Anatrophic Nephrolithotomy

Anatrophic nephrolithotomy is a procedure that has been used by urologists for nearly 30 years in the removal of large renal calculi, specifically branched or staghorn calculi. These stones are often associated with urinary tract infections, and the coexistence of these two conditions makes it difficult to eradicate either. Definitive treatment of these stones is generally advocated because of the significant morbidity and mortality associated with untreated staghorn calculi. Blandy and Singh found that patient survival is reduced with untreated staghorn calculi, with a mortality rate of 28% at 10 years.
Since the early 1980s, with the development of less invasive approaches such as extracorporeal shock wave lithotripsy and percutaneous nephrolithotomy, the role of anatrophic nephrolithotomy and other open stone operations has certainly diminished.2 However, anatrophic nephrolithotomy remains the gold standard for the treatment of staghorn calculi and thus maintains a role in the treatment of these large complex stones.
The original description of anatrophic nephrolithotomy was by Smith and Boyce in 1968. The operation they described was based on the principle of placing the nephrotomy incision through a plane of the kidney that was relatively avascular. This approach would avoid damage to the renal vasculature with resulting atrophy of the renal parenchyma, hence the term anatrophic. The operation also involves reconstruction of the intrarenal collection system to eliminate anatomic obstruction, thus improving urinary drainage, reducing the likelihood of urinary tract infection, and preventing recurrent stone formation.
DIAGNOSIS
The diagnosis of staghorn calculi is usually established in a similar fashion as other forms of urolithiasis. Patients may have the typical symptoms of flank pain, fever, and hematuria, or they may be asymptomatic. The diagnosis of chronic urinary tract infection is common in patients with these types of stones. Urine culture is often positive, and typical organisms include urea-splitting organisms such as Proteus, Klebsiella, Providencia, and Pseudomonas.
Useful radiographic studies traditionally include plain abdominal radiographs, nephrotomograms, and excretory urograms to identify the stones, the collecting system, and, if present, to define the degree of obstruction. Computed tomography can be helpful for detection of radiolucent or poorly calcified stones. Retrograde pyelography is usually performed in cases of equivocal findings on excretory urography. Nuclear renal scans can help to determine differential renal function when such information might affect the surgical approach. Renal arteriography is usually not indicated unless there is suspicion of anomalous arterial anatomy such as in renal fusion anomalies.
Before elective surgery, a metabolic evaluation is recommended to attempt to determine an etiology for stone formation and to aid in preventing a recurrence. For instance, it is important to determine the presence of hypercalciuria, hyperuricosuria, hyperoxaluria, cystinuria, hyperparathyroidism, and renal tubular acidosis. The measurement of serum and urine calcium, phosphorus, creatinine, uric acid, and electrolytes should be routine. A 24-hour urine collection for creatinine clearance as well as urinary calcium, phosphorus, oxalate, citrate, cystine, and uric acid is also an integral part of the workup.
INDICATIONS FOR SURGERY
Anatrophic nephrolithotomy should be performed for the removal of branched or staghorn calculi, usually complete staghorn stones, or those associated with infundibular stenosis or other intrarenal anatomic obstruction, for the combined goals of removing all calculi and open surgical correction of the anatomical obstruction. This procedure may also be preferred in the treatment of a staghorn calculus in a kidney with a small intrarenal pelvis, making access to the renal pelvis difficult, or in a patient who has undergone prior renal surgery to avoid a more risky renal sinus dissection. This operation is also indicated for the treatment of staghorn calculi in patients who would benefit from or prefer a single therapeutic procedure versus multiple, less invasive, procedures such as extracorporeal shock wave lithotripsy and/or percutaneous nephrolithotomy.
The goals of the procedure should be to remove all calculi and fragments, to improve urinary drainage of any obstructed intrarenal collecting system, to eradicate infection, to preserve and improve renal function, and to prevent stone recurrence.10
ALTERNATIVE TREATMENTS
Most staghorn calculi can now be preferentially treated with percutaneous nephrolithotomy, with or without extracorporeal shock wave lithotripsy. The stone-free rates reported are approaching comparability with traditional anatrophic nephrolithotomy, and there is probably an advantage to be gained in shorter convalescent periods following the less invasive methods. These alternative odalities can sometimes require multiple different procedures to accomplish a stone-free state. The American Urological Association Nephrolithiasis Clinical Guidelines Panel recommended as a guideline that initial percutaneous nephrolithotomy followed by extracorporeal shock-wave lithotripsy and/or further percutaneous procedures should be the treatment for most standard patients with staghorn calculi. Open surgery is recommended as an appropriate option in unusual cases when a stone is not expected to be removed with a reasonable number of the less-invasive procedures.8 Despite impressive advances with the less-invasive techniques, anatrophic nephrolithotomy remains a treatment option for large complete staghorn calculi or staghorn stones associated with anatomic obstruction and requiring open surgical correction.
SURGICAL TECHNIQUE
After administration of general anesthesia and placement of a Foley catheter, the patient is placed in the standard flank position with elevation of the kidney rest and flexion of the operating table to achieve adequate spacing between the lower costal margin and the iliac crest. Three-inch-wide adhesive tape applied at the shoulders and hips can be used to secure the patient to the table. Adequate padding should be used to protect pressure points.
A standard flank approach is used. The incision can be placed through the bed of either the 11th or 12th rib, depending on the estimated position of the kidney. If a previous flank incision has been made for renal surgery, it is preferable to place the incision above the old scar, ensuring that access to the kidney can be achieved through unscarred tissue. After rib resection, when access has been gained into the retroperitoneal space, Gerota’s fascia is identified overlying the kidney. Gerota’s fascia is incised in a cephalad–caudal direction, which facilitates returning the kidney to its fatty pouch at the end of the operation. The kidney is then fully mobilized, and the perinephric fat is carefully dissected off the renal capsule with care taken not to disrupt the renal capsule. Should the capsule become inadvertently incised, it can be closed at that time with chromic catgut sutures. The kidney is now free to be suspended in the operative field by utilizing two 1-inch umbilical tapes as slings. At this point a preliminary portable plain radiograph can be obtained.
The renal hilar dissection is the next step. The main renal artery and its branches are carefully dissected and identified. The avascular plane, or Brodel’s line, can be identified by temporarily clamping the posterior segmental artery and injecting 20 ml of methylene blue intravenously, which results in the blanching of the posterior renal segment while the anterior portion turns blue5 . This allows identification of this avascular plane. Placing the nephrotomy incision through this plane will achieve maximal renal parenchymal preservation and minimize blood loss. The avascular plane can also be identified with the use of a Doppler stethoscope to localize the area of the kidney with minimal blood flow.
Extensive renal hilar dissection can be avoided by utilizing a modification of the original procedure described by Smith and Boyce. Redman and associates relied on the relatively constant segmental renal vascular supply in advocating placing the incision at the expected location of the avascular line after clamping the renal pedicle with a Satinsky clamp, seeking to prevent vasospasm of the renal artery and warm ischemia. This modification can be time-saving and spare extensive dissection of the renal hilum. However, we continue to advocate precise identification of the avascular plane to minimize parenchymal loss.
At this point, 25 g of intravenous mannitol is administered. This promotes a postischemic diuresis and prevents the formation of intratubular ice crystals by increasing the osmolarity of the glomerular filtrate. The main renal artery can now be occluded with a noncrushing bulldog vascular clamp. A bowel bag or barrier drape is placed around the kidney, and hypothermia is initiated with the placement of iced saline slush within the barrier surrounding the kidney. Dry laparotomy sponges are used to pack away the peritoneal contents and to protect and insulate them from hypothermia. The kidney should be cooled for 10 to 20 minutes before the nephrotomy incision is made. This should allow achievement of a core temperature in the 5° to 20°C range, which will allow safe ischemic times from 60 to 75 minutes and minimize renal parenchymal damage.

The renal capsule is then incised sharply over the previously identified avascular plane, and the renal parenchyma can be bluntly dissected with the back of the scalpel handle. Blunt dissection minimizes injury to the intrarenal arteries that are traversed. Small bleeding vessels can be controlled with 5-0 or 6-0 chromic catgut suture ligature. If renal back bleeding continues to be a problem despite these measures, the main renal vein can be occluded. As the incision is angled toward the midportion of the renal hilum, the nephrotomy should theoretically remain close to the avascular plane.
As the nephrotomy incision proceeds toward the renal hilum, the ideal location to enter the collecting system is at the base of the posterior infundibula. Occasionally, with large posterior calyceal calculi, a dilated posterior calyx will be entered initially. The remainder of the collecting system can then be identified and opened with a probe or stone forceps. If a posterior infundibulum is entered first, the incision is then carried toward the renal pelvis. The stone is palpated, and the remainder of the infundibula are incised in a similar fashion. Attention is then turned towards the anterior infundibula. All of the calyceal extensions should be identified and incised. In order to minimize stone fragment formation and retained calculi, the stone should not be manipulated or removed until all of the calyceal and infundibular extensions are appropriately identified and incised, allowing for complete visualization and mobilization of the collecting system and calculi. Ideally, the stone or stones should be removed without fragmentation; however, often it is inevitable that there will be some piecemeal extraction. After removal of all stone fragments, the renal pelvis and calyces are copiously irrigated with cold saline and carefully inspected for retained fragments. A plain radiograph is obtained at this point to rule out residual calculi or fragments.
At this time, a “double-J” stent is passed from the renal pelvis into the bladder. The routine use of internal ureteral catheters is encouraged. They provide good urinary drainage and protect the freshly reapproximated collecting system and minimize postoperative urinary extravasation. The stents also prevent intraoperative migration of smaller calculi into the ureter.
The next step in the procedure is the reconstruction of the intrarenal collecting system. Infundibular stenosis or stricture, which results in obstruction promoting urinary stasis and recurrent stone formation, should be corrected with calyorrhaphy or calycoplasty. The former is the repair of a single narrowed calyx, achieved by incising the calyx along its appropriate margin (anterior margin for posterior calyces and posterior margin for anterior calyces) and suturing those margins to the renal pelvis, resulting in a shorter, wider calyx. The infundibulum can also be incised longitudinally and then closed transversely in a Heinecke–Mickulicz fashion. Calycoplasty is the repair of adjacent stenotic calyces by suturing the adjacent walls of the neighboring calyces, thus forming a single structure. All intrarenal reconstructive suturing should be accomplished with 5-0 or 6-0 chromic catgut sutures. When suturing the mucosal edges, it is important to avoid incorporation of underlying interlobular arteries, thus preventing ischemia.
The renal pelvis is then closed with a running 6-0 chromic catgut suture. The renal capsule is closed with a running 4-0 chromic suture. The use of mattress-type parenchymal sutures can lead to tissue ischemia and should be avoided if possible. One should inspect closely for further parenchymal bleeding points and ensure good hemostasis before closing the renal capsule. After the capsule is closed and hemostasis has been achieved, the slush surrounding the kidney is removed, and the renal artery unclamped. The kidney is observed for good hemostasis and return of pink color and good turgor after unclamping. The kidney is then returned into Gerota’s fascia, and the kidney and proximal ureter are covered with some perirenal fat to minimize the postoperative scar formation. If Gerota’s fascia is unavailable because of prior surgery, omentum can be mobilized through a peritoneal opening and wrapped around these structures. The peritoneal opening should be sutured to the omentum to prevent herniation of the abdominal viscera.
A Penrose or suction-type drain is placed within Gerota’s fascia and brought out through a separate stab incision. This drain is left in place until minimal drainage occurs, usually by the third or fourth postoperative day. Nephrostomy tubes are generally avoided because of their potential for causing infection or further renal damage. The flank musculature and skin are closed in the standard fashion.
Postoperative management after anatrophic nephrolithotomy should follow the same principles that guide management after other major operations. Intravenous fluids are maintained to achieve brisk urine output and until the patient is able to tolerate a clear liquid diet. Broad-spectrum intravenous antibiotics are administered perioperatively and continued postoperatively. Antibiotic coverage is guided by preoperative urine culture and sensitivity results. The patient is usually converted to appropriate oral antibiotics and maintained on a 14-day course. The ureteral stent is removed cystoscopically at approximately 6 weeks after the operation in uncomplicated cases.
OUTCOMES
Complications
Pulmonary complications are perhaps the most common following anatrophic nephrolithotomy, especially atelectasis. Patients with a history of pulmonary disease should probably undergo preoperative evaluation with pulmonary function testing and initiation of vigorous pulmonary toilet prior to surgery. Postoperatively, patients should be encouraged to breathe deeply, and use of an incentive spirometer should be routine. Early ambulation will also be beneficial.
Pneumothorax should occur in fewer than 5% of patients.10 Inadvertent opening of the pleura, usually during incision and resection of a rib, should be readily identified intraoperatively. The defect should be closed immediately with a running chromic catgut suture. The lung is hyperinflated just before the final suture is placed to ensure reexpansion of the lung. Chest tubes are not routinely used but may be necessary if any question remains regarding the reliability of the pleural closure. A chest radiograph should be obtained in the recovery room for any patient who undergoes repair of a pleural defect.
Pulmonary embolism remains a potential complication of any major surgery. Routine use of elastic support hose and sequential-compression stockings can lower the risk of deep venous thrombosis. Encouragement of early ambulation is also an important preventative measure.
Significant postoperative renal hemorrhage should occur in fewer than 10% of patients. Assimos and associates reported an incidence of 6.4%.1 Bleeding usually occurs immediately or about a week postoperatively. Extensive intrarenal reconstruction, older age, worse renal function, and presence of blood dyscrasias were found to be significant risk factors. Slow bleeding will usually resolve on its own; management includes correction of any bleeding abnormalities and replacement with blood products as necessary. Oral e-aminocaproic acid can be successful in certain cases. Bleeding that is brisk or cannot be adequately treated conservatively will require a more aggressive approach. A renal arteriogram can help identify the lesion, and an attempt at arteriographic embolization can be considered. Reexploration may be required in the remainder of the cases, with reinstitution of hypothermia and suture ligation of the bleeding vessel(s). Persistent hematuria 1 to 4 weeks postoperatively should alert the clinician to the possibility of renal arteriovenous fistula formation.1
Stone recurrence rates following anatrophic nephrolithotomy have been reported from 5% to 30%.10 Inspection, intraoperative plain radiographs, intraoperative ultrasound, and nephroscopy can all aid in the identification and treatment of retained calculi. Recurrent calculi usually form in those with persistent urinary tract infections, persistent urinary drainage impairment, and those with previously unidentified or refractory metabolic disturbances.
Urinary drainage or extravasation should occur infrequently with the routine use of perinephric drains and internal ureteral catheter drainage. Should drainage recur or persist following removal of the drain and/or ureteral stent, replacement of the ureteral stent should be considered to decompress the system and relieve any obstruction.
Results
When performed for appropriate indications and with meticulous technique, anatrophic nephrolithotomy can achieve successful removal of all calculi, preservation of renal function, improved urinary drainage, and eradication of infection. Stone-free rates greater than 90% should be achieved. We believe that for large complex staghorn calculi and those associated with some anatomic abnormality leading to impaired urinary drainage, anatrophic nephrolithotomy remains superior to percutaneous nephrolithotomy or combination therapy with respect to both stone-free rates and the achievement of a stone-free state with a single operative procedure. In the long term, treatment of these staghorn calculi with anatrophic nephrolithotomy should preserve renal function in the involved kidney and, in a majority of patients, eradicate stone disease and chronic urinary infection.

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