A training simulator for ultrasound-guided percutaneous nephrostomy insertion

Increasing trainee numbers and changes to working patterns have resulted in a scarcity of training opportunities for training-grade doctors wishing to learn nephrostomy tube insertion techniques. A method of introducing trainees to the skills required to perform percutaneous nephrostomy in a safe, non-threatening environment, without risk to patients, is desirable. Commercial and biological nephrostomy phantoms are available, but they are expensive and not widely available, and a cheap, safe, valid alternative is desirable. We describe a simple technique for producing a gelatin-based phantom, which we suggest has face and content simulator validity. The use of this nephrostomy phantom could optimise existing clinical training opportunities through familiarisation with nephrostomy technique and equipment, and development of the psychomotor skills required for successful nephrostomy insertion prior to undertaking supervised procedures on patients.Skills in ultrasound-guided percutaneous nephrostomy insertion are desirable for trainee radiologists. Nephrostomy is often the method of choice for emergency decompression of an obstructed renal system, particularly in the presence of urinary infection. This intervention is frequently required as an "on-call" procedure. Moreover, the skills required for ultrasound needle guidance and the Seldinger technique are cross-transferable, being of use in the drainage of collections elsewhere in the body and in the performance of ultrasound-guided biopsies. Preferably, trainees should acquire these skills in a safe, non-threatening environment, without patient risk.Commercial nephrostomy phantoms are available and biological phantoms have been described [1, 2], but both of these have disadvantages (including cost and hygiene considerations, respectively). Gelatin-based phantoms have been described for developing ultrasound-guided biopsy technique [3, 4], but these do not facilitate the complex procedural sequence required to insert a drain into a dilated pelvicalyceal system. A gelatin-based system has recently been described that allows ultrasound-guided puncture of a simulated pelvicalyceal system [5], but the costs and complexity of production may be prohibitive for routine use by trainees. We therefore describe a cheap and relatively simple technique, adapted from previously described methodology [3, 4], for producing a gelatin-based phantom that permits ultrasound-guided puncture, wire insertion, serial dilatation and drainage of a fluid-filled cavity that simulates the dilated collecting system of a hydronephrotic kidney.     

Redefinitions of indications for percutaneous nephrostomy

An analysis of treatment response in 215 patients treated by percutaneous nephrostomy identified obstruction of the urinary tract, complicated by infection and sometimes gram-negative septicemia, as the single most important indication for this intervention. Percutaneous nephrostomy reduced the mortality from gram-negative septicemia from 40% to 8%. Similarly, the length of hospitalization for patients with severe infection complicating urinary tract obstruction was reduced by half in the group undergoing percutaneous nephrostomy. In 43 patients with longstanding obstruction, percutaneous nephrostomy was used to predict recoverable renal function based on the response of renal plasma flow rate to decompression. In 13 patients, percutaneous nephrostomies were used either for the introduction of solvents to dissolve calculi or to serve as pathways for their extraction. Percutaneous nephrostomies in 21 patients were expanded to serve as points of entry for the placement of stent catheters to treat fistulas or bougie catheters to dilate and subsequently catheterize ureteral strictures. While six serious complications were encountered, five of these might have been prevented by meticulous adherence to proper technique.     

Intercostal-space nephrostomy for percutaneous stone removal

Intercostal-space nephrostomies were created in 50 kidneys for removal of 17 staghorn, 9 calyceal, and 24 ureteral calculi. Complications were encountered in six [12%] of 50 patients. These included large pleural effusions in four patients and hydropneumothoraces in two patients. Four patients (8%) had chest tubes placed. The intercostal approach provides direct, straight access to both upper-pole and ureteral calculi as well as to the major portion of most staghorn calculi. Although the morbidity rate is slightly higher than for the more traditional approach via the subcostal lower pole or middle calyx complications generally can be avoided by using a working sheath and placing a large nephrostomy tube after the procedure.     

Interactive MR-guided percutaneous nephrostomy

Open-configuration MRI systems have been recently introduced and hold promise to allow the performance of a variety of minimally invasive procedures. Experience with MR-guided catheter-based luminal interventions is experimental to date. This is the first case of a successful percutaneous nephrostomy tube placement in a patient in an interventional MR system. The procedure was performed completely under MR guidance, and technical aspects are reviewed and compared with other, established techniques for percutaneous nephrostomy placement.     

Antibiotic bonded nephrostomy catheters for percutaneous nephrostomies

A prospective controlled trial of the effectiveness of a cefoxitin-bonded nephrostomy catheter was undertaken to determine the effectiveness of an antibiotic bonded catheter in decreasing the infectious complications of percutaneous nephrostomy. The study concludes that bonding of the antibiotic cefoxitin to percutanoeus nephrostomy catheters did not influence the incidence of bacteriuria or urinary tract infection. In addition, observations on the overall incidence of complications from percutaneous nephrostomy are made.     

Retroperitoneal hemorrhage after percutaneous nephrostomy

Sixty-two kidneys in 57 patients were studied by computed tomography (CT) after percutaneous nephrostomy. Clinically unsuspected retroperitoneal hematomas were detected in eight kidneys (13%). In eight other patients, extrarenal collections of contrast material were noted. In none of the cases was a large hematoma seen or surgical intervention required.     

Do''s and don''t''s of percutaneous nephrostomy

Percutaneous nephrostomy procedures generally are safe. The associated mortality rate is approximately 0.04%, and the incidence of important complications is 5% (2-4). To minimize complications, certain precautions always should be followed. First, radiologists should perform a preprocedural evaluation of the patient, with correction of marked coagulopathy or thrombocytopenia before all but the most emergent procedures. Second, antibiotics should be administered routinely before nephrostomy drainage; the choice of antibiotics can be based on the specific patient's risk factors for bacteriuria. To minimize the risk of clinically important renal vascular damage, radiologists should do the following: 1. Always achieve adequate visualization of the calices. 2. Identify a posterior calix for puncture that will give access to the appropriate segment of the kidney for anticipated procedures and allow safe creation of a tract. 3. Puncture below the 11th rib (and preferably below the 12th rib when feasible). 4. Puncture the tip of a posterior calix from a 20 degrees-30 degrees, posterolateral oblique approach to avoid major blood vessels. 5. Make a single-wall puncture of the calix. 6. Perform exchange transfusion for opacification of the renal pelvis and calices during percutaneous nephrostomy procedures to minimize the risk of sepsis. Overdistention can increase the likelihood of sepsis or retroperitoneal contamination. 7. Inject contrast material via a catheter placed over a wire to confirm the intracollecting system location of the entry. 8. Avoid unnecessary (complicated, prolonged) procedures in an infected, obstructed system. 9. Use only self-retaining drainage catheters to minimize the risk of inadvertent catheter dislodgment. 10. Create large-bore tracts with a balloon dilation system. By contrast, radiologists should not do the following: 1. Puncture above the 11th rib (unless all other avenues of approach have been exhausted). 2. Lose access to an obstructed kidney once the kidney has been punctured. Placement of a "safety" wire for all complex manipulations is recommended. 3. Panic if excessive bleeding or evidence of adjacent organ injury is seen. Excessive bleeding usually can be stopped with tract tamponade by using a balloon catheter advanced through the tract or with placement of an appropriate-sized nephrostomy tube to occlude the tract. If active bleeding continues or recurs, arteriography should be considered. The quantity of bleeding can be monitored with sequential hematocrit measurements. Almost all renal artery injuries can be treated with minimally invasive procedures, such as selective embolization of the branch artery involved, and this will lead to infarction of only a small segment of kidney, with preservation of functioning renal parenchyma. Injury to an adjacent organ usually can be treated nonsurgically (21,23). The most commonly injured extrarenal abdominal organ is the colon (Fig 6). On occasion, a percutaneous nephrostomy needle may traverse the retroperitoneal segment of the colon, and this type of injury generally can be treated nonsurgically, as well (23). If the colon has been traversed, adequate urinary drainage should be ensured before the transcolonic nephrostomy catheter is removed (so that a nephrocolonic fistula is not maintained). This can be done by placing a ureteral stent and a bladder catheter (18). Once adequate urinary drainage is provided, the nephrostomy catheter can be withdrawn into the colon and used as a percutaneous colostomy drain. The percutaneous colostomy tract should be allowed to mature for several days before this catheter is removed. In addition, appropriate antibiotics should be administered from the time a transcolonic tract is identified until the percutaneous tract has healed completely. Transthoracic entry can cause pneumothorax and pleural effusions. These should be treated only if they are large or cause symptoms (21). (ABSTRACT TRUNCATED)     

Direct percutaneous transrenal embolization for renal artery injury following percutaneous nephrostomy.

The use is reported of percutaneous transrenal embolization for renal artery injury during percutaneous nephrostomy. If a nephrostomy catheter is seen to transfix the renal pelvis, the possibility of injury to a large renal artery must be considered. The misplaced nephrostomy catheter should be withdrawn over a guidewire. Percutaneous renal artery embolization may enable rapid arrest of life threatening haemorrhage.     

Is routine micropuncture access necessary for percutaneous nephrostomy? A randomized trial.

OBJECTIVE: To compare the micropuncture technique and the conventional large-bore needle approach for renal access. METHODS: From July 1999 to July 2000, patients referred to interventional radiology for emergent or elective percutaneous nephrostomy with normal coagulation profiles were considered for the study. Nephrostomy procedures were performed using a micropuncture system or large-bore needle for collecting system access; 24 nephrostomy procedures were randomized to each group using permuted blocks and opaque sealed envelopes. Gross hematuria, quantitative urine red blood cell counts, pain scores and procedural success were compared between the 2 groups. RESULTS: There was a small difference in the incidence of gross hematuria between the large-bore needle and micropuncture groups (12 [50%] v. 8 [33%] patients), but this difference was not statistically significant. Quantitative urine red blood cell counts obtained immediately after and 24 hours after nephrostomy placement showed no significant differences. Significantly fewer needle passes were required for access in the large-bore needle group than the micropuncture group (1.7 v. 2.8, p = 0.01), and mean procedure duration was 7 minutes longer in the micropuncture group, although this difference was not significant. No differences in pain scores or procedure success were seen. CONCLUSION: Percutaneous nephrostomy performed with a micropuncture system in patients with normal coagulation profiles does not significantly decrease organ bleeding or pain. More needle passes and manipulations are required, which may increase procedure duration. The additional costs of routine micropuncture access for percutaneous nephrostomy are not supported by this study.     

MRI-guided percutaneous nephrostomy: a feasibility study

The purpose of this study was to assess the feasibility and safety of magnetic resonance imaging (MRI)-guided PCN in an open-configuration low-field MRI system. Eight patients were prospectively enrolled in the study. The degree of the dilatation of the renal collecting system varied from minimal to severe. All procedures were performed solely under MRI guidance with a 0.23-T open configuration C-arm-shaped MRI system with interventional optical tracking. In each case, PCN was performed with a MRI-compatible drainage kit using the Seldinger technique. Seven out of eight nephrostomies were successfully performed under MRI guidance. All PCN procedures in dilated renal collection systems were successful; however, nephrostomy catheter could not be placed in a nondilated system. The mean time needed for the MRI-guided PCN was 26 min. No major complications occurred during the procedure or follow-up. MRI-guided PCN in dilated renal collection system is feasible and safe. The presented technique has limitations that necessitate further technical developments before the procedure can be applied to nondilated kidneys and recommended for routine clinical use.     

选择性肾动脉栓塞治疗肾造瘘术后出血

目的评价选择性肾动脉栓塞治疗肾造瘘术后出血的临床价值。方法对12例肾造瘘术后出血患者,使用选择性肾动脉栓塞术,栓塞材料为明胶海绵微粒、聚乙烯醇(PVA)微粒或弹簧圈。结果造影显示肾实质动静脉瘘2例;对比剂外溢4例;假性动脉瘤3例;假性动脉瘤合并动静脉瘘3例。栓塞治疗后异常血管征象消失,12例患者的血尿3～7d内消失,随访期间未出现严重并发症及再次血尿。结论选择性肾动脉栓塞是治疗肾造瘘术后出血的微创、安全、有效的方法。     

CT-guided antegrade pyelography and percutaneous nephrostomy.

Percutaneous antegrade pyelography and percutaneous nephrostomy can be easily performed using CT guidance. CT provides cross-sectional images which facilitate accurate needle placement into the renal pelvis. CT is capable of detecting subtle density differences within the tissues so that even renal pelvises which do not contain contrast material and are not dilated can be accurately punctured. In addition to these procedures, CT accurately displays the perinephric space so that assessment of complications is possible. Four of five attempted percutaneous nephrostomies and two antegrade pyelograms were successfully performed using CT gudance.     

Carbon dioxide as a lighter-than-urine contrast medium for percutaneous nephrostomy

Carbon dioxide was used either alone or in combination with standard triiodinated contrast media in 32 patients who underwent percutaneous nephrostomy. Carbon dioxide was used to opacify the posterior calyces, which are the uppermost structures in the kidney of the prone or prone-oblique patient. Carbon dioxide is usually injected in small amounts (20-40 cm3), although clinical and laboratory data indicate that it can be used as the only medium in large amounts with complete safety. There were no complications.     

A ten-year,single institution experience with percutaneous nephrostomy during pregnancy

PurposeTo evaluate the safety and efficacy of percutaneous nephrostomy (PCN) in pregnancy.Materials and methodsPCN tubes were placed during 52 pregnancies in 49 patients from 2008 to 2018. The medical records during pregnancies were retrospectively reviewed for imaging findings, procedural parameters, outcomes of delivery, and complications.ResultsThe mean gestational age on percutaneous nephrostomy placement was 27 weeks (range, 8–36 weeks). PCN catheters were placed for the following indications: 1) flank or lower abdominal pain (42%), 2) obstructing calculi (37%), 3) pyelonephritis (20%), and 4) obstructing endometrioma (2%). Prior to PCN, retrograde ureteric stenting was performed in 17 of 49 patients (34%) and attempted but failed in 4 patients (8%). Nephrostomy drainage relieved pain completely or significantly in all 12 patients without prior ureteral stenting, but in only 4 of 10 with retrograde ureteric stents. In one patient in whom the ureteral stent had been removed, PCN relieved her flank pain. The mean number of PCN catheter exchanges was 1.6, ranging from 0 to 9, with a mean time interval of 21.3 days between exchanges. There were 29 difficult exchanges due to encrustation in 15 patients with a mean of 20.5 days between exchanges.ConclusionsPCN drainage is a safe and effective treatment for managing symptomatic hydronephrosis in pregnant patients but is less effective in treating pain when retrograde ureteral stents are in place. Rapid encrustation, seen more commonly in pregnancy, tends to recur in the same patients and requires more frequent exchanges than the general population.