Stones and Obstructions

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🌱 來自: Huppert’s Notes

Stones and Obstructions🚧 施工中

Stones and Obstructions

Nephrolithiasis (kidney stones)

•   Types:

-   Calcium stones (80%): Radiodense. Calcium oxalate (90%, envelope shape, malabsorption) or calcium phosphate (10%, hyperparathyroidism, RTA).

-   Uric acid stones (10%): Radiolucent, flat square plates. Hyperuricemia due to gout, tumor lysis syndrome

-   Struvite stones (5–10%): Radiodense; rectangular prisms, staghorn morphology. Recurrent UTIs by protease-producing organism (Proteus, Klebsiella, Serratia, Enterobacter convert urea to ammonia, which combines with magnesium or phosphorus to form struvite calculi).

-   Cystine stones (1%): Poorly visualized by x-ray, hexagon-shaped crystals. Screen with urinary cyanide nitroprusside.

•   Clinical features: Acute renal colic (sudden onset, can’t sit still, cramping abdominal/flank pain in waves), nausea/vomiting, dysuria, +/- fever/chills

•   Diagnosis:

-   UA with microscopy (evaluate for microscopic/gross hematuria, crystals)

-   Imaging (confirm diagnosis, stone size/location, assess for hydronephrosis): Noncontrast CT abd/pelvis if nephrolithiasis has not been previously established (superior sensitivity, specificity), ultrasound is useful to avoid radiation in patients who may be pregnant

•   Treatment:

-   Acute treatment:

•   IVF, pain control (NSAIDs > morphine), medical expulsive therapy with an alpha blocker

•   Urgent stone removal required if:

-   Stone unlikely to pass: Stone >10 mm, GU anatomical abnormality

-   Infection: UTI, sepsis

-   Severe symptoms: Intractable pain or nausea/vomiting

•   If stone not removed urgently, consider follow-up imaging in 14 days to monitor stone position

•   Prevention:

-   Adequate fluid intake (goal >2 L urine output/24 hr)

-   If high risk for stone recurrence (large stone burden, non-calcium stone, abnormal urological anatomy, history of GI disease or bariatric surgery, family history), then refer for metabolic assessment to tailor preventive measures

-   Almost all patients with nephrolithiasis should adhere to a low-sodium diet, which reduces calcium excretion. Other dietary changes may be beneficial based on urine lab abnormalities.

-   Pharmacologic treatments include thiazides for hypercalciuria, allopurinol for hyperuricemia, alkali supplementation for hypocitraturia

Urinary tract obstruction

•   Etiology:

-   Lower tract: Neurogenic bladder (e.g., due to diabetes), bladder cancer, BPH, prostate cancer, urethral stricture, blood, stone, trauma

-   Upper tract:

•   Intrinsic: Kidney stones, blood clots, sloughed papillary, tumor, ureteral stricture

•   Extrinsic: Pregnancy, tumor, abdominal aortic aneurysm, retroperitoneal fibrosis, endometriosis, hematomas, IBD, diverticulitis

•   Clinical features: Renal colic and pain (especially if acute), oliguria, recurrent UTIs, hematuria/proteinuria, renal failure

•   Diagnosis:

-   Renal ultrasound

-   Advanced diagnostics: Intravenous pyelography (IVP) for ureteral obstruction, voiding cystourethrography for lower tract obstruction, cystoscopy for bladder

•   Treatment:

-   Lower tract: Foley Catheter, BPH medications (e.g., alpha-blockers; 5-alpha-reductase inhibitor)

-   Upper tract: Ureteral stent via cystoscopy if possible, otherwise percutaneous nephrostomy tube