HYDRONEPHROSIS

Long Answer Question (LAQ) - Standard Surgical Textbook

DEFINITION

• S Das, Manual on Clinical Surgery, 13th Ed.
• Robbins & Kumar Basic Pathology

ETIOLOGY / CAUSES

A. UNILATERAL HYDRONEPHROSIS

• Idiopathic pelviureteric junction (PUJ) stenosis - commonest cause; results from an aperistaltic/hypoplastic muscular segment
• Calculus at PUJ
• Tumour of the renal pelvis
• Pressure from an aberrant (crossing) renal artery at PUJ
• High insertion of ureter into the pelvis

• Ureteric calculus
• Tumour of the ureter
• Tumour infiltrating from adjacent organs (bladder, cervix, rectum, colon)
• Ureterocele
• Schistosomiasis
• Bladder tumour (involving one ureteric orifice)
• Retroperitoneal fibrosis

B. BILATERAL HYDRONEPHROSIS (obstruction below the level of ureters)

• Benign prostatic hyperplasia (BPH)
• Carcinoma of the prostate
• Carcinoma of the bladder
• Urethral stricture or posterior urethral valve (PUV)
• Phimosis
• Neurogenic bladder (spinal cord damage)
• Schistosomiasis
• Retroperitoneal lymphoma
• Carcinoma of the cervix or uterus

C. CONGENITAL CAUSES

• Atresia of the urethra
• Valve formations in ureter or urethra
• Aberrant renal artery compressing ureter
• Abnormal position of kidney with torsion/kinking of ureter

D. MISCELLANEOUS

• Pregnancy (mild, physiological - due to progesterone effect and uterine compression on right ureter)
• Inflammatory lesions: prostatitis, ureteritis, urethritis, retroperitoneal fibrosis

PATHOPHYSIOLOGY

• Arterial insufficiency and venous stasis
• Most severe effects at the papillae (greatest pressure concentration)
• Early: tubular dysfunction - impaired concentrating ability
• Late: glomerular filtration decreases
• Interstitial inflammatory reaction leading to fibrosis

• Robbins & Kumar Basic Pathology

PATHOLOGICAL ANATOMY (MORPHOLOGY)

• With subtotal/intermittent obstruction: kidney massively enlarged (up to 20 cm length)
• Organ consists almost entirely of greatly distended pelvicalyceal system
• Renal parenchyma compressed and atrophied
• Obliteration of papillae and flattening of pyramids
• Depending on level of obstruction, ureter also dilated (hydroureter)

Hydronephrosis of the kidney with marked dilation of the pelvis and calyces, and thinning of renal parenchyma. (Robbins & Kumar Basic Pathology)

• Early: tubular dilation and atrophy
• Progressive loss of glomeruli
• Replacement of renal parenchyma by fibrous tissue
• Minimal inflammatory reaction in uncomplicated cases
• Superimposed pyelonephritis is common
• Robbins & Kumar Basic Pathology

CLINICAL FEATURES

Symptoms

• Onset is insidious; females more commonly affected than males
• Dull ache or sense of weight/dragging in the loin
• May be dismissed as mild backache
• If hydronephrosis develops quickly: severe colicky pain
• Pain exacerbated by drinking excess water, alcohol, or taking diuretics
• Referred pain to epigastrium - may mimic duodenal ulcer
• Dietl's crisis: After severe pain, large quantity of urine is passed and swelling reduces in size - due to intermittent obstruction at PUJ being transiently overcome
• Haematuria (if calculus or tumour present)
• Recurrent UTI / pyelonephritis
• In bilateral cases: features of the underlying cause dominate

Signs

• Cystic renal swelling in the loin/flank - smooth, fluctuant
• Ballottable (due to retroperitoneal position)
• Better palpable bimanually (one hand in loin, one anteriorly)
• Moves with respiration
• In advanced bilateral disease: features of chronic renal failure (anuria, uraemia, hypertension)
• Paradox: incomplete bilateral obstruction may cause polyuria (not oliguria) due to tubular concentrating defects

INVESTIGATIONS

1. Ultrasound (USG)

• First-line investigation - least invasive
• Shows dilated pelvicalyceal system
• Confirms cystic nature of renal swelling
• Can detect cause (e.g. calculi)
• Can detect hydronephrosis in utero (antenatal detection of PUJ obstruction)

2. Intravenous Urography (IVP / Excretory Urography)

• Early films may fail to visualize pelvis and calyces (poor contrast excretion)
• Better delineation after 6-hour delayed films
• Earliest change depends on type of renal pelvis:
  • Extrarenal pelvis (majority): pelvis itself dilates first
  • Intrarenal pelvis: decreasing concavity then flattening of minor calyces
• Progressive dilation of major calyces
• Clubbing (convexity) of minor calyces
• Pelvis becomes markedly distended; its convex lower margin forms an acute angle with the ureter
• If pelvis and calyces not seen properly: Retrograde urography needed
• Sometimes the cause (stone) visible on plain X-ray (KUB)

3. Retrograde Ureteropyelography

• When IVP fails to show pelvis/calyces clearly
• Defines the site and cause of obstruction

4. Diuretic Renography (MAG-3 / DTPA scan)

• Isotope renography detects dilatation of the renal collecting system
• MAG-3 preferred in children and patients with impaired function
• Obstructive pattern: delayed transit on time-activity curve, hold-up of tracer
• Provides differential renal function - critical for management decisions
• Helps distinguish obstructed from non-obstructed dilated systems

5. CT Scan / CT Urography

• Best for defining the cause of obstruction
• Shows level of obstruction
• Useful for retroperitoneal pathology (fibrosis, lymphoma)

6. Whitaker Test

• Used in specialised units
• Percutaneous puncture of kidney to monitor intrapelvic pressure
• Perfusion pressure > 22 cm H2O = significant obstruction

7. VCUG (Voiding Cystourethrogram)

• To detect vesicoureteral reflux (VUR)
• Assess posterior urethral valves in bilateral cases

8. Blood Tests

• Serum creatinine, urea - assess renal function
• FBC - infection markers
• PSA in elderly males

TREATMENT

GENERAL PRINCIPLES

1. Relieving the obstruction
2. Preserving/restoring renal function
3. Treating infection
4. Removing the cause

A. CONSERVATIVE (Watchful Waiting)

• Asymptomatic antenatal/mild hydronephrosis without functional deterioration
• Prenatal fetal hydronephrosis: most mild-to-moderate cases resolve spontaneously after birth
• Postnatal ultrasound at least 48 hours after birth; MAG-3 at 4-6 weeks
• High-risk infants: VCUG, antibiotic prophylaxis, functional scan, monthly follow-up
• Low-risk infants: 1-3 monthly ultrasound follow-up

B. SURGICAL - BASED ON CAUSE

1. PUJ Obstruction (Pyeloplasty)

• Symptomatic patients (pain, UTI, haematuria)
• Obstructive pattern on diuretic renography
• Deterioration of differential renal function
• Progressive hydronephrosis on serial ultrasound
• Renal function < 40% on MAG-3

• Transection at the PUJ obstruction
• Excision of the aperistaltic/stenotic segment
• Fashioning a funnel-like, tension-free, dependent anastomosis
• Temporary ureteral stent and drain placed
• Can handle crossing vessels (vessels are transposed behind the anastomosis)
• Success rate ~95%

• For a high ureteral insertion (not crossing vessel)
• Success rate ~86%

• Laparoscopic pyeloplasty: now the standard in many centres; equal success to open
• Robotic-assisted pyeloplasty: increasing use
• Endopyelotomy (incision of the PUJ endoscopically): less invasive; results inferior to pyeloplasty; best for short segment stricture without a crossing vessel

2. For Ureteric Obstruction

• Ureteric calculus: ESWL, ureteroscopy, PCNL, or open ureterolithotomy
• Ureteric stricture: Balloon dilation, endoscopic incision, ureteric reimplantation, or substitution (ileal ureter)
• Ureterovesical junction (UVJ) obstruction / Megaureter: Ureteric reimplantation
• Retroperitoneal fibrosis: Ureterolysis ± corticosteroids; wrap ureter in omentum
• External compression by tumour: Treat primary tumour; stenting

3. For Bladder Outlet / Lower Urinary Tract Obstruction

• BPH: TURP, open prostatectomy, or medical (alpha-blockers, 5-alpha reductase inhibitors)
• Carcinoma prostate: Hormonal/radiotherapy; TURP for palliation
• Urethral stricture: Urethrotomy, urethroplasty
• Posterior urethral valves (PUV): Transurethral valve ablation

4. Temporary Drainage Procedures

• Nephrostomy (percutaneous): Emergency drainage for infected obstructed kidney, impaired function awaiting definitive surgery, anuria
• Ureteral stenting (JJ stent): Bypasses obstruction; maintains ureteric patency
• Urethral catheter: Initial drainage for bladder outlet obstruction

5. Nephrectomy

• Grossly hydronephrotic kidney with <15% differential function (poorly functioning/non-functioning kidney)
• Chronic pyonephrosis
• Recurrent calculi with destroyed parenchyma
• Irreversible renal damage with no salvageable function
• Note: After removal of obstruction, function may return if obstruction duration was short

COMPLICATIONS

1. Pyonephrosis - infected hydronephrosis (pus in collecting system) - surgical emergency
2. Pyelonephritis - recurrent infection
3. Hypertension - due to renal ischaemia (renin-angiotensin activation)
4. Renal failure - bilateral hydronephrosis or single kidney involvement
5. Rupture - rare; periurinoma / urinoma
6. Renal calculi - secondary to stasis and infection
7. Irreversible renal damage if obstruction unrelieved

KEY SURGICAL POINTS (Summary Box)

• S Das, A Manual on Clinical Surgery, 13th Edition (primary surgical reference)
• Bailey and Love's Short Practice of Surgery, 28th Edition
• Robbins & Kumar Basic Pathology
• Campbell-Walsh-Wein Urology, 3-Volume Set
• Smith & Tanagho's General Urology, 19th Edition