Renal colic • LITFL • FFS

Renal colic (or nephrolithiasis) is an extremely common presenting problem to the Emergency Department. The immediate priority will be pain relief.

Introduction

~90% of stones pass spontaneously within 1 month. Stones >5 mm are less likely to pass without intervention. Most patients managed in ED; admission criteria include:

Fever/sepsis (urological emergency)
Intractable pain
Severe hydronephrosis
Impaired renal function
Single functioning kidney
Bilateral ureteric stones
Transplanted kidney

History

Long historical context: ancient surgical records of stone management.
Modern imaging: CT-KUB replaced IVP.
Treatment: ureteroscopic laser lithotripsy preferred over extracorporeal shock wave lithotripsy (ESWL).

Epidemiology

50% have single episode; 50% recur in 5 years.
Common in ages 20-50; alternative diagnoses in young/elderly.

Pathophysiology

Contributing factors: dehydration, genetics.
Stone types:
1. Calcium-based (75%). States of hypercalcaemia (from any cause) may predispose to calcium stones [Calcium oxalate, Calcium phosphate, Calcium oxalate/ phosphate mix]
2. Uric acid (8%) – associated with a urinary pH of less than 5.5, high dietary purine intake or malignancy (i.e., rapid cell turnover).
3. Struvite (15%) – (magnesium ammonium phosphate) – associated with chronic urinary tract infection with gram-negative bacilli. Usual organisms include Proteus, Pseudomonas, and Klebsiella species.
4. Cystine (2%) – metabolic defect resulting in failure of renal tubular reabsorption of cystine, ornithine, lysine, and arginine.
5. Xanthine (rare) – inborn defect of the enzyme xanthine oxidase
Common points of obstruction:
- PUJ – Pelviureteric junction
- Pelvic brim
- VUJ – Vesicoureteric junction

Complications

Infection – urological emergency
Severe hydronephrosis (risk of atrophy, ureteric rupture)

Clinical Assessment

Symptoms: severe, colicky loin to groin pain, N/V
Pain location varies with stone position
- Pain confined to the RIF/ LIF may indicate a stone in the region of the VUJ
- Bladder stone may result in suprapubic pain or a sense of urgency/ frequency
Assess for coagulopathy (e.g. warfarin/DOAC)
Key exam points: vitals, flank/abdominal pain, testicular exam

Differential Diagnosis

The clinical diagnosis of renal colic is usually straight forward, although without radiological imaging can never be definitive. Not all presentations of renal colic are “classical” and important differential diagnoses are legion and the risk profile for various pathologies needs to be carefully assessed in each patient.

AAA
Lung pathology (e.g. PE, pneumonia)
Retroperitoneal hematoma
Renal malignancy
PUJ obstruction
Testicular torsion
GIT (e.g. appendicitis, diverticulitis, bowel obstruction)
Spinal pathology; disc disease/sciatica/malignancy
Gynecological: ectopic pregnancy, ovarian torsion

Investigations

Bloods: FBE, CRP, U&E, glucose, LFT/lipase, beta-HCG (if needed)
Metabolic screen (Ca, PO4, uric acid)
FWT: hematuria often present but not definitive
Stone analysis: if passed
KUB X-ray: done if CT-positive for stone to guide follow-up. Note that 100% of stones are seen on CT, whilst only 85% of stones are seen on plain x-ray. Whether a stone is seen on plain x-ray largely depends on its composition.
CT-KUB: gold standard for diagnosis. It can accurately determine the size of the stone – an essential parameter for planning both disposition and management. CT may also distinguish complicating pyelonephritis and uroma
Ultrasound: detects hydronephrosis, less sensitive for stones
MRI: alternative for pregnancy

Management

Analgesia
- NSAIDs preferred (ibuprofen, ketorolac, indomethacin)
- Opioids (morphine or fentanyl IV)
IV Fluids
- For dehydration or prolonged NBM
Tamsulosin
- May assist passage of distal stones 5-10 mm
Intervention Options
- ESWL: least invasive, limited efficacy
- Ureteroscopic laser lithotripsy: most common, high efficacy
- Percutaneous nephrolithotomy: for >2 cm/staghorn calculi
- Open surgery: rarely used
- Nephrostomy: urgent drainage in obstruction + sepsis

Disposition

ED discharge if:
- Symptoms controlled
- No complicating factors
- Small stone (<5 mm)
Admission if:
- Fever
- Intractable pain
- Deteriorating renal function.
- Severe hydronephrosis
- Single kidney or bilateral obstruction
- Patients with a transplanted kidney
- Stone >5 mm (especially proximal) – have high rates of re-presentation

Follow-Up

Urology outpatient referral:
- Ureteric stone ≥ 5 mm
- Recurrent stones
- Intrarenal calculi
GP follow-up:
- Single episode, stone <5 mm, uncomplicated

Appendix 1:

Patients with intractable pain:

Intractable pain may be due to a large stone (> 5 mm), which will have difficulty in passing spontaneously or severe hydronephrosis or even a “uroma”(ruptured caylaceal system). In general terms:

Stone Size	Likely outcome
≤ 4 mm	90 % will pass within a month
5- 7 mm	50 % will pass within a month
≥ 7 mm	5 % will pass within a month

The overall passage rates for a stone within the ureter are:

Position within the Ureter	Overall likelihood of passage
Proximal ureteric stones	25%
Mid ureteric stones	45%
Distal ureteric stones	75%

Appendix 2:

Appendix 3:

The Double J Stent:

The double J stent is a thin, hollow stent that is often placed inside the ureter during surgery to ensure drainage of urine from the kidney into the bladder. J shaped curls are present at both ends to hold the tube in place and prevent migration, hence the description “double J stent”.

They allow the kidney(s) to drain urine by temporarily relieving any blockage, or to assist the kidney(s) in draining stone fragments freely into the bladder if definitive kidney stone surgery is carried out.