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Major complications after percutaneous nephrostomy—lessons from a department audit
Clinical Radiology (2004) 59, 171–179
Major complications after percutaneous nephrostomy—lessons from a department audit S. Lewis, U. Patel* Department of Radiology, St George’s Hospital, London, UK Received 26 March 2003; accepted 23 July 2003
KEYWORDS Ureteral obstruction; Hydronephrosis; Nephrostomy; Complications; Audit
AIM: To audit the performance of our percutaneous nephrostomy service by comparing the major complication rate with the standards recommended by the Society of Cardiovascular and Interventional Radiology and the American College of Radiology: major haemorrhage in ,4%, and septic shock in , 4%. Secondary aims were to identify common sources of errors for quality improvement measures. METHODS: Major complications sustained between January 1997 – December 2002 were identified. All cases had been carried out by the interventional radiology service of a large teaching hospital with the assistance of a nurse and radiographer, under fluoroscopic and ultrasound guidance using a Seldinger technique. Existing department protocols specified pre-procedure antibiotics for suspected infected cases and normal coagulation studies. From records and review of case notes pertinent clinical/procedural details and eventual outcome were assessed. The following were particularly noted: adherence to protocols, clinical status at time of procedure, delay in referral, complication sustained, signs of infection or coagulopathy, timing of procedure (in versus out of hours), level of operator and technical faults. RESULTS: Ten of 318 (3.1%) cases sustained a major complication: five had sepsis alone, two haemorrhage (one with sepsis as well) and three patients had a major pelvic injury (one with sepsis as well). Thus the major sepsis and haemorrhage rates were 2.2 and 0.6%, and were within the recommended threshold limits but proportionately more complications occurred out of hours: six of 105 (5.7%) versus four of 312 (1.8%; p ¼ 0:087). Sepsis was the most serious complication and may have contributed to the death of two patients. On individual case analysis, failed instrumentation with delay to definitive renal drainage was a common factor with sepsis; but the following were contributory factors in one or more cases: omitted antibiotics (in three of 10; two became septic), technical factors in four cases [medial renal puncture ðn ¼ 1Þ; damage due to fascial dilator ðn ¼ 1Þ or peelaway sheath ðn ¼ 2Þ] and delay in diagnosis/therapy (of 1–8 days, in six of 10 cases of whom four out of six became septic). One pelvic injury required surgical correction (contributory factor—faulty use of peelaway sheath). Patients with haemorrhage settled with prolonged tube drainage alone. CONCLUSION: An adequately staffed percutaneous nephrostomy service can perform within published clinical standards. Best practice factors identified were: attention to agreed protocols and algorithms, pre-procedure antibiotics, careful renal puncture and care with use of dilators/peelaway sheaths, but the paramount finding was that sepsis was the most serious complication, contributing to death (two of 10 in this study) or a significant increase in the level of care required. The risk is greatest after failed instrumentation (retrograde ureteral stent or percutaneous nephrostomy insertion) and particularly if there is a further delay before establishment of renal drainage. A close working relationship between interventional radiologists and urologists is crucial. q 2004 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.
*Guarantor and correspondent: U. Patel, Department of Radiology, St George’s Hospital, Blackshaw Road, London SW17 0QT, UK. Tel.: þ 44-208-725-3667/1481; fax: þ 44-208-725-2936. E-mail address: [email protected] 0009-9260/$ - see front matter q 2004 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved. doi:10.1016/S0009-9260(03)00336-2
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Introduction Percutaneous nephrostomy (PN) is one of the most common interventional procedures, performed by many general, and almost all interventional, radiologists. Performance statistics of this common procedure can be taken as a surrogate of on-call interventional provision and its lessons may be generally applicable. Recent standards of practice document by the Society of Cardiovascular and Interventional Radiologists (SCVIR) quoted major complication rates after PN of 1 – 4% for haemorrhage or vascular injury and 1 – 9% for septic shock.1 A separate document issued under the aegis of the American College of Radiologists (ACR), but authored by the same experts, went further and recommended a department threshold level of 4% for septic shock and 4% for major haemorrhage.2 These figures apply to a general interventional service and may vary depending on the referral pattern, but a complication rate in excess of these thresholds should prompt a performance review to identify deficient practice. There are no similar UK or European recommendations, but the audit sub-committee of the Royal College of Radiologists (RCR) used a threshold of 8% (all major complications) for a recent pilot audit (www.rcr.ac.uk). This is a retrospective case series audit of the major complication rates after PN insertion in a relatively well-staffed department compared with the UK average:3 four interventional radiologists with on-call interventional nurse assistance. The aim of the audit was to compare our service performance against the recommended thresholds above. Additionally, common lessons are extracted from these case studies to identify areas for quality improvement.
Methods Patients Between January 1997 – December 2002, one of the authors (U.P.) has maintained a contemporaneous record of all major complications after PN with relevant technical/procedural details. Major complications were defined using the system recommended by the Society of Cardiovascular and Interventional Radiology (see Appendix A). PNs were carried out by four interventional radiologists, or by interventional fellows/specialist registrars. During working hours, the PN was carried out/ supervised by a consultant uroradiologist, and by
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one of the other consultant interventionalists in the absence of a consultant uroradiologist. Out-ofhours cases were carried out by the on-call consultant, or the specialist registrar (SpR)/fellow if the consultant felt that the SpR/fellow was competent. If, however, the case was complicated or there were inter-procedural difficulties the consultant came in to assist. Whether during working hours or out-of-hours, all cases were carried with at least one radiologist, one radiographer and one dedicated interventional nurse in attendance (on call since Sept 2000).
Technique of PN Our departmental protocol during this study period specified that all patients should have normal preprocedure coagulation and platelet estimation [international normalized ratio (INR) , 1.3 and . 80 000/dl, respectively], and all with suspected sepsis (pyrexia defined as temperature . 38.0 8C, rigors and/or raised white blood cell count) should receive 120 mg gentamicin (or an alternative agent), unless the patient was already receiving antibiotics. All cases were carried out in a dedicated interventional room under fluoroscopic and ultrasound guidance, with haemodynamic monitoring facilities (continuous measurement of oxygen saturation and pulse rate, with blood pressure recorded every 5 min or sooner), as well as controlled piped oxygen. The nurse, who also administered intravenous sedo-analgesia as prescribed by the radiologist, monitored the patient. The medication used and doses given were recorded in the case notes. As this is a retrospective study full technical details of every procedure were not available except in those cases with major complications. All cases were done under fluoroscopic or ultrasound/fluoroscopic guidance using a Seldinger technique. Initially the system was opacified by inserting a 22 G needle into the renal pelvis under ultrasound guidance and contrast media (iodinated and/or air/CO2) were introduced directly into the collecting system, but occasionally intravenous injection of iodinated contrast media was given. An appropriate calyx was selected for the nephrostomy. A 21 G needle or a combined 18 G needle/5 F sheath system was used for definitive access, an appropriate wire (0.018 inch or 0.035 inch, respectively) was inserted and an 8 F locking pigtail nephrostomy placed after serial dilatation using fascial dilators. No case was performed under sonographic guidance alone or using a trocar method.
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Table 1 Clinical factors of 10 patients who suffered a major complication after percutaneous nephrostomy Patient Diagnosis no.
Delay in Clinical Coagulopathy Clinical Out-of-hours Operatora Successful Complication referral evidence status procedure suffered of sepsis
1 2 3 4 5 6
8 days 2 days 1 day 2 days No No
Yes No Yes Yes No No
No No No No No No
Stable Stable Stable Stable Stable Stable
Yes No Yes Yes No No
C C SpR C Fell C
No Yes No No Yes Yes
Sepsis Sepsis Sepsis Sepsis Sepsis Haemorrhage
7
Stone Ca prostate Stone Papillary necrosis Ca prostate Transplant ureteric stenosis Post-op stricture
2 days
Yes
No
Stable
Yes
C
Yes
8 9 10
Ca bladder Post-op leak Ca rectum
2 days No No
No No Yes
No No No
Stable Stable Stable
Yes No Yes
SpR Fell Fell
No No Yes
Haemorrhage (and sepsis) Pelvic rupture Pelvic rupture Pelvic rupture (and sepsis)
a
C, consultant (two vascular, one biliary, one uro-radiologist); Fell, interventional fellow; SpR, specialist registrar.
Data-collection The total number of PNs carried out over this period were extracted from the departmental database. The clinical case and radiographic records of those patients who had sustained a major post-PN complication were retrieved. From these the following points were noted: (1) patient demographics; (2) cause of ureteric obstruction; (3) clinical/haemodynamic status prior to PN; (4) delay in diagnosis/referral for PN and reason for delay; (5) complications sustained; (6) predisposing factors involved in complications (existing sepsis/coagulopathy, planned/emergency procedure, antibiotic therapy, operator factors etc); (7) extra care necessary/delay in discharge because of complication.
Data analysis The descriptive data relating to those patients who had a major complication were tabulated. Common trends and deficiencies in care identified. Where appropriate categorical data were compared for statistical significance using a commercially
available statistics program (GraphPad InStat version 3.00 for Windows 95, GraphPad Software, San Diego, CA, USA, www.graphpad.com) and p , 0:05 was taken to be significant.
Results Over the study period 318 PNs were performed, of which 105 (33%) were performed outside working hours. All except seven were in adult patients, age range 16 months—89 years. Ten patients (3.1%; male:female ¼ 7:3; age range 35 – 72 years) suffered a major complication. There were five cases with sepsis alone, two had major haemorrhage (one with concurrent sepsis) and three patients had a major renal pelvic injury with urine leak (of which one also became septic). The patient demographics and complications sustained are listed in Table 1. Sepsis was the most common major complication: five had sepsis alone and two became septic as an added complication (Tables 1 and 2). The rate of major sepsis in the whole group was seven out of 318 (2.2%). It was also the most severe complication seen, leading to intensive therapy unit (ITU) stay in
Table 2 Major complication after percutaneous nephrostomy (PN): sepsis Patient no.
Notes
Outcome
1 2 3
Failed PN Failed retrograde stent exchange successful PN Failed PN
4 5
Failed PN mild dilatation Failed retrograde stent exchange mild dilatation
Ureteric stent next day. ITU for 2 days. Hospital stay 10 days Settled with intravenous antibiotics. Hospital stay for 7 days ITU care for 2 days. PN after 1 day. Pneumonia. Hospital stay 5 days ITU for 2 days. Stent inserted next day. Hospital stay 11 days Developed multi-organ failure and died 8 days later
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Table 3 Major complications: haemorrhage and pelvic injury Patient no.
Complication
Notes
Outcome
6
Haemorrhage
Suspected transplant ureteric stenosis. Undilated system
7
Haemorrhage
8
Pelvic injury (dilator injury)
Single kidney. Dilated system. Segmental artery transected (Fig. 1) Dilated system. Restless patient. Failed PN
9
Pelvic injury (sheath injury)
Undilated system
10
Pelvic injury (sheath injury)
Dilated system
Three-unit transfusion. Bladder catheterization. Bleeding stopped after 6 days Also became septic. Bleeding settled after 4 weeks of PN drainage Successful PN next day. Developed sepsis and multi-organ failure. Died 5 days later Successful PN same day. Pelvic injury required surgical repair at 6 weeks Settled after 1 week
three out of five cases and was a contributory factor in the death of two of 10 patients (patients 5 and 8). A common feature in these cases (Table 3) was a history of failed instrumentation: either prior failed retrograde ureteric exchange or failure to insert a PN. This was further complicated by a delay in referral in five cases (Table 1). It was not possible to retrospectively identify the reasons for delayed referral from the notes in every case, but diagnostic delay and delay in referral for PN were noted in some cases. Over distension of the collecting system was also difficult to identify retrospectively. There were two cases of major haemorrhage (0.6%) and both had a satisfactory outcome. In both patients the bleeding stopped after prolonged tube drainage within 6 days and 4 weeks, respectively. There were no common features in these two cases. Neither had a coagulopathy but one had an undilated system, which may have contributed to the difficulty of the procedure; and in the other patient a medial puncture had been made, with the nephrostomy entering the kidney through the infundibulum (Fig. 1). In comparison the pelvic injuries had a poorer outcome. Only one third healed after prolonged nephrostomy drainage. In one case surgical correction was necessary as there was no evidence of healing after 6 weeks, and the final patient died 5 days after the onset of multi-organ failure. Although this patient had advanced carcinomatosis, the pelvic injury may have exacerbated the sepsis and multi-organ failure. On review of the radiographic images and records in all three pelvic injuries a preventable technical error was identified. In one case the injury was due to overadvancement of an 8 F dilator through the renal pelvis over a kinked guidewire, as illustrated in Fig. 2. In the other two cases, the injury was felt to be faulty use of a peelaway sheath. The postulated mechanism is illustrated in Fig. 3; on insertion the
outer sheath was advanced farther than its dilator. This may have caught and torn the urothelium. Overall our department protocols were adhered to. All patients had satisfactory pre-procedure haematological investigations; blood pressure/pulse rate and oxygen saturation were monitored during the procedure and the amounts of sedation and intravenous analgesia used were recorded in the notes. However, the antibiotic policy was not strictly followed, and three of 10 patients did not
Figure 1 Major haemorrhage after PN. Patient details are given in Table 1 (patient 7). A segmental division of the renal artery has been transected by the catheter (arrow), indicating a medial puncture through the infundibulum rather than through the calyx. The important anatomical factors in avoiding major arterial injury are illustrated in Fig. 4.
Major complications after percutaneous nephrostomy—lessons from a department audit
Figure 2 Postulated mechanism of a major injury of the renal pelvis due to a dilator. The dilator is over-advanced into the collecting system, over a kinked guide wire (arrowed). The wire tears a long laceration through the pelvis.
receive any antibiotics, of whom two of the three had clinical evidence of infection and both these patients became septic post-PN. Overall, major complications were more common when the PN was performed out of hours: six of 105 (5.7%) compared with four of 213 (1.8%), but the proportions do not reach statistical significance (p ¼ 0:087; Fisher’s test). On retrospective review of case notes the general clinical status of patients treated out of hours ðn ¼ 6Þ was not any poorer than the remainder of the group ðn ¼ 4Þ; for example no ITU cases or post-operative patients were treated out of hours. This probably reflects the department protocol, which stipulates that haemodynamically
Figure 3 The postulated mechanism of pelvic injury by a peelaway sheath. The sheath with its dilator should be advanced as single unit. If the sheath is ahead of the dilator the smooth transition between the two devices is lost. The step created may entrap adjacent urothelium, which is stripped/dissected as the outer sheath is further advanced. There is a particular danger of this injury when the sheath is advanced round the pelvis and down the ureter.
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unstable patients should be stabilized before PN. Consequently, most unstable patients were deferred and their treatment carried out during working hours, when staffing levels were better and consultant interventionalists were on-site. The level of experience of the operator was not important in that 50% of all cases in or out of hours were carried out by an SpR/fellow, and although the pelvic injuries were all accounted for by SpR/fellows, both cases of major haemorrhage occurred after PN inserted by a consultant. Of the five failed cases, SpR/fellows carried out three.
Discussion The purpose of this audit was to look at our performance figures and identify areas for quality improvement. The study was retrospective and has limitations. Although we believe that the number of major complications identified is accurate, we cannot be categorical that none were missed. Neither can we be absolutely certain about the denominator—the total number of PNs carried out during the study period. Department records were used to identify all PNs, and it is possible that some mis-categorized cases did not appear in the search results. Consequently we may have underestimated the total number of PNs. It is also likely that some further patients became mildly or temporarily septic, or had sufficient haematuria to drop their haemoglobin level, but did not require transfusion. Such cases may have not come to our notice. However, these cases would not be classified as having a major complication as defined, and would not, therefore, be part of this study. Finally, the focus of this audit was limited to major complications and ignores many other aspects of PN service performance, e.g. success rate, catheter dislodgement, repeat procedures etc. Many of these limitations are common to audit studies, nevertheless we have shown that a wellstaffed PN service can perform within the threshold rates suggested by the SCVIR1 and the ACR2 (department threshold of , 4% for either haemorrhage or septic shock) or the standard (major complication rate of , 8%) used recently by the RCR (www.rcr.ac.uk). However, on individual case analysis areas for service improvement were identified. Sepsis was the most common and serious major complication likely to significantly increase the level of care or contribute to the death of a patient. In comparison, major haemorrhage was a retrievable situation. Theoretically sepsis should be controllable as the
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individual risk factors are identifiable. Our department policy stipulated pre-procedural antibiotics for all patients with suspected pyonephrosis as usually recommended,4 but this was not followed, for unknown reasons, in three of 10 patients. The importance of pre-procedure antibiotics has been re-emphasized in our new protocols. We have also altered our antibiotic policy to bring it in line with hospital recommendations for “blind” treatment of septicaemia originating from the urinary tract. The existing policy was to give 120 mg gentamicin preprocedure, but after discussion with our hospital microbiology departments we have now changed to a policy of using 500 mg gentamicin as an intravenous infusion, or intravenous cefotaxime if this is contra-indicated. However, even with antibiotics, it is paramount that renal drainage is rapidly established. A striking finding was that failed instrumentation, and any further delay, dramatically augments the risk of septicaemia. The two factors have clinical governance importance, as both are linked to the lack of trained manpower. Delays may be due to patients waiting for a diagnostic investigation, be it ultrasound or computed tomography (CT), etc., or patients may wait for a urological/renal opinion before requesting either PN or retrograde ureteric stenting; and there may be a further delay until an interventional radiologist or urologist can find the time and/or room/theatre time. One or more of these features was present in some of our cases. Close liaison and co-operation between the interventional, urological and renal services is vital. We have now agreed a new protocol with our clinical colleagues: all failed ureteric stent or PN cases are discussed directly with the radiologists or urologists, respectively, to expedite the alternative drainage procedure. Poor technique can also contribute to septic shock. Over-distension of the collecting system should be scrupulously avoided, as this further increases the intra-renal pressure and risk of bacteraemia. Contrast medium injection into the collecting system should be minimized, by either prior aspiration of some urine or the use of carbon dioxide/air to selectively opacify posterior calyces. Theoretically, PN insertion under ultrasound or CT guidance alone should be safer as a catheter may be inserted without requiring contrast medium distension. A study of a series of CT-guided nephrostomies5 reported no major complications in 129 patients (144 PNs), but from the text it is clear that contrast medium was injected into some collecting systems to confirm needle position. The selection criteria was also not specified, i.e. whether “difficult” cases were excluded, and the authors
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emphasized that fluoroscopy was necessary after initial access under CT. There are no recent series on ultrasound-guided PN using modern high-quality machines. Previously reported ultrasound series6 – 9 also do not specify caseload selection, but two noted significant complications8,9 (nephrectomy for haemorrhage, cardiac arrest and death) and both used a trocar method. At present one cannot say whether nephrostomy of dilated pyonephrotic kidneys is safer under CT or ultrasound guidance alone. Non-selected or randomized studies using CT/ultrasound guidance without fluoroscopy are necessary. Regarding haemorrhage, this audit does not suggest any particular correctable deficiencies, except to highlight the importance of the fundamental anatomical principles that underlie PN10 and illustrated in Fig. 4, i.e. the importance of adhering to the relatively avascular plane between the anterior and posterior arterial divisions (Bro ¨del’s line) for needle entry and to target the centre of a posterior facing calyx. Punctures closer to the renal hilum increase the risk of injuring larger branch arteries (Fig. 1). Intuitively, the size of the needle or the catheter inserted should be important, but these are not proven risk factors. Small bore (21 or 22 G needle) access systems were no safer than an 18 G needle/sheath combination in one small study.11 Catheter size, a surrogate for the size of the “hole” made in the kidney, has not been studied as an independent risk factor for post-PN bleeding. Neither has safety of a trocar versus Seldinger technique for PN, although previous studies using the trocar method have reported a high bleeding rate with cases of renal loss8,9. Pre-procedure coagulation studies are routinely recommended and it is almost a universal practice to aim for “normal” clotting and blood indices. Our department policy stipulates that the INR should be , 1.3 and the platelet count . 80,000/dl. These levels are not based on any firm data and other departments may have different levels, but Farell et al.12 found that patients with a platelet count , 100,000/dl had a higher transfusion rate after PN. In our series, renal pelvic injuries had a worse outcome than bleeding. In all three cases there was an avoidable technical fault, i.e. incorrect use of a dilator or peelaway sheath. Properly used dilators or peelaway sheaths help catheter placement, particularly in those with tough renal/retroperitoneal tissues. But they should be used carefully and only to dilate through the renal parenchyma. Advancement well into the renal pelvis serves no added purpose and may puncture the wall of the renal pelvis. A dilator/sheath injury in the presence of a “tented” or kinked guidewire is worse still
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177
Figure 4 This montage demonstrates the importance of calyceal entry (also see Table 4). The right-hand fluoroscopic image shows a needle targeted onto the centre of a calyx or tip of the papilla. Entry through the centre of a calyx will reduce the chances of arterial injury, as shown in the left-hand Doppler ultrasound image.
(Fig. 2). Instead of a round hole in the renal pelvis the linear shearing force of the tented wire creates a long urothelial tear. For antegrade stent insertion, long sheaths are often used to support the catheter as it is pushed round the pelviureteric junction (PUJ), in which case the dilator/sheath assembly should be advanced as a single unit to maintain a smooth and tapered profile without trauma (Fig. 3). Proportionately more complications occurred in out of hours PN. The numbers are small and did not reach statistical significance, but this type of comparison has not been attempted before.13 It may be argued that this is to be expected as emergency procedures are carried out in sicker patients, otherwise they would not require urgent intervention. We were not able to show that out of hours cases were in a clinically poorer state, but our study is retrospective and the possibility remains. In which case, the issue of out of hours staffing raises concerns, as the margin for error in sick patients should be less. Yet a recent survey3 identified staffing deficiencies in the UK whereby only 11% had a full on-call interventional service (though nursing staff were on-call in 43% of hospitals surveyed) and also touched on the issue of maintaining technical expertise. Nearly a quarter of the consultants inserted PNs only out of hours;3 this is contrary to recommendations by the RCR.14,15 Undoubtedly, this reflects the staffing difficulties
experienced across the health service; in a department of health survey in March 2002 (www.doh.gov. uk) 8% of consultant radiology posts were vacant. There is no easy solution to this problem of insufficient staff. Indeed, since the completion of this audit our department can no longer support a one in four on-call interventional rota. Staffing levels may improve in the future, or there may be innovative local solutions, e.g. sharing interventional on-call between adjacent hospitals; but perhaps a mature technique like PN should no longer be the sole territory of interventional radiologists. A study by Lee et al.16 is sometimes used to advocate that an operator should perform around 10 – 20 PNs/year to maintain competency, yet the authors themselves only concluded that those with little regular experience had a higher repeat nephrostomy and minor complication rate. Regarding technical success and major complication rates, there was no performance difference. It could be argued that it is not how many PNs per year, but the breadth of the operators skills that is important— someone skilled in ultrasound/CT guidance may target a calyx more expertly than an interventional radiologist whose skills lie in wire and catheter manipulation alone. If the service is expanded so that dilated obstructed kidneys have PN inserted by whichever service (ultrasound, CT or interventional) that can perform it without delay, then the issue of
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Table 4 Avoiding major complications after percutaneous nephrostomy—the lessons from an audit of 10 cases Complication
Lessons
Sepsis
1. Pre-procedure antibiotics 2. Avoid over-distension of collecting system a. Minimize volume of contrast medium injected b. Use air/CO2 c. ? Use ultrasound/CT guidance alone 3. Avoid delay If stenting or nephrostomy fails, renal drainage should be expedited
Haemorrhage
1. Pre-procedure coagulation studies 2. Careful puncture onto target calyx 3. Avoid medial punctures
Pelvic injury
1. Do not advance dilator further than the calyx 2. Care in use of peelaway sheaths particularly when advanced around the pelvi-ureteric junction 3. Kinked guidewires augment dilator/sheath injuries
General considerations
1. Written protocols and algorithms should be agreed between the radiology department and relevant clinical services 2. Protocols should be followed 3. If possible cases should be done during normal working hours 4. Patients should be well resuscitated and stable before PN. If not, procedure best performed by an experienced consultant 5. All patients should be monitored by a nurse/another member of staff so the interventionalist can concentrate on the case 6. Meticulous technique
maintaining skills becomes less important, as more radiologists are involved, all of whom are performing a sufficient number of procedures under crosssectional guidance, be it biopsies, catheter drainages or PNs. In Barbaric’s5 study nine faculty members and 31 trainees performed 144 PNs but they reported the lowest complication rate and felt that CT/fluoroscopic-guided PN was no different from guided biopsy or drainage. But modern data of the performance of ultrasound/CT-guided PN in unselected cases, ideally without fluoroscopy at all and using the trocar or Seldinger methods are required before this type of service dissemination can be recommended. In conclusion, a well-staffed PN service can perform within the threshold limits used by the SCVIR, ACR and RCR. The major complication rate was higher in out of hours cases, although the patients’ clinical state may have contributed. Of the major complications, sepsis was the most serious, followed by pelvic injury and haemorrhage. Important best practice factors are (Table 4): agreed departmental protocols, stabilizing patients before PN, pre-procedure antibiotics, careful renal puncture, care in the use of dilators and sheaths, but above all, urgency in the management of those cases who have had a failed attempt at percutaneous/retrograde urinary tract drainage.
Appendix A SCVIR standards of practice committee classification of complications by outcome Minor complications A. B.
No therapy, no consequence, or Nominal therapy, no consequence; includes overnight admission for observation only.
Major complications C. D.
E. F.
Require therapy, minor hospitalization (, 48 h), Require major therapy, unplanned increase in level of care, prolonged hospitalization (. 48 h), Have permanent adverse sequelae, or Result in death.
References 1. Ramchandani P, Cardella JF, Grassi CJ, et al. Quality improvement guidelines for percutaneous nephrostomy. J Vasc Interv Radiol 2001;12:1247—51. 2. American College of Radiologists, Standards for the performance of percutaneous nephrostomy. Reston, VA: American College of Radiologists; 2001.
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3. Riddell AM, Charig MJ. A survey of current practice in out of hours percutaneous nephrostomy insertion in the United Kingdom. Clin Radiol 2002;57:1067—9. 4. McDermott VG, Schuster MG, Smith TP. Antibiotic prophylaxis in vascular and interventional radiology. AJR Am J Roentgenol 1997;169:31—8. 5. Barbaric ZL, Hall T, Cochran ST, Heitz DR, Schwartz RA, Krasny RM, Deseran MW. Percutaneous nephrostomy: placement under CT and fluoroscopy guidance. AJR Am J Roentgenol 1997;169:151—5. 6. Gupta S, Gelatin M, Uday Shankar K, Rungta U, Suri S. Percutaneous nephrostomy with real time sonographic guidance. Acta Radiol 1997;38:454—7. 7. Mahaffey KG, Bolton DM, Stoller ML. Urologist directed percutaneous nephrostomy tube placement. J Urol 1994; 152:1973—6. 8. Nielsen OS, Grossman E. Ultrasonically guided percutaneous nephrostomy. Scand J Urol Nephrol 1990;24:219—21. 9. Von der Recke P, Nielsen MB, Pedersen JF. Complications of ultrasound-guided nephrostomy. Acta Radiol 1994;35: 452—4.
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10. Papanicolaou N. Renal anatomy relevant to percutaneous interventions. Semin Intervent Radiol 1995;12:163—72. 11. Clark TW, Abraham RJ, Flemming BK. Is routine micropuncture access necessary fro percutaneous nephrostomy? A randomised trial. Canad Assoc Radiol J 2002;53:87—91. 12. Farrell TA, Hicks ME. A review of radiologically guided percutaneous nephrostomies in 303 patients. J Vasc Interv Radiol 1997;8:769—74. 13. Lee WJ, Patel U, Patel S, Pillari GP. Emergency percutaneous nephrostomy: results and complications. J Vasc Interv Radiol 1994;5:135—9. 14. Board of the Faculty of Clinical Radiology, Good Practice Guide for Clinical Radiologists. London: Royal College of Radiologists; 1999. 15. Board of the Faculty of Clinical Radiology, Risk Management in Clinical Radiology. London: Royal College of Radiologists; 2002. 16. Lee WJ, Mond DJ, Patel M, Pillari GP. Emergency percutaneous nephrostomy: technical success based on level of operator experience. J Vasc Interv Radiol 1994;5:327—30.
Major complications after percutaneous nephrostomy—lessons from a department audit S. Lewis, U. Patel* Department of Radiology, St George’s Hospital, London, UK Received 26 March 2003; accepted 23 July 2003
KEYWORDS Ureteral obstruction; Hydronephrosis; Nephrostomy; Complications; Audit
AIM: To audit the performance of our percutaneous nephrostomy service by comparing the major complication rate with the standards recommended by the Society of Cardiovascular and Interventional Radiology and the American College of Radiology: major haemorrhage in ,4%, and septic shock in , 4%. Secondary aims were to identify common sources of errors for quality improvement measures. METHODS: Major complications sustained between January 1997 – December 2002 were identified. All cases had been carried out by the interventional radiology service of a large teaching hospital with the assistance of a nurse and radiographer, under fluoroscopic and ultrasound guidance using a Seldinger technique. Existing department protocols specified pre-procedure antibiotics for suspected infected cases and normal coagulation studies. From records and review of case notes pertinent clinical/procedural details and eventual outcome were assessed. The following were particularly noted: adherence to protocols, clinical status at time of procedure, delay in referral, complication sustained, signs of infection or coagulopathy, timing of procedure (in versus out of hours), level of operator and technical faults. RESULTS: Ten of 318 (3.1%) cases sustained a major complication: five had sepsis alone, two haemorrhage (one with sepsis as well) and three patients had a major pelvic injury (one with sepsis as well). Thus the major sepsis and haemorrhage rates were 2.2 and 0.6%, and were within the recommended threshold limits but proportionately more complications occurred out of hours: six of 105 (5.7%) versus four of 312 (1.8%; p ¼ 0:087). Sepsis was the most serious complication and may have contributed to the death of two patients. On individual case analysis, failed instrumentation with delay to definitive renal drainage was a common factor with sepsis; but the following were contributory factors in one or more cases: omitted antibiotics (in three of 10; two became septic), technical factors in four cases [medial renal puncture ðn ¼ 1Þ; damage due to fascial dilator ðn ¼ 1Þ or peelaway sheath ðn ¼ 2Þ] and delay in diagnosis/therapy (of 1–8 days, in six of 10 cases of whom four out of six became septic). One pelvic injury required surgical correction (contributory factor—faulty use of peelaway sheath). Patients with haemorrhage settled with prolonged tube drainage alone. CONCLUSION: An adequately staffed percutaneous nephrostomy service can perform within published clinical standards. Best practice factors identified were: attention to agreed protocols and algorithms, pre-procedure antibiotics, careful renal puncture and care with use of dilators/peelaway sheaths, but the paramount finding was that sepsis was the most serious complication, contributing to death (two of 10 in this study) or a significant increase in the level of care required. The risk is greatest after failed instrumentation (retrograde ureteral stent or percutaneous nephrostomy insertion) and particularly if there is a further delay before establishment of renal drainage. A close working relationship between interventional radiologists and urologists is crucial. q 2004 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.
*Guarantor and correspondent: U. Patel, Department of Radiology, St George’s Hospital, Blackshaw Road, London SW17 0QT, UK. Tel.: þ 44-208-725-3667/1481; fax: þ 44-208-725-2936. E-mail address: [email protected] 0009-9260/$ - see front matter q 2004 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved. doi:10.1016/S0009-9260(03)00336-2
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Introduction Percutaneous nephrostomy (PN) is one of the most common interventional procedures, performed by many general, and almost all interventional, radiologists. Performance statistics of this common procedure can be taken as a surrogate of on-call interventional provision and its lessons may be generally applicable. Recent standards of practice document by the Society of Cardiovascular and Interventional Radiologists (SCVIR) quoted major complication rates after PN of 1 – 4% for haemorrhage or vascular injury and 1 – 9% for septic shock.1 A separate document issued under the aegis of the American College of Radiologists (ACR), but authored by the same experts, went further and recommended a department threshold level of 4% for septic shock and 4% for major haemorrhage.2 These figures apply to a general interventional service and may vary depending on the referral pattern, but a complication rate in excess of these thresholds should prompt a performance review to identify deficient practice. There are no similar UK or European recommendations, but the audit sub-committee of the Royal College of Radiologists (RCR) used a threshold of 8% (all major complications) for a recent pilot audit (www.rcr.ac.uk). This is a retrospective case series audit of the major complication rates after PN insertion in a relatively well-staffed department compared with the UK average:3 four interventional radiologists with on-call interventional nurse assistance. The aim of the audit was to compare our service performance against the recommended thresholds above. Additionally, common lessons are extracted from these case studies to identify areas for quality improvement.
Methods Patients Between January 1997 – December 2002, one of the authors (U.P.) has maintained a contemporaneous record of all major complications after PN with relevant technical/procedural details. Major complications were defined using the system recommended by the Society of Cardiovascular and Interventional Radiology (see Appendix A). PNs were carried out by four interventional radiologists, or by interventional fellows/specialist registrars. During working hours, the PN was carried out/ supervised by a consultant uroradiologist, and by
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one of the other consultant interventionalists in the absence of a consultant uroradiologist. Out-ofhours cases were carried out by the on-call consultant, or the specialist registrar (SpR)/fellow if the consultant felt that the SpR/fellow was competent. If, however, the case was complicated or there were inter-procedural difficulties the consultant came in to assist. Whether during working hours or out-of-hours, all cases were carried with at least one radiologist, one radiographer and one dedicated interventional nurse in attendance (on call since Sept 2000).
Technique of PN Our departmental protocol during this study period specified that all patients should have normal preprocedure coagulation and platelet estimation [international normalized ratio (INR) , 1.3 and . 80 000/dl, respectively], and all with suspected sepsis (pyrexia defined as temperature . 38.0 8C, rigors and/or raised white blood cell count) should receive 120 mg gentamicin (or an alternative agent), unless the patient was already receiving antibiotics. All cases were carried out in a dedicated interventional room under fluoroscopic and ultrasound guidance, with haemodynamic monitoring facilities (continuous measurement of oxygen saturation and pulse rate, with blood pressure recorded every 5 min or sooner), as well as controlled piped oxygen. The nurse, who also administered intravenous sedo-analgesia as prescribed by the radiologist, monitored the patient. The medication used and doses given were recorded in the case notes. As this is a retrospective study full technical details of every procedure were not available except in those cases with major complications. All cases were done under fluoroscopic or ultrasound/fluoroscopic guidance using a Seldinger technique. Initially the system was opacified by inserting a 22 G needle into the renal pelvis under ultrasound guidance and contrast media (iodinated and/or air/CO2) were introduced directly into the collecting system, but occasionally intravenous injection of iodinated contrast media was given. An appropriate calyx was selected for the nephrostomy. A 21 G needle or a combined 18 G needle/5 F sheath system was used for definitive access, an appropriate wire (0.018 inch or 0.035 inch, respectively) was inserted and an 8 F locking pigtail nephrostomy placed after serial dilatation using fascial dilators. No case was performed under sonographic guidance alone or using a trocar method.
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Table 1 Clinical factors of 10 patients who suffered a major complication after percutaneous nephrostomy Patient Diagnosis no.
Delay in Clinical Coagulopathy Clinical Out-of-hours Operatora Successful Complication referral evidence status procedure suffered of sepsis
1 2 3 4 5 6
8 days 2 days 1 day 2 days No No
Yes No Yes Yes No No
No No No No No No
Stable Stable Stable Stable Stable Stable
Yes No Yes Yes No No
C C SpR C Fell C
No Yes No No Yes Yes
Sepsis Sepsis Sepsis Sepsis Sepsis Haemorrhage
7
Stone Ca prostate Stone Papillary necrosis Ca prostate Transplant ureteric stenosis Post-op stricture
2 days
Yes
No
Stable
Yes
C
Yes
8 9 10
Ca bladder Post-op leak Ca rectum
2 days No No
No No Yes
No No No
Stable Stable Stable
Yes No Yes
SpR Fell Fell
No No Yes
Haemorrhage (and sepsis) Pelvic rupture Pelvic rupture Pelvic rupture (and sepsis)
a
C, consultant (two vascular, one biliary, one uro-radiologist); Fell, interventional fellow; SpR, specialist registrar.
Data-collection The total number of PNs carried out over this period were extracted from the departmental database. The clinical case and radiographic records of those patients who had sustained a major post-PN complication were retrieved. From these the following points were noted: (1) patient demographics; (2) cause of ureteric obstruction; (3) clinical/haemodynamic status prior to PN; (4) delay in diagnosis/referral for PN and reason for delay; (5) complications sustained; (6) predisposing factors involved in complications (existing sepsis/coagulopathy, planned/emergency procedure, antibiotic therapy, operator factors etc); (7) extra care necessary/delay in discharge because of complication.
Data analysis The descriptive data relating to those patients who had a major complication were tabulated. Common trends and deficiencies in care identified. Where appropriate categorical data were compared for statistical significance using a commercially
available statistics program (GraphPad InStat version 3.00 for Windows 95, GraphPad Software, San Diego, CA, USA, www.graphpad.com) and p , 0:05 was taken to be significant.
Results Over the study period 318 PNs were performed, of which 105 (33%) were performed outside working hours. All except seven were in adult patients, age range 16 months—89 years. Ten patients (3.1%; male:female ¼ 7:3; age range 35 – 72 years) suffered a major complication. There were five cases with sepsis alone, two had major haemorrhage (one with concurrent sepsis) and three patients had a major renal pelvic injury with urine leak (of which one also became septic). The patient demographics and complications sustained are listed in Table 1. Sepsis was the most common major complication: five had sepsis alone and two became septic as an added complication (Tables 1 and 2). The rate of major sepsis in the whole group was seven out of 318 (2.2%). It was also the most severe complication seen, leading to intensive therapy unit (ITU) stay in
Table 2 Major complication after percutaneous nephrostomy (PN): sepsis Patient no.
Notes
Outcome
1 2 3
Failed PN Failed retrograde stent exchange successful PN Failed PN
4 5
Failed PN mild dilatation Failed retrograde stent exchange mild dilatation
Ureteric stent next day. ITU for 2 days. Hospital stay 10 days Settled with intravenous antibiotics. Hospital stay for 7 days ITU care for 2 days. PN after 1 day. Pneumonia. Hospital stay 5 days ITU for 2 days. Stent inserted next day. Hospital stay 11 days Developed multi-organ failure and died 8 days later
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Table 3 Major complications: haemorrhage and pelvic injury Patient no.
Complication
Notes
Outcome
6
Haemorrhage
Suspected transplant ureteric stenosis. Undilated system
7
Haemorrhage
8
Pelvic injury (dilator injury)
Single kidney. Dilated system. Segmental artery transected (Fig. 1) Dilated system. Restless patient. Failed PN
9
Pelvic injury (sheath injury)
Undilated system
10
Pelvic injury (sheath injury)
Dilated system
Three-unit transfusion. Bladder catheterization. Bleeding stopped after 6 days Also became septic. Bleeding settled after 4 weeks of PN drainage Successful PN next day. Developed sepsis and multi-organ failure. Died 5 days later Successful PN same day. Pelvic injury required surgical repair at 6 weeks Settled after 1 week
three out of five cases and was a contributory factor in the death of two of 10 patients (patients 5 and 8). A common feature in these cases (Table 3) was a history of failed instrumentation: either prior failed retrograde ureteric exchange or failure to insert a PN. This was further complicated by a delay in referral in five cases (Table 1). It was not possible to retrospectively identify the reasons for delayed referral from the notes in every case, but diagnostic delay and delay in referral for PN were noted in some cases. Over distension of the collecting system was also difficult to identify retrospectively. There were two cases of major haemorrhage (0.6%) and both had a satisfactory outcome. In both patients the bleeding stopped after prolonged tube drainage within 6 days and 4 weeks, respectively. There were no common features in these two cases. Neither had a coagulopathy but one had an undilated system, which may have contributed to the difficulty of the procedure; and in the other patient a medial puncture had been made, with the nephrostomy entering the kidney through the infundibulum (Fig. 1). In comparison the pelvic injuries had a poorer outcome. Only one third healed after prolonged nephrostomy drainage. In one case surgical correction was necessary as there was no evidence of healing after 6 weeks, and the final patient died 5 days after the onset of multi-organ failure. Although this patient had advanced carcinomatosis, the pelvic injury may have exacerbated the sepsis and multi-organ failure. On review of the radiographic images and records in all three pelvic injuries a preventable technical error was identified. In one case the injury was due to overadvancement of an 8 F dilator through the renal pelvis over a kinked guidewire, as illustrated in Fig. 2. In the other two cases, the injury was felt to be faulty use of a peelaway sheath. The postulated mechanism is illustrated in Fig. 3; on insertion the
outer sheath was advanced farther than its dilator. This may have caught and torn the urothelium. Overall our department protocols were adhered to. All patients had satisfactory pre-procedure haematological investigations; blood pressure/pulse rate and oxygen saturation were monitored during the procedure and the amounts of sedation and intravenous analgesia used were recorded in the notes. However, the antibiotic policy was not strictly followed, and three of 10 patients did not
Figure 1 Major haemorrhage after PN. Patient details are given in Table 1 (patient 7). A segmental division of the renal artery has been transected by the catheter (arrow), indicating a medial puncture through the infundibulum rather than through the calyx. The important anatomical factors in avoiding major arterial injury are illustrated in Fig. 4.
Major complications after percutaneous nephrostomy—lessons from a department audit
Figure 2 Postulated mechanism of a major injury of the renal pelvis due to a dilator. The dilator is over-advanced into the collecting system, over a kinked guide wire (arrowed). The wire tears a long laceration through the pelvis.
receive any antibiotics, of whom two of the three had clinical evidence of infection and both these patients became septic post-PN. Overall, major complications were more common when the PN was performed out of hours: six of 105 (5.7%) compared with four of 213 (1.8%), but the proportions do not reach statistical significance (p ¼ 0:087; Fisher’s test). On retrospective review of case notes the general clinical status of patients treated out of hours ðn ¼ 6Þ was not any poorer than the remainder of the group ðn ¼ 4Þ; for example no ITU cases or post-operative patients were treated out of hours. This probably reflects the department protocol, which stipulates that haemodynamically
Figure 3 The postulated mechanism of pelvic injury by a peelaway sheath. The sheath with its dilator should be advanced as single unit. If the sheath is ahead of the dilator the smooth transition between the two devices is lost. The step created may entrap adjacent urothelium, which is stripped/dissected as the outer sheath is further advanced. There is a particular danger of this injury when the sheath is advanced round the pelvis and down the ureter.
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unstable patients should be stabilized before PN. Consequently, most unstable patients were deferred and their treatment carried out during working hours, when staffing levels were better and consultant interventionalists were on-site. The level of experience of the operator was not important in that 50% of all cases in or out of hours were carried out by an SpR/fellow, and although the pelvic injuries were all accounted for by SpR/fellows, both cases of major haemorrhage occurred after PN inserted by a consultant. Of the five failed cases, SpR/fellows carried out three.
Discussion The purpose of this audit was to look at our performance figures and identify areas for quality improvement. The study was retrospective and has limitations. Although we believe that the number of major complications identified is accurate, we cannot be categorical that none were missed. Neither can we be absolutely certain about the denominator—the total number of PNs carried out during the study period. Department records were used to identify all PNs, and it is possible that some mis-categorized cases did not appear in the search results. Consequently we may have underestimated the total number of PNs. It is also likely that some further patients became mildly or temporarily septic, or had sufficient haematuria to drop their haemoglobin level, but did not require transfusion. Such cases may have not come to our notice. However, these cases would not be classified as having a major complication as defined, and would not, therefore, be part of this study. Finally, the focus of this audit was limited to major complications and ignores many other aspects of PN service performance, e.g. success rate, catheter dislodgement, repeat procedures etc. Many of these limitations are common to audit studies, nevertheless we have shown that a wellstaffed PN service can perform within the threshold rates suggested by the SCVIR1 and the ACR2 (department threshold of , 4% for either haemorrhage or septic shock) or the standard (major complication rate of , 8%) used recently by the RCR (www.rcr.ac.uk). However, on individual case analysis areas for service improvement were identified. Sepsis was the most common and serious major complication likely to significantly increase the level of care or contribute to the death of a patient. In comparison, major haemorrhage was a retrievable situation. Theoretically sepsis should be controllable as the
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individual risk factors are identifiable. Our department policy stipulated pre-procedural antibiotics for all patients with suspected pyonephrosis as usually recommended,4 but this was not followed, for unknown reasons, in three of 10 patients. The importance of pre-procedure antibiotics has been re-emphasized in our new protocols. We have also altered our antibiotic policy to bring it in line with hospital recommendations for “blind” treatment of septicaemia originating from the urinary tract. The existing policy was to give 120 mg gentamicin preprocedure, but after discussion with our hospital microbiology departments we have now changed to a policy of using 500 mg gentamicin as an intravenous infusion, or intravenous cefotaxime if this is contra-indicated. However, even with antibiotics, it is paramount that renal drainage is rapidly established. A striking finding was that failed instrumentation, and any further delay, dramatically augments the risk of septicaemia. The two factors have clinical governance importance, as both are linked to the lack of trained manpower. Delays may be due to patients waiting for a diagnostic investigation, be it ultrasound or computed tomography (CT), etc., or patients may wait for a urological/renal opinion before requesting either PN or retrograde ureteric stenting; and there may be a further delay until an interventional radiologist or urologist can find the time and/or room/theatre time. One or more of these features was present in some of our cases. Close liaison and co-operation between the interventional, urological and renal services is vital. We have now agreed a new protocol with our clinical colleagues: all failed ureteric stent or PN cases are discussed directly with the radiologists or urologists, respectively, to expedite the alternative drainage procedure. Poor technique can also contribute to septic shock. Over-distension of the collecting system should be scrupulously avoided, as this further increases the intra-renal pressure and risk of bacteraemia. Contrast medium injection into the collecting system should be minimized, by either prior aspiration of some urine or the use of carbon dioxide/air to selectively opacify posterior calyces. Theoretically, PN insertion under ultrasound or CT guidance alone should be safer as a catheter may be inserted without requiring contrast medium distension. A study of a series of CT-guided nephrostomies5 reported no major complications in 129 patients (144 PNs), but from the text it is clear that contrast medium was injected into some collecting systems to confirm needle position. The selection criteria was also not specified, i.e. whether “difficult” cases were excluded, and the authors
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emphasized that fluoroscopy was necessary after initial access under CT. There are no recent series on ultrasound-guided PN using modern high-quality machines. Previously reported ultrasound series6 – 9 also do not specify caseload selection, but two noted significant complications8,9 (nephrectomy for haemorrhage, cardiac arrest and death) and both used a trocar method. At present one cannot say whether nephrostomy of dilated pyonephrotic kidneys is safer under CT or ultrasound guidance alone. Non-selected or randomized studies using CT/ultrasound guidance without fluoroscopy are necessary. Regarding haemorrhage, this audit does not suggest any particular correctable deficiencies, except to highlight the importance of the fundamental anatomical principles that underlie PN10 and illustrated in Fig. 4, i.e. the importance of adhering to the relatively avascular plane between the anterior and posterior arterial divisions (Bro ¨del’s line) for needle entry and to target the centre of a posterior facing calyx. Punctures closer to the renal hilum increase the risk of injuring larger branch arteries (Fig. 1). Intuitively, the size of the needle or the catheter inserted should be important, but these are not proven risk factors. Small bore (21 or 22 G needle) access systems were no safer than an 18 G needle/sheath combination in one small study.11 Catheter size, a surrogate for the size of the “hole” made in the kidney, has not been studied as an independent risk factor for post-PN bleeding. Neither has safety of a trocar versus Seldinger technique for PN, although previous studies using the trocar method have reported a high bleeding rate with cases of renal loss8,9. Pre-procedure coagulation studies are routinely recommended and it is almost a universal practice to aim for “normal” clotting and blood indices. Our department policy stipulates that the INR should be , 1.3 and the platelet count . 80,000/dl. These levels are not based on any firm data and other departments may have different levels, but Farell et al.12 found that patients with a platelet count , 100,000/dl had a higher transfusion rate after PN. In our series, renal pelvic injuries had a worse outcome than bleeding. In all three cases there was an avoidable technical fault, i.e. incorrect use of a dilator or peelaway sheath. Properly used dilators or peelaway sheaths help catheter placement, particularly in those with tough renal/retroperitoneal tissues. But they should be used carefully and only to dilate through the renal parenchyma. Advancement well into the renal pelvis serves no added purpose and may puncture the wall of the renal pelvis. A dilator/sheath injury in the presence of a “tented” or kinked guidewire is worse still
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Figure 4 This montage demonstrates the importance of calyceal entry (also see Table 4). The right-hand fluoroscopic image shows a needle targeted onto the centre of a calyx or tip of the papilla. Entry through the centre of a calyx will reduce the chances of arterial injury, as shown in the left-hand Doppler ultrasound image.
(Fig. 2). Instead of a round hole in the renal pelvis the linear shearing force of the tented wire creates a long urothelial tear. For antegrade stent insertion, long sheaths are often used to support the catheter as it is pushed round the pelviureteric junction (PUJ), in which case the dilator/sheath assembly should be advanced as a single unit to maintain a smooth and tapered profile without trauma (Fig. 3). Proportionately more complications occurred in out of hours PN. The numbers are small and did not reach statistical significance, but this type of comparison has not been attempted before.13 It may be argued that this is to be expected as emergency procedures are carried out in sicker patients, otherwise they would not require urgent intervention. We were not able to show that out of hours cases were in a clinically poorer state, but our study is retrospective and the possibility remains. In which case, the issue of out of hours staffing raises concerns, as the margin for error in sick patients should be less. Yet a recent survey3 identified staffing deficiencies in the UK whereby only 11% had a full on-call interventional service (though nursing staff were on-call in 43% of hospitals surveyed) and also touched on the issue of maintaining technical expertise. Nearly a quarter of the consultants inserted PNs only out of hours;3 this is contrary to recommendations by the RCR.14,15 Undoubtedly, this reflects the staffing difficulties
experienced across the health service; in a department of health survey in March 2002 (www.doh.gov. uk) 8% of consultant radiology posts were vacant. There is no easy solution to this problem of insufficient staff. Indeed, since the completion of this audit our department can no longer support a one in four on-call interventional rota. Staffing levels may improve in the future, or there may be innovative local solutions, e.g. sharing interventional on-call between adjacent hospitals; but perhaps a mature technique like PN should no longer be the sole territory of interventional radiologists. A study by Lee et al.16 is sometimes used to advocate that an operator should perform around 10 – 20 PNs/year to maintain competency, yet the authors themselves only concluded that those with little regular experience had a higher repeat nephrostomy and minor complication rate. Regarding technical success and major complication rates, there was no performance difference. It could be argued that it is not how many PNs per year, but the breadth of the operators skills that is important— someone skilled in ultrasound/CT guidance may target a calyx more expertly than an interventional radiologist whose skills lie in wire and catheter manipulation alone. If the service is expanded so that dilated obstructed kidneys have PN inserted by whichever service (ultrasound, CT or interventional) that can perform it without delay, then the issue of
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Table 4 Avoiding major complications after percutaneous nephrostomy—the lessons from an audit of 10 cases Complication
Lessons
Sepsis
1. Pre-procedure antibiotics 2. Avoid over-distension of collecting system a. Minimize volume of contrast medium injected b. Use air/CO2 c. ? Use ultrasound/CT guidance alone 3. Avoid delay If stenting or nephrostomy fails, renal drainage should be expedited
Haemorrhage
1. Pre-procedure coagulation studies 2. Careful puncture onto target calyx 3. Avoid medial punctures
Pelvic injury
1. Do not advance dilator further than the calyx 2. Care in use of peelaway sheaths particularly when advanced around the pelvi-ureteric junction 3. Kinked guidewires augment dilator/sheath injuries
General considerations
1. Written protocols and algorithms should be agreed between the radiology department and relevant clinical services 2. Protocols should be followed 3. If possible cases should be done during normal working hours 4. Patients should be well resuscitated and stable before PN. If not, procedure best performed by an experienced consultant 5. All patients should be monitored by a nurse/another member of staff so the interventionalist can concentrate on the case 6. Meticulous technique
maintaining skills becomes less important, as more radiologists are involved, all of whom are performing a sufficient number of procedures under crosssectional guidance, be it biopsies, catheter drainages or PNs. In Barbaric’s5 study nine faculty members and 31 trainees performed 144 PNs but they reported the lowest complication rate and felt that CT/fluoroscopic-guided PN was no different from guided biopsy or drainage. But modern data of the performance of ultrasound/CT-guided PN in unselected cases, ideally without fluoroscopy at all and using the trocar or Seldinger methods are required before this type of service dissemination can be recommended. In conclusion, a well-staffed PN service can perform within the threshold limits used by the SCVIR, ACR and RCR. The major complication rate was higher in out of hours cases, although the patients’ clinical state may have contributed. Of the major complications, sepsis was the most serious, followed by pelvic injury and haemorrhage. Important best practice factors are (Table 4): agreed departmental protocols, stabilizing patients before PN, pre-procedure antibiotics, careful renal puncture, care in the use of dilators and sheaths, but above all, urgency in the management of those cases who have had a failed attempt at percutaneous/retrograde urinary tract drainage.
Appendix A SCVIR standards of practice committee classification of complications by outcome Minor complications A. B.
No therapy, no consequence, or Nominal therapy, no consequence; includes overnight admission for observation only.
Major complications C. D.
E. F.
Require therapy, minor hospitalization (, 48 h), Require major therapy, unplanned increase in level of care, prolonged hospitalization (. 48 h), Have permanent adverse sequelae, or Result in death.
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3. Riddell AM, Charig MJ. A survey of current practice in out of hours percutaneous nephrostomy insertion in the United Kingdom. Clin Radiol 2002;57:1067—9. 4. McDermott VG, Schuster MG, Smith TP. Antibiotic prophylaxis in vascular and interventional radiology. AJR Am J Roentgenol 1997;169:31—8. 5. Barbaric ZL, Hall T, Cochran ST, Heitz DR, Schwartz RA, Krasny RM, Deseran MW. Percutaneous nephrostomy: placement under CT and fluoroscopy guidance. AJR Am J Roentgenol 1997;169:151—5. 6. Gupta S, Gelatin M, Uday Shankar K, Rungta U, Suri S. Percutaneous nephrostomy with real time sonographic guidance. Acta Radiol 1997;38:454—7. 7. Mahaffey KG, Bolton DM, Stoller ML. Urologist directed percutaneous nephrostomy tube placement. J Urol 1994; 152:1973—6. 8. Nielsen OS, Grossman E. Ultrasonically guided percutaneous nephrostomy. Scand J Urol Nephrol 1990;24:219—21. 9. Von der Recke P, Nielsen MB, Pedersen JF. Complications of ultrasound-guided nephrostomy. Acta Radiol 1994;35: 452—4.
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10. Papanicolaou N. Renal anatomy relevant to percutaneous interventions. Semin Intervent Radiol 1995;12:163—72. 11. Clark TW, Abraham RJ, Flemming BK. Is routine micropuncture access necessary fro percutaneous nephrostomy? A randomised trial. Canad Assoc Radiol J 2002;53:87—91. 12. Farrell TA, Hicks ME. A review of radiologically guided percutaneous nephrostomies in 303 patients. J Vasc Interv Radiol 1997;8:769—74. 13. Lee WJ, Patel U, Patel S, Pillari GP. Emergency percutaneous nephrostomy: results and complications. J Vasc Interv Radiol 1994;5:135—9. 14. Board of the Faculty of Clinical Radiology, Good Practice Guide for Clinical Radiologists. London: Royal College of Radiologists; 1999. 15. Board of the Faculty of Clinical Radiology, Risk Management in Clinical Radiology. London: Royal College of Radiologists; 2002. 16. Lee WJ, Mond DJ, Patel M, Pillari GP. Emergency percutaneous nephrostomy: technical success based on level of operator experience. J Vasc Interv Radiol 1994;5:327—30.