blood pressure	Children, Adults	2
Rare Symptoms	Unusual symptoms like intractable hiccups	Adults (rare)	3

Table 1: Key Symptoms

Common Presentations

The clinical presentation of hydronephrosis depends on several factors, including age, cause, and whether the condition is acute or chronic.

• Infants and Children: In neonates, hydronephrosis is often detected before birth via prenatal ultrasound, and most are asymptomatic at birth. A palpable abdominal mass was historically common in infants but is now less frequent due to early detection. In older children, symptoms can include abdominal or flank pain, hematuria, urinary tract infection, or palpable mass 1 2 5.
• Adults: Flank or abdominal pain is the most common presenting symptom in adults. Other symptoms include hematuria, urinary symptoms, nausea, vomiting, and, less commonly, hypertension. When hydronephrosis develops gradually, symptoms may be subtle until significant renal impairment occurs 1 9 12.

Symptom Severity and Progression

• Acute vs. Chronic: Sudden obstruction (e.g., kidney stone) often produces severe pain, while chronic or partial obstruction may present with milder, intermittent symptoms or may remain silent for long periods 11.
• Complications: Prolonged hydronephrosis can lead to urinary tract infections, stone formation, loss of kidney function, hypertension, and in rare cases, unusual symptoms such as intractable hiccups due to massive kidney swelling compressing adjacent organs 3.
• Systemic Effects in Children: Chronic cases in children may result in growth retardation, anemia, and hypertension, especially if bilateral or associated with infection 2.

Types of Hydronephrosis

Hydronephrosis is not a single disease but a manifestation that can be classified by laterality, anatomical location, obstruction status, and severity. Understanding the types is essential for guiding diagnosis and management.

Type	Characteristic	Distinction Basis	Source
Unilateral	Affects one kidney	Laterality	6 9
Bilateral	Involves both kidneys	Laterality	6
Obstructive	Caused by physical blockage	Etiology	7 11
Non-obstructive	Not caused by obstruction	Etiology	7
Renal	Dilatation mainly in the kidney	Anatomical location	6
Pelvic	Dilatation predominantly in the renal pelvis	Anatomical location	6 7
Open	Urine escapes from the sac	Functional status	6
Closed	Urine does not escape from the sac	Functional status	6
Giant	Extreme dilation with massive enlargement	Severity	3 15

Table 2: Hydronephrosis Types

Laterality

• Unilateral Hydronephrosis: Involves one kidney and is often due to obstruction above the bladder, such as stones, congenital junction anomalies, or strictures 6 9.
• Bilateral Hydronephrosis: Both kidneys are affected, usually due to bladder outlet obstruction, prostatic disease, or congenital lower urinary tract anomalies 6 7.

Obstructive vs. Non-obstructive

• Obstructive Hydronephrosis: Results from a physical blockage in the urinary tract (e.g., stones, strictures, tumors), leading to increased pressure, backflow, and kidney swelling 7 11.
• Non-obstructive Hydronephrosis: Occurs without a mechanical blockage; possible causes include congenital abnormalities, pregnancy-related changes, or functional disturbances such as neurogenic bladder 7.

Anatomical and Functional Variants

• Renal vs. Pelvic: The degree and location of dilation depend on the level of obstruction and kidney anatomy. Lower ureteral obstruction leads to more renal-type hydronephrosis; higher obstructions result in pelvic predominance 6.
• Open vs. Closed: "Open" hydronephrosis allows some urine to escape from the dilated system, while "closed" does not, potentially worsening the condition 6.

Severity and Grading

Hydronephrosis is often graded (I-IV) based on imaging findings, which reflect the extent of dilation and thinning of renal tissue. "Giant hydronephrosis" refers to massive enlargement where the kidney is replaced by a large fluid-filled sac, sometimes occupying much of the abdomen 3 15.

Causes of Hydronephrosis

A wide array of conditions, both congenital and acquired, can cause hydronephrosis. Identifying the underlying cause is key to selecting appropriate treatment and preventing irreversible kidney damage.

Cause Category	Example Conditions	Typical Age Group	Source
Congenital	Ureteropelvic junction obstruction (UPJO), vesicoureteral reflux, posterior urethral valves	Infants, Children	1 2 5 7
Acquired	Kidney/ureteric stones, tumors, strictures, infection, trauma, pregnancy	Adults, Elderly	1 7 9 12
Functional	Neurogenic bladder, dysfunctional voiding	All Ages	7
Extrinsic Compression	Tumors, aneurysms, fibrous bands, prostatic hypertrophy	Adults	7 12
Inflammatory	Ureteritis, post-infective strictures	All Ages	1 13

Table 3: Causes of Hydronephrosis

Congenital Causes

• Ureteropelvic Junction Obstruction (UPJO): The most common cause of hydronephrosis in children, often due to abnormal muscle arrangement at the junction preventing normal urine flow 1 2 8.
• Vesicoureteral Reflux: Backflow of urine from the bladder to the kidneys, which can cause dilation and infection 5.
• Posterior Urethral Valves: Congenital abnormality in boys causing bladder outlet obstruction and often bilateral hydronephrosis 5.

Acquired Causes

• Stones: Ureteric and kidney stones are the leading causes of hydronephrosis in adults, accounting for up to 70% of unilateral cases 9 12.
• Tumors: Both benign and malignant tumors (bladder, prostate, gynecologic) can compress or invade the urinary tract, leading to obstruction 7 12.
• Strictures and Trauma: Post-surgical, inflammatory, or ischemic strictures, as well as direct injury, can narrow the urinary tract 1 7.
• Pregnancy: Physiological changes during pregnancy can lead to transient hydronephrosis due to uterine compression or hormonal effects 7 12.

Functional and Inflammatory Causes

• Neurogenic Bladder: Disorders affecting nerve control of the bladder can cause urinary retention and secondary hydronephrosis 7.
• Ureteritis: Inflammation of the ureter can cause swelling and narrowing, as seen in certain immune-mediated or infectious conditions 13.
• Other Factors: Extrarenal causes such as fibrous bands, aneurysms, or abnormal vessels can compress the ureter externally 7.

Treatment of Hydronephrosis

Treatment of hydronephrosis is highly individualized, depending on the etiology, severity, patient age, and degree of renal function impairment. The main goals are to relieve obstruction, preserve or restore kidney function, and prevent complications.

Treatment Approach	Indication/Goal	Typical Methods	Source
Observation	Mild/asymptomatic, stable renal function	Regular imaging, monitoring	1 2 5
Minimally Invasive	Stones, mild obstruction	Ureteroscopy, stenting, endourology	1 9 12
Surgical	Significant obstruction, failed minimally invasive	Pyeloplasty, nephrectomy, ureteric reconstruction	1 3 15
Medical	Infection, inflammation, symptom control	Antibiotics, analgesics	2 13
Special Procedures	Giant hydronephrosis, complex cases	Open/laparoscopic surgery, nephrectomy	3 15

Table 4: Treatment Strategies

Observation and Monitoring

• When Appropriate: Asymptomatic or mild cases, especially those detected prenatally or incidentally, may only require regular follow-up with imaging and renal function tests 1 2 5.
• Goal: Monitor for progression, development of symptoms, or declining function that would necessitate intervention.

Minimally Invasive and Endourological Interventions

• Stone Disease: The majority of adult cases are managed effectively by removing stones via ureteroscopy, lithotripsy, or DJ stenting to relieve obstruction 9 12.
• Stenting: Placement of a temporary stent can bypass the obstruction, restore urine flow, and allow for definitive treatment later 9 12.

Surgical Management

• Pyeloplasty: Gold standard for UPJO, especially in children and young adults, using open, laparoscopic, or robotic approaches to reconstruct the obstructed segment 1.
• Nephrectomy: Reserved for non-functioning kidneys or giant hydronephrosis with irreversible damage 3 15.
• Complex Reconstructions: In extensive or recurrent strictures or after failed primary surgery, ureteral substitution with a segment of bowel or bladder may be considered 15.

Medical Therapy

• For Infections: Antibiotics are essential for urinary tract infections, especially in children, to prevent pyelonephritis and further renal injury 2.
• Symptom Relief: Analgesics and supportive care for pain and associated symptoms 2.

Special Considerations

• Giant Hydronephrosis: May require nephrectomy or complex reconstruction, based on residual function and underlying cause 3 15.
• Pediatric Patients: Early detection and close follow-up are critical to minimize the risk of irreversible kidney damage; surgical intervention is guided by symptoms, severity, and function 2 5.

Conclusion

Hydronephrosis is a complex condition that can present with a range of symptoms, from silent dilation to severe pain and kidney damage. It encompasses various types and causes, from congenital anomalies in infants to acquired obstructions in adults. Timely diagnosis through imaging and careful assessment of symptom severity and renal function are essential for optimal management.

Key Takeaways:

• Hydronephrosis can be asymptomatic or present with pain, hematuria, infection, and rare symptoms like intractable hiccups.
• It is classified by laterality, obstruction status, anatomical location, and severity.
• Causes range from congenital anomalies (e.g., UPJO, vesicoureteral reflux) to acquired conditions (stones, tumors, strictures).
• Treatment is tailored to the cause and severity, from observation and minimally invasive procedures to complex surgery and nephrectomy.
• Early detection and intervention are crucial to preserve kidney function, especially in children.

By understanding the nuances of hydronephrosis, clinicians and patients alike can better navigate the path from diagnosis to recovery, ensuring the best possible outcomes.