Hydronephrosis

Question 1

Definition of hydronephrosis

Answer 1

dilation of the renal pelvis and calyces caused by the backward pressure of trapped urine

Question 2

Risk factors of hydronephrosis

Answer 2

• mechanical:
- congenital: see Congenital Abnormalities, U36
- acquired:
○ intrinsic: trauma, inflammation and bleeding, calculi, urologic neoplasms, BPH, urethral stricture, phimosis
○ extrinsic: trauma, neoplasms (uterine fibroid; colorectal, uterine, and cervical malignancies; lymphoma), aortic aneurysm, pregnancy (gravid uterus)
• functional:
- neurogenic: neurogenic bladder, diabetic neuropathy, spinal cord disease
- pharmacologic: anticholinergics, α-adrenergic agonists
- hormonal: pregnancy (progesterone decreases ureteral tone)

Question 3

Can hydronephrosis occur bilaterally?

Answer 3

Can occur bilaterally due to bladder neck obstruction or retroperitoneal causes (e.g. paraaortic lymph nodes)

Question 4

Ix for hydronephrosis

Answer 4

• focused hx, inquiring about pain (flank, lower abdomen, testes, labia), U/O, medication use, pregnancy, trauma, fever, hx of UTIs, calculi and PID
• CBC, electrolytes, Cr, BUN, U/A, C&S
• imaging studies (U/S is >90% sensitive and specific)

Question 5

Rx of hydronephrosis

Answer 5

• aimed at relieving the cause of obstruction/stasis
• urgent treatment is required if associated with infection, acute renal failure, or severe pain
- percutaneous nephrostomy tube or ureteral stenting to relieve pressure
Nephrostomy by fluoroscopic/US approach
Nephrostomy risks: haematoma/bleeding, infections,