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Staghorn Calculi
Large branching kidney stones that fill the renal collecting system, requiring specialist surgical expertise for safe and complete removal.
Clinically Reviewed By
Mr Alberto Coscione
Consultant Urological Surgeon · Reviewed June 2026 · Review due June 2027
What Are Staghorn Calculi?
Staghorn calculi are large, branching kidney stones that occupy the renal pelvis and extend into one or more of the renal calyces, giving them a characteristic shape that resembles a stag's antlers. They are among the most complex stones encountered in urological practice and require specialist management at a centre with the appropriate surgical expertise and facilities.
These stones are often composed of struvite (magnesium ammonium phosphate), also known as infection stones, because they form in the setting of chronic or recurrent urinary tract infections caused by urease-producing bacteria such as Proteus mirabilis and Klebsiella. However, staghorn calculi can also be of mixed composition or, less commonly, composed of uric acid or cystine in patients with underlying metabolic disorders.
Despite their often considerable size, staghorn calculi can be surprisingly asymptomatic for long periods. Many patients are unaware of the stone until it is discovered incidentally on imaging performed for another reason. However, if left untreated, staghorn stones may carry a significant risk of progressive renal damage, chronic infection, sepsis, and ultimately loss of kidney function. For this reason, active treatment is almost always recommended.
Staghorn calculi are classified by their extent within the collecting system and by their mineral composition. Understanding the type of staghorn stone is essential for planning the most effective treatment approach.
Why treatment matters
Untreated staghorn calculi are associated with a significant risk of progressive worsening of kidney function and serious infections. Although monitoring may be appropriate in some cases, it is important to have a discussion with a kidney stone specialist to ensure this is the best option.
Symptoms of Staghorn Calculi
One of the most notable features of staghorn calculi is that they cause no symptoms despite their large size. Because the stone forms gradually within the kidney and does not typically obstruct the ureter (water pipe connecting the kidney to the bladder), the classic acute renal colic pain may be absent. Many staghorn stones are discovered on imaging performed for unrelated reasons.
When symptoms do occur, they may include:
Recurrent Urinary Tract Infections
Repeated UTIs, sometimes with the same organism, are a hallmark sign and may be the initial presentation.
Dull Flank Ache
A persistent, dull pain in the loin or flank rather than the acute, severe colic typically associated with smaller ureteric stones.
Haematuria
Blood in the urine, which may be visible (macroscopic) or detected only on urine testing (microscopic).
Progressive Renal Impairment
Gradual decline in kidney function, often detected on routine blood tests, due to chronic obstruction and infection.
Sepsis Risk
Staghorn calculi are sometimes associated with serious infection called urosepsis. Symptoms include fever, rigors, confusion, and low blood pressure require emergency medical attention.
How Are Staghorn Calculi Diagnosed?
Accurate diagnosis and thorough pre-operative assessment are essential for planning the safest and most effective treatment strategy. The following investigations form the cornerstone of the diagnostic workup:
CT KUB (Non-Contrast CT Scan)
The gold standard imaging investigation. CT KUB provides a detailed three-dimensional view of the stone burden, accurately delineating the size, shape, position, and density of the stone. It also identifies the anatomy of the collecting system and any associated complications such as hydronephrosis. This information is critical for surgical planning.
DMSA Renogram
A nuclear medicine scan that assesses the split (differential) renal function — that is, how much each kidney contributes to overall function. This is particularly important for staghorn calculi because it helps determine whether the affected kidney is worth preserving or whether removal of the kidney may be the most appropriate option.
Blood Tests
A full panel of blood tests including renal function (creatinine and eGFR), full blood count, inflammatory markers (CRP), electrolytes, calcium, phosphate, uric acid, and parathyroid hormone to assess both kidney function and identify any underlying metabolic causes.
Urine Culture & Analysis
A mid-stream urine sample is sent for culture and sensitivity testing to identify the causative organism and guide appropriate antibiotic therapy before, during, and after any surgical intervention. This is especially important for struvite stones where infection is the driving factor.
Treatment of Staghorn Calculi
The treatment of staghorn calculi is almost always surgical, as these stones rarely pass spontaneously and carry significant risks if left untreated. The goal is to achieve complete stone clearance wherever possible, as residual fragments — particularly in struvite stones — serve as a nidus for regrowth and recurrent infection. Treatment is tailored to the individual patient based on stone size, composition, renal anatomy, kidney function, and overall fitness.
PCNL — Percutaneous Nephrolithotomy
First-Line TreatmentPCNL is the primary treatment for most staghorn calculi and is recommended by all major international guidelines as the first-line approach. The procedure involves creating a small tract (approximately 1 cm) through the skin of the back directly into the kidney, through which a telescope is passed to visualise and fragment the stone.
For large or complex staghorn calculi, multiple percutaneous tracts or staged procedures may be required to achieve complete clearance. The procedure is performed under general anaesthesia and typically requires a hospital stay of 1–4 days.
Combination Therapy
Multimodal ApproachFor complex staghorn stones, a combination of techniques may be employed in a planned, staged fashion to maximise stone-free rates:
- › PCNL as the primary debulking procedure
- › Flexible nephroscopy to access and treat stones in difficult-to-reach calyces
- › ESWL (shockwave lithotripsy) for residual fragments after PCNL
- › Staged second-look procedures to ensure complete clearance
Flexible Ureteroscopy (RIRS)
Adjunctive ProcedureRetrograde intrarenal surgery using a flexible ureteroscope and holmium laser may be used as an adjunct to PCNL to treat residual fragments in calyces that are difficult to access percutaneously. While not typically used as a standalone treatment for large staghorn stones, RIRS plays a valuable complementary role in achieving stone-free status.
Open / Robotic Surgery
Complex CasesIn highly complex cases — such as very large stones in kidneys with abnormal anatomy, or where multiple percutaneous approaches have been unsuccessful — open or robotic-assisted anatrophic nephrolithotomy may be considered. This involves surgically opening the kidney along its avascular plane to remove the stone intact. While more invasive, it can achieve excellent stone-free rates in carefully selected patients.
Nephrectomy (Kidney Removal)
When the affected kidney has lost most or all of its function as a result of long term blockage and infection a nephrectomy (surgical removal of the kidney) may be the safest and most appropriate option. This eliminates the source of infection.
Follow-Up & Long-Term Care
Achieving stone-free status is the primary surgical goal, but long-term follow-up is equally important to prevent recurrence, monitor kidney function, and detect any residual or new stone formation early.
Stone-Free Rate Assessment
Post-operative imaging (typically a CT KUB at 4–6 weeks) is performed to confirm complete stone clearance. Any significant residual fragments may require a further procedure to reduce the risk of regrowth, particularly for struvite stones.
Metabolic Screening
A comprehensive metabolic evaluation — including 24-hour urine collection for calcium, oxalate, citrate, uric acid, cystine, and pH — is carried out to identify treatable risk factors and guide personalised prevention strategies.
Antibiotic Prophylaxis
For patients with infection stones, targeted antibiotic therapy is essential. Pre-operative antibiotics are given based on urine culture results, and in some cases long-term low-dose prophylactic antibiotics may be recommended to prevent recurrent infection and stone regrowth.
Long-Term Imaging Surveillance
Regular imaging follow-up with ultrasound or low-dose CT to monitor for stone recurrence. Staghorn stones carry a higher recurrence rate than simple stones, making ongoing surveillance a critical part of long-term care.
Meet your Specialist
At London Urology Specialists, the assessment and treatment of staghorn calculi is led by Mr Alberto Coscione, a consultant urological surgeon with specialist expertise in endourology and the surgical management of complex kidney stones.
Key Takeaways
Staghorn Calculi — What You Need to Know
Staghorn calculi are among the most complex kidney stones encountered in clinical practice. They require expert assessment and treatment at a specialist stone centre with the surgical expertise, equipment, and multidisciplinary support needed to achieve the best possible outcomes.
At London Urology Specialists, our dedicated stone team offers the full range of treatment options for staghorn calculi, from percutaneous surgery and combination therapy to complex open and robotic procedures. We provide individualised treatment plans, comprehensive metabolic evaluation, and structured long-term follow-up to minimise the risk of recurrence.
Further Reading — BAUS Patient Information
Frequently Asked Questions
A staghorn calculus is a large kidney stone that fills the central part of the kidney (the renal pelvis) and extends into two or more of its branches (the calyces), giving it a shape reminiscent of a stag’s antlers. These stones can grow rapidly to fill the whole kidney and, if untreated, cause severe infection and affect kidney function.
The majority of staghorn calculi are caused by chronic urinary tract infection with specific bacteria and an important part of the management of the stone is assessing its cause and reducing the risk of it forming again.
Untreated staghorn calculi carry a risk of kidney damage, recurrent urine infections which can be severe and spread to the blood.
The treatment of choice for most staghorn calculi is percutaneous nephrolithotomy (PCNL) which is a keyhole operation performed through a small incision in the back. Sometimes very large stones may require multiple staged procedures to ensure they are treated completely and safely.
Percutaneous nephrolithotomy is a minimally invasive keyhole operation in which a small incision is made in the skin of your back. A specialised telescope is passed into the kidney and used to break the stone and its fragments are removed. The procedure will usually require at least an overnight stay in hospital to monitor patients.
Most staghorn stones are not dissolvable with medication although medications such as antibiotics to prevent repeat infections and certain medications depending on the type of stone may be helpful.
Complete stone clearance is one of the most important factors in preventing stones coming back, but this needs to be balanced with ensuring the procedure is performed safely including avoiding damage to the kidney and not performing an overlong procedure. This is why at times a staged procedure needs to be performed.
Staghorn calculi should be assessed promptly, but are not medical emergencies unless symptoms such as pain, fever or feeling unwell are also present. In these situations we advise patients to seek urgent medical attention.
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