Ureteric calculi or stones are those lying within the ureter, at any point from the pelvicoureteric junction to the vesicoureteric junction. They are the classic cause of renal colic type abdominal pain. They are a subset of the broader topic of urolithiasis.
Lifetime prevalence of ureteric calculus is relatively high, occurring in approximately 12% of men and 7% of women 1. The risk is increased with a past history of ureteric calculi or with positive family history. Most patients present aged between 30 and 60 years of age 2, with peak incidence between 35-45 years old. Initial calculus presentation occurring past 50 years of age is uncommon.
Patients with ureteric calculus may present with peristaltic pain (renal colic), haematuria, nausea and vomiting.
The quality and location of pain is dependent on the calculi's location within the ureter. Calculi within the pelvicoureteric junction may cause deep flank pain without radiation to the groin due to distension of the renal capsule, whereas pain from upper ureteral calculi radiate to the flank and lumbar areas. Calculi in the mid ureter results in pain radiating anteriorly while distal ureteric calculi pain radiates to the groin via referred pain from the genitofemoral or ilioinguinal nerves.
Calculi in the versicoureteric junction may also cause irritative voiding symptoms such as dysuria and urinary frequency.
Up to 80% of renal calculi are formed by calcium stones 3. Other types include struvite, uric acid and cystine stones. In specific patient groups, mucoprotein (matrix), xanthine or indinivir stones may be (rarely) encountered.
Calculi formation is likely due to two mechanisms. The first is where stone forming substances such as calcium or uric acid supersaturates the urine beginning crystal formation. The other mechanism depends on stone forming substances depositing on the renal medullary interstitium forming a Randall's plaque 4 and eventually erode into the papillary urothelium creating a calculus.
In addition to history of prior ureteric calculi and family history, other risk factors for ureteric calculi include low fluid intake, frequent urinary tract infections and medications that my crystalise the urine.
A plain abdominal (KUB) film can identify large radiopaque calculi. However, smaller calculi and/or radiolucent stones may go undetected. Obstruction/hydronephrosis cannot be adequately assessed.
For low-dose initial investigation, plain film with ultrasound is used in some centers for specific patient groups. For follow up, plain film is useful when stone has been demonstrated on abdominal x-ray and/or CT scanogram.
CT KUB is the gold standard for imaging ureteric stones, with the vast majority (99%) being radiodense. Stones > 1 mm in size are visualised, with the specificity of helical CT as high as 100% 5.
Scanning the patient in the prone position is preferred as this gives certainty as to whether a stone remains impacted within the vesicoureteric orifice or if it has passed freely into the bladder 9. A stone will always fall dependently and sit along the anterior bladder wall once it is free of the orifice in a prone patient. Alternatively some centres will 'flip' the patient and re-scan the pelvis if a stone is identified at the VUJ/bladder base on the supine scan acquisition. The choice is often one of practicalities depending on the list supervision and staff involved.
In patients with little pelvic fat, distinguishing a ureteric calculus from a phlebolith can be challenging. Two signs have been found helpful:
While CT is the gold standard test, there is recent evidence that screening patients with ultrasound in the emergency department can help avoid CT in more half of patients leading to reduced cumulative radiation dose without increasing complications, pain scores, emergency department visits or hospitalisations 8.
Ultrasound may be used for patients needing to avoid radiation such as pregnant women. It is also useful for assessing for the complications, such as hydronephrosis or pyonephrosis and in aiding percutaneous nephrostomy tube insertion in septic patients. Features include:
Treatment and prognosis
Most patients presenting with acute renal colic due to ureteric calculi can be managed conservatively with hydration and analgesia until the calculi passes. NSAID's are as effective as opioids 6. Hospitalisation may be required where oral analgesia is insufficient, patients with a solitary kidney or in patients with urosepsis or acute kidney failure.
Calculi size and location as well as ureter anatomy are important factors in determining likelihood of spontaneous calculi passage 7, with stones less than 5 mm having high likelihood of passing down the ureter. However even small calculi may be impossible to pass if it is located at the pelvicoureteric junction or in patients with ureteral strictures. Passage of calculi may be facilitated with tamsulosin and nifedipine.
In calculi >10 mm or with failed conservative management, urological procedures such as extracorporeal shock wave lithotripsy (ESWL), ureteroscopic lithotripsy or percutaenous nephrostomy may be required.
Once the calculus is passed it should be retained and sent for analysis to evaluate for possible underlying causes of stone disease and better plan for prevention.
It is good practice to report if the calculus is visible on the scanogram of the study to establish if a plain radiograph is sufficient for follow up purposes rather than a higher radiation CT study.
- 1. Pearle MS, Calhoun EA, Curhan GC et-al. Urologic diseases in America project: urolithiasis. J. Urol. 2005;173 (3): 848-57. doi:10.1097/01.ju.0000152082.14384.d7 - Pubmed citation
- 2. Tamm EP, Silverman PM, Shuman WP. Evaluation of the patient with flank pain and possible ureteral calculus. Radiology. 2003;228 (2): 319-29. doi:10.1148/radiol.2282011726 - Pubmed citation
- 3. Coe FL, Parks JH, Asplin JR. The pathogenesis and treatment of kidney stones. N. Engl. J. Med. 1992;327 (16): 1141-52. doi:10.1056/NEJM199210153271607 - Pubmed citation
- 4. Kim SC, Coe FL, Tinmouth WW et-al. Stone formation is proportional to papillary surface coverage by Randall's plaque. J. Urol. 2005;173 (1): 117-9. doi:10.1097/01.ju.0000147270.68481.ce - Pubmed citation
- 5. Dalrymple NC, Verga M, Anderson KR et-al. The value of unenhanced helical computerized tomography in the management of acute flank pain. J. Urol. 1998;159 (3): 735-40. Pubmed citation
- 6. Teichman JM. Clinical practice. Acute renal colic from ureteral calculus. N. Engl. J. Med. 2004;350 (7): 684-93. doi:10.1056/NEJMcp030813 - Pubmed citation
- 7. Miller OF, Kane CJ. Time to stone passage for observed ureteral calculi: a guide for patient education. J. Urol. 1999;162 (3 Pt 1): 688-90. Pubmed citation
- Smith-Bindman R, Aubin C, Bailitz J et-al. Ultrasonography versus computed tomography for suspected nephrolithiasis. N. Engl. J. Med. 2014;371 (12): 1100-10. doi:10.1056/NEJMoa1404446 - Pubmed citation
- 9. Levine J, Neitlich J, Smith RC. The value of prone scanning to distinguish ureterovesical junction stones from ureteral stones that have passed into the bladder: leave no stone unturned. AJR Am J Roentgenol. 1999;172 (4): 977-81. doi:10.2214/ajr.172.4.10587131 - Pubmed citation
- 10. Dalrymple NC, Casford B, Raiken DP et-al. Pearls and pitfalls in the diagnosis of ureterolithiasis with unenhanced helical CT. Radiographics. 2000;20 (2): 439-47. doi:10.1148/radiographics.20.2.g00mc13439 - Pubmed citation