Stones - GU Flashcards
1
Q
Stone Composition
A
- Supersaturation of urine by stone forming constituents
- Calcium compound deposits/forms in renal papilla, gradually erode through papillary urothelium, eventually breaking free
Types of Stones:
- Calcium Oxalate
- Calcium Chloride
- Less common: Uric acid, cystine, ammonium acid urate, xanthine
2
Q
Pathophysiology of Obstruction
A
Decreased ureteral flow initially results in:
- Increased ureteral peristalsis and dilatation of ureter proximally
- Increased renal blood flow
- By 24 hours, both of these have decreased
- Increased renal interstitial edema with increased lymphatic absorption
- Increased blood flow to contralateral kidney
3
Q
Stone Formation
A
- Dehydrated state
- Higher concentration of stone forming solutes (Calcium, oxalate, urate, etc.)
4
Q
Calcium Stone
A
- Any condition that may result in hypercalciuria
- Increased intake (dietary)
- Increased absorption or resorption (hyperparathyroidism)
- Renal calcium and phosphate leak
- Hyperoxaluria, hyperuricosuria, hypocitraturia, hypomagnesuria
5
Q
Struvite (Magnesium Ammonium Phosphate) Stone
A
- Associated w/ gram negative bacterial infection (Pseudomonas, Proteus and Klebsiella but not E. coli)
- These bacteria split urea and form ammonium which combine w/ magnesium and phosphate
- May form a “stag horn” calculus
- Need to remove calculus for UTI to resolve
6
Q
Other Stones (far less common)
A
- Urate (associated w/ gout, high purine intake and some malignancies)
- Cystine (metabolic renal issue resulting inability to reabsorb cystine)
- Drugs: HIV, triamterine, sulfa drugs, guaifenesin, magnesium silicate containing antacids
7
Q
Epidemiology
A
- Men (12%) > Women (7%) lifetime risk
- Risk doubles if + family history
- Upper tract stones more common in developed world
- Peak incidence 35-45 years of age
- Rare in children
- Race: More common in Asians and whites than all other ethnicities
- Geography: more common in dry/hot areas
Locations: UVJ, pelvic brim, UPJ
8
Q
Prognosis
A
- Majority of stones will pass (80-85%)
- Hospital admission rate approximately 20% (refractory pain, dehydration, infection, unable to pass stone)
- Many patients will experience recurrence, up to 70% by ten years from initial presentation
9
Q
Tx - stones
A
- Anti-inflammatory (ketorolac parenterally)
- Opioid (morphine, hydromorphone parenterally)
- Antiemetics
- Hydration (IV Normal Saline:) Not necessary always in well hydrated patient, May contribute to increased hydrostatic pressure
Meds:
- Ketorolac parenterally (antiprostaglandin and has ureteral relaxation effects) - NSAID
- Ketorolac intranasal (outpatient, for up to 5 days)
- Ibuprofen (orally)
- Pain meds/Narcotics
- Desmopressin (DDAVP): Desmopressin (DDAVP)
- Anitemetics: Metoclopramide (CNS dopamine receptor blocker) has been well studied. Also provides pain relief. Ondansetron, Prochlorperazine
10
Q
History
A
- VERY Uncomfortable appearing, marked distress, writhing about on the exam bed
- Very painful
- Came on all of a sudden
- Pain in back can radiate and shoot to abdomen
- nausea and vomiting
- Continuous pain: nothing really makes it better
- nothing makes it better, cant get comfortable
- no guarding of abdomen
11
Q
Diagnostic Tests
A
- Urinalysis: so simple, but don’t rely solely upon this (may be absent in 5-15% of patients)
- Screen for infection
- May indicate type of stone if crystals are seen
CT
- Standard test for acute presentation of renal/ureteral colic
- Allows accurate diagnosis of stone, degree of obstruction and other incidental findings (inflammation, tumor, AAA, etc.)
- Rapid assessment (most CT scanners take 5 minutes maximum now)
- Negatives: radiation exposure, $$
Intravenous Pyelogram (IVP)
- No longer first line imaging test
- Longer accession time
- Need for IV contrast resulting in allergy and contrast nephropathy
- Was sufficient for evaluating degree of obstruction, and location of stone in many cases
Ultrasonography
- Limited use in diagnosing smaller stones (<5mm), especially in ureters
- Detect significant urinary obstruction
- Hyperechoic stones (of more significant size) can be seen in kidney and UPJ at times
- Doppler ultrasonography could be used to detect ureteral obstruction (this is not commonly used)
12
Q
Retrograde Pyelogram
A
- Performed when a precise diagnosis cannot be made by other means
- When exact anatomy of the ureter must be clarified (prior to ureteroscopy)
- Prior to surgery due to uncontrollable pain, infection, large stone (typically > 8 mm) or possible anatomic problems (ureteral strictures)
- Not used commonly
13
Q
Medical Expulsive Therapy
A
- NSAID
- Opioid analgesic (narcotic/acetaminophen combination)
- Alpha-adrenergic blocker (Tamsulosin (flomax) 0.4 mg by mouth daily)
- Treat no longer than 10-14 days (stone should have passed in this amount of time)
14
Q
Diet
A
- HYDRATION!
- Calcium, oxalate, uric acid and citrate assessed
- 24 hr urine collection (can assess for output as well)
Western diet as we know it not conducive to stone prevention
- High Protein
- High Dairy
- High Oxalate
15
Q
Surgical Treatment
A
- ESWL (extracoporeal shockwave lithotripsy): Intense shockwaves focused on the stone(s)
- Best for stones less than 2 cm
- Upper to mid calyx preferred
- Varying degrees of analgesia
16
Q
Ureteral Stents
A
- Used to immediately drain the obstructed proximal ureter
- Bypass stone/obstruction
- Dilate ureter to allow for future procedures and improve stone passing
- Adverse Effects: infection (low rate), pain, migration, blockage
17
Q
Ureteroscopy
A
- Lower calyx stones (dependent portion of calyces)
- 1-2 cm in size
- Stones are either moved proximally for subsequent SWL or they are fragmented (laser, etc.)
18
Q
Percutaneous Nephrostolithomy
A
- Needed for more complex or larger stones
- Passed using Seldinger technique
- Higher morbidity, more invasive
19
Q
Complications from Urinary Stones
A
- Infection
- Post-renal failure secondary to prolonged obstruction
20
Q
Urinary Obstructions
A
Think anatomic and gender:
- Men: Prostate, tumor
- Women: Pelvic prolapse (older), tumor (old, middle aged and young), Pregnancy (young)
- Children: Congenital (UPJ, UVJ, etc.) obstruction
Causes:
- Medications (anticholinergics)
- Perform thorough medication history
- Detailed List of Medications
21
Q
Urinary Obstructions - sxs
A
Acute Painful: -Not always the degree of obstruction, but more the abrupt onset -Instrumentation or surgery -Medications
Chronic:
- Less painful or pain free
- Chronic prostate issues
- Tumor
- Neurogenic
22
Q
Bladder/Urethra (Pediatric)
A
- Urethral atresia
- Phimosis
- Meatal stenosis
- Anterior and posterior urethral valves (males)
- Calculus (Southeast Asia)
- Blood clot
- Neurogenic bladder (meningomyelocele)
- Ureterocele
- Retrocaval ureter
- Vesicoureteral reflux (girls more common)
- Ureterovesical junction narrowing or obstruction
- Retroperitoneal tumor
- Megaureter -Prune belly syndrome
23
Q
Bladder/Urethra (Adult)
A
- Stricture (men usually)
- Sexually transmitted diseases (STDs), women with severe genital herpes involving the urethral orifice, occasionally in males (severe prostatitis or urethritis)
- Trauma
- Phimosis
- Blood clot
- Calculi
- BPH
- Cancer (bladder or prostate), Cancer (cervix or colon)
- Neurogenic bladder (diabetes mellitus, spinal cord disease, multiple sclerosis, Parkinsons, Multiple medications)
- AAA
- Uric acid crystals
- Pregnancy
- Papillary necrosis (sickle cell disease, diabetes mellitus, pyelonephritis)
- Vesicoureteral reflux (female preponderance)
24
Q
Diagnosis - obx
A
- Clinical (detailed history and physical exam)
- Laboratory: UA , Blood (CBC, BMP)
Imaging IVP: Contrast complications -CT : Detailed images, radiation -MRI: High sens/spec for obstruction -Ultrasound: up to 90% sensitive, Non-invasive/painless, Rapid
25
Q
Treatment - obstruction
A
- Foley catheter
- Help maintain adequate urinary flow
- Alpha-adrenergic blockers (Tamsulosin, terazosin, prazosin, silodosin-new agent)
- Approx 40% of prostate is comprised of smooth muscle
