Hydronephrosis

Definition/diagnostic criteria Hydronephrosis is characterised by the dilation or swelling of one or both kidneys due to the accumulation of urine. It occurs as a result of an obstruction in the urinary tract or from a condition that impedes the normal flow of urine. This can lead to kidney dysfunction if not promptly addressed.

Epidemiology Hydronephrosis can affect individuals of any age, including neonates, where it is often detected prenatally during routine ultrasounds. Its prevalence is not fully defined due to the variability of underlying causes, but it is a relatively common finding in urological practice. It is crucial to differentiate between congenital and acquired causes to manage the condition effectively.

Diagnosis
Clinical features: Patients with hydronephrosis may present with flank pain, abdominal pain, urinary tract infection symptoms, or the condition may be asymptomatic, found incidentally during imaging for other reasons. The presentation can vary significantly depending on the underlying cause, duration, and whether the condition is unilateral or bilateral.

Investigations: Investigations aim to confirm the diagnosis, identify the underlying cause and assess the impact on kidney function. Typical first-line investigations include:

• Ultrasound scan: A non-invasive method to detect dilation of the renal pelvis and assess the severity.
• Blood tests: To assess kidney function (serum creatinine, urea and electrolytes).
• Urinalysis: To detect infection or haematuria.

Further diagnostic imaging, like CT urography or MRI, may be necessary for certain cases, especially if the ultrasound findings are inconclusive or if there is a need to delineate the anatomy more precisely.

Treatment Treatment of hydronephrosis focuses on relieving the obstruction, treating the underlying cause, and preserving kidney function. Management may vary significantly based on the underlying cause, severity, and presence of symptoms or complications:

• Conservative management: Observation and regular follow-up may be appropriate for mild, asymptomatic cases.
• Medical treatment: In cases caused by infection or stones, appropriate antibiotics or medications to facilitate stone passage.
• Surgical intervention: Required for cases where there is a structural obstruction (like ureteropelvic junction obstruction or urolithiasis) or for decompression of the urinary system (e.g. stent placement or percutaneous nephrostomy).

The choice of treatment is individualised, taking into consideration patient-specific factors, the underlying cause, and the severity of hydronephrosis.

Prognosis The prognosis of hydronephrosis largely depends on the cause, severity at diagnosis, and promptness of treatment. Early diagnosis and management are crucial for a favourable outcome. Chronic, untreated hydronephrosis can lead to permanent kidney damage and renal failure. However, with timely and appropriate treatment, most individuals can expect good recovery and preservation of kidney function.