Urinary Tract Stones Flashcards
Describe methods for assessing and treating urinary tract stones, and their complications
What are renal calculi and why do they form?
Renal stones form due to solutes precipitating within the urinary tract. This can occur when there is increasing levels of solute or decreasing levels of solvent
What are the most common sites for urinary tract calculi?
Pelvic-uteric junction
Pelvic brim- where the ureters cross over the iliac vessels
Vesicouteric junction- entry of the ureters into the bladder
What is the most common type of renal stone?
Calcium oxylate stones- these contain calcium so are radio-opaque and visible on an x-ray
What is a struvite stone? What can it indicate?
A struvite stone is also called a stag horn stone. It is formed from magnesium ammonium phosphate and they occur with infections of the urinary tract. They’re also called stag horn stones.
What kind of renal stones may form in patients with Gout?
Uric Acid Stones-
Risk factor is a diet high in purines- shelfish, beer, red meat
Describe the presentation of renal calculi?
Asymptomatic
Pain- Typically at the loin and radiating to the groin.
Nausea and Vomiting- Pain can be very severe.
Infection- Urinary stagnation increases the risk of infection and so patients may have symptoms of a UTI/Pyelonephritis (Fever, rigours, confusion, urgency). Note an obstructed infected system is an emergency requiring urgent intervention
Haematuria- Patients may complain of visible haematuria
For patients complaining of loin pain/lower back pain what must you rule out- how would you do this?
Must rule out Abdominal Aortic Aneurysm and so palpate the abdomen.
Aorta is retroperitoneal so can cause back pain.
How may you differentiate renal calculi pain from pain due to peritonitis?
Patients are unlikely to lie still with renal calculi whereas in peritonitis movement worsens the pain
If suspected renal calculi what investigations should be done?
Urine Dip - Haematuria - Signs of UTI- White cells, protein, nitrites Midstream Urine Testing - For Microscopy, Culture and Sensitivity Pregnancy Test- -Rule out ectopic pregnancy as a cause in women Bloods - FBC- Increase WCC in infection - Inflammatory markers- CRP, EST Renal Function - Serum Creatinine - U&Es - eGFR Possible causes of the stone: - Calcium - Phosphate - Uric Acid - PTH Imaging- - CT KUB (Gold Standard)- Non- Contrast and helps to rule out other causes of the acute abdomen - X-Ray KUB- Calcium Oxylate stones are radiolucent
How would you initially manage a patient presenting with a renal stone without infection?
Acute Management-
Analgesia-
- Diclofenac 75mg IVIM, 100mg PR
- If NSAIDs CI- IV Paracetamol, Opioids
- Monitor the patients pain and step up as required
Increase Fluid Intake
- Dehydration is a risk factor for stones
- Assess fluid status and advice to drink more
- IV fluids if indicated
Watchful Waiting-
- Small stones will pass naturally and there is often no intervention needed
- If <5mm 90-95% will pass
- Takes approximately 31-40 days so arrange a follow up appointment for after this
- Advise the patient that if there are any signs of infection (fever, fatigue, rigours) or severe intolerable pain then come back to hospital
What should be done if a patient has the presentation of renal stones with signs of infection?
This is an infected obstructed system which requires urgent intervention- time wasted= loss of nephrons
Make patient NBM
Blood cultures
IV ABx- according to trust guidelines- piperacillin, gentamycin, tazobactam
Senior review for urgent consideration to relieve obstruction
Relieve the obstruction- Ureteric Stenting, Percutaneous Nephrostomy
Risk of urosepsis- Do sepsis 6
When managing a patient with renal calculi what should prompt intervention over
Pain that fails to respond to analgesia
Infection- Obstructed infected system
Impaired Renal Function
- Especially if only one kidney or bilateral stones
- Risk of post-renal AKI
Social Reasons
- Young and working patients may require interventions sooner to return to normal life
Beyond analgesia (mainly with diclofenac) what other interventions can be considered?
Medical-
- Medical Expulsive Therapy
- Nifedipine (calcium channel blocker) or an alpha blocker (tamulosin)
Extracorpeal Shock Wave Lithotripsy (ESWL)
- If the stone is less than 1 cm, used for stone in the pelvic to the upper ureter and lower donw the bony pelvis gets in the way
Surgical-
- Uteroscopy and stone removal using basket
- Open surgery- very rarely done
Note- Nephrostomy and ureteric stenting relieve the obstruction (for infected obstructed system) but do not treat the actual cause.
What are some of the risk factors for developing renal calculi?
Dehydration Hypertension Gout Hyperparathyroidism Diuretics Calcium/Vit D supplements Family history Hotter Climates Previous stone disease
What might be done to prevent renal calculi developing in the future?
Drink plenty of water
Normal calcium intake
If high levels of calcium in tubules- Thiazide diuretics reduce calcium excretion
If high oxylate levels- Pyridoine
Ig high urate levels- Allopurinol
If infection- Treat the infection (ABx) and investigate the cause of recurrent infections (could be a sign of malignancy)
What are the symptoms from urinary calculi?
Flank pain- Radiates from loin to groin Colickly pain Decreased urine output N+V Urinary stasis---> Infection Fever, Fatigue, Confusion, Rigors Haematuria- may be visible, likely invisible
What condition must be ruled out for patients presenting with lower back/loin pain?
Abdominal aortic aneurysm must be ruled out
Examine for a pulsatile, expansile mass in the abdomen
How feature in the patient presentation would help you to differentiate between peritonitis and urinary calculi?
Patients with peritonitis will lie very still as movement causes pain
Patients with urinary calculi, experience radiating pain from loin to groin, are unlikely to lie still
What is the most common type of urinary calculi?
Calcium oxylate
What type of kidney stone is visible on an X-ray?
Calcium oxalate stones
What type of kidney stone is more likely to form in patients with a UTI/ascending infection?
Struvite stone
What type of kidney stone is more likely to occur in patients with gout or tumour lysis syndrome?
Uric acid stone
What are some risk factors for urate stones?
Same as risk factors for gout
Diet high in beer, red meat, shelfish
(High in purines)
Note- Tumour lysis is also a risk factor as it causes release of DNA which is broken down to produce urate.
What is a risk factor for the development of calcium oxalate stones?
Hypercalcaemia
Hyperparathyroidism- Primary or may be secondary to CKD
Malignancy
XS Vitamin D
