GU Packet #3

What are symptoms of kidney stones?

-colicky, sharp, unilateral, back, flank pain that comes and goes (constancy is concerning) -> paroxysmal (acute onset), radiates to groin and scrotum/labia

-gross hematuria

-dysuria

-frequency

What does severity of pain depend on?

-more about location than size of stone

-pain in ureters/urethra (thin) not kidneys/bladder

How long do pain cycles last?

20-60 mins

What are diagnostic tests for kidney stones?

-non-contrast helical CT

-ultrasound

What is the preferred exam for renal calculi?

CT of the abdomen and pelvis without contrast performed using low-radiation-dose scanning technology is the preferred exam for most adults as it reliably detects hydronephrosis and demonstrates the highest diagnostic accuracy for nephrolithiasis

How accurate is a helical CT without contrast?

sensitivity of 95-100%

What is hydronephrosis?

dilation of the kidney

What is CT?

test of choice for adults with renal calculi - first line diagnostic test

Why do imaging for renal calculi?

need to determine where the stone is to determine treatment

What is an ultrasound the preferred test for?

-preferred diagnostic modality for pts who are pregnant due to radiation of CT/x-ray

-useful in patients and those older than 60 in whom you want to d/dx AAA

What are the risk factors for renal calculi?

-activities that cause dehydration by increasing sweating can promote stone formation (exercise, steam rooms, swimming)

-decreased fluid intake (immobilization and sedentary occupations)

-anatomic abn that cause urinary obstruction and stasis increase the possibility of stone formation (prostatic obstruction or urethral stricture)

-south of mason dixon line (stone belt; more sun exposure -> increased vitamin D absorption -> increased calcium absorption (small intestine - duodenum, jejunum))

-past medical history of renal calculi

-family history of renal calculi

How does rate of renal calculi increase with PMHx?

"the rate of stone recurrence is 10 to 30 percent at three to five years among patients with idiopathic calcium oxalate stones"

How does the rate of renal calculi increase with FHx?

"a greater than twofold increased risk of stones among individuals with a positive family history compared with those without such a history"

What are signs of renal calculi?

-the classic patient with renal colic is writhing in pain, pacing about, and unable to lie still (in contrast to pt with peritoneal irritation, who remains motionless to minimize discomfort)

-CVA tenderness

-fever is not part of presentation

-abd exam is unremarkable

-secondary to pain: diaphoresis, tachycardia, tachypnea, HTN

If fever is present during exam for kidney stones, what should you suspect?

-infected hydronephrosis

-pyelonephritis

-perinephric abscess

What is the pharmacological/non-surgical treatment for renal calculi?

-pain control with NSAIDs and opioids

-hydration (controversial)

-strain all urine

What patients can be managed at home and which ones need hospitalization?

-pts can be managed at home if they are able to take oral medications and fluids

-hospitalization is required for those who cannot tolerate oral intake or who have uncontrollable pain or fever

What is traditionally used for pain control of renal calculi?

NSAIDs and opioids - Both nonsteroidal anti-inflammatory drugs (NSAIDs) and opioids have traditionally been used for pain control in patients with acute renal colic. NSIADs have the possible advantage of decreasing ureteral smooth muscle tone, thereby directly treating the mechanism by which pain is thought to occur (ureteral spasm)

What are some examples of opioids?

codeine, morphine, heroin

Why is hydration controversial?

can push the stone out but don't want to give if there is an obstruction

Why strain all urine?

-to catch renal calculi

-stones don't all look the same. the color depends on etiology, most are yellow or brown. stones can be round, jagged, or even have branches. they vary in size from specks to pebbles to stones as big as golf balls

-can see if stone was passed or determine composition

-allows for stone analysis and appropriate intervention

What are the two complications that may require consults?

-infection

-obstruction

Who do you consult if there is ureterolithiasis with proximal UTI?

consult urology immediately in cases of ureterolithiasis with proximal UTI. infected hydronephrosis (infection prior to the stone) is a true urologic emergency and requires hospital admission, IV antibiotics, and immediate drainage of the infected hydronephrosis via percutaneous nephrostomy or ureteral stent placement

What findings may suggest infection with renal calculi?

-leukocytes

-nitrites

-fever

What other complication besides infection can nephrolithiasis lead to?

nephrolithiasis may lead to persistent renal obstruction, which could cause permanent renal damage if left untreated

What percent of ureteral stones pass spontaneously?

approximately 80% of ureteral stones pass spontaneously without hospitalization or invasive intervention

Stones of which size have the highest spontaneous pass rate?

-stones below 5 mm in size have the highest spontaneous pass rate

-stones 10 mm or larger often require intervention

What percent of patients require invasive intervention?

about 15-20% of patients require invasive intervention due to stone size, continued obstruction, infection, or intractable pain. several techniques are available to the urologist when the stone fails to pass spontaneously

How many days before procedure should NSAIDs be stopped?

NSAIDs should be stopped 3 days prior to interventions to reduce bleeding risk during procedure

What is the interventional treatment for renal calculi?

-extracorporeal shock wave lithotripsy (ESWL)

-cystoscopy

-ureteroscopy

-percutaneous nephrolithotomy

What is ESWL?

-utilizes an underwater energy wave focused on the stone to shatter it into passable fragments

-approximately 70% of stones can be treated with ESWL alone

-pt is packed with water bags around the flank or submerged in water

-painful so may require anesthesia

-120 shocks/min

What is cystoscopy?

-scope through the bladder

-useful if the stone is in the bladder

-also used if pt has painless hematuria to examine for abnormal cells suggesting bladder cancer

What is a ureteroscopy?

-most stones occur here so suitable for removal of (smaller) stones lodged below the iliac crest

-can have a basket instrument to scoop the stones out or have a shock wave laser to pulverize the stone

-dye may be inserted to make sure there is flow to renal pelvis

-fluid is flushed into bladder to expand it and bladder is examined for abnormal cells

What is the challenge with a ureteroscopy?

-ureter may become irritated (erythematous wall) leading to spasms that close off the ureter

-can give muscle relaxer or insert a stent

What is a stent?

-mechanical device that holds the ureter open

-proximal end is a string taped to the medial thigh

-can be pulled out after 4-14 days

What is a percutaneous nephrolithotomy?

-involves entering the renal pelvis percutaneously (through the skin)

-renal calyces, pelvis, and proximal ureter can be examined and stones extracted with or without prior fragmentation (can pulverize stones)

-may need nephrostomy tube or stent after procedure

What kind of stones is percutaneous nephrolithotomy useful for?

-stones larger than 2.5 cm in diameter

-hard or cystine stones

-staghorn calculi

-lower calyceal stones

-stones associated with obstruction

-in cases of ESWL failure or contraindication

What is a nephrostomy tube?

catheter directed from kidney that is normally removed when discharged

What is worse than hydronephrosis?

infected hydronephrosis

What are calcium oxalate stones?

-85% of stones

-made of calcium and oxalate

-too much calcium (absorbed from intestine or bone) or oxalate in urine (IBD or intestinal surgery)

-males > females 3:1

What are struvite stones?

-15% of stones

-mixture of magnesium, ammonium, phosphate

-common in women with history of UTIs

-caused by Gram-negative bacteria that convert urea to ammonia (Proteus, Klebsiella, Pseudomonas)

-different than others -> different tx

-large (2.5 in)

-cookie cutter of renal pelvis (inside of kidney)

-females > males

What does nephrolithiasis mean?

kidney stones but they are not necessarily in the kidneys

How common are renal calculi?

exceeded in frequency as a urinary tract disorder only by UTIs and prostate disease

What is a kidney stone?

a hard mass developed from crystals that separate from the urine and build up on the inner surfaces of the kidney

When does stone formation occur?

stone formation occurs when normally soluble material (eg, calcium, oxalate) supersaturates the urine and begins the process of crystal formation

What does supersaturates mean?

-a lot of solutes in the urine

-solutes precipitate out of the urine and form crystals by adding to nidus

-shows high specific gravity on urinalysis

-common with dehydration

What is the nidus?

where more solute can be added to the crystal to make the stone

What pain is kidney stones compared to?

acute passage of a kidney stone from the renal pelvis through the ureter gives rise to pain at times so excruciating that it has been likened to the discomfort of childbirth

How many Americans are affected by kidney stones?

700,000 Americans per year

What is management focused on?

management is focused on excluding other serious diagnoses and providing adequate pain relief

What is a true urologic emergency?

-a ureteral stone associated with obstruction and upper UTI

-no urine gets past so it builds up in the kidney and stationary urine can lead to infection

-complications include perinephric abscess, urosepsis, death

-immediate involvement of the urologist is essential

For patients over 60 with no history of renal calculi, what disease process should you think of?

-AAA - abdominal aortic aneurysm which can rupture

-it is rare for patients over 60 to have new onset of renal calculi

Where can renal calculi occur?

anywhere on pathway from kidney to urethra

What are the types of stones?

1. calcium oxalate

2. uric acid

3. struvite

What are uric acid stones?

-5% of renal calculi

-common in pts with a history of gout

-common in those with a high purine diet (organ meats and gravy)

-disease of kings and queens

What is the predominant age for kidney stones?

-30-50 years old (most common in 3rd decade)

-recurrence rates after first stone are 14%, 35%, and 52% at 1, 5, and 10 years respectively

What should be done when nephrolithiasis is clinically suspected?

when a diagnosis of nephrolithiasis is clinically suspected, imaging of the kidneys, ureters, and bladder should be performed to confirm the presence of a stone and assess for signs of urinary obstruction (eg, hydronephrosis)