Percutaneous Nephrostomy: Technical Aspects and Indications Mandeep Dagli, M.D.,1 and Parvati Ramchandani, M.D.1 ABSTRACT First described in 1955 by Goodwin et al as a minimally invasive treatment for urinary obstruction causing marked hydronephrosis, percutaneous nephrostomy (PCN) placement quickly found use in a wide variety of clinical indications in both dilated and nondilated systems. Although the advancement of modern endourological techniques has led to a decline in the indications for primary nephrostomy placement, PCNs still play an important role in the treatment of multiple urologic conditions. In this article, the indications, placement, and postprocedure management of percutaneous nephrostomy drainage are described. KEYWORDS: Nephrostomy, interventional radiology, kidney, hydronephrosis, nephroureterostomy Objectives: Upon completion of the article, the reader should be able to list the indications, placement, and postprocedure management of percutaneous nephrostomy drainage. Accreditation: Tufts University School of Medicine is accredited by the Accreditation Council for Continuing Medical Education to provide continuing medical education for physicians. Credit: Tufts University School of Medicine designates this journal-based CME activity for a maximum of 1 AMA PRA Category 1 CreditTM. Physicians should claim only the credit commensurate with the extent of their participation in the activity. First described in 1955 by Goodwin et al as a INDICATIONS minimally invasive treatment for urinary obstruction There are four broad indications for the placement of a causing marked hydronephrosis, percutaneous nephros- PCN. These are (1) relief of urinary obstruction, (2) tomy (PCN) placement quickly found use in a wide diagnostic testing, (3) access for therapeutic interven- variety of clinical indications in both dilated and non- tions, and (4) urinary diversion (Table 1). To deter- dilated systems. Although the advancement of modern mine the appropriateness of nephrostomy placement, endourological techniques has led to a decline in the familiarity with the clinical presentation, diagnostic indications for primary nephrostomy placement, PCNs work-up, and typical management of each specific still play an important role in the treatment of multiple indication is essential. In addition, because nephros- urologic conditions. In this article, we will describe the tomy placement is often a second-line therapy to indications, placement, and postprocedure management retrograde endourological techniques, which typically of percutaneous nephrostomy drainage. have a lower associated morbidity, it is important to be 1University of Pennsylvania Medical Center, Philadelphia, Pennsylvania. Semin Intervent Radiol 2011;28:424–437. Copyright # 2011 by Address for correspondence and reprint requests: Parvati Thieme Medical Publishers, Inc., 333 Seventh Avenue, New York, Ramchandani, M.D., University of Pennsylvania Medical Center, NY 10001, USA. Tel: +1(212) 584-4662. Philadelphia, PA 19104 (e-mail: [email protected]). DOI: http://dx.doi.org/10.1055/s-0031-1296085. Genitourinary Intervention; Guest Editor, Darryl A. Zuckerman, ISSN 0739-9529. M.D. 424 PERCUTANEOUS NEPHROSTOMY: TECHNICAL ASPECTS AND INDICATIONS/DAGLI, RAMCHANDANI 425 Table 1 Indications renal obstruction, imaging is the most sensitive diagnos- A. Indications include, but are not limited to tic method. 1. Relief of urinary obstruction The imaging diagnosis of renal obstruction can be a. Urosepsis or suspected infection made with ultrasound, computed tomography (CT), b. Acute renal failure nuclear medicine, or magnetic resonance imaging c. Intractable pain (MRI). Ultrasound is usually the first choice due to 2. Urinary diversion relative availability, minimal risk, and high sensitivity a. Hemorrhagic cystitis for detecting a dilated collecting system. However, b. Traumatic or iatrogenic ureteral injury compared with other imaging methods it is not as c. Inflammatory or malignant urinary fistula effective in determining the etiology and location of 3. Access for endourologic procedure obstruction. In very large patients with renal impair- a. Stone removal ment, noncontrast CT can effectively detect hydroneph- b. Dilatation or stenting of a ureteral stricture rosis and has the added benefit of being highly sensitive c. Endopyelotomy for the detection of obstructing stones. In patients with d. Foreign body retrieval (e.g., fractured stent) normal renal function, contrast-enhanced CT has a very e. Ureteral occlusion for urinary fistula high success rate for detecting and identifying the cause 3 f. Tumor fulguration of hydronephrosis. For uroenteric diversions, MR ur- 4 g. Delivery of medications and chemotherapy ography can be helpful in delineating the anatomy. It h. Biopsy of a urothelial lesion should be noted that early renal obstruction does not 4. Diagnostic testing always have associated hydronephrosis particularly when a. Antegrade pyelography the collecting system is relatively noncompliant or there b. Ureteral perfusion (Whitaker test) is poor underlying renal function and reduced urine production. Conversely, hydronephrosis can occur in the absence of obstruction when there is (1) a high rate of urine production such as in pregnancy or after over- familiar with the typical situations in which endouro- hydration (particularly when there is a mild stenosis that logical approaches fail. becomes flow limiting only at abnormally high urine flow rates), (2) persistent residual hydronephrosis after a chronic obstruction has been relieved, (3) significant Relief of Urinary Obstruction persistent ureteral reflux producing megaureter such as Relief of urinary obstruction represents the most com- in the setting of a uroenteric conduit. In situations where mon indication for PCN placement representing 85 to the ultrasound or CT diagnosis of obstruction is inde- 90% of patients in several large series1. The three most terminate, diuretic renography with technetium common causes of renal obstruction in adults are urinary 99m-MAG3 can be helpful. Obstructed systems typi- stones, malignancy, and iatrogenic benign stricture. In cally have a continuously rising renogram both before one large series, 26% of all nephrostomy tubes were and after diuretic administration, whereas unobstructed placed because of calculus disease and 61% due to systems have a postdiuretic T1/2 time of collecting malignancy.2 system emptying of less than 10 to 15 minutes. If the The clinical presentation of the patient with patient’s underlying renal function is very poor, the urinary obstruction varies depending on the etiology, diuretic response is diminished and a false- positive location, degree, and timing of the obstruction. The finding for mechanical obstruction may be seen. typical symptom is flank pain. In general, the more In general, because an uninfected obstructed kid- rapidly developing and complete an obstruction, the ney is not acutely threatened, nephrostomy placement is greater the acute distension of the renal capsule, and an urgent rather than emergent procedure. Clinical data the more intense the feeling of pain. An abrasive process in humans suggests that complete recovery of the glo- irritating the sensitive urothelium, such as a stone will merular filtration rate (GFR) can be expected with one also produce flank pain. However, a slowly developing week of complete obstruction with very little recovery partial obstruction, such as due to malignancy, may be seen after 12 weeks of complete obstruction.5,6 Com- painless and only incidentally discovered on imaging. plete or partial obstruction of urine flow leads to elevated Abnormal laboratory values are an insensitive sign of urinary pressure with associated afferent arteriolar vaso- early renal obstruction. Plasma creatinine concentration constriction causing marked reduction in glomerular is rarely elevated in the setting of a normally functioning blood flow. Over time, chronic obstruction leads to contralateral kidney, although bilateral renal obstruction permanent progressive functional loss through a combi- can produce the constellation of acute renal failure with a nation of ischemic or disuse-induced tubular injury as distal renal tubular metabolic acidosis and hyperkalemia. well as inflammation and interstitial renal fibrosis7,8 Ultimately, however, when there is clinical suspicion for Although in a rat model complete unilateral ureteral 426 SEMINARS IN INTERVENTIONAL RADIOLOGY/VOLUME 28, NUMBER 4 2011 obstruction for 24 hours led to 15% of nephrons being tally increased to a maximum of 20 mL/min if there is no nonfunctional on examination 2 months later, the GFR rise in the pressure gradient. A gradient greater than of the kidney was preserved due to compensatory hyper- 22 mm H2Oorlessthan15mmH2O suggests ob- trophy and hyperfiltration of the remaining nephrons.9 structed or unobstructed systems, respectively. A gra- Ultimately, however, the rate of irreversible obstructive dient between 15 to 22 mm H2O is considered injury is a multifactorial process influenced by the indeterminate. Currently, the availability of less-invasive degree, level, and duration of the obstruction, as well diagnostic methods such as diuretic renography has as by the presence of infection.8 In a clinical situation, it replaced the Whitaker test in most circumstances. How- is difficult to predict how much renal function will be ever, in the setting of equivocal or discordant renography recoverable in an individual patient; thus, a therapeutic results, some authors