Staghorn Kidney Stones

Staghorn Stones

A staghorn kidney stone is a term used to describe a large stone that takes up more than one branch of the collecting system in the renal pelvis of the kidney.

By way of review, the urinary tract begins with the kidneys.

The kidneys, one on each side, sit high in the upper abdomen partially underneath the rib cage. They filter the blood to extract excess waste products and fluid to form the urine. Urine, once formed in the kidneys, is collected in the renal pelvis, the first part of the urinary drainage system. Urine travels through a tube on each side, the ureter, down to the bladder. Urine is constantly being made by the kidneys and transported through the ureters into the bladder. The bladder stores urine until full and then empties to the outside through the urethra. The urinary system is the same in both men and women from the kidneys to the bladder. In men, the urethra is longer and encircled by the prostate which is a gland that is part of the reproductive system.

Staghorn stones form in the renal pelvis.

Some of the risk factors for staghorn stone formation include long standing history of stones, certain unique metabolic defects, and repeated urinary tract infections with particular types of bacteria. If a staghorn stone occurs in association with infection, there may be a pattern of intermittent and recurrent infection which may persist until the staghorn stone is removed.

Recommendations

A patient with a staghorn stone should be treated.

If a staghorn stone is not treated, then renal deterioration occurs in at least 1 out of 4 patients. Over time, an untreated staghorn calculus is likely to destroy the kidney and/or cause life-threatening infections (sepsis). Complete removal of the stone is important in order to eradicate infection, relieve obstruction, prevent further stone growth, and preserve kidney function.

Types of Treatment

Types of treatment include: Percutaneous nephrolithotomy (PNL), combinations of PNL and shock-wave lithotripsy (SWL) (see ESWL newsletter), SWL alone and open surgery.

In some cases the staghorn stone may have already caused significant damage to the affected kidney and the kidney may not contribute much to the overall level of a patient’s kidney functioning. An imaging study called a Lasix renal scan may help determine if the Kidney has any significant function. If the kidney does not work, and there’s chronic infection or pain, then removal of the kidney may be recommended (see nephrectomy newsletter).

Stone-free Rates and Complications

To help decide how to proceed, it is worthwhile to consider the stone-free rates and the potential complications. A useful way to interpret this information is to consider the following: a staghorn stone can pose a significant risk to a patient’s health; what are the types of help that are available; what are the hazards that go along with the efforts to help?

Some technical answers to those questions follow:

The overall estimated stone-free rate following treatment is highest for PNL (78%) and lowest for SWL (54%).

Comparing PNL with combination therapy, stone-free rates are higher with PNL (78% versus 66%, respectively) and PNL requires fewer total procedures (1.9 versus 3.3, respectively). On average, PNL requires 1.9 total procedures while combination therapy and SWL require 3.3 and 3.6 total procedures, respectively.

Complications

Estimated rates for overall significant complications are similar for the four therapeutic modalities and range from 13% to 19%.

For PNL: acute loss of kidney; colon injury; hydrothorax; perforation; pneumothorax; prolonged leak; sepsis; ureteral stone; vascular injury.

For SWL: acute loss of kidney; colic requiring admission; hematoma (significant); obstruction; pyelonephritis; sepsis; steinstrasse; ureteral obstruction.

For combination therapy: any listed for the above plus deep vein thrombosis; fistula; impacted ureteral stones; renal impairment.