Endgames Case Report

A man with bilateral loin pain

BMJ 2013; 346 doi: http://dx.doi.org/10.1136/bmj.f2850 (Published 09 May 2013) Cite this as: BMJ 2013;346:f2850
  1. Mohammed Hayat Ashrafi, core trainee year 2, general surgery1,
  2. Usman Bhatty, foundation year 2 doctor, urology1,
  3. Katie Hall, clinical fellow, urology1,
  4. Moeketsi Mokete, consultant urologist1
  1. 1Department of Urology, Lancashire Teaching Hospitals NHS Foundation Trust, Preston PR2 9HT, UK
  1. Correspondence to: M H Ashrafi mohammedashrafi{at}doctors.org.uk

A 65 year old man presented with a 12 month history of bilateral flank pain but no fever or lower urinary tract symptoms. Over the preceding 10 years he had had multiple interventions, including extracorporeal shock wave lithotripsy and ureteroscopic laser stone fragmentation, for cystine renal stones. He had type 2 diabetes and hypertension, and he was also obese.

A plain radiograph showed a large renal pelvic calculus measuring 3.4 cm in the right kidney and a 4.4 cm partial staghorn calculus projected over the left kidney. A dimercaptosuccinic acid scan showed a relative function of 47.5% for the right kidney and 52.5% for the left kidney.

A staged percutaneous nephrolithotomy was performed successfully on the simpler right stone, but postoperatively he developed pain in the right loin. A nephrostogram showed debris partially occluding the right ureter, which resulted in a filling defect; this was thought to be a clot and it later passed. Stone analysis confirmed cystine stones. Three months later a percutaneous nephrolithotomy was undertaken on the left side. Postoperative recovery was uneventful and radiography showed no residual stones.

Questions

  • 1 What is the most common clinical presentation of renal tract stones?

  • 2 What are the causative factors for renal tract stones?

  • 3 What are the causes of loin pain and what investigations are used to differentiate them?

  • 4 What is the best management approach for staghorn calculi?

Answers

1 What is the most common clinical presentation of renal tract stones?

Short answer

Loin pain.

Long answer

The presentation of renal tract stones can vary. The classic presentation is sudden onset excruciating loin to groin pain, which causes restlessness and severe distress.

The narrow areas in the urinary tract include the ureteropelvic junction, pelvic brim, and vesicoureteric junction. The location and quality of pain are related to position of the stone. Stones obstructing the ureteropelvic junction may present with flank pain without radiation to the groin, owing to distension of the renal capsule. Ureteric calculi tend to cause pain that radiates anteriorly and caudally. Stones at the vesicoureteric junction cause pain that tends to radiate into the groin. They may also cause dysuria and storage symptoms, such as urinary frequency. Small calculi that have entered the bladder are usually passed without difficulty.

Other associated symptoms include haematuria, dysuria, strangury, nausea, vomiting, fever, and rigors. Stones can be an incidental finding, and a third of such patients develop symptoms.1 Patients with staghorn calculi are relatively asymptomatic, although they can present with loin pain, haematuria, or urinary tract infections. Occasionally they present with a perinephric abscess, often a tender erythematous swelling in the loin on the affected side.

A high index of suspicion for renal calculi is needed in patients presenting to non-urological disciplines with unexplained abdominal pain and systemic sepsis because misdiagnosis can be life threatening.

2 What are the causative factors for renal tract stones?

Short answer

Factors that contribute to stone formation include age, sex, genetics (such as cystinuria, as in this case), climate, geographical location, occupation, and diet.

Long answer

Intrinsic factors including age (peak incidence 20-50 years); sex (male:female ratio 3:1); genetics; and extrinsic factors such as geographical location, climate, water intake, occupation, and diet all play a part in stone formation.2 Other predisposing factors include genetic diseases such as cystinuria and cystic fibrosis; non-genetic diseases such as obesity, hyperparathyroidism, and inflammatory bowel disease; and abnormalities of renal tract anatomy.2 3

Cystine stones represent 1-2% of all renal stones and are most common in the first to third decades of life, although they can occur at any age, as in this case.4 Cystinuria is caused by a genetic defect of two genes that results in defective reabsorption of four amino acids in the proximal renal tubules and gastrointestinal tract.4 Urine becomes supersaturated with cystine at concentrations greater than 300 mg/L, with the excess precipitating as stones and crystals. Patients with cystic fibrosis also have an increased incidence of renal stones.5 This increased risk seems to be due to a combination of hyperoxaluria, urinary calcium oxalate supersaturation, hypocitraturia, and low urine output.6

Although hot climates can increase stone formation, some populations (black Africans and Aborigines) have a low incidence of stones. Paradoxically, some populations in cooler climates such as northern Europe have a relatively high incidence, probably because poor dietary habits lead to obesity, a sedentary lifestyle, and low fluid intake (<1200 mL/day).

3 What are the causes of loin pain and what investigations are used to differentiate them?

Short answer

Renal tract stones are the main cause of loin pain. However, other causes need to be considered. Non-enhanced computed tomography is the ideal modality for the investigation of loin pain.

Long answer

Loin pain is commonly caused by renal tract stones. There are, however, many other important causes that need to be considered. Other renal tract causes include pyelonephritis, renal abscesses, renal tract tumours, and renal infarction. Non-renal causes of loin pain include musculoskeletal injury, pulmonary disease, and gastrointestinal disease. Of particular importance is abdominal aortic aneurysm, which can present with loin pain similar to renal colic in 10% of cases.7

Many diagnostic tools are available to investigate loin pain. Common tests performed include urinalysis, plain and contrast radiographic imaging (fig 1), ultrasound, and computed tomography. Non-contrast computed tomography is the investigation of choice for most patients with loin pain owing to its unrivalled accuracy, speed, and ability to demonstrate other renal and non-renal diseases.8 Urinalysis is usually insufficient for diagnosis in patients with loin pain, and plain film radiography is not accurate in the identification of ureteric stones. Ultrasound can diagnose ureteric obstruction with a high degree of accuracy but cannot directly demonstrate ureteric calculi in most cases.8

Figure1

Fig 1 Plain radiograph showing a large renal calculus measuring 3.4 cm in the right kidney and a 4.4 cm partial staghorn calculus projected over the left kidney

4 What is the best management approach for staghorn calculi?

Short answer

Staghorn calculi are best managed by percutaneous nephrolithotomy or nephrectomy.

Long answer

If left untreated staghorn calculi can lead to a reduction in kidney function, end stage renal disease, and sepsis.9 10 Most patients require definitive surgical management, because medical treatment alone is usually not successful.

Staghorn calculi are best managed by percutaneous nephrolithotomy if there is sufficient renal function in the affected renal unit as assessed by dimercaptosuccinic acid scan (fig 2). If the differential function is under 15% then nephrectomy is the treatment of choice. Percutaneous nephrolithotomy allows direct inspection of the collecting system, permitting identification and removal of small fragments. Almost all accessible stones can be removed and a successful outcome is obvious immediately.11 Stone-free rates are also higher with procedures that are more invasive. Stone-free rates are 50% for shock wave lithotripsy and over 75% for percutaneous nephrolithotomy.10 12 However, combination treatment has shown significant superiority in the treatment of stones.13

Figure2

Fig 2 Dimercaptosuccinic acid scan showing a relative kidney function of 47.5% for the right kidney and 52.5% for the left kidney

The most undesirable effects of percutaneous nephrolithotomy are pain, renal parenchymal damage, scarring, bleeding, iatrogenic organ injury, and septicaemia.14 However, studies have confirmed that renal function is often preserved or even improved after percutaneous stone removal.15 Another disadvantage is that the expertise required for this operation is not widely available.

Periodic monitoring of both kidneys with ultrasound scanning and radiography (fig 3) is indicated after successful treatment, because new stone formation can occasionally affect the contralateral kidney.16

Figure3

Fig 3 Plain radiograph showing no residual stones after percutaneous nephrolithotomy

Patient outcome

Three months after the last procedure the patient was well and stone free. He has been advised to increase his fluid intake by drinking more than 3 L in 24 hours, including at night. He has also been started on potassium citrate to make his urine more alkaline.

Notes

Cite this as: BMJ 2013;346:f2850

Footnotes

  • Competing interests: We have read and understood the BMJ Group policy on declaration of interests and declare the following interests: None.

  • Provenance and peer review: Not commissioned; externally peer reviewed.

  • Patient consent obtained.

References