Obstructive Nephropathy - NACE Flashcards
What is Hydronephrosis?
Dilation of the Renal Pelvis
What is proximal and distal when discussing the urinary tract?
Proximal = Close to the kidney
Distal = Far from the kidney
What is an example of a function obstruction in urinary outflow?
• Neurogenic Bladder
What are some common intraluminal causes of mechanical Obstruction to urinary outflow?
Intraluminal • Stones • Blood Clots • Papillary Necrosis (SODA; sickle-cell, obstructive pyelonephritis, diabetes, analgesic use) • Tumors
What are some intramural causes of mechanical obstruction to urinary outflow?
- Neurologic/Neuromuscular dysfunction (kind of a functional problem too)
- Strictures (from infection or instrumentation)
What are some common causes of compression in the urinary tract?
- Retroperitoneal Tumors (from prostate tumors)
- Local Extension of Prostate Cancers, Colon Cancer, Cervical Carcinoma
- AAA
- PROSTATIC HYPERTROPHY = big one
Differentiate the severity of disease on the basis of UT obstruction relative to bladder?
Distal to Bladder:
• this BAD because it leads to damage in BOTH kidneys - something the body is not well-equipped to handle
Proximal to Bladder:
• Will lead to damage of single kidney only - body can handle this
How can radiocontrast be used to detect Ureter Obstruction?
RETROGRADE PYLOGRAPHY can be performed
- inject radiocontrast from beginning of ureter in the bladder and follow it backwards
- It will stop wherever the obstruction is located
What would you expect to see happen on Retrograde Pylography of someone with Retroperitoneal Fibrosis?
• Contrast Will just stop wherever retroperitoneum has fibrosed over the ureter
What are the two types of consequence that result from obstruction in the GU system?
- Mechanical Consequences
* Functional Consequences
What are the MECHANICAL consequences of GU obstruction?
- Dilation of the urinary Tract Proximal to the Obstruction
* Eventual Compression and thinning of the renal cortex with parenchymal Atrophy over time
What are the FUNCTIONAL consequences of GU obstruction?
• early.
• Time associated with this?
Early (4-6 hours):
• Ureteral Pressure and Renal Blood flow increase, PROSTAGLANDINS (Vasoactive mediators) are released to attempt to maintain GFR
What are the FUNCTIONAL consequences of GU obstruction?
• later.
• Time associated with this?
Later (greater than 6 hours)
• Vasocontrictors (Renin, Angiotensin, Thromboxane) are produced in the MACULA DENSA
• Leads to GRADUAL SUSTAINED decrease in GFR to about 20% of pre-obstructive values
What are the FUNCTIONAL consequences of GU obstruction?
•Chronically
Chronic
• Ischemia and Inflammatory cytokines result in interstitial fibrosis
What is the histopathology seen on H and E in the late stages of obstructive nephropathy?
INFLAMMATION and FIBROSIS
• both mononuclear cells and fibrin
Why is GFR not completely predictive of renal damage?
• Other Nephrons Hypertrophy and Hyperfiltrate to pick up the slack
This means creatinine isn’t a great indicator of damage especially in unilateral renal dysfunction
What important factors determine the signs and symptoms seen in urinary tract obstruction?
- Time Course
- Degree of Obstruction
- Level of Obstruction
- Cause
- Developement of Secondary Complications
What are some secondary complications that may result from urinary tract obstruction?
- Infection
- Fluid and Electrolytes
- Renal Failure
T or F: chronic progressive obstruction in urinary tract may be asymptomatic.
True, acute obstructions are more likely to have symptoms
How will complete and partial obstruction affect urinary outflow?
• creatinine
Complete:
• ANURIA
• Serum Creatinine results in full blown renal failure
Partial:
• POLYURIA - this is the result of concentrating defects
• small transient effect on Serum Creatinine
What type of GU obstruction is associated with the following:
•acute, excruciating flank pain radiating to the groin
Ureteral Stones
What type of GU obstruction is associated with the following:
prevention of complete emptying of the bladder, producing urinary hesitancy,
diminished stream, dribbling, nocturia, frequent small volume voiding, and straining
Prostatic Disease
What type of GU obstruction is associated with the following:
Gross Hematuria
may suggest a clot as the cause of obstruction or may accompany a kidney stone
or sloughed papilla (from papillary necrosis).
**What are the Functional Consequences of CHRONIC Bilateral PARTIAL obstruction of ureters?
SYMPTOMS RESEMBLE Type 4 RTA (renal tubule acidosis)
- Polyuria
- Volume Depletion
- Azotemia
- ELECTROLYTE PROFILE of non-anion gap metabolic acidosis
- Hyperkalemia
What diagnostic Tests are useful in determining if there has been an obstruction in the GU system?
• advantages and disadvantages to each.
Ultrasound:
•Advantage: easy availability, good at detecting kidney stones
•Disadvantage: Depends on demonstration of hydronephrosis
CT:
• Advantages: Highly sensitive for obstruction, no contrast is necessary for this indication
• Disadvantages: Inconvenient, Ionizing radiation
Why is it a disadvantage that ultrasound depends on hydronephrosis to aid in Dx?
Hydronephrosis Can be FALSELY NEGATIVE in cases of:
• Recent Obstruction
• Volume Depletion
• Retroperitoneal Fibrosis
What are your 3 Treatment goals for a patient with Urinary Tract Obstruction?
- Relieve the Obstruction
- Treat the underlying Cause
- Prevent and Treat Infection*** this is a big one because obstruction + infection = BAD combo. for the kidney
T or F: recovery of the kidney even after LONG periods (several days/weeks) of obstruction is possible.
True, degree of recovery will be correlated to the extend of obstruction and duration
What are some common locations of intraluminal obstruction?
• Uretero-Pelvic Junction, Uretero-Vescicle Junction, Intersection of Ureters and Iliac Vessels
An adult male with 2 healthy kidneys developes ACUTE RENAL FAILURE. What is the most likely obstructive cause?
• what would his labs show?
• Urethral Obstruction by Prostatic Hyperplasia
Labs:
• Hyperchloremic Metabolic Acidosis with Hyperkalemia
T or F: UT obstruction is always associated with Intraluminal Obstruction or Extrinsic Compression.
FALSE
T or F: allergy medication s may cause difficulty urinating
True
NOTE about distention of structures under acute and chronic conditions
ACUTE:
• things that distend quickly Hurt
CHRONIC:
• things that gradually distend will distend much more and be less symptomatic
What determines the consequences and symptoms of obstruction?
The level at which it occurs
T or F: polyuria excludes UT obstruction
FALSE, could be bilateral partial obstruction
How would EKG indicate Chronic Obstruction?
• explain these findings
EKG:
• Big T waves from HYPERKALEMIA - (excessve repolarization)
T or F: if you put the catheter in and they start making a lot of urine, you have made the diagnosis
True, ***note that if someone has been obstructed for a long time and you catheterize them they may DIURESE SO MUCH THEY THEY BECOME HYPOCALCEMIC.
