Hydronephrosis and Upper Urinary Tract Obstruction

Definition of Hydronephrosis

Hydronephrosis is caused by an obstruction of the urine flow from the kidney. Hydronephrosis means literally "water inside the kidney" and refers to the distension and dilation of the pyelocaliceal system.

Differential diagnosis of Hydronephrosis

Urinary retention:

Prostate diseases: benign prostatic hyperplasia, prostate cancer, prostatic cyst.
Bladder diseases: bladder tumors, bladder stones, bladder neck sclerosis, detrusor sphincter dyssynergia (DSD).
Diseases of the urethra: urethral stricture, carcinoma, foreign bodies, phimosis, urethral valves.
Medication, alcohol, postoperative urinary retention, diabetes mellitus.

Ureter diseases causing hydronephrosis (intrinsic causes):

Ureteral stone
Ureteral clot due to hematuria
Congenital diseases: ureteropelvic-junction obstruction, vesicoureteral reflux, megaureter, ureterocele.
Benign ureteral stricture: after ureteral stone therapy, infection (tuberculosis, schistosomiasis), idiopathic.
Ureteral cancer

Iatrogenic Causes of Hydronephrosis:

Intraoperative injuries: ureteroscopy, rectal surgery, hysterectomy, vascular surgery. The spectrum of injury ranges from ischemic strictures due to coagulation to complete transection and ligature.
Irradiation, radiation injury of the bladder trigone

Hydronephrosis due to Vascular Diseases:

Aortic aneurysm
Renal artery aneurysm
Aneurysm of the iliac vessels
Retrocaval ureter or retroiliac ureter
Puerperal ovarian vein thrombophlebitis: 1/3000 pregnancies. Hydronephrosis most common on the right side, spontaneous healing is common.
After vascular surgery: hydronephrosis triggered by a periureteral fibrosis or by intraoperative injury.

Gynecological Diseases Causing Hydronephrosis:

During pregnancy, the enlarged uterus can compress the ureter (right more than left) and may cause pyelonephritis during pregnancy.
Puerperal ovarian vein thrombophlebitis: 1/3000 pregnancies. Hydronephrosis most common on the right side, spontaneous healing is common.
Endometriosis: recurrent flank pain, dysuria, hematuria
Extra-uterine pregnancy
Tuboovarial abscess
Pelvic floor insufficiency with organ prolapse
Tumors: cervical cancer, ovarian cysts, ovarian cancer, uterine leiomyoma ...

Hydronephrosis caused by Diseases of the Retroperitoneum:

Retroperitoneal tumors: lymphoma, retroperitoneal sarcoma, retroperitoneal germ cell tumors.
Lymph node or distant metastases: prostate cancer, cervical cancer, breast cancer, colon cancer, stomach cancer, bladder cancer, ....
Retroperitoneal fibrosis
Pelvic lipomatosis : rare disease with pelvic fat accumulation and cranial displacement of bladder and ureters.

Diseases with Upper Urinary Tract Dilatation without Obstruction:

Ureteropelvic-junction obstruction
Megacalicosis
Caliceal diverticula
Renal scintigraphy is necessary to judge the significance of the upper urinary tract obstruction.

Diagnostic Work-Up in Hydronephrosis

**Classification of hydronephrosis in grade I–IV (Beetz and others, 2001).**
*Hydronephrosis grade I:* dilatation of the renal pelvis *without* dilatation of the calices. Prominent reflex of the renal sinus without signs of parenchymal atrophy.
*Hydronephrosis grade II:* dilatation of the renal pelvis *and* calices. Attenuated sinus reflex. No signs of parenchymal atrophy.
*Hydronephrosis grade III:* Missing or marginal sinus reflex. Minor signs of organ atrophy present (flat papillae and blunt fornices).
*Hydronephrosis grade IV:* massive dilatation of the renal pelvis and calices. Borders between renal pelvis and calyces are missing. Significant signs of renal atrophy (thin parenchyma).

Sonography of kidney and ureter (see above).
Intravenous urography or computed tomography of the abdomen (with or without contrast media) or MRI abdomen.
Renal scintigraphy: to differentiate between relevant obstruction or dilatation of the caliceal system without obstruction. Renal scintigraphy can determine renal function and the need for surgical interventions.
Retrograde pyelography and ureterorenoscopy: necessary for diagnosis and treatment of upper urinary tract obstruction (ureteral stenting, ureterotomy).

Hydronephrosis

Index

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Index: 1–9 A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

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References

Gleason, P. E.; Kelalis, P. P.; Husmann, D. A. & Kramer, S. A.: Hydronephrosis in renal ectopia: incidence, etiology and significance
J Urol, 1994, 151, 1660-1

Deutsche Version: Differentialdiagnose Harnstau

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