Urolithiasis

Perhaps the most commonly encountered problem in day-to-day urology.

An understanding of stone passage and complications requiring urgent intervention will minimise unnecessary hospitalisation and allow for an appropriate follow-up and procedure.

Urinary tract stones can occur in one in ten of the population. Risk factors include gender (males), age (40-50 year olds), ethnicity (caucasians), excess salt/oxalate and meat intake, dehydration, obesity, Anatomical causes such as horseshoe kidneys, genetic causes such as cystinuria and GI pathology such as Crohn’s disease.

While some kidney stones are incidental findings, while on call, you will be expected to deal with ureteric colics where a calculus drops into the ureter, causing pain and associated symptoms en route to the bladder (if it were to reach).

History:

1. Acute onset of pain

2. Initially in the loin (around the costovertebral angle), which then radiates towards the groin/scrotum/labia

3. Traces of visible blood in urine are not uncommon; however, almost all patients will have blood on a urine dipstick

4. A history of previous stones is significant, as recurrences become more frequent with each passing episode

5. Systemic feature - fever, nausea, vomiting and chills

Systemic features should prompt the consideration of infection (pyelonephritis)

An infected obstructed stone is the only true emergency in stone disease requiring urgent intervention at the risk of sepsis.

Examination:

1. Abdominal examination is often unremarkable

2. Tenderness in the affected renal angle can occur, and tenderness can be pronounced if there is urinary stasis and infection due to the obstruction

Investigations:

1. Urine dipstick - positive for blood. Leucocytes and nitrites indicate infection. pH is a useful marker as alkaline urine implies urea-splitting micro-organisms, while acidic pH may imply a uric acid stone.

2. Routine blood tests - a mildly elevated white cell count is often noted and should not cause alarm unless significantly elevated. Correlate this with a NEWS score, pain and systemic symptoms

3. Stone profile - calcium, phosphate and uric acid. In some hospitals, this may be included as a part of a ‘bone profile’

4. Imaging - CT KUB is the gold standard for diagnosis. NICE guidance notes that imaging should be done within 24 hours of clinical diagnosis. It may confirm the presence of a stone, hydronephrosis secondary to obstruction or elicit features significant of a recently passed stone

5. If the stone is visible on the scout image, further imaging would not be needed. However, if scout images are not available, an X-RAY KUB is useful as it helps with follow-up of the patient in an outpatient setting

Indications for admission:

1. An infected, obstructed urinary system

2. Pain not resolving with analgesia

3. Vomiting and dehydration

4. Acute kidney injury

5. Large stones unlikely to pass (> 5 mm)

Management:

1. Analgesia - Per rectal Diclofenac is the gold standard and should be used as first-line analgesia. Up to 150mg in 24 hours can be used. Paracetamol can be given if diclofenac is contraindicated or the patient is allergic to NSAIDs

2. Antiemetics

3. IV antibiotics - if there is evidence of infection (consult trust antibiotic policies for choice)

4. Encourage fluid intake unless undergoing emergency surgery

5. Antispasmodics have no role in the current management of ureteric colics

6. Medical expulsion with alpha agonists - Tamsulosin is useful in distal ureteric stones > 5mm in size

7. Stones < 5 mm will usually pass by themselves. Counsel the patient about the possibility of it not passing, causing obstruction. Safety nets to return, such as fever, nausea, vomiting and worsening pain, should be clearly discussed

8. Stones > 5 mm - counsel patients about expectant vs active management with risks and benefits explained. Surgical intervention is outlined below

9. Infected - obstructed stones are an emergency and will require decompression by either a nephrostomy or stenting (antegrade stents are usually done by interventional radiology, whereas retrograde stents are done by urologists)

Surgical options:

1. ESWL can be considered for stones < 2 cm as well as ureteric calculi in a non-pregnant cohort. Contraindicated in bleeding disorders, including anticoagulated patients, AAA, and active UTIs

2. Ureteroscopy and stone fragmentation +/- ureteric stenting

3. PCNL - reserved for stones > 1.5 - 2 cm within the kidney

4. Open/laparoscopic surgery - rarely done in the era of miniaturised PCNL, reserved for complicated cases with multiple calculi

Complications:

1. Obstruction causing AKI in the short term

2. CKD / atrophic / non-functional kidneys if obstruction is left untreated

3. Infective complications - Pyelonephritis, emphysematous pyelonephritis, xanthogranulomatous pyelonephritis, renal and perinephric abscesses and sepsis

4. Ureteric stricture

Useful resources:
Using the MIMIC tool from BURST - Predicts the chances of spontaneous stone passage - https://bursturologycollaborative.github.io/

BAUS provides excellent information for patients. These leaflets can be printed and provided to patients to help them make an informed decision about the management of their condition. https://www.baus.org.uk/patients/conditions/6/kidney_stones/

NICE guidelines: https://cks.nice.org.uk/topics/renal-or-ureteric-colic-acute/background-information/risk-factors/

EAU guidelines: https://uroweb.org/guidelines/urolithiasis/chapter/guidelines