Urosurgery Hydronephrosis

Hydronephrosis is an aseptic dilatation of the kidney caused by obstruction.

• Extramural obstruction
• ¬ Tumour from adjacent structures, e.g. cervix, prostate, rectum, colon or caecum
• ¬ Idiopathic retroperitoneal fibrosis
• ¬ Retrocaval ureter

• Intramural obstruction
• ¬ Congenital stenosis, physiological narrowing of the pelviureteric junction leading to pelviureteric junction obstruction
• ¬ Ureterocele and congenital small ureteric orifice
• ¬ Inflammatory stricture following removal of ureteric calculus, repair of a damaged ureter or tuberculous infection
• ¬ Neoplasm of the ureter or bladder cancer involving the ureteric orifice

• Intraluminal obstruction
• ¬ Calculus in the pelvis or ureter
• ¬ Sloughed papilla in papillary necrosis (especially in diabetics, analgesic abusers and sickle cell disease)

• Congenital:
• • posterior urethral valves
• • urethral atresia
• • Marion's disease

• Acquired:
• • benign prostatic enlargement or carcinoma of the prostate;
• • postoperative bladder neck scarring;
• • urethral stricture;
• • phimosis

Marion's disease is obstruction of the outlet of the bladder caused by enlargement of the muscle cells in the neck of the bladder

• There is calyceal dilatation and pressure atrophy of the kidney.
• A kidney destroyed by longstanding hydronephrosis is a thinwalled, lobulated, fluid-filled sac

More common in women and on the right.

• Presenting features include the following:
• • Mild pain or dull aching in the loin, often a dragging heaviness worstened by excessive fluid intake. The kidney may be palpable.
• • Intermittent hydronephrosis (Dietl’s crisis). Loin swelling is associated with acute renal pain. The pain goes and the swelling disappears when a large volume of urine is passed.
• • Antenatal detection in the fetus by ultrasound scan. Many of these cases are benign, but postnatal investigation is required to detect those with significant pelviureteric junction obstruction

From lower urinary obstruction - Symptoms of bladder outflow obstruction predominate. The kidneys are usually impalpable because renal failure intervenes before they enlarge.

From bilateral upper urinary tract obstruction - Idiopathic retroperitoneal fibrosis affects both ureters and idiopathic pelviureteric junction obstruction can be bilateral. Symptoms may be referred to one side

• „ Infection of the hydronephrotic kidney—lead to pyonephrosis.
• „ Nonfunctioning kidney—Long standing hydronephrosis causes back pressure changes in the kidney leading to thinning of the cortex and ultimately nonfunctioning kidney.
• „ Chronic renal failure—in bilateral hydronephrosis with deterioration of renal function on both sides will ultimately lead to chronic renal failure.

Obstruction of the ureter is diagnosed by a combination of ultrasound scanning and isotope renography

An obstructed kidney is worth preserving if it is contributing more than 20 per cent of total renal function

• The indications for operation
• - Bouts of renal pain
• - Increasing hydronephrosis
• - Evidence of parenchymal damage and
• - Infection.

A. Anderson–Hynes Pyeloplasty  -  upper third of the ureter and the renal pelvis are mobilised. A renal vein overlying the distended pelvis can be divided, but an artery in this situation should be preserved to avoid infarction of the territory that it supplies. The anastomosis is made in front of such an artery. A nephrostomy tube or a ureteric stent protects the anastomosis. 

B. Endoscopic pyelolysis - Disruption of the pelviureteric junction by a balloon passed up the ureter and distended under radiographic control has been used to treat idiopathic pelviureteric junction obstruction.

C. Nephrectomy should be considered only when the kidney has been largely destroyed. Mild cases should be followed by serial ultrasound scans and operated upon if dilatation is increasing.

• Congenital UPJ obstruction typically results from intrinsic disease. A frequently found defect is the presence of an aperistaltic segment of the ureter, perhaps similar to that found in primary obstructive megaureter.
• Controversy persists regarding the potential role of “aberrant” vessels in the etiology of UPJ obstruction
• Ureteral polyps and valves are seen but are rare.
• There is almost always an angulation and kink at the junction of the dilated renal pelvis and ureter

• Many cases are now diagnosed in utero. These tend to be primarily intrinsic lesions and many resolve spontaneously.
• Later, pain and vomiting are the most common symptoms; however, hematuria and urinary infection also may be seen.
• Complications such as calculi, trauma to the enlarged kidney

Prenatal USG - Hydronephrosis

Diuretic renography remains a commonly used study for diagnosing both UPJ and ureteral obstruction because it provides quantitative data regarding differential renal function and obstruction, even in hydronephrotic renal units. 

Significant difference - >20% (indication of intervention)

• Presence of symptoms associated with the obstruction
• Impairment of overall renal function or progressive impairment of ipsilateral function
• Development of stones or infection
• Causal hypertension

All successful repairs have in common the creation of a dependent and funnel-shaped ureteropelvic junction of adequate caliber.


Dismembered pyeloureteroplasty (Anderson & Hynes) is the procedure of choice. Anterior or posterior transposition of the UPJ can be achieved when the obstruction is due to accessory or aberrant lower pole vessels.

Both the Y-V plasty and the flap techniques are useful in managing ureteropelvic junction obstructions in horseshoe or pelvic kidneys, in which the anatomy may prevent creation of a dependent ureteropelvic junction if a dismembered technique is attempted.


Minimally invasive surgery - Endopyelotomy can be performed percutaneously or via ureteroscopy and treats the problem by incising directly through the obstruction, stenting the area and allowing healing via secondary intention.

• Indication of nephrectomy 
• - <1oml/min - in children 
• - <15ml/min - in adults 

• Tension free
• Dependent and funnel shaped drainage 
• Wide and watertight  anastomosis

• Refers to dramatic increase in urine output after the release of Urinary tract Obstruction. It is defined as high urine output exceeding (>200ml/hr) 0.5-1 L per hour after the obstruction is relieved.
• Patients with edema, hypertension, weight gain, and azotemia are most likely to exhibit this condition.

• Pyonephrosis refers to bacterial infection of a hydronephrotic, obstructed kidney, which leads to suppurative destruction of the renal parenchyma and potential loss of renal function.
• Because of the extent of the infection and the presence of urinary obstruction, sepsis may rapidly ensue, requiring rapid diagnosis and management.

Infection in the upper renal tract and obstruction - E.coli, Klebsiella, proteus, Candida

Obstruction due to stone in kidney, metastatic tumor arising from cancer of testis and colon, PUJO

Past history of kidney surgery and chronic infection of kidney can also lead to formation of renal abscess.

People with weakened immunity such as patients of HIV or diabetics are at greater risk of developing pyonephrosis due to infectious agents.

• Patients with pyonephrosis are usually very ill, with high fever, chills, and flank pain.
• Lower tract symptoms are not usually present.
• Bacteriuria and pyuria may not be present when there is complete obstruction of the affected kidney.

• - Fluid–debris level within the dilated renal pelvis that shift with position changes
• - Air in collecting system.
• - Renal or ureteral calculi may also be identified on ultrasonography.

• Immediate institution of antibiotic therapy and drainage of the infected collecting system.
• Performing drainage of the obstruction through the lower urinary tract (such as using a ureteral stent) should be reserved for patients who are not septic. Extensive manipulation may rapidly induce sepsis and toxemia.
• In the ill patient - percutaneous nephrostomy tube
• Once the infection is treated, additional imaging evaluation is required to identify the cause of the urinary obstruction, such as urolithiasis or ureteropelvic junction obstruction.

• Xanthogranulomatous pyelonephritis is a rare, severe, chronic renal infection typically resulting in diffuse renal destruction. Most cases are unilateral and result in a nonfunctioning, enlarged kidney associated with obstructive uropathy secondary to nephrolithiasis.
• Xanthogranulomatous pyelonephritis is characterized by accumulation of lipid-laden foamy macrophages. It begins within the pelvis and calyces and subsequently extends into and destroys renal parenchymal and adjacent tissues. It has been known to imitate virtually every other inflammatory disease of the kidney, as well as renal cell carcinoma, on radiographic examination. 

Pathogenesis - The primary factors involved in the pathogenesis of xanthogranulomatous pyelonephritis are nephrolithiasis, obstruction, and infection. 

Pathology -  The kidney is usually massively enlarged and has a normal contour. 

Clinical Presentation - It should be suspected in patients with UTIs and a unilateral  enlarged nonfunctioning or poorly functioning kidney with a stone or a mass lesion indistinguishable from malignant tumor. Most patients present with flank pain (69%), fever and chills (69%), and persistent bacteriuria (46%). Additional vague symptoms, such as malaise, may be present. On physical examination, 62% of the patients had a flank mass and 35% had previous calculi.

Bacteriology - Proteus to be the most common organism. E. coli is also common.

Investigation - CT is probably the most useful radiologic technique in evaluating patients with xanthogranulomatous pyelonephritis. Classic triad of unilateral renal enlargement with little or no function and a large calculus in the renal pelvis. CT usually demonstrates a large, reniform mass with the renal pelvis tightly surrounding a central calcification but without pelvic dilatation. 

• Treatment - 
• - Antimicrobial therapy
• - Rule out malignancy
• -  Nephrectomy - partial or total

The essential features are asymmetry and irregularity of the kidney outlines,blunting and dilation of one or more calyces, and cortical scars at the corresponding site

Obstructive uropathy is structural or functional hindrance of normal urine flow, sometimes leading to renal dysfunction (obstructive nephropathy).

Obstructive nephropathy is renal dysfunction (renal insufficiency, renal failure, or tubulointerstitial damage) resulting from urinary tract obstruction.

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The terms radionuclide, radioisotope, radio tracer or nuclear imaging agent all refer to the radioactive material that is used to make the nuclear medicine images. These substances are molecules that contain radioactive atoms. When those atoms decay, they emit energy in the form of gamma rays or alpha or beta particles that are detected by the nuclear medicine camera

• Isotope renography is the best test to confirm obstructive dilatation of the collecting system.
• A substance (usually diethylene triaminepenta-acetic acid (DTPA) or MAG-3) is injected intravenously.
• The DTPA is labelled with technetium-99m, a gamma-ray emitter, so that the passage of 99mTc-labelled DTPA through the kidneys can be tracked using a gamma camera.
• DTPA is filtered by the glomeruli and not absorbed hence is helpful for evaluation of patients with hydronephrosis and may delineate the site of obstruction. 
• DTPA stays in the renal pelvis on the obstructed side and is retained even if urine flow is increased by administering frusemide

After intravenous injection of the radionuclide the nuclear camera (radiation detection instrument) is usually placed behind the patient, so the image of the left kidney is on the left. 



Notice the label? RPO means right posterior oblique. The patient is lying on her right side rotated about 45 degrees. The camera is closer to the right kidney so that image is somewhat sharper.

• Decreased tracer uptake - photopenic region.
• Increased tracer uptake - photogenic region

• Well hydration 
• Kidney function should be good (GFR >30)

• DTPA and MAG3 are filtered through the glomerulus.
• This is useful in evaluating:
• – Perfusion - Vascular supply
• – Filtration - Measuring renal function (glomerular filtration rate)
• – Drainage - Detects obstruction

• DMSA and Glucoheptonate are accumulated in the cortex so they are helpful in evaluating:
• – Renal scarring from chronic infection
• – Infarction
• – Renal mass
• –Differential renal mass (proportion of total renal mass contributed by each kidney)

• Three image panels:
• – Perfusion - Images are accumulated over intervals of 10 seconds, 
• – Excretion/drainage - 3 minute intervals on this scan
• – Analysis/curves

About 15 minutes after injection of the radionuclide, lasix is given intravenously.

On the line graphs, radioactivity counts are plotted on the Y axis while time is plotted on the X axis. 

Normally, the curves show rapid uptake (flow curve on left) and rapid drainage (function curve on right). Each kidney is plotted separately (see labels) on each graph.

• Lasix Renogram
• •Normal T ½ is < 12 min. If the kidney doesn’t reach T ½ by 20 min. the kidney is considered to be obstructed.
• • T ½ from 12 min. to 20 min. is considered to be indeterminate.

• The Whitaker test is useful in evaluating patients with questionable ureteropelvic or ureterovesical junction obstruction, or primary defects in the ureteral musculature, such as prune-belly syndrome.
• Percutaneous puncture of the renal pelvis is performed or an indwelling nephrostomy tube is used. The upper urinary tract is then perfused at a constant rate of 5--10 ml/min with saline or diluted contrast media, and a serial pressure recording is made in the renal pelvis and bladder. The high flow rate used will be tolerated easily in a nonobstructed system without a progressive rise in renal pelvic pressure. In obstructed systems abnormally high pressure above 12 cm water or a constant rise in pressure will be recorded.