See also: [[Haematuria]] see: [Dunn - ureteric calculi](x-devonthink-item://276A387C-08E4-446A-AB4F-90B56B80358D) > heuristic: don’t diagnose renal colic without excluding [[Abdominal Aortic Aneurysm|AAA]]! > [!key points] > - size 5-7mm pass 50% of time, >7 : 30%, > 8 : 5% > - ==stone size **≥6** is associated with an **80% chance of a urological complication** requiring surgical intervention== > - urology admission stones >5 or 6mm, infected, significant renal impairment, solitary kidney, or renal transplant ## Risk factors for renal calculi - recurrent UTI - hyperuricaemia - eg following *chemotherapy* - Gout - [[hypercalcaemia|hypercalcemia]] - hyperparathyroidism - drugs - carbonic anhydrase inhibitors - topirimate - calcium and vitamin D - retrovirals - sulfadiazine - *laxative abuse* - [[Renal tubular acidosis|RTA]] type I - genetic - Cystic fibrosis - congenital malformation eg bifid ureters, PCD, horseshoe kidney, ureterocoeles - sarcoidosis - Hot arid climates - male gender - prior kidney stone - Dehydration ## Types of calculi - Calcium phosphate and calcium oxalate are 70% of stones - prevent with thiazides , reduce animal protein, increase urine output - infection stones: "struvite" (MgNH4PO4); women > M - urate -- radiolucent . urine pH always < 6 - prevent with allopurinol - cysteine stones -- most likely to cause end-stage renal failure ## Urolithiasis spontaneous passage factors The size, shape and site of the stone at initial presentation are factors that determine whether a stone passes spontaneously or requires removal. - ==Stones < 5 mm== in patients **without associated infection** or anatomic abnormality pass within 1 month in 90% of cases - stones 4–6 mm pass 50% of the time - Stones > 7 mm only pass 5% of the time and usually require elective surgical removal. > Dunn says ==≥ 5-7 pass 50% of time, >7 : 30%, > 8 : 5%== > stone size **≥6** is associated with an **80% chance of a urological complication** requiring surgical intervention > The overall passage rate for ureteral stones is: > - proximal ureteral stones 25% > - midureteral stones 45% > - distal ureteral stones 70% ![[Pasted image 20241107205115.png|variation in calibre of ureter]] - The probability of spontaneous passage of stones is determined by multiple factors, including size, shape, location, and degree of ureteral obstruction. Bizarre or irregularly shaped stones with spicules or sharp edges have a lower spontaneous passage rate. - With complete obstruction, there is a lower rate of spontaneous passage than if the blockage is partial. - The most common sites of obstruction include the *ureteropelvic junction, where the 1-cm pelvis constric*ts into the 2- to 3-mm ureter; the pelvic brim, where the ureter courses over both the pelvis and the iliac vessels; and finally, the ureterovesical junction, because this is the most constricted site of the ureter due to the muscular coat of the bladder. Based on stone size alone, 98% of stones 7 mm will pass within 4 weeks without intervention. Sixty percent of stones 5 to 7 mm and 39% of stones >7 mm will pass within 4 weeks. ## management - IN fentanyl or IV; titrate IV until pain settles - NSAIDs - diclofenac 75mg IM - indomethacin 100mg suppository - oral NSAIDs - tamsulosin 0.4mg od for 2 weeks - no expulsive value for stones < 5mm, may reduce analgesic use - increases passage rate of larger stones by 10% and reduces analgesia by 2/3; most effective for distal ureteric stones - caution adverse effect postural hypotension ## Indications for hospitalisation **SSU** - ongoing pain 4 hours post adequate analgesia - stone <6mm diameter - in distal ureter **urology admission** - obstruction of a solitary kidney or renal transplant - infected obstructed stone - high degree of obstruction - ==large >6mm proximal stone== - bilat ureteric stones - significant renal impairment and associated urinary obstruction - persistent or multiple repetitive episodes of pain requiring parenteral analgesia Rosen: *Absolute* - infected obstructing stone - intractable nausea or vomiting - severe pain requiring parenteral analgesia - urinary extravasation - hypercalcaemic crisis *relative* - significant illness complicating outpatient management - high-grade obstruction - leukocytosis - solitary kidney or intrinsic renal disease ## infective obstructive stone - 5-7mg/kg gentamicin + IV amoxicillin 2g - supportive care IVF +/- vasopressors - theatre for urgent ureteric stent - appropriate analgesia ## Definitive treatment - not required in 95% of cases - spont passage occurs in majority 1-3 weeks - indicated for - infection + obstruction - high degree obstruction not resolving - failure of conservative tx by 4-6 weeks - large calculi not likely to pass spontaneously options: - percutaneous nephrolithotomy - ureteroscopy and retrograde renal surgery - preferred in pregnancy, obesity, coagulopathy - shock-wave lithotripsy ## Discharge advise - NSAIDs od for 5 days - PRN opiate for breakthrough pain - return to ED if - episode of severe pain without relief with oral analgesics - fever, vomiting - urinary obstruction - average time for stone to pass is 7-10 days - GP review - repeat plain AXR if radioopaque stone - 24 hour collection for recurrent calculi ## Imaging in Renal colic **purpose** - confirm diagnosis - rule out other significant causes (eg diverticulitis, pelvic mass, pyelonephritis, **AAA**) - to detect high grade obstruction within 48 hours - renal tract imaging should occur wihin 24-48 hours of first painful episode *ultrasound*- first line in pregnant patients *CT* - if other dx considered, suggestion of concurrent urinary sepsis - standard abdo CT if DDx includes non-renal causes, high BMI - ==sensitivity for ureteric calculi of > 98%, specificity > 98%== - "low dose" CT KUB beter in younger patients as a "rule in" - ## CT ![[Pasted image 20241107215950.png|non-contrast CT demonstrating LEFT hydronephrosis and perinephric stranding. some incidental gallstones]] ### Renal POCUS #pocus - ==ureteric jets== flow into bladder is *most sensitive marker for detection of urinary obstruction* - midline, transverse probe position in suprapubic area - PRF set to low - normally, 1-12 jets/min on each side - **abnormal** if no jet seen on one side after 3 min of observation - ==hydronephrosis== - hydronephrosis is present in only about 70% of cases of ureteric colic, especially early in symptoms; therefore, USS is not as sensitive as CT at visualising stone or features of stones - ~70-90% sensitive and specific - note that AAA can cause hydronephrosis, more commonly on the left; ∴ specifically screen for AAA when hydronephrosis is found on POCUS in pts >50 other USS findings: - simple cysts - renal massses - pernephric collections - effective at excluding AAA as cause for pain ![[hydronephrosis-pocus.png|grades of hydronephrosis]] *Mild hydronephrosis* - often quite subtle. The renal pelvis and calyces are dilatated, but they may not always be seen to be connected in a single plane unless the beam is perfectly aligned with that plane. Instead, black areas can be seen in the renal hilum, which is normally uniformly white from connective tissue and fat. Mild hydronephrosis can be caused by an over-filled bladder causing back pressure (which should be checked for). Some medical imaging departments do not report mild hydronephrosis at all, because it is seen in a different patient population when they have had to hold on to a very full bladder. In **moderate hydronephrosis**, the calyces become more dilated and clearly become joined to the pelvis, and look like a branching, interconnected anechoic area. This is sometimes referred to as ‘cauliflower appearance’, or a ‘bear claw’. The medullary pyramids start to flatten due to back pressure. Cortical thickness is normal. Many patients have a mild-to-moderate appearance, in which there are clearly dilated calyces which join to the pelvis in some, but not all, parts of the scan plane, forming the classic ‘bear claw’ appearance. In **severe cases**, the renal pelvis and calyces appear ballooned, the medullary pyramids are difficult to recognise, and the cortex becomes thin (< 1 cm). The normal shape of the kidney can be difficult to recognise. These cases should be considered for CT for further evaluation.