Staghorn calculus – etiology, diagnosis, management

basic ppt of staghorn calculus

1. Staghorn Calculus – Etiology , Management & Prevention

2. BACKGROUND infection stones, struvite , triple phosphate stones, staghorn calculus. Magnesium Ammonium Phosphate (MgNH4PO4·6H2O ) + calcium carbonate apatite crystals (Ca10(PO4)6·CO3 ) Potential for morbidity and mortality: Untreated infection stones – progressive renal demise Inadequately treated struvite stone – niduses for recurrent UTI and recurrent struvite stone formation. bacteria reside within these stones – life-threatening sepsis

3. Pathogenesis Infection stone = urine pH is > 7.2 urease -producing bacteria

4. (NH 2 ) 2 CO + H 2 O → 2NH 3 + CO 2 NH 3 + H 2 O → NH 4 + + OH − pK = 9.0 presence of urease , ammonia continues to be produced despite alkaline urine, further increasing urinary pH . Promotes the hydration of carbon dioxide to carbonic acid CO 2 + H 2 O→ H 2 CO 3 pK = 4.5 H 2 CO 3 → H + + HCO 3 − pK = 6.3 HCO3 - → H + + CO 3 2- pK = 10.2

5. The dissociation of hydrogen phosphate under alkaline conditions provides phosphate OTHER FACTORS: The relative decrease in stone inhibitors( citrate ) may also play a role in struvite physicochemistry . GAGs theory Stasis

6. Bacteriology family Enterobacteriaceae comprises the majority of urease -producing pathogens The most common urease -producing pathogens are Proteus, Klebsiella , Pseudomonas , and Staphylococcus species Proteus mirabilis the most common organism associated with infection stones Bacterial urease can be detected by the Urea-Rapid Test E. coli and Proteus, may alter the activity of urokinase and sialidase ,

7. Epidemiology Infection stones comprise 5% to 15% of all stones More often in women (ratio of 2 : 1) Increased risk for infection calculi: Elderly premature infants diabetics urinary stasis as a result of urinary tract obstruction , urinary diversion, or neurologic disorders. Spinalcord –injured patients use of indwelling catheters

8. CLINICAL FINDINGS A complete history of chronic flank pain, malaise, fever, dysuria , and intermittent hematuria immunosuppressed state (diabetes mellitus, steroid intake, etc.), history of previous stone disease past surgical history - for urological procedures history of using multiple, alternating antibiotics

9. Physical Examination a chronically ill-appearing patient Body habitus , presence of vertebral kyphoscoliosis In acute pyelonephritis or pyonephrosis - toxic appearance costovertebral angle tenderness

10. Laboratory studies complete blood count basic metabolic panel Urinalysis Urine culture

11. Imaging Modalities Renal sonography X ray KUB IVP CT urography Nuclear renography

12. NATURAL HISTORY OF INFECTION STAGHORN CALCULI Pyonephrosis xanthogranulomatous pyelonephritis end stage hydronephrotic kidney severe pyelonephritic changes Perinephric abscess Carcinoma the overall rate of renal deterioration was 28 % Solitary, previous, recurrent, hypertension, complete, diversion, neurogenic bladder, refused treatment asymptomatic

13. TREATMENT The primary goal of staghorn stone management is complete stone eradication. Various modalities of treatments are: Surgical PCNL E SWL OPEN SANDWICH THERAPY Non surgical Dissolution therapy Antibiotics urease inhibitors, urinary acidification, dietary modification.

14. Percutaneous Nephrostolithotomy (PCNL) the treatment of choice superior stone-free outcomes acceptably low morbidity . Stone free rate of ~80% overall risk of transfusion was 18 % serious complications was 15 %. i.e. injury to adjacent organs (colon, spleen, liver), hydropneumothorax , collecting system perforations, sepsis , vascular injury, renal loss.

15. Technical advances in PCNL flexible nephroscopy is mandatory after debulking the dominant stone to establish multiple percutaneous tracts second look nephroscopy .

16. Extracorporeal Shockwave Lithotripsy ( Monotherapy ) SWL is the least invasive of the operative approaches SWL monotherapy had the lowest success rate . Risks included colic requiring admission , significant perirenal hematoma, obstruction including steinstrasse , pyelonephritis , renal loss. “ sandwich therapy ”- pcnl -> eswl -> pcnl

17. Ureteroscopy flexible ureteroscopy has been used in combination with PCNL to avoid multiple access tracts to access calyces that would be difficult to access in an antegrade manner

18. Open & Laparoscopic Surgery Anatrophic nephrolithotomy and pyelolithotomy operations alternative in patients who require concomitant heminephrectomy , pyeloplasty in those with ectopic kidneys that cannot be safely accessed percutaneously Other indications: morbid obesity, large symptomatic anterior caliceal diverticular stones , large stone volume with infundibular stenosis massive collecting system dilation

19. Dissolution therapy Boric acid and permanganate Suby’s solution G Hemiacidrin or Renacidin ® adding D- gluconic acid. following precautions must be exercised during intrarenal chemolysis : Low intrarenal pressures must be maintained (<30 cm water), Serum magnesium and phosphate must be monitored closely, The urine must be sterile. Broad-spectrum antibiotics are given for 14 days in the perioperative period, The collecting system must be unobstructed and there must be no extravasation . Indication: in high-risk patients, with residual calculi after percutaneous renal surgery . Demerits : prolonged hospital stay, cost and risk of complications.

20. Antibiotics Culture-specific preoperative and perioperative antibiotics are critical to prevent sepsis Long-term, low-dose , culture specific antimicrobials are important to prevent new stone growth and progression after surgery. AUA Guidelines Panel stated emphatically that treatment with antibiotics alone is not standard of care .

21. Urease Inhibitors Acetohydroxamic acid (AHA) is the only FDA-approved urease inhibitor. Irreversibly inhibits bacterial urease High renal clearance, Penetrate the bacterial cell wall, Acts synergistically with several antibiotics Adverse effects- tremulousness, thrombophlebitis , neurologic, hematologic, and dermatologic. Contraindicated in patients with serum creatinine greater than 2.5 mg/ dL

22. Urinary acidification L- methionine to acidify urine oral intake of 1,500–3,000 mg daily of L- methionine gastric patch pyeloplasty (animal model)

23. Dietary modification Aim : T o deplete the substrates of struvite calculi, including urinary phosphate, magnesium , and ammonia. ( Shorr regimen) a regimen of a low-phosphorous, low-calcium diet with oral estrogens and aluminum hydroxide gel Adverse effects: constipation, anorexia, lethargy, bone pain, and hypercalciuria , increased risk of breast and uterine cancers.

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