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Vascular and Interventional Radiology |
1 From the Department of Radiology, St George’s Hospital, Blackshaw Rd, London SW11 5PF, England. Received August 28, 2003; revision requested October 23; revision received December 18; accepted January 30, 2004. Address correspondence to U.P. (e-mail: uday.patel@stgeorges.nhs.uk).
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ABSTRACT |
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 TOP ABSTRACT INTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
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MATERIALS AND METHODS: Over a 5-year period, 15 patients (26 kidneys) without calyceal dilatation at ultrasonography (US) who required nephrostomy drainage were studied. Eleven patients (21 kidneys) had ureteral leaks or fistulas, one patient (one kidney) had a renal pelvic stone, one patient (one kidney) was suspected of having a ureteral tumor, and the final two patients (three kidneys) had acute nondilated renal failure. Mean age was 62 years (range, 20–78 years); 13 patients were men and two were women. A double-puncture technique was used with fluoroscopic guidance (supplemented with US in some patients who had renal failure). After intravenous administration of iodinated contrast material, a 22-gauge needle was inserted into the opacified renal pelvis, and double-contrast pyelography was performed by using air or carbon dioxide to allow visualization and distention of the nondependent calyces for definitive renal access with an 18-gauge 5-F sheath-needle set and a hydrophilic wire. After serial dilation, a nephrostomy or nephroureteral catheter was inserted. Success and major complication rates were studied by reviewing radiologic and clinical case notes.
RESULTS: Catheter placement was successful in 25 (96%) of 26 kidneys after one, two, or three passes with the sheath-needle set. In all successful cases, the calyx was accurately punctured. There were two major complications. One patient developed hematuria that required transfusion but no further intervention; another sustained a renal pelvic injury, but this was believed to be due to excessive dilation of the pelviureteral junction, not faulty renal puncture. There were no cases of septicemia.
CONCLUSION: With a double-puncture technique and air or carbon dioxide distention, nephrostomy was achieved in 25 (96%) of all nondilated renal collecting systems. There were two major complications (two [8%] of 25 kidneys, two [13%] of 15 patients), but only one was secondary to the renal puncture.
© RSNA, 2004
Index terms: Kidney, interventional procedures, 81.1263 • Ureter, obstructions, 82.843
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INTRODUCTION |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
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When patients are in the prone position, a nondilated calyx presents two difficulties: poor visualization and absence of distention. Poor visualization makes for difficult targeting, and secure guidewire navigation into the renal pelvis and down the ureter is demanding because of the absence of distention. Some radiologists and urologists consider nondilated and/or unobstructed kidneys unsuitable for safe antegrade nephrostomy.
The purpose of our study was to retrospectively review our experience with the double-puncture technique for percutaneous nephrostomy of nondilated renal collecting systems.
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MATERIALS AND METHODS |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
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This was a retrospective study in which existing clinical data were used with no change in patient care; our hospital does not require formal institutional review board approval or informed consent from the patient for this type of study.
Technique for Nephrostomy
All patients were given 120 mg of gentamicin (Hoechst Marion Roussel, West Malling, United Kingdom) or 1 g of cefotaxime (Claforan; Aventis Pharma, West Malling, United Kingdom), according to our department protocol, unless the patient was already taking antibiotics. No patient was taking anticoagulants, and the results of coagulation studies were normal in all (eg, platelet count of more than 80 000 x 109/L, prothrombin time of less than 3 seconds above our laboratory control value, international normalized ratio of less than 1.3). All patients were in a clinically stable condition with normal blood pressure and pulse recordings.
A standard technique was used. First, informed consent was obtained after an explanation of the procedure and a discussion of its benefits and risks. The senior author (U.P.) was assisted by a trainee radiologist in all cases. Conscious sedation was achieved intravenously by using 2.5–10.0 mg of midazolam (Hypnoval; Roche Products, Welwyn Garden City, United Kingdom) and 50–100 mg of pethidine (Auden McKenzie, Wembley, United Kingdom). A nurse continuously monitored all patients and regularly measured pulse rate, oxygen saturation, and blood pressure.
Stage 1: Initial Opacification and Distention of the Nondependent Posterior-facing Calyces
Patients were placed in the prone position (the patient who underwent renal transplantation was placed in the supine position), and 50 mL of iodixanol 320 (Visipaque; Nycomed Amersham, Buckinghamshire, United Kingdom) was injected intravenously. After about 5 minutes, the renal pelvis was visualized on the fluoroscopy monitor and scrupulously centered by using strict anteroposterior orientation (Fig 1a). The skin overlying the center of the renal pelvis was anesthetized; with intermittent fluoroscopy, a 22-gauge Chiba needle (Becton Dickinson & Company, Franklin Lakes, NJ) was advanced vertically toward the renal pelvis until the needle tip was seen to move with respiration, which indicates entry into the renal parenchyma (Fig 1b). The C-arm of the fluoroscope was rotated to 20° right posterior-oblique angulation for imaging of the left kidney and vice versa; the needle tip was advanced further into the renal pelvis with continuous fluoroscopy (Fig 1c). This maneuver was accomplished swiftly before the renal pelvis emptied of all contrast material. In some patients, the renal pelvis was inaccessible because of an overlying rib. In these patients, an alternative site, such as the infundibulum (Fig 2a), was used; this sometimes required intercostal needle entry.
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Stage 2: Definitive Nephrostomy Insertion
From the double-contrast pyelogram, a gas-filled nondependent lower or interpolar calyx was selected for the nephrostomy entry site. The skin overlying the center of the chosen calyx was anesthetized, and a sheath-needle set (eg, 18-gauge needle with a 5-F sheath [Leigen; Angiomed, Karlsruhe, Germany]) was directed into the calyx with intermittent screening and C-arm rotation. The arm was rotated to the 20° right posterior-oblique position for imaging of the left kidney and vice versa. Because of its buoyancy, the gas in the nondependent calyces drains slowly—unlike iodinated contrast media, which remains visible and distended for prolonged periods—and the chosen calyx can be carefully targeted without any haste.
At entry, the needle was removed, and a 0.035-inch curved-tip hydrophilic guidewire (Terumo, Leuven, Belgium) was inserted into the sheath and advanced into the calyx. Often the needle, sheath, or both had gone through the calyx, and withdrawal of the sheath with wire manipulation was necessary before space in the calyx was found with the wire, which then glided into the infundibulum. It is not uncommon for the wire, because of its hydrophilic properties, to be advanced within the fat alongside the calyces toward the renal sinus. This can be mistaken for satisfactory wire position, as the wire direction follows the expected path of the collecting system. The surest sign of location within the fat is if the wire cannot be easily advanced into the ureter. A wire comfortably within the collecting system will readily glide across the pelviureteral junction, and in all difficult cases, we advanced the wire well into the renal pelvis (Fig 2b) and down the ureter before the sheath was advanced over the hydrophilic wire. We have found that watching for gas return through the needle is an unreliable sign.
Next, the hydrophilic wire was exchanged for a 0.035-inch guidewire (Superstiff Amplatz; Boston Scientific, Watertown, Mass). The track was dilated by using fascial dilators and either an 8-F nephrostomy catheter (Soft Drain; Angiomed) in four patients or a 14-F nephroureteral custom-made occlusion catheter (William Cook Europe, Bjaeverskov, Denmark) in 11 patients (Fig 3) through an appropriately sized peel-away sheath. The nephroureteral catheter was used in most patients with ureteral leaks or fistulas. This is a customized 14-F Malecot-tipped straight nephrostomy catheter with a short blind-ending tapering cuff that occludes the pelviureteral junction; it is a modification of an existing catheter and has been described elsewhere (4).
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The remaining two patients (three kidneys) were referred with renal failure; one had newly diagnosed lymphoma with large volume retroperitoneal lymphadenopathy, and the other had a dysfunctional renal transplant. Both had rapidly deteriorating renal function with nondilatation at US; thus, percutaneous nephrostomy was requested because obstructive uropathy was suspected. Intravenous contrast material could not be used because of renal failure; therefore, with US guidance, the recently visualized renal pelvis was punctured with a 22-gauge Chiba needle (Becton Dickinson & Company). At aspiration of urine, iodinated contrast material and air were injected to create a double-contrast pyelogram. Definitive entry was made with fluoroscopic guidance, as described in stage 2, and an 8-F nephrostomy catheter was inserted bilaterally in the patient with lymphoma.
Data Collection
The success and major complication rates were recorded (U.P. or F.H.) with retrospective review of the departmental database and were supplemented by review of case notes and communication with referring clinicians. Technical success was defined as satisfactory placement of a nephrostomy or nephroureteral catheter; clinical success was defined as uncomplicated establishment of renal drainage. Major complications were defined according to the classification criteria of the Society of Cardiovascular and Interventional Radiology (2) and involved specific therapy, an unplanned increase in hospitalization or the level of care, a permanent sequelae, or a fatality. Examples of major complications are substantial hemorrhage or septicemia, and these were identified. Examples of minor complications are catheter dislodgement, blockage, or hematuria. Minor complications were not further analyzed, as reliable data were not obtained at retrospective review—many patients recently underwent (a) bladder surgery or instrumentation, which may have contributed to hematuria, or (b) further antegrade ureteral procedures or stone extraction, which would bias catheter dislodgement and/or manipulation data.
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RESULTS |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
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The patient in whom percutaneous nephrostomy insertion was unsuccessful had carcinoma in situ of the bladder, and intravenous urography showed a suspected stricture of the lower ureter. Retrograde ureteroscopy failed because the ureteral orifice could not be visualized. Antegrade access was required for pyelography and insertion of a catheter across the ureteral orifice, which aided in retrograde endoscopy. After injection of intravenous contrast material, 22-gauge needle puncture of the renal pelvis was unsuccessful, and the procedure was abandoned after six attempts and an additional 50 mL of intravenous contrast material was administered. There were no procedure-related complications in this patient, and minor hematuria resolved after 1 day. Repeat intravenous urography over 2 years has shown no change, and the results of surveillance cystoscopy and urine cytology have been negative. The ureteral appearances are now thought to represent a normal variation, such as forme fruste megaureter.
Major Complications
There were two major complications. One patient required a three-unit blood transfusion because of hematuria that lasted 4 days. This patient had a deteriorating renal transplant, and an 8-F nephrostomy catheter had been inserted. The hemoglobin level decreased from 10.7 g/dL (107 g/L) to 8.7 g/dL (87 g/L), but the bleeding settled after supportive therapy alone. A urinary catheter was inserted to guard against bladder outflow obstruction that was caused by a clot; however, no further intervention was necessary, and renal function later recovered.
The second major complication was an injury to the renal pelvis and upper ureter in a patient with anastomotic breakdown after cystectomy and creation of an ileal conduit (Fig 4). When the 14-F peel-away sheath was advanced, some resistance was felt around the pelviureteric junction, and the sheath could only be advanced less than an inch around the corner. When the inner dilator was removed, contrast injection with fluoroscopy showed extravasation. We believe that urothelial tear or dissection was caused by the dilator tip or the sheath edge, although they were advanced over a guide wire with the wire tip well down the ureter. The ureter was not thought to be necrotic; however, this possibility could not be excluded. In spite of prolonged external drainage over a 6-week period, the pelvic injury failed to heal, and open surgical reconstruction was required. A loop of the transverse colon was interposed between the renal pelvis and the contralateral ureter.
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DISCUSSION |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
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Some reports have focused on nephrostomy insertion into nondilated systems and are listed in Table 2 (8–15). Other reports deal with nephrostomy in general and have included some discussion or observations about nondilated kidneys (6,7). To our knowledge, the retrograde technique was first described by Lawson et al (16). Lawson et al reported their experience in only one patient, but others have used it in larger groups of patients (8,9); a ureteral catheter with a customized needle-stylet combination is passed in a retrograde fashion, advanced into a calyx, and punctured to exit at the skin surface. A wire advanced through the needle is used for an antegrade catheter. This technique has now fallen out of favor, as the needle tends to exit laterally with a danger of bowel or viscus injury.
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Many radiologists (Rickards D, written communication, 2003) generally use one of two fluoroscopic techniques. The first is a single-puncture technique, which relies on the transient opacification of the posterior calyces after administration of intravenous contrast material. A large contrast material volume is necessary to maximize distention, and a rapid technique is vital. A sheath-needle set is used to puncture the poorly opacified nondistended calyx. Purposefully, the needle tip is traversed through the calyx so its tip lies in the renal parenchyma. A curved-tip hydrophilic wire is inserted until the wire tip is flush with the end of the sheath. The sheath is then slowly withdrawn while constantly probing with the wire tip; the slipperiness of the hydrophilic wire is used to locate the restricted space of the nondilated calyx. If successful, the moment the sheath enters the collecting system, the tip of the wire bounces off the far wall and characteristically glides into the infundibulum. The drawback of this technique is that when patients are in the prone position, iodinated contrast media preferentially gravitates into the dependent calyces. A rapid technique is required, because the time window of visualization and distention is short.
The second technique is a double-puncture technique in which only iodinated contrast material is used. This partly overcomes the poor visibility and distention of the posterior calyces that limits the single-puncture technique described previously. The first needle is placed into the renal pelvis by using US guidance or anatomic landmarks, and iodinated contrast media is injected to distend the collecting system, particularly just before calyceal entry with a second needle. The nondependent posterior calyces are seen only momentarily, however, because the heavier iodinated contrast material preferentially gravitates to the renal pelvis and ureter. Repeated distention is necessary, but this makes the situation worse by further stimulating peristalsis, with ever more frequent emptying of the calyces. Consequently, the time window for posterior calyceal distention and visualization is short and gets even shorter with repeated injection. To our knowledge, neither of these techniques has been formally described, and the success and complication rates are not known. In our experience, these techniques required multiple attempts before successful entry, with the accompanying risks of vascular injury. Large volumes of intravenous contrast material were sometimes necessary, and even when access was gained, the entry site often proved to be an infundibulum.
The technique we have described overcomes all these limitations and provides prolonged distention and visualization of nondependent calyces. Gaseous distention for percutaneous nephrostomy has a long history. To our knowledge, this technique was first described by Hunter et al (17), and it is in now in common use (18) because it preferentially highlights those nondependent calyces that are best suited for percutaneous entry. A further advantage of the buoyancy of gaseous contrast material, which we used in the described method, is that it is relatively resistant to drainage when compared with iodinated media. A gas-distended calyx will retain contrast material much longer, even with continued peristalsis. Our experience with 15 nondilated unobstructed renal units has shown that a nondependent gas-filled calyx remained visibly distended for a mean time of 13 minutes (range, 2–30 minutes) compared with a mean time of less than 2 minutes after administration of iodinated contrast material (19). Because of this longevity with gas distention and a double-puncture technique, percutaneous nephrostomy was technically successful in 96% of all nondilated kidneys in our study.
There were two major complications. Although there were no instances of renal loss, one patient had long-term sequelae. Major hemorrhage occurred in one (7%) of 15 patients, a percentage that is greater than that reported after nephrostomy drainage of dilated systems (1%–4%) (2). It has been suggested that nondilated kidneys may bleed more because the needle traverses a greater thickness of the renal parenchyma (20); however, a more recent study found no association between the presence of hydronephrosis and transfusion requirements (7). The absence of distention, however, almost certainly contributed to the second complication. In this case, we hypothesize that overdilation of the ureter traumatized the urothelium at insertion of a large-bore peel-away sheath. This may not have occurred if the collecting system and ureter were dilated and capacious.
Even with the previously described technique, the fundamental principles of fluoroscopy-guided intervention should be followed. Isocentric positioning of the calyx of entry is crucial because the margin of error for targeting is less with small calyces. If additional craniocaudal and/or horizontal tilt is used (we find this ensures a less acute angle of needle entry vis-à-vis the calyx), isocentricity should be reestablished. A further benefit of our technique is the perceptual advantage of double-contrast pyelography. On images obtained with rotational fluoroscopy, spatial relationships are immediately apparent, with the radiolucent nondependent calyces easily differentiated from the radioopaque calyces. Finally, we believe that a sheath-needle set and a curved-tip hydrophilic wire are crucial to success. In our experience, a 0.035-inch hydrophilic wire is much better at making its way through restricted volumes than the finer but higher-friction 0.018-inch platinum-tip wire that is often used for percutaneous nephrostomy of dilated kidneys. The hydrophilic wire can easily glide into the sinus fat, however, and this pitfall should be recognized by using the signs mentioned in Materials and Methods. Further drawbacks of this technique are (a) the initial 22-gauge needle puncture of the renal pelvis may require fine readjustment before injection and (b) extensive care is necessary during introduction of air or carbon dioxide to avoid gas embolism or an explosive expansive effect. Techniques to safeguard against these particular shortcomings are discussed in Materials and Methods.
Some limitations of our study should be recognized. This is a retrospective study, and although there are no gaps in the data presented here, we were unable to study patient comfort or radiation dose in detail. Furthermore, the complex nature of many of the ureteral injuries precluded the study of minor complications, such as hematuria.
Antegrade access to nondilated calyces is feasible by using a double-puncture technique. First, a double-contrast pyelogram is obtained, which allows prolonged visualization of the nondependent posterior-facing calyces, and entry can be carefully targeted on the center of the calyx without undue haste. A sheath-needle set and hydrophilic wire are also important. With this, we achieved a success rate of 96%, which is higher than that suggested in a standards-of-practice article (2); however, a major complication occurred in two of 15 patients (two of 25 kidneys) in our study. In one patient, the complication may have been averted if the collecting system had not been overmanipulated; however, it is possible that the hemorrhage rate is higher in nondilated systems. Further experience and reports of complication rates in this subgroup are necessary.
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FOOTNOTES |
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REFERENCES |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
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This article has been cited by other articles:
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  A Horton, L Ratnam, J Madigan, G Munneke, and U Patel Nephrostomy -- why, how and what to look out for Imaging, March 1, 2008; 20(1): 29 - 37. [Abstract] [Full Text] [PDF]
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