Hydronephrosis is defined as the aseptic dilation of the kidney's collecting system due to urinary outflow obstruction, which can lead to kidney atrophy and hydroureter. Causes include structural issues like urinary calculi, tumors, benign prostatic hyperplasia, and congenital abnormalities, as well as neurogenic factors. Treatment varies based on the underlying cause and severity, with potential complications including urinary tract infections and pyelonephritis.

1. HYDRONEPHROSIS
Dr. Salman Ansari
Dept. of Pathology
Kanachur Institute of Medical Sciences

2. Contents
● Definition
● Causes
● Pathogenesis
● Morphology
● Clinical features
● Investigations, Treatment, Complications

3. Hydronephrosis
● Defined as aseptic dilation of collecting system
of kidney due to obstruction of urinary outflow
● Atrophy of kidney is seen
● Dilation of the ureter due to obstruction of
urine outflow is called hydroureter.

5. Causes
Structural
Functional

6. Structural causes:
● Urinary calculi
● Tumour of prostate, bladder, uterus, cervix
● BPH in men
● Congenital abnormalities like urethral stricture
● Inflammation: prostatitis, urethritis
● Pregnancy

7. Neurogenic causes:
Neurogenic bladder, due to spinal cord injury or diabetic
nephropathy

9. Pathogenesis
● Obstruction: complete or incomplete, which leads to
accumulation of urine proximal to obstruction
● Dilatation: accumulated urine causes dilatation of calyces
and pelvis due to back pressure, which is transmitted back
into renal tissue
● Reduced GFR: if obstruction continues, tubule loses
concentrating function and GFR decreases
● Inflammatory reaction in interstitium with fibrosis

10. Morphology
Types of obstruction:
- Sudden and complete obstruction: GFR is reduced
and mild dilation of renal pelvis and calyces occurs
- Intermittent or subtotal obstruction: GFR is not
affected and dilation is progressive
Level of obstruction:
- depending upon where the obstruction is, the first part

11. Gross features
- Obstruction can be unilateral or bilateral, with dilation
of ureter(called hydroureter)
- Kidney enlargement can be slight to massive
- Thin-walled kidney, with cysts
- Renal parenchyma shows destruction due to
severe pressure atrophy and thinning of cortex

12. thin-walled, lobulated,
fluid-filled sac

14. Microscopy
- Tubules: dilated and atrophied
- Glomeruli: partial or complete sclerosis
- Interstitium: fibrosis, chronic inflammatory cells

15. Clinical features
Features depend upon cause of obstruction
- Renal calculus presents with renal colic, whereas BPH
presents with bladder symptoms
- Unilateral hydronephrosis: can be asymptomatic
- Bilateral partial obstruction: polyuria, nocturia
- Bilateral complete obstruction: oliguria/anuria

16. Investigations: USG to diagnose obstructive uropathy
Treatment: depends upon cause and severity of
hydronephrosis

17. Complications:
- UTI
- pyelonephritis

18. References:
● Ramadas Nayak - Textbook of Pathology for Allied Health Sciences
Questions:
salman.s.ansari92@gmail.com
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