Hydronephrosis overview
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# Overview

# Historical Perspective
Ureteral anatomy and the function of the ureterovesical junction was first discovered by Galen, Leonardo da Vinci and John Sampson.In 1950s, Hodson and Edwards was the first to discover the association between association of VUR with renal scarring.
- Ureteral anatomy and the function of the ureterovesical junction was first discovered by Galen, Leonardo da Vinci drawings and John Sampson dissections.
- In 1950s, Hodson and Edwards was the first to discover the association between association of VUR with renal scarring from bacterial infection and the development of hydronephrosis.
- In 1952, Hutch performed the first antireflux surgery in paraplegic patients.
- In 1717,  the first to description of obstruction of the posterior urethra (PUO) was by Morgagni.

# Classification

# Pathophysiology
Hydronephrosis can result from anatomic or functional processes interrupting the flow of urine. This interruption can occur anywhere along the urinary tract from the kidneys to the urethral meatus. The rise in ureteral pressure leads to marked changes in glomerular filtration, tubular function, and renal blood flow. The glomerular filtration rate (GFR) declines significantly within hours following acute obstruction. This significant decline of GFR can persist for weeks after relief of obstruction. In addition, renal tubular ability to transport sodium, potassium, and protons and concentrate and to dilute the urine is severely impaired.

# Causes
Hydronephrosis is commonly caused by conditions that obstruct urine outflow anywhere between kidneys and urethral opening. It is also caused by non obstructive conditions in some cases. Most common causes of hydronephrosis are renal calculi, ureteropelvic junction obstruction, vesicoureteric reflux, carcinoma involving urinary tract, prostate enlargement and cancer, blood clots retention and external compression from pelvic and abdominal tumors such as ovarian cysts, and retroperitoneal fibrosis.

# Differentiating Hydronephrosis from other Diseases
Hydronephrosis must be differentiated from parapelvic cyst, renal sinus lymphangiectasia, pyelonephritis, cystitis, ovarian cyst, pelvic tumor

# Epidemiology and Demographics
The incidence and prevalence of hydronephrosis varies according to the underlying cause. Case fatality rate of hydronephrosis is 3.1 per 100 000 individuals.

# Risk Factors
Common risk factors in the development of hydronephrosis include renal calculi, external compression from abdominal and pelvic masses and tumors such as prostate enlargement and cancer, cervical cancer, diabetes mellitus and neurogenic bladder, congenital anomalies of the kidney and urinary tract (CAKUT) such as vesicoureteric reflux, ureteropelvic junction obstruction and posterior urethral valves.

# Screening
There is insufficient evidence to recommend routine screening for hydronephrosis.

# Natural History, Complications and Prognosis
Common complications of hydronephrosis include infections, hyperkalemia, metabolic acidosis, and distal renal tubular acidosis, hypertension and renal failure.

# Diagnosis

## Diagnostic study of choice
Early diagnosis of hydronephrosis is important because most of the cases can be reversed if not treated promptly lead to irreversible renal injury.Hydronephrosis is usually diagnosed using an ultrasound scan.

## History and symptoms
The majority of patients with hydronephrosis are asymptomatic.The most common symptoms of hydronephrosis include alteration in urine output, pain, hematuria and hypertension.

## Physical examination
Patients with hydronephrosiscomplain presence of pain based on the site of the obstruction and the degree of the obstruction. Patients commonly present with abdominal distension, palpable kidney, costovertebral tenderness and palpable bladder may be seen.

## Lab findings
Some patients with hydronephrosis may have elevated WBC count, serum creatinine, BUN, potassium levels and pyuria.

## EKG
- There are no EKG findings associated with hydronephrosis

## X-ray
An x-ray may be helpful in the diagnosis of hydronephrosis. Findings on an x-ray suggestive of hydronephrosis include renal enlargement, cortical thinning and rim sigh.

## Echocardiogram and Ultrasound
Early diagnosis of hydronephrosis is important because most of the cases can be reversed if not treated promptly lead to irreversible renal injury.Hydronephrosis is usually diagnosed using an ultrasound scan.

## CT scan
Abdominal CT scan may be helpful in the diagnosis of hydronephrosis. Findings on CT scan suggestive of hydronephrosis include dilation of the proximal ureter, identification of the site of obstruction and calyceal blunting.

## MRI
Abdomen MRI may be helpful in the diagnosis of hydronephrosis. Findings on MRI suggestive of hydronephrosis include renal perfusion and renal diffusion during acute ureteral obstruction.

## Other Imaging findings
There are no other imaging findings associated with hydronephrosis.

## Other diagnostic studies
There are no other diagnostic studies associated with hydronephrosis.

# Treatment

## Medical therapy
The goal of treatment for hydronephrosis is to restart the free flow of urine from the kidney and decrease the swelling and pressure that builds up and decreases kidney function.The initial care for the patient is aimed at minimizing pain and preventing urinary tract infections. Otherwise, surgical intervention may be required.

## Surgery
- Surgery is the mainstay of treatment for Hydronephrosis. The type of surgery depends on the underlying cause and also depending on whether the obstruction is acute or chronic.

## Primary prevention
There are no established measures for the primary prevention of hydronephrosis

## Secondary prevention
There are no established measures for the secondary prevention of hydronephrosis