Hydronephrosis

HYDRONEPHROSIS

1. Hydronephrosis DR.TALAL BALLOUT 2016

2. - Hydronephrosis is the term used to describe dilation of the renal pelvis and calyces associated with progressive atrophy of the kidney due to obstruction to the outflow of urine. -Types of Obstruction • SUDDEN • INSIDIOUS • acute • chronic • PARTIAL • COMPLETE • UNILATERAL • BILATERAL

3. Pathophysiology Hydronephrosis can result from anatomic or functional processes interrupting the flow of urine. This interruption can occur anywhere along the urinary tract from the kidneys to the urethral meatus . The rise in ureteral pressure leads to marked changes in glomerular filtration, tubular function, and renal blood flow. The glomerular filtration rate (GFR) significantly within hours following acute obstruction. This significant of GFR can persist for weeks after relief of obstruction. In addition, renal tubular ability to transport sodium, potassium, and protons and concentrate and to dilute the urine is severely impaired. The extent and persistence of these functional insults is directly related to the duration and extent of the obstruction. Brief disruptions are limited to reversible functional disturbance with little associated anatomic changes. More chronic disruptions lead to profound tubular atrophy and permanent nephron loss.

4. CAUSES Can be intrinsic, extrinsic or functional and can be classified as to : level within the urinary tract - Ureter : Intrinsic : congenital ureteropelvic junction stricture papillary necrosis Ureteral stricture iatrogenic blood clot Benign fibroepithelial polyps ureteral tumor Extrinsic: retroperitoneal cancer aortic aneurysm retrocaval ureter inflammatory bowel disease retroperitoneal hemorrhage lymphocele

5. Functional : gram-negative infection neurogenic bladder -Bladder Intrinsic : calculi bladder neck contracture : Functional VUR neurogenic bladder

6. - Urethra Intrinsic : urethral stricture Extrinsic : BPH -ANTENATAL PERIOD :The most common cause is physiologic dilation. Metanephric urine production begins at 8 weeks, even before ureteral canalization is complete. Transient obstruction with hydronephrosis occurs.

7. MOST COMMON CAUSES IN NEONATES: Ureteropelvic Junction Obstruction Ureterovesical Junction Obstruction Posterior Urethral Valves Prune Belly Syndrome Vesicoureteral Reflux Ureterocele

8. GRADING OF SEVERITY OF HYDRONEPHROSIS

9. Presentation -With severe hydronephrosis , the kidney may be palpable. -With bilateral hydronephrosis , lower extremity edema may occur. Costovertebral angle tenderness on the affected side is common. -A palpably distended bladder adds evidence of lower urinary tract obstruction. -A digital rectal examination should be performed to assess sphincter tone and to look for hypertrophy, nodules, or induration of the prostate. In children, the physical examination, especially in a newborn, can help detect abnormalities that suggest genitourinary abnormalities associated with antenatal hydronephrosis . These include the following: -The presence of an abdominal mass could represent an enlarged kidney due to obstructive uropathy or multicystic dysplastic kidney (MCDK). -A palpable bladder in a male infant, especially after voiding, may suggest posterior urethral valves. -A male infant with prune belly syndrome will have deficient abdominal wall musculature and undescended testes. The presence of associated anomalies should be noted. -The presence of outer ear abnormalities is associated with an increased risk of congenital anomalies of the kidney and urinary tract . -A single umbilical artery is associated with an increased risk of CAKUT, particularly VUR.

10. Imaging Studies Renal ultrasonography is the test of choice to exclude urinary tract obstruction, avoiding the potential allergic and toxic complications of radiocontrast media. [10] It can, in the majority of affected patients, help diagnose hydronephrosis and establish its cause; it can also detect other causes of renal disease such as polycystic kidney disease. Indications for computed tomography (CT) scanning include the following: Ultrasonography results are equivocal The kidneys cannot be well visualized The cause of the obstruction cannot be identified

11. IVP can be used to screen for urinary tract obstruction in the following settings: -In patients with staghorn calculi or multiple renal or parapelvic cysts, since hydronephrosis is usually not distinguishable from cysts or stones by ultrasonography or CT -When CT scanning cannot identify the level of obstruction -With suspected acute obstruction due to kidney stones (or less frequently, to other problems, such as a sloughed papilla or blood clot): Dilatation of the collecting system may not be seen at this time, but the presence and location of the obstructing stone can be identified

12. -Diffusion-weighted magnetic resonance imaging (MRI) may allow noninvasive detection of changes in renal perfusion and diffusion that occur during acute ureteral obstruction. Hydronephrosis without apparent obstruction or with asymptomatic obstruction: In some cases, one of the above radiologic tests demonstrates hydronephrosis without evidence of obstruction. This is a normal finding in pregnant women.

13. Treatment -Most conditions require either minimally invasive or open surgical treatment. Two notable exceptions are : (1) oral alkalinization therapy for uric acid stones (2) steroid therapy for retroperitoneal fibrosis. -The management approach to infants with antenatal hydronephrosis is based on the confirmation of persistent postnatal hydronephrosis and the following two predictive factors: *Bilateral involvement *Severe hydronephrosis : Fetuses with a renal pelvic diameter greater than 15 mm during the third trimester are at the greatest risk for significant renal disease

14. Bilateral hydronephrosis Infants with severe bilateral antenatal hydronephrosis and/or bladder distension are at increased likelihood of having significant disease. These infants and those with a severe hydronephrotic solitary kidney should be evaluated initially by ultrasonography on the first postnatal day. Bilateral hydronephrosis suggests an obstructive process at the level of or distal to the bladder, such as ureterocele or posterior urethral valves (PUV) in a male infant, which can be associated with impaired renal function and ongoing renal injury. If postnatal ultrasonography demonstrates persistent hydronephrosis , voiding cystourethrography (VCUG) should be performed. In male infants, the posterior urethra should be fully evaluated to detect possible PUVs.

15. Severe unilateral hydronephrosis In newborns with severe antenatal unilateral hydronephrosis (renal pelvic diameter >15 mm in the third trimester), ultrasonography should be performed after the infant returns to birth weight (after age 48 h and within the first 2 wk of life).

16. Moderate and mild unilateral hydronephrosis In newborns with less severe antenatal unilateral hydronephrosis (renal pelvic diameter < 15 mm during third trimester), ultrasonography can be performed after age 7 days. Moderate hydronephrosis resolves by age 18 months in most cases. Antibiotic prophylaxis???

17. Surgical Care -In general, any signs of infection within the obstructed system warrant urgent intervention because infection with hydronephrosis may progress rapidly to sepsis. -low-grade fever in a diabetic or immunosuppressed patient ( ie , on steroid therapy) requires immediate treatment. -The potential for loss of renal function also adds to the urgency ( eg , hydronephrosis or hydroureter bilaterally or in a solitary kidney). -Refractory pain in a patient with an obstructing ureteral calculus necessitates intervention, as does intractable nausea and vomiting.

18. -Urethral catheterization is important to help rule out a lower tract cause for hydronephrosis and hydroureter . Difficulty in placing a Foley catheter may suggest urethral stricture or bladder neck contracture. - ureteral stent placement in cases of intrinsic and extrinsic causes of hydronephrosis . The procedure is usually performed with cystoscopy and retrograde pyelography . Stents can bypass an obstruction and dilate the ureter for subsequent endoscopic treatment.

19. - percutaneous nephrostomy tube if ureteral stenting is not possible. Nephrostomies are typically placed when: *a retrograde stent cannot be passed because of anatomic changes in the bladder or high-grade obstruction in the ureter . *Because this procedure can be performed under local anesthesia, patients who are too hemodynamically unstable for general anesthesia * nephrostomy tube placement may be performed with minimal use of radiation and may be useful in pregnant patients.

20. Advances in endoscopic and percutaneous instrumentation have decreased the role of open or laparoscopic surgery for hydronephrosis . Certain causes of hydronephrosis , mostly extrinsic, still require treatment with open surgery. Examples include : -retroperitoneal fibrosis - retroperitoneal tumors, -and aortic aneurysms. -Some stones that cannot be treated endoscopically or with extracorporeal shockwave lithotripsy require open removal. -Although endoscopic management does play a role in low-grade low-stage ureteral tumors, these lesions also usually require open or laparoscopic surgical management. ***Urine should be collected from the kidney when obstruction is relieved to allow identification and targeted treatment of any infection that may be present.

21. Fetal surgery Although several prospective and retrospective studies have examined antenatal surgery in fetuses with sonographic findings consistent with lower urinary tract obstruction, no good evidence supports that this intervention improves renal outcome. [34] Although these procedures may increase the amount of amniotic fluid, thus necessitating renal replacement therapy in almost two thirds of the cases

22. Further Inpatient Care Monitor patients for postobstructive diuresis . This is a marked polyuria observed after relief of an obstructed system. Patients who are most likely to experience postobstructive diuresis present with chronic obstruction, edema, congestive heart failure, hypertension, weight gain, and azotemia . Clinically significant postobstructive diuresis is usually seen only in the setting of prior bilateral obstruction or, similarly, a unilateral obstruction of a solitary functioning kidney. This postobstructive diureses can lead to a marked diuresis with the wasting of sodium, potassium, phosphate, and the divalent cations . Management involves avoiding severe volume depletion, hypokalemia , hyponatremia , hypernatremia , and hypomagnesemia . Volume or free-water replacement is appropriate only when the salt and water losses result in volume depletion or a disturbance of osmolality . In many cases, excessive volume or fluid replacement prolongs the diuresis and natriuresis . An appropriate starting fluid for replacement is 0.45% saline. During this period, vital signs, volume status, urine output, and serum and urine chemistry and osmolality should be monitored. Postobstructive diuresis is usually self-limited. It usually lasts for several days to a week but may, in rare cases, persist for months.