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. CAUSESCan 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
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
11. 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.
12. Imaging StudiesRenal 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
13. 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
14. -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.
15. 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
16. 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.
17. 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).
18. 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???
19. 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.
20. -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.
21. -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.
22. 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.
23. 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
24. Further Inpatient CareMonitor 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.
