Renal disease: post-renal

Question 1

What is post-renal disease?

Answer 1

Post-renal disease refers to a condition that occurs distal to the nephron, involving the intrarenal collecting system, ureter, bladder, prostate, or urethra.

Question 2

What is the main cause of post-renal disease?

Answer 2

The main cause of post-renal disease is obstruction, which can lead to the development of hydronephrosis and/or hydroureter.

Question 3

What are the consequences of acute ureteric obstruction?

Answer 3

Acute ureteric obstruction can result in dilatation of the afferent arteriole, increased glomerular filtration rate (GFR), increased tubular pressure, reduced flow at the macular densa, release of renin, and the production of prostaglandins (PgI, PgE) and nitric oxide.

Question 4

What happens during Phase 1 of acute ureteric obstruction?

Answer 4

Phase 1, which occurs within the first 0-90 minutes, is characterized by increased tubular pressure, reduced flow at the macular densa, release of renin, prostaglandins (PgI, PgE), and nitric oxide, as well as dilatation of the afferent arteriole and increased GFR.

Question 5

What happens during Phase 2 of acute ureteric obstruction?

Answer 5

Phase 2, which occurs between 90 minutes to 4 hours, is characterized by sustained increased tubular pressure, reduced filtration pressure, and decreased glomerular filtration rate (GFR). There is no further dilatation of the afferent arteriole.

Question 6

What occurs during Phase 3 of acute ureteric obstruction?

Answer 6

Phase 3, which takes place from 4 hours to 18 hours, involves afferent vasoconstriction, shunting of blood flow from the outer to inner cortex, lack of perfusion of many glomeruli, reduced glomerular colloid osmotic pressure, and reduced tubular pressure. Glomerular shutdown and decreased GFR are also observed.

Question 7

What are the consequences of chronic obstruction in the urinary tract?

Answer 7

Chronic obstruction can lead to dilatation of tubules, interstitial fibrosis, relatively preserved glomeruli, damage to collecting ducts and distal tubules in the medulla, and obstructive atrophy. In dogs, nephron loss occurs after 4-7 days, and little recoverable renal function is observed after 1 month.

Question 8

What are the symptoms of urinary tract obstruction?

Answer 8

Symptoms of urinary tract obstruction include flank pain, urinary tract infection with flank pain, pain after drinking, haematuria (blood in urine), exercise-induced haematuria, and it can also be a chance finding.

Question 9

What are the functions affected by chronic obstruction in the distal tubules?

Answer 9

Chronic obstruction can affect the concentration of urine, excretion of H+ (hydrogen ions), and excretion of K+ (potassium ions) in the distal tubules.

Question 10

Is urinary tract obstruction considered an emergency?

Answer 10

Yes, urinary tract obstruction is considered an emergency.

Question 11

What are the initial investigations for urinary tract conditions?

Answer 11

Initial investigations may include renal function tests, a full blood count, prostate-specific antigen (PSA) test (for males), urinalysis, urine culture, blood gases, and imaging.

Question 12

What imaging techniques are used for urinary tract evaluation?

Answer 12

Ultrasound scan and CT scan are commonly used for imaging the urinary tract. Ultrasound scan can detect dilated renal pelvis, while a non-contrast CT scan (CT KUB) is used to identify stones in the upper right ureter. However, it is important to note that stones can be missed on contrast CT scans.

Question 13

What is dynamic renography and what does it measure?

Answer 13

Dynamic renography is a technique that involves the use of Technetium-99m labeled MAG3 (Mercapto Acetyl Tri Glyceride) to measure blood flow and assess obstruction. The initial uptake of the tracer is used to measure blood flow, and the area under the curve is calculated to evaluate kidney function. The rate of washout quantifies the degree of obstruction.

Question 14

What is MAG3?

Answer 14

MAG3 is a radiopharmaceutical used in dynamic renography for evaluating kidney function and assessing obstruction in the urinary tract.

Question 15

What should be considered when performing a CT scan for urinary tract evaluation?

Answer 15

When performing a CT scan, particularly for identifying stones, it is important to be aware that stones can be missed on contrast CT scans.

Question 16

What is MAG3 renography used for?

Answer 16

MAG3 renography is a diagnostic imaging technique used to evaluate kidney function and assess obstruction in the urinary tract.

Question 17

How is acute obstruction in the urinary tract treated as an emergency?

Answer 17

The emergency treatment of acute obstruction may include relieving the obstruction through measures such as ureteral stenting or nephrostomy tube placement to restore urine flow and relieve symptoms.

Question 18

What are the causes of obstruction in the urinary tract?

Answer 18

Obstruction in the urinary tract can be classified based on the location of the obstruction. It can occur in the lumen of a tube (e.g., stones), within the wall (e.g., tumors, strictures), or outside the wall (e.g., lymph nodes, tumors, retroperitoneal fibrosis). Obstruction can also occur at different levels, including the pelviureteric junction, ureter, or bladder outflow.

Question 19

What are the common types of urinary tract stones?

Answer 19

The most common types of urinary tract stones are calcium oxalate and phosphate stones, often mixed together. Staghorn stones, which are large and fill the renal pelvis, are typically composed of triple (calcium, magnesium, ammonium) phosphate and are associated with infection. Uric acid stones are associated with gout and acidic urine. Cystine stones are rare and associated with a genetic disorder called cystinuria.

Question 20

What are the common symptoms of ureteric colic?

Answer 20

Ureteric colic is characterized by severe pain, nausea and vomiting, intermittent waves of pain, restlessness, pain radiating from the loin to the groin, urinary frequency (strangury), and blood in the urine.

Question 21

What are the treatment options for urinary tract stones?

Answer 21

The treatment options for urinary tract stones include extracorporeal shockwave lithotripsy (ESWL), ureteroscopy, and cystolitholapaxy.

Question 22

What is extracorporeal shockwave lithotripsy (ESWL)?

Answer 22

Extracorporeal shockwave lithotripsy (ESWL) is a non-invasive procedure used to break down urinary tract stones into smaller fragments using shockwaves generated outside the body. It is typically used for the treatment of kidney stones or larger stones in the upper urinary tract.

Question 23

What is ureteroscopy?

Answer 23

Ureteroscopy is a procedure that involves inserting a thin tube with a camera (ureteroscope) into the ureter to visualize and remove or break down urinary tract stones. It may be combined with laser stone fragmentation or the use of ureteric baskets to remove or extract the stone fragments.

Question 24

What is cystolitholapaxy?

Answer 24

Cystolitholapaxy is a procedure used for the fragmentation and removal of bladder stones. It involves inserting instruments through the urethra to access and break down the bladder stones.

Question 25

What is the pathology of pelviureteric junction (PUJ) obstruction?

Answer 25

Pelviureteric junction (PUJ) obstruction is characterized by the failure of peristalsis through the PUJ, resulting in chronic obstruction. It can be either congenital or acquired.

Question 26

How is pelviureteric junction (PUJ) obstruction diagnosed?

Answer 26

Pelviureteric junction (PUJ) obstruction can be diagnosed based on symptoms such as pain with high fluid intake or alcohol, as well as through imaging modalities such as ultrasound (USS), CT urogram, and MAG3 renogram. These tests can reveal anatomical appearance, reduced split function, and obstruction on renogram.

Question 27

What is the recommended treatment for pelviureteric junction (PUJ) obstruction?

Answer 27

The recommended treatment for pelviureteric junction (PUJ) obstruction is laparoscopic or robotic pyeloplasty, a surgical procedure aimed at reconstructing the narrowed or obstructed area.

Question 28

What is the most common type of bladder and ureter cancer?

Answer 28

Transitional cell carcinoma (TCC) is the most common type of bladder and ureter cancer, accounting for approximately 80% of cases.

Question 29

What is the treatment for superficial transitional cell carcinoma (TCC)?

Answer 29

The treatment for superficial TCC involves cystoscopy and transurethral resection (TURBT) to remove the tumor from the bladder lining.

Question 30

How can transitional cell carcinoma (TCC) in the bladder or ureter cause obstruction?

Answer 30

Tumors located at the ureteric orifice in the bladder can cause obstruction in the urinary tract, leading to symptoms and complications.

Question 31

What are some common causes of urinary retention?

Answer 31

Urinary retention can be caused by conditions such as benign prostatic hyperplasia (BPH), a thick-walled bladder, ureteric obstruction, diverticulum, and bladder stones. These conditions can lead to bladder outflow obstruction.

Question 32

What medical treatments are used for urinary retention?

Answer 32

Medical treatment options for urinary retention include alpha blockers, such as tamsulosin, which help relax the smooth muscles in the prostate and bladder neck, and 5-alpha reductase inhibitors, such as finasteride and dutasteride, which work to shrink the prostate gland in cases of BPH.

Question 33

What is the surgical treatment for benign prostatic hyperplasia (BPH)?

Answer 33

The surgical treatments for BPH include Holmium Laser Enucleation of the Prostate (HoLEP) and Transurethral Resection of the Prostate (TURP). These procedures involve removing or reducing the size of the prostate gland to alleviate urinary obstruction and improve urine flow.

Question 34

What is Holmium Laser Enucleation of the Prostate (HoLEP)?

Answer 34

Holmium Laser Enucleation of the Prostate (HoLEP) is a surgical technique used to remove excess prostate tissue using a laser. It is a minimally invasive procedure that is effective in relieving urinary obstruction caused by BPH.

Question 35

What is Transurethral Resection of the Prostate (TURP)?

Answer 35

Transurethral Resection of the Prostate (TURP) is a surgical procedure in which excess prostate tissue is removed using a resectoscope inserted through the urethra. It is a common surgical treatment for BPH and can significantly improve urinary flow.

Question 36

What is prostate carcinoma?

Answer 36

Prostate carcinoma is the most common type of cancer in men. It is often asymptomatic in the early stages and is commonly diagnosed through screening. It primarily involves the peripheral zone of the prostate gland. Symptoms may include hematuria, lower urinary tract symptoms (LUTS), hematospermia, bone pain in cases of metastasis, and rarely, bladder outflow obstruction leading to acute kidney injury (AKI).

Question 37

How is prostate cancer diagnosed?

Answer 37

Prostate cancer can be diagnosed through various methods, including an elevated serum Prostate Specific Antigen (PSA) level, digital rectal examination (DRE) to assess for induration, asymmetry, or nodules, and prostate biopsy to confirm the presence of cancer cells.

Question 38

What are the common pathways through which drugs can cause kidney damage?

Answer 38

Drugs can cause kidney damage through various pathways, including altered intraglomerular hemodynamics, tubular cell toxicity, inflammation, crystal nephropathy, rhabdomyolysis, and thrombotic microangiopathy.

Question 39

Which drugs are associated with post-renal obstruction?

Answer 39

Drugs such as anticholinergics, mirabegron (an adrenergic beta-3 agonist), and indinavir (an antiviral drug used in HIV) have been associated with post-renal obstruction, potentially leading to urinary tract obstruction.