URETERAL STONES: A Brief Review of Diagnosis and Treatment

EPIDEMIOLOGY 12% risk in lifetime 2-3% risk of renal colic Recurs within 2-3 years Occurs in men three times more than woman Peak incidence from 30 to 50 Factors that may increase incidence: diet, lifestyle, social status, heredity, geography

TYPES OF STONES 75% calcium oxalate or phosphate 15% phosphate-containing, most commonly struvite (magnesium ammonium phosphate) 5-10% uric acid 1% cystine Rarely, pure matrix and indinavir deposition

LOCATIONS OF STONES Ureteropelvic junction (UPJ) Pelvic brim (at the bifurcation of the iliac vessels where the ureter courses anterior and medial to the vessels and is compressed) Ureterovesical junction (UVJ)

URETERAL CALCULI

L1/L2 Junction Tips of transverse processes Stone Sacroiliac joint Curves medially, Lateral to curve of sacrum Enters bladder near sacro-coccygeal junction. Level with Ischial spines Phlebolith

SIGNS AND SYMPTOMS Severe, intermittent unilateral flank that radiates to the groin causing the patient to writhe around at its height of intensity Microscopic hematuria If febrile, then may be a complicated ureteral obstruction by either infection with obstruction or acute pyelonephritis

DIFFERENTIAL DIAGNOSIS Genitourinary causes: pyelonephritis, torsion of a pelvic mass Gastrointestinal causes: appendicitis, diverticulitis, cholecystitis, choledocholithiasis, pancreatitis, bowel obstruction, Crohn’s disease, torsion of an abdominal mass Vascular causes: aortic dissection, ruptured abdominal aortic aneurysm

PLAIN RADIOGRAPHY Relies solely on the identification of a calcific density along the expected ureteral tract Only 59% of ureteral calculi are visible Cystine stones are mildly radiodense Uric acid, pure matrix, and indinavir stones are radiolucent

ULTRASOUND Not recommended Detects indirect signs of obstruction: collecting system dilatation, a change in renal blood flow, a loss of a ureteric jet Rarely identifies urolithiasis except at the UPJ or UVJ Difficulty in measuring the size of a stone

INTRAVENOUS PYELOGRAM (IVP) Advantages: availability, low cost, ability to assess renal function Disadvantages: requires intravenous contrast, prolonged exam time, inability to assess other causes of the clinical presentation, difficulty in distinguishing calcific densities Sensitivity 87% and specificity 94%

IVP: Radiographic Findings of Ureteral Stone Obstruction Opacity along the urinary tract Dilatation of ureter down to obstruction Dilatation of collecting system Delay in contrast of nephrogram Delay in contrast of collecting system Delay in contrast excretion

IVP: Radiographic Findings of Ureteral Stone Obstruction Figure1. a. An opacity is visible within the pelvis on the right side. b. The right ureter is full of contrast down to the site of obstruction.

NONCONTRAST HELICAL CT (NCCT) Imaging modality of choice Advantages: speed, safety, ability to assess other causes of the clinical presentation, and in some places, equivalent cost to IVP Disadvantages: Inability to assess renal function, difficulty in assessing patients that have insufficient renal fat, difficulty in distinguishing calcific densities Sensitivity 95% and specificity 95%

NCCT: Direct Stone Visualization Hallmark finding is a stone in the lumen of the ureter on the side of renal colic Virtually all stones are seen on CT except pure matrix and indinivar stones

NCCT: Secondary Signs of Ureteral Obstruction Ureteral dilatation Collecting system dilatation Perinephric stranding Periureteric stranding Nephromegaly “Rim sign” Absence of the white pyramids

MAGNETIC RESONANCE UROGRAPHY (MRU) Identifies stones and some secondary signs of obstruction Advantages: no radiation and contrast Disadvantages: inability to image unobstructed urinary tract, expensive, slow Figure 7. MRU show obstruction of the right ureter.

TREATMENT CONSIDERATIONS URETERAL CALCULI TREATMENT CONSIDERATIONS Location Size Chronicity Equipment Expertise

URETERAL CALCULI TREATMENT OPTIONS Observation Shock wave lithotripsy Ureteroscopy Blind basket extraction Percutaneous approach Open surgery

CONSERVATIVE MANAGEMENT Analgesics, hydration, and possibly antispasmodics Follow plain radiographs at 1-2 week intervals

URETERAL CALCULI SPONTANEOUS PASSAGE

URETERAL CALCULI SPONTANEOUS PASSAGE Of all stones that pass spontaneously, 95% will pass within 6 weeks Miller & Kane, 1999

URETERAL CALCULI MEDICAL MANAGEMENT Hollingsworth & Hollenbeck, 2006

URETERAL CALCULI MEDICAL MANAGEMENT Hollingsworth & Hollenbeck, 2006

INTERVENTIONAL MANAGEMENT: Current Therapy Extracorporeal shock wave lithotripsy (for proximal ureteral stones and least invasive therapy) Ureteroscopy (for mid and distal ureteral stones)

URETERAL CALCULI PARAMETERS FOR COMPARISON Stone-free is not everything !!

PARAMETERS FOR COMPARISON URETERAL CALCULI PARAMETERS FOR COMPARISON Effectiveness Morbidity Convalescence Cost

DISTAL URETERAL CALCULI COMPARISON OF MONOTHERAPY STUDIES URS is 10 - 18% more effective than SWL (depending on type of SWL unit) Morbidity / convalescence reduced with SWL Need for stents 40-60% less with SWL Cost issues not addressed in monotherapy studies

DISTAL URETERAL CALCULI OVERVIEW OF HISTORICAL CONTROL STUDIES SWL URS Effectiveness Slightly better Morbidity Less Hospitalization Less Cost Slightly less

DISTAL URETERAL CALCULI PROSPECTIVE, RANDOMIZED TRIAL 80 patients randomized to receive SWL or URS 40 patients had stones > 5 mm 40 patients had stones < 5 mm SWL performed on Dornier MFL 5000 URS performed with 6.5F or 9.5F semi-rigid ureteroscopes (basket vs. pneumatic lithotripsy) Peschel & Bartsch, 1999

DISTAL URETERAL CALCULI PROSPECTIVE, RANDOMIZED TRIAL STONES < 5 MM URS SWL OR time (min) 19 63 Fluoro time (min) 0.8 5.1 Stone-free (days) 0.2 10.8 Stent (days) 7.2 0 Re-treatment rate 0 15% * * * * * Peschel & Bartsch, 1999

URETEROSCOPY

Ureteroscopy Easier for lower stones Extraction of stone fragments Fragmentation Laser Homium Yg Mechanical EKL Explosive EHL Ultrasound Risks

FLEXIBLE URETEROSCOPY URETERAL CALCULI FLEXIBLE URETEROSCOPY

URETERAL STONE MANAGEMENT URETEROSCOPY Advantages Highest success rate Definitive Rx - No waiting for stone passage Disadvantages More invasive than SWL Higher complication rate Requires greater technical expertise

Rigid ureteroscope specifications include the following: Tip diameter - 4.5-9.5F (6.9F most common) Optics - Fiberoptic bundles Working channels - One, 2, or 3 (2 channels preferred) Accessory length - Average, 40 cm

Flexible ureteroscope specifications include the following Tip diameter - 6.9-9.8F (7.5F most common) Optics - Fiberoptic bundles Working channel - Single, 3.6F Access - Guidewire (0.035 in nitinol or 0.038 in stainless steel) Accessory length - Average, 100 cm

INTERVENTIONAL MANAGEMENT: More Invasive Treatments Intracorporeal shock wave lithotripsy (through ureteroscope) Percutaneous nephrostomy (for stones >2 cm and in proximal collecting system) Laparoscopy (if complicated) Open surgery (rarely done)

Thank you