The signs and symptoms of hydronephrosis depend upon whether the obstruction is acute or chronic, partial or complete, unilateral or bilateral. Unilateral hydronephrosis may occur without any symptoms, while acute obstruction can cause intense pain.
Where the obstruction occurs in the lower urinary tract, suprapubic tenderness (with or without a history of bladder outflow obstruction) along with a palpable bladder are strongly suggestive of acute urinary retention, which left untreated is highly likely to cause hydronephrosis.
Upper urinary tract obstruction is characterised by pain in the flank, often radiating to either the abdomen or the groin. Where the obstruction is chronic, renal failure may also be present. If the obstruction is complete, an enlarged kidney is often palpable on examination.
The obstruction may arise from either inside or outside the urinary tract or may come from the wall of the urinary tract itself. Intrinsic obstructions (those that occur within the tract) include blood clots, stones, sloughed papilla along with tumours of the kidney, ureter and bladder. Extrinsic obstructions (those that are caused by factors outside of the urinary tract) include pelvic or abdominal tumours or masses, retroperitoneal fibrosis or neurological deficits. Strictures of the ureters (congenital or acquired), neuromuscular dysfunctions or schistosomiasis are other causes which originate from the wall of the urinary tract.
Blood (U&E, creatinine) and urine (MSU, pH) tests should be taken. IVUs, ultrasounds, CTs and MRIs are also important tests. Ultrasound allows for visualisation of the ureters and kidneys and can be used to assess the presence of hydronephrosis and/or hydroureter. An IVU is useful for assessing the position of the obstruction. Antegrade or retrograde pyelography will show similar findings to an IVU but offer a therapeutic option as well.
The choice of imaging depends on the clinical presentation (history, symptoms and examination findings). In the case of renal colic (one sided loin pain usually accompanied by a trace of blood in the urine) the initial investigation is usually an intravenous urogram. This has the advantage of showing whether there is any obstruction of flow of urine causing hydronephrosis as well as demonstrating the function of the other kidney. Many stones are not visible on plain xray or IVU but 99% of stones are visible on CT and therefore CT is becoming a common choice of initial investigation. MRI is less commonly used, often when there is a reason to avoid radiation exposure, e.g. in pregnancy.
Acute obstruction of the upper urinary tract is usually treated by the insertion of a nephrostomy tube. Chronic upper urinary tract obstruction is treated by the insertion of a ureteric stent or a pyeloplasty.