December 22, 2008 Leave a comment
Pyelolithotomy is an operation that is now uncommonly performed. The advent of percutaneous nephrolithotomy with contact lithotripsy (PCN) and extracorporeal shockwave lithotripsy (ESWL) has reduced the indications for pyelolithotomy, which is a considerably more invasive procedure.
It is interesting to note that when surgeons were first performing pyelolithotomy, there was considerable disagreement as to which was the preferred approach to stone removal. Clearly, people liked to argue even then, when one had to do so mainly by letter or book rather than by published article, conference, phone call, telefax, or Internet. Vincenz Czerny probably performed the first pyelotomy, with Sir Henry Morris performing a similar operation to remove a stone in the same year, 1880.
Further developments took place over the years, with many incisions through the thorax and abdomen being introduced, and then many incisions through the renal pelvis and renal parenchyma following. The introduction of radiologic visualization of the kidney completed the picture. It is clear, however, that the landmark contributions to open surgical removal of stones from the kidney were made in recent years by Gil Vernet, Marshall, Boyce, and Wickham.
The usual presenting symptom for renal calculi is radiating colicky flank pain, usually associated with hematuria. Larger stones, however, may be relatively asymptomatic or present with persistent infection and/or hematuria. The diagnosis of renal calculi is generally made radiographically. Currently, the most common radiologic method of diagnosis is via a KUB and intravenous pyelography, though some centers are investigating the use of ultrasound and computed tomography.
INDICATIONS FOR SURGERY
Although its use is limited because of this relative invasiveness, it sometimes has a role to play, particularly when the stone burden is large or when problems with body shape or habitus prevent percutaneous access to renal calculi or focusing on the stone by ESWL.
Alternatives to pyelolithotomy include ESWL, percutaneous stone extraction/destruction, ureteroscopic stone destruction, chemolysis (uric acid or struvite stones), or anatrophic nephrolithotomy.
Surgical Access to the Kidney
The urologist may consider five possible approaches to the kidney for open stone removal:
b.Costal (11th or 12th rib)
c.Intercostal (above the 11th or 12th rib)
The advantages of the flank approach are described after I explain why, in my opinion, the transabdominal and posterior lumbotomy incisions are rarely required in what is, after all, a relatively uncommon procedure. Transabdominal and transperitoneal access may be required if the patient has spinal deformities and very occasionally after several previous surgical procedures. It is the most invasive of all the approaches, and recovery is delayed postoperatively. It should not be used as the standard approach for pyelolithotomy.
The posterior lumbotomy incision has its advocates, particularly because postoperative pain is minimal, and recovery is quick with shortened hospital stay. The patient is placed either in the lateral decubitus position or prone, with pillows under the upper abdomen. The incision is made about 2.5 cm lateral to the erector spinae muscle from the 12th rib down to the superior border of the iliac crest. The incision is extended through fat and fascia and then through the aponeurotic fibers of the latissimus dorsi. If further access is required, a small part of the 12th rib can be removed, or the lower end of the incision can be curved inferolaterally along the iliac crest. The advantages of this approach have been listed above, but a major disadvantage is that access to the upper pole is difficult, as is access to the ureter below its upper portion. I feel that when an open operation is being performed today for stone removal, it is unlikely to be a simple procedure but rather a more complex one for which greater exposure may be required than is afforded by this incision.
Of the flank incisions, I prefer the costal route of access. The subcostal approach is usually too low for renal surgery of any complexity. In considering the incision, it is worth remembering that although it is possible to be too low, preventing complete visualization of each step of the subsequent dissection, it is never possible to be too high. For this reason, the skin incision should be made on top of or superior to one of the ribs. In this way, damage to the subcostal or infracostal nerves is prevented, and the likelihood of a wound hernia is minimized. The intercostal approach requires division of the posterior costotransverse ligament in order to allow the rib to “bucket-handle.” Otherwise, access between the ribs may be suboptimal, and, indeed, the ribs may break when spread apart by a self-retaining retractor.
When an incision is based on a rib (the costal approach), removal of the end of the rib is required. A careful review of the preoperative x-ray films and examination of the patient with the table broken will clarify whether the 12th, 11th, or even, on some occasions, the tenth rib should be the line of the skin incision. The patient should be placed on the table in the lateral decubitus position with the side to be operated on facing directly upward. The patient can be stabilized by inserting three T-pieces along the sides of the table or by fastening tape to the upper thorax and over the hip, thereby fixing the patient on the table. The table is broken, thus opening up the space between the ribs and the iliac crest, and then tilted 20 degrees laterally toward the surgeon. The surgeon and assistant are both positioned behind the patient, and the surgeon can sit down throughout the procedure.
The incision is made in the skin over the distal 6 cm of the rib, extending medially for another 10 to 12 cm. It should be deepened down to the rib before any muscles are cut. Once the rib can be clearly seen, the skin, fat, and fascial layers are retracted on both sides to give a better view. The intercostal muscles are divided above the rib with a knife until the diaphragm can be seen; this is then divided with a scissors until the distal 6 cm of rib is cleared. Then the same approach is made below the rib, with the intercostal muscles being divided if the 11th rib is being used, or the latissimus dorsi if it is the 12th. The diaphragm will not be divided inferior to the rib, but it is advisable to identify the nerve bundle and sweep it inferiorly. Once the rib has been dissected free of the surrounding muscles, the distal 6 cm is removed with a rib shears. I do not approach the rib subperiosteally, as leaving the periosteum does not confer any advantage.
Once the rib has been removed, Gerota’s fascia can be visualized, and through it the kidney can be palpated. Two fingers should be introduced under the abdominal muscles through this incision, and the peritoneum swept away from their under surface. The incision is then deepened through the external oblique, internal oblique, and transversus abdominus muscles using the knife or cutting diathermy. The incision should not extend as far medially as the rectus sheath.
At this stage, a body wall retractor should be inserted, preferably the Wickham retractor, which is self-retaining and shaped to the body wall. Gerota’s fascia is then opened, and this incision is extended upward toward the diaphragm and inferiorly toward the pelvic brim. The peritoneum can then be mobilized medially away from the ureter, which is visualized exiting from the perirenal fat, and the ureter is encircled with a loop or tape. The perirenal fat is then grasped over the lateral border of the kidney, elevated by two Babcock forceps, and incised, revealing the capsule of the kidney. The degree of mobilization of the kidney required depends on how large the stone is. If full mobilization is required, it can be performed easily but should always be carried out by sharp dissection with a Metzenbaum scissors under direct vision. Remember that the main renal vein is always best accessed from anterior to the kidney (although there may be tributaries lying posteriorly). The main renal artery is best approached from above and posterior to the kidney, although there may be other branches, particularly an upper pole or lower pole branch directly from the aorta. The artery need not be isolated in the unusual situation that small stones are being removed, unless a parenchymal incision is being contemplated. When it is isolated, a loop or tape should be put around it.
In the case of surgical access after previous surgery and after many previous surgical procedures, great care must be taken. After incision of the muscles, the fascial and perirenal areas are likely to be greatly thickened and indurated. It is very helpful to isolate the ureter first (prestented if required) and to trace the ureter upward to the ureteropelvic junction. The kidney can then be dissected free from the surrounding tissues with the scissors. Care must be taken not to incise the renal capsule because considerable hemorrhage can occur under these circumstances. Because the kidney is likely to be encased in dense fibrous tissue, the perirenal anatomy will be difficult to define accurately, and upper and lower pole arteries can be damaged. In addition, identification of the renal artery can be somewhat more difficult; palpation of the tissues medial to the kidney will reveal its position.
Access to the Renal Pelvis
In general terms, it is preferable to open the renal pelvis posteriorly rather than anteriorly. This approach will avoid the renal vein, which often runs along the upper part of the anterior surface of the pelvis. Damage to the renal parenchyma can be avoided if only the renal pelvis is incised. The degree of dissection around the renal pelvis will not affect renal function.2 The subparenchymal and intrasinusal pyelotomy5 has made easier the removal of even the most complex calculi.
This method of opening the renal pelvis would only be considered if the stone to be removed is only 1 to 2 cm in diameter in the renal pelvis or in a calyx, or if there were a number of such sized calculi in several calyces.
After opening Gerota’s fascia and the perirenal fat and putting a tape around the upper ureter, as described above, the amount of dissection in the region of the renal pelvis that is required is not extensive. The ureteropelvic junction and the pelvis itself should be clearly defined, but a subparenchymal dissection is not required unless the pelvis is intrarenal . After placing two stay sutures of 4-0 polyglycolic acid or chromic catgut, make a longitudinal incision in the renal pelvis using a scalpel. The incision must not extend through or into the ureteropelvic junction because of the risk of subsequent scarring.
When the urologist is certain that all stones have been removed, the pelvis should be closed with continuous 4-0 polyglycolic acid or chromic catgut suture. The attempt is to make the closure watertight, but even making the suture continuous does not guarantee this, so the peripelvic tissues should be drained.
In most cases, the reason for performing open pyelolithotomy will be the complexity of the stone in the renal pelvis and its multiple extensions into the calyces. In many cases it will be possible to remove the stone completely by extending the dissection under the parenchyma and exposing the renal pelvis and calyceal infundibula in the manner described by Gil Vernet. In this way, incisions into the renal parenchyma can be avoided, thus reducing the potential for renal injury.
The anatomy of the renal hilum allows for extensive exposure of the renal pelvis, but care must be taken that the correct planes of dissection are adhered to. There is a thin layer of connective tissue extending from the renal capsule into the fat in the renal hilum and then onto the renal pelvis. This closes off the renal hilum, and it is this layer that must be incised in order to gain access to the infundibula in carrying out an extended pyelolithotomy. Once this layer of connective tissue has been incised, the dissection is continued by inserting specially designed retractors under the parenchyma. The dissection is carried out by inserting and spreading a fine scissors or by the use of a Küttner dissector. This dissection is carried out between the fatty layer in the hilum and the pelvis itself. If, mistakenly, the surgeon enters the layer between the fat and the parenchyma, considerable hemorrhage can be encountered because of many venous channels in this area.
Even if there is perihilar inflammation, or if there has been previous surgery, it is possible to develop this plane. Sharp dissection is required, but early insertion of Gil Vernet retractors moves the vessels in the hilum out of the way so that damage to important structures is avoided. Even if veins in this area are opened, they can be compressed by the insertion of small sponges between the retractors and the hilum, and bleeding kept to a minimum.
The subparenchymal dissection can be extended to the infundibula without damaging the superior or inferior apical branches of the renal artery. An incision is then made with a scalpel into the renal pelvis, directly down onto the main bulk of the stone. It is extended in a curved fashion with angled scissors into the necks of the superior and inferior calyces. Alternatively, a straight incision is made in the parenchyma from side to side, and perpendicular extensions are made into the necks of the individual calyces.
In general, the large central bulk of the stone is removed first. The best way to do this is to pass a stone dissector around the stone and lever it out of the pelvis. This is preferable to grasping the stone with a forceps, as the stone may break. Once the main fragment is out, fine Turner–Warwick stone forceps, either straight or curved, can be inserted into the calyces, and individual fragments can be removed.
After the surgeon feels that all of the stone has been removed, it is advisable to irrigate the renal pelvis and flush smaller fragments out of the calyces. This is done by inserting a wide-bore tube into the calyces, through which a high pressure jet of saline can be passed; the high flow of the saline is essential for effectiveness, and this is best induced by a pressure cuff around a bag of saline attached to an infusion cannula.
Contact radiography should then be performed by putting a kidney film behind the kidney. It is helpful to put the kidney into an elastic net sling and then tie the sling to the retractor or to a gantry on the retractor. Ligaclips can then be clipped onto the sling, thereby facilitating the location of even small residual fragments on the x-ray film.
The renal pelvis is then closed by using a continuous 4-0 polyglycolic acid or chromic catgut suture. Sometimes it may be easier to put one or two interrupted sutures in the apical parts of the necks of the infundibula, and this will facilitate closure. Again, the closure may not be watertight, and drainage of the area is thus required. Unless there is noticeable intrarenal hemorrhage, no nephrostomy tube is necessary.
On some occasions, it may not be possible to remove the entire stone through a pyelotomy, and additional transparenchymal access is required; the anatrophic nephrolithotomy1 would be excessive if the renal pelvis has been opened in the manner described above, and multiple radial paravascular nephrotomies are a relatively atraumatic method of access. The method of doing this is to make a small (1 cm) radial incision over the stone, which can be localized either by palpation with a needle through the parenchyma or by intraoperative ultrasonography. The parenchyma is then separated by spreading with two MacDonald’s stone dissectors until the calyx is opened and the stone removed. This can be done in a number of positions with a minimal effect on renal function. The nephrotomies are closed with a continuous 4-0 polyglycolic acid or chromic catgut suture, which is placed superficially, incorporating only capsule and a thin layer of parenchyma. A nephrostomy tube should be placed into the most dependent calyx opened; a 12-Fr whistle-tip catheter is satisfactory. This should be brought out through a separate stab incision in the skin.
If a radial paravascular incision is to be made, the renal artery must be located and either a silastic loop or a cotton tape passed around it in order to gain control. A single nephrotomy may not require vascular occlusion, and occlusion can be avoided altogether by the use of the Doppler ultrasound, which is especially valuable in kidneys with decreased function and thinned parenchyma.4 If the renal artery must be occluded, renal function should be preserved during the period of ischemia. Renal hypothermia is achieved by surface cooling with sterile crushed ice6 or by external cooling coils.
A less complex method of protecting against renal ischemic damage is the use of intravenous inosine. This can be injected into a peripheral vein and is valuable in protecting renal function, particularly if the ischemic period is less than 60 minutes and overall preoperative renal function is good.
After complete stone removal and adequate hemostasis are ensured, the wound is closed. A Robinson drain is brought out through a separate stab incision. A gravity drainage system such as this is preferable to a suction drain, which may cause a urinary fistula to develop.
The wound is closed using a series of interrupted #1 polyglycolic acid sutures. These are passed through all muscular layers at 2-mm intervals and are left untied until all are placed. The table is then unbroken, which brings the wound edges closer together and allows the sutures to be tied without tension. A continuous layer of #1 polyglycolic acid suture is then passed through the outer layer of the external oblique muscle and the fascial layers. The skin can be closed with 3-0 monofilament nylon or with skin clips.
Complications from open renal stone surgery are significant and include hemorrhage, urinary fistula, recurrent stones, and actual or functional loss of the renal unit. The risk of these complications is dependent on the associated findings of chronic infection, prior surgery, and surgeon’s expertise.
There is a small chance that the pleura may be opened when a costal or intercostal incision is made, and the probability of this increases the higher the incision is made. A pleurotomy is readily identified by hearing the sound of air being sucked into the thorax and by seeing the lung on inspiration. The diaphragm should be dissected free from the ribs and used to strengthen the closure of the pleura, which is itself too thin and fragile to hold a suture. The 3-0 chromic catgut suture should include the diaphragm, pleura, and intercostal muscles, and the anesthesiologist should inflate the lung before the last suture is put in. This usually prevents a pneumothorax. A postoperative chest x-ray must be performed, and, in the relatively uncommon event of a persistent pneumothorax, a chest tube should be inserted.
Stone-free rates in patients undergoing pyelolithotomy are variable, depending on the number of stones, the composition of the stone, and the presence of calyceal stones or obstruction. Solitary stones have virtually a 100% stone-free rate, whereas staghorn stones (stru-vite) or patients with multiple stones scattered among the calyces may have an incidence of retained stones of 10% or more.