![]() It allows the ureter to be kept patent and temporarily relieve the obstruction.Ī nephrostomy is a tube placed directly into the renal pelvis and collecting system, relieving the obstruction proximally (Fig. Retrograde stent insertion is the placement of a stent within the ureter, approaching from distal to proximal via cystoscopy (Fig. Patients with any evidence of obstructing stones may warrant primary ureteroscopy or ESWL (see below) to clear the stone, but if they have any evidence of infection or acute kidney injury, they need urgent decompression with stent insertion or a nephrostomy. Uncontrollable pain from simple analgesics.However, criteria that often warrant the need for hospital admission include: The majority of renal stones can be treated in the outpatient setting. However, if a patient is known to have radio-opaque urinary tract calculi an AXR may be used as part of stone surveillance. Plain film abdominal radiographs (AXR) are rarely used for the initial assessment of stone disease, as not all stones are radio-opaque which limits their use, alongside their associated radiation exposure. Its benefits are in no radiation risk, however are often operator dependent. Ultrasound scans of the renal tract can often be used concurrently in cases of known stone disease, to assess for any hydronephrosis (they can also often detect renal stones, however not ureteric stones). 3) as an imaging modality is the high sensitivity and specificity in identifying stone disease, as well as concurrent assessment of any alternative pathology. The gold standard for diagnosis of renal stones is a non-contrast CT scan of the renal tract (KUB). Urate and calcium levels can also aid in the assessment of stone analysis if the patient notices they have passed the stone during micturition, retrieval of the stone and sending for analysis can also be of use. Routine bloods should be performed, include FBC & CRP (for evidence of infection) and U&Es (to assess renal function). red meats) or through haematological disorders (such as myeloproliferative disease), results in increase of urate formation and subsequent crystallisation in the urine.įor cystine stones, these are typically associated with homocystinuria, an inherited defect that affects the absorption and transport of cystine in the bowel and kidneys as citrate is a stone inhibitor, hypocitraturia from the condition can thus predispose affected individuals to recurrent stone formation.Ī urine dip can show microscopic haematuria, as well as evidence of infection (always ensure to send a urine culture as well in such cases). Urease catalyses urea into carbon dioxide and ammonia, which leads to the precipitation of magnesium ammonium phosphate crystals.įor urate stones, high levels of purine in the blood, either from diet (e.g. However, certain stone types that form may also be caused by a specific underlying pathology.įor struvite stones, also called infection stones, form in alkaline urine in the presence of urease-producing organisms, such as Proteus and Klebisella species. Calcium and oxalate precipitate at lower saturation levels and are therefore the most common stone composition. The basis for formation of urinary tract stones is over-saturation of urine. By Nevit Dilmen įigure 1 – A large staghorn calculi, as seen on plain film abdominal radiograph Pathophysiology
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