Urinary Tract Obstruction and kidney stones Flashcards Preview

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Flashcards in Urinary Tract Obstruction and kidney stones Deck (29)
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What are complications of urinary tract obstructions

Hydroureters, hydronephrosis and pyelonephritis


Examples of intrinsic and extrinsic UTO

- calculi
- strictures
- tumors inside the bladder
- blood clots
- neurogenic (neurons damaged)

- pregnancy
- periureteral inflammation
- endometriosis
- prostate hypertrophy
- tumors outside of the bladder (usually prostate)


What is the relationship between location of UTO and unilateral vs bilateral UTO?

Unilateral = tends to be more proximal

Bilateral = tends to be more distal


Sclerosis retroperitoneal fibrosis
(Ormond disease)

Rare cause of urethral narrowing due to fibrosis of the retroperitoneal structures.

Causes hydronephrosis and is more common in middle- late aged males
- infection, prior surgery, drug exposures and excess radiation are common risk factors
- **most cases however are idiopathic

Etiology = IgG4 released disease in which IgG4 secreting plasma cells cause the fibrosis due to autoimmune functions

Treatment = corticosteroids and urethral stents (once resistance starts to develop)



Affects 5-10% of Americans and can present anywhere in the renal system (however usually inside the kidney)

Men are more affected and the peak onset age is 20-30s
- there is a genetic component released to this
- direct correlate with obesity and diabetes
- recurrence rates = 20% within 5 years

80% are unilateral and tend to have an average diameter of 2-3 mm in the renal pelvis

Can sometimes look “stag horn apperence” when they surround collecting tubules

- abdominal and renal colic pain
- hematuria
- increased risks of super infections


What are the four main types of urolithiasis?

1) calcium stones (70%)
- consist of calcium oxalate or calcium phosphate
- are radioopaque (white) appearing

2) triple stones/struvite stones (15%)
- consists of ammonium phosphate
- are radioopaquish(white) appearing (not as bright as calcium but brighter than uric acid)

3) uric acid stones (5-10%)
- are radiolucent (clear/gray) appearing

4) cystine stones (1-2%)


Calcium stones (urolithiasis)

Are associated with 5% of all patients who have hypercalcemia and hypercalciuria

Can occur with hyperparathyrodism, diffuse bone diseases and sarcoidosis

** about 55% of patients though have hypercalciuria without hypercalcemia
- this is caused either by intestinal hyper absorption or impaired renal tubular reabsoption of calcium

***these are radioopaque stones***


Struvite (magnesium ammonium and phosphate stones)

Largely formed after infections by urea-splitting bacteria which convert urea -> ammonia
- includes proteus and staph species as well as e. Coli and klebsiella
- *more common in women since they are more likely to get UTIs

High levels of ammonia produces alkaline urine which causes precipitation of magnesium ammonium salts which can accumulate

**often appear “stag horn” appearance since they occur in the renal pelvis and take its shape**


Uric acid stones

Common in individuals with gout or rapid cell turnover diseases (such as cancer and tumor lysis syndrome)
- more common in men

**however more then half of the patients with these stones have neither hyperuricemia nor increased urinary excretion of uric acid**
- this is believed to be due to lower pH (acidic urine) since uric acid is insoluble in acidic urine

**patients will always have acidic urine (<5.5)

***these are radiolucent stones***


Cystine stones

Caused by cystineuria

**Form only at acidic pH urine (<5.5)


What are some common inhibitors of stone formations in the renal system?







***it is proposed that a deficiency in any of these can lead to an increase in urolithiasis formation***



Dilation of the renal pelvis and calyces with accompanying atrophy of the parenchyma

Obstruction may be sudden of insidious and can occur at any level of the urinary tract

*can only be bilateral if the lesion/obstruction is below the ureters*
- if unilateral = can be anywhere but most likely a over the ureters
- bilateral = renal failure

Causes diminished GFR overtime
- irreversible damage:
Takes 3 weeks in complete obstruction
Takes 3 months in incomplete obstruction

**uremia tends to stop natural course of lesion


Causes of hydronephrosis

Congenital causes:
- atresia of the urethra
- poor valvular formations
- aberrant renal arteries

- foreign bodies
- proliferative lesions
- inflammatory lesions/ infection
- neurogenic causes
- pregnancy


How does bilateral complete obstruction and incomplete bilateral obstruction differ in hydronephrosis symptoms?

Complete = anuria

**Incomplete = polyuria
- this is kinda strange but this is due to defective tubular concentration which just wants to push everything out without filtration


Medications that have known risks for developing urinary stones

Carbonic anhydrase inhibtors

HIV medications

Laxative abuse

Loop diuretics




What causes the pain in kidney stones?

The hydronephrosis that occurs with the kidney stone. This stretches the gerotas fascia that surrounds the ureters and causes pain
**not solely because there is a stone in the kidney, the stretching is the source of pain**

***because of this smaller kidney stones that dont cause obstruction WONT cause pain


Pathophysiology of stones

Most are 2-3mm
- 98% of these pass with nothing

5mm = 50% pass normally

7mm or are sharpe/irregular shaped = almost never passes by itself and will cause hydronephrosis

**90% of stones will block the UVJ (urethralveseical junction next its valve)

**Overall numbers of kidney stones = increasing due to increases in obesity and diabetes**
- men are more common than female and reoccurrence is 20% in all patient’s**


Clincial presentation of urolithiasis

Will present with sudden flank colicky pain that can radiate towards the abdomen/back and upper left quadrant

*** will mimic AAA so NEED TO CHECK FOR THIS
- 70% of AAA’s are misdiagnosed as kidney stones = death

(+/-) hematuria

(+/-) vomiting/ nausea

**often presents with at least 1 risk factor**


What does POCUS show for urolithiasis

Dilated renal pelvis and may show a kidney stone
- kidney stones have shadows!!

**if you see free fluid surrounding the kidney = ruptured AAA!**


What are other DDX especially gynecological causes of urolithiasis like pain?

Renal artery or vein thrombosis

Mesenteric ischemia


GI ischemia

Testicular torsions in males

1) Ectopic pregnancies
- get a pregnancy test = (+)

2) Torsions of the uterus


Can shingles cause renal colicky pain?

- sometimes the rash doesnt break out until a Day or two later
- need to monitor for rash but this is usually a diagnosis of occlusion


What are risk factors that associated with poor outcomes with urolithiasis

History of difficulty with stones or past stones

Symptoms of infection are present

History of: diabetes, HTN, renal insufficiency, single kidney, horseshoe kidney or past transplant


Are urinary diagnosis labs confirmation for kidney stones?

- however there are some values that are usually seen.
- 85% will present with blood
- calcium levels and uric acid levels will be elevated with their respective stones
- Stones always show WBC rise, but doesn’t necessarily mean infection
- ** NOTE: if hypotension starts to occur, STOP working on kidney stone diagnosis. Kidneys stones NEVER cause hypotension**

**imaging will NOT always show stones. That doesnt mean one isnt there**

***should still get a BMP and urinalysis as well as imaging though***
- can help save your butt if you have a bad initial diagnosis


What is the imaging studies of choice for urolithiasis?

CT is gold standard
- ***contraindicated in pregnancy
- good in all types of stones

Can also use Ultrasound//POCUS
- ***#1 in pregnancy
- better for larger stones


Common treatments for urolithiasis

NSAIDs/ pain meds
- be careful with NSAIDs though especially with bleeding and CKD
- **ketorlac is gold standard
- can use opiods as fallback

Dont have to necessarily give IV fluids everytime since it Can actually exacerbate pain
- however give fluids if they are hypotension

Lidocaine = can use for pain as well as long given slowly
- actually better than opioids often (as long as slow giving)

Antibiotics if infections are also present
- also need to admit since you have to go in sand get the stones

Medical expulsion via alpha-blockers
- **#1 in larger stones >5mm

- works but be careful since it can cause numerous smaller stones that can be passed but may cause pain


Admission criteria for urolithiasis

10 mm stones every time

Have any comorbidities

Go home with a 5mm or greater stone and dont end up passing and coming back
- admit during the second visit

Look ill appearing and/or are septic

Patinets with CKD


Pregnancy and urolithiasis

Stones typically occur in 2nd/3rd trimesters

Symptoms are usually the same as normal
**if they present with hematuria and lower quad pain = think about placenta ruptures. CANT MISS THIS**

Need to give ultrasound for imagining (cant give other types due to radiation unless given the green light to do so by OBGYN)
- **if urethral jets are “firing” on ultrasound, they dont have kidney stones**

Pain management = opioids
- never give NSAIDs especially 3rd trimester (causes the babies ductus arteriosus to premature close = pulmonary HTN)


How does a patients pain location correlate with stone location in the urinary system

Flank pain = kidney/upper ureter

Lower right or left quadrant = lower ureter/bladder stone


what two findings on imaging signal a kindey stone, even if you dont actually see the stone on imaging?

Hydroureter and paranephric stranding
- 96 % chance has a stone

**if they have neither of these = 96% they DONT have a stone