Authors: Subhanir Sunil Chitnis, MD (@ChitnisMD, EM Resident Physician, Rutgers NJMS), Dawn Kabba, MD (EM Resident Physician, Rutgers NJMS), and Miriam Kulkarni, MD (EM Attending Physician, Rutgers NJMS) // Edited by: Alex Koyfman, MD & Justin Bright, MD Introduction Calcium oxalate (and to some degree calcium phosphate) stones account for 80% of all kidney stones Remaining stones are uric acid (10%), struvite (10-15%) and cystine (1%) stones It is possible for patient to have multiple stones and for them to be more than one type of stone Epidemiology Prevalence in the US is 5%, with annual incidence of 0.5-1% Lifetime risk is about 10%, male predominance of 2:1 Average age is 20, with range from 20-50, and first occurrence is rarely after 60 In pediatric population, sex distribution is 1:1, with 50% due to metabolic abnormalities, 20% due to urologic anomalies, and 15% due to infection Risk Factors Crystallization occurs when otherwise soluble solutes precipitate due to supersaturation or changes in urinary pH, protein content, or due to reaction with other solutes Crystals cause epithelial injury, deposition of stone formation, bleeding, obstruction, and pain Frequently identified risk factors include hypercalciuria, hyperoxaluria, hypocitraturia, decreased calcium intake, increased oxalate intake, increased animal protein intake, and decreased hydration There is more than 2-fold increase in risk of kidney stones with positive family hx of kidney stones Patients with history of kidney stones have a 10-30% 3-5 year recurrence rate 25% of people with gout will get kidney stones Signs and Symptoms Classic presentation is severe acute intermittent flank pain lasting 20-30 minutes per episode with radiation to the groin, testicles, or vulva, often with hematuria CVA tenderness is found in approximately 50% of patients with kidney stones Rebound tenderness is found in 29% and guarding in 61% Nausea and vomiting is present in 50% of the patients Microscopic hematuria is present in 85% of patients; gross hematuria is seen in 30% of cases Frequency, urgency and dysuria occur in 3-24% of patients Poor outcomes are associated with diabetes, hypertension, renal insufficiency, history of complicated stone disease, urinary tract instrumentation, urinary tract infection, and single, transplanted or horseshoe kidney Diagnosis Use of CT scans has increased by factor of 10-fold over the past 15 years (2, 3) Bedside or Radiology Department ultrasonography has lower cumulative radiation exposure, without significant differences in complications, adverse events, pain scores, return emergency department visits, or hospitalizations when compared to CT scan. (2) In recent study, 40.7% of patients who had point of care U/S and 27.0% of people who had radiology department U/S underwent CT scan to evaluate for stones in the ED (2) Mean total costs and total radiation exposures are lower when patient undergoes ultrasound, despite the additional CT scans required for some cases Ultrasound is the recommended test of choice, with some cases requiring CT scan where ultrasound is equivocal or additional diagnostics are required. For all patients with suspected or diagnosed nephrolithiasis, obtain CBC with differential (assess for infection, anemia from gross hematuria, thrombocytopenia), serum chemistry (assess for acute and/or chronic kidney injury, hyperglycemia), UA + cx (assess for crystals, evidence of infection, casts) Differential Diagnosis High-risk diagnoses include: abdominal aortic aneurysm with or without rupture, pneumonia with sepsis, appendicitis with rupture, diverticulitis with abscess or perforation, bowel ischemia or perforation, renal infarction, renal stone with abscess, pyelonephritis with sepsis or bacteremia, ovarian torsion with or without necrosis, testicular torsion, aortic dissection, ectopic pregnancy with or without rupture Other diagnoses include: cystitis, pancreatitis, pelvic inflammatory disease, epididymitis, colitis, ovarian cysts, endometriosis, biliary colic, renal tumors, bladder tumors, ureteral tumors, ureteral strictures, malingering In one study evaluating 714 patients, alternate diagnoses included appendicitis (4%), pyelonephritis (2.8%), ovarian cysts (1.7%), abdominal aortic aneurysm (1.3%), cholelithiasis (5%). (5) Management Pain control: either NSAIDs (toradol) or opioids (morphine, dilaudid) or combination of both.18,24,25 NSAIDs: decrease spasm of ureter and decrease kidney capsule pressure by decreasing GFR.24,25 Use caution in those with underlying renal disease or problems with GI bleeding.7 Opiates: fast onset. Combination therapy with NSAID and opiate may decrease length of stay in ED.24,7 Antiemetics: Ondansetron (Zofran) and metoclopramide (Reglan) are commonly used. Reglan is the only antiemetic that has been studied in patients with renal colic.15,24,25 Reglan not only has antiemetic properties, but enhances the effects of analgesia. Two studies revealed that reglan provided equivalent pain relief compared to opioids.18,15 IV hydration: routinely done, but no studies show that fluids enhance stone passage or affect outcome.24,25 Medical expulsive therapy (MET): Alpha-1 antagonists are frequently used to relax ureteral smooth muscle cells and improve stone passage. A recent systematic review concluded that Tamsulosin (Flomax) improved stone passage when compared to placebo.9 While a few trials suggested that tamsulosin is an effective way to clear ureteral stones,9,11 other studies suggest that there is no benefit.10 So, the bottom line is that it is unclear if this is actually beneficial for the passage of renal stones, and therefore is not employed as primary management of renal colic in the Emergency Department. Indications for admission ABSOLUTE INDICATIONS RELATIVE INDICATIONS *intractable pain or vomiting fever *sepsis 2/2 UTI/pyelo obstructing stone with signs of urinary infection *solitary or transplanted kidney with obstruction solitary or transplanted kidney without obstruction *Acute renal injury urinary extravasation *hypercalcemic crisis stone unlikely to pass: >5mm and located proximal ureter Table 97-5 Adapted from Manthey et al., 2011.25 Does Stone Size affect Outcome? stone size (mm) average # of days to passage % likelihood of need for intervention ≤ 2 8 3 3 12 14 4-6 22 50 > 6 99 Adapted from AUA, 2014.21 Does Stone location affect rates of passage? Stone Location % Spontaneous passage rate proximal ureter 48 mid-ureter 60 distal ureter 75 ureterovesical junction 79 Adapted from Coll et al., 2002.12 Most stones that pass spontaneously pass within 1 month of symptom onset.21 Who can be discharged home without urology consult? small stones, symptoms resolved, no evidence of infection 25 Discharge Instructions 24,25 Rx for NSAIDs or opioids or combination