DOI: 10.1148/rg.265065701
RadioGraphics 2006;26:1419-1429
© RSNA, 2006
CT and MR Imaging of Complications of Partial Nephrectomy1
Gary M. Israel, MD,
Elizabeth Hecht, MD and
Morton A. Bosniak, MD
1 From the Department of Radiology, Yale University School of Medicine, PO Box 208042, 333 Cedar St, New Haven, CT 06520-8042 (G.M.I., E.H.); and Department of Radiology, New York University Medical Center, New York, NY (E.H., M.A.B.). Received January 4, 2006; revision requested March 13 and received March 28; accepted March 29. All authors have no financial relationships to disclose.
Address correspondence to G.M.I. (e-mail: gary.israel{at}yale.edu).
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Abstract
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The standard treatment for renal cell carcinoma for many years was radical nephrectomy, but in the past decade there has been a trend toward elective nephron-sparing surgery. Initially, partial nephrectomy was performed with an open surgical approach; more recently and with increasing frequency, a laparoscopic approach has been used in selected cases. Nephron-sparing surgery with either approach is more complex than is traditional radical nephrectomy and more frequently results in complications. The possible complications of partial nephrectomy include vascular, collecting system, and technical complications as well as recurrent tumor and infection. For prompt diagnosis and appropriate management of these complications, radiologists must be familiar with normal and abnormal features in the postoperative appearance of the kidney at computed tomography and magnetic resonance imaging.
© RSNA, 2006
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Introduction
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Over the past 10 years, there has been a trend toward the use of nephron-sparing surgery to treat renal cell carcinoma.
Although radical nephrectomy was long considered the reference standard for the treatment of renal cell carcinoma, the results of numerous studies have demonstrated equivalent cancer survival rates for patients who underwent radical nephrectomy and those who underwent partial nephrectomy for small renal neoplasms.
Elective partial nephrectomy is therefore now considered a valid treatment approach in patients with small renal neoplasms, and it is accepted and used by most urologists. The procedure can be performed by using open or laparoscopic techniques. However, partial nephrectomy, especially when performed with laparoscopic techniques, is a more complex operation than is traditional radical nephrectomy, and higher complication rates have been reported (4,5).
A worldwide literature review revealed a major complication rate of 10% for patients who underwent laparoscopic partial nephrectomy. An overall complication rate of 23% was reported for laparoscopic partial nephrectomy in a European multi-institutional series.
In one case series in which laparoscopic and open techniques of partial nephrectomy were compared (8), the laparoscopic technique was shown to be associated with a higher rate of major complications (5% vs 0%), although the rate of overall postoperative complications was not significantly different from that of the open technique. As both open and laparoscopic partial nephrectomy procedures gain in acceptance and in frequency of use, it is important that radiologists be familiar with the imaging features of postsurgical complications as well as with normal findings after partial nephrectomy. Such familiarity allows accurate diagnosis and prompt and appropriate management of any complications. The article provides an overview of expected imaging features in the postoperative kidney and of complications that may be seen at computed tomography (CT) and magnetic resonance (MR) imaging after open or laparoscopic partial nephrectomy.
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Postoperative Appearance
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After partial nephrectomy, the postoperative kidney commonly has a more posterior retroperitoneal location and abuts or adheres to the posterior abdominal wall (Fig 1). This finding, especially if accompanied by reactive or fibrotic changes in the perinephric space, is indicative of previous renal surgery. The appearance of the postoperative kidney depends to a great extent on the size and location of the resected tumor. After partial nephrectomy for a small peripheral tumor, a wedge-shaped defect in the renal parenchyma typically is visible at CT and MR imaging (Fig 2).
In some cases, the surgeon may pack perinephric fat into the surgical bed to help achieve hemostasis. The fatty packing material later may be mistaken for a fatty mass such as an angiomyolipoma.(Figs 3, 4).
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Figure 1. Typical postoperative findings in a 48-year-old man after a laparoscopic right partial nephrectomy. Axial contrast-enhanced CT image shows a posterior location of the right kidney, which abuts the posterior abdominal wall. Mild reactive changes (arrows) adjacent to the psoas muscle and liver also can be seen. These are common findings after partial nephrectomy.
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Figure 2a. Postoperative findings in a 62-year-old woman who underwent a laparoscopic left partial nephrectomy for renal cell carcinoma. (a) Preoperative axial contrast-enhanced CT image demonstrates a solid and well-marginated left renal mass in the lateral aspect of the kidney. (b) Coronal T2-weighted MR image obtained 6 months after surgery demonstrates a wedge-shaped postoperative defect (arrows) in the lateral aspect of the kidney. At the apex of the defect, a small focal area of hypointense signal characteristic of postoperative scar tissue is visible.
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Figure 2b. Postoperative findings in a 62-year-old woman who underwent a laparoscopic left partial nephrectomy for renal cell carcinoma. (a) Preoperative axial contrast-enhanced CT image demonstrates a solid and well-marginated left renal mass in the lateral aspect of the kidney. (b) Coronal T2-weighted MR image obtained 6 months after surgery demonstrates a wedge-shaped postoperative defect (arrows) in the lateral aspect of the kidney. At the apex of the defect, a small focal area of hypointense signal characteristic of postoperative scar tissue is visible.
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Figure 3a. Fat-filled postoperative defect at MR imaging in a 58-year-old man after an open left partial nephrectomy for renal cell carcinoma. (a) Preoperative sagittal gadolinium-enhanced T1-weighted fat-suppressed image shows a small mass (arrow) in the posterior aspect of the kidney. (b) Axial T1-weighted image, obtained 5 months after surgery, demonstrates a round fat-containing mass (arrow) in the postoperative bed. If a history of surgery were not provided, the mass might be mistaken for an angiomyolipoma. (c) Sagittal gadolinium-enhanced T1-weighted fat-suppressed image, obtained at the same time as b, shows an area of low signal intensity consistent with fat surgically packed into a wedge-shaped postoperative defect. This finding corresponds to the apparently round mass in b. Extensive postoperative reactive changes (arrows) in the retroperitoneum also are visible.
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Figure 3b. Fat-filled postoperative defect at MR imaging in a 58-year-old man after an open left partial nephrectomy for renal cell carcinoma. (a) Preoperative sagittal gadolinium-enhanced T1-weighted fat-suppressed image shows a small mass (arrow) in the posterior aspect of the kidney. (b) Axial T1-weighted image, obtained 5 months after surgery, demonstrates a round fat-containing mass (arrow) in the postoperative bed. If a history of surgery were not provided, the mass might be mistaken for an angiomyolipoma. (c) Sagittal gadolinium-enhanced T1-weighted fat-suppressed image, obtained at the same time as b, shows an area of low signal intensity consistent with fat surgically packed into a wedge-shaped postoperative defect. This finding corresponds to the apparently round mass in b. Extensive postoperative reactive changes (arrows) in the retroperitoneum also are visible.
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Figure 3c. Fat-filled postoperative defect at MR imaging in a 58-year-old man after an open left partial nephrectomy for renal cell carcinoma. (a) Preoperative sagittal gadolinium-enhanced T1-weighted fat-suppressed image shows a small mass (arrow) in the posterior aspect of the kidney. (b) Axial T1-weighted image, obtained 5 months after surgery, demonstrates a round fat-containing mass (arrow) in the postoperative bed. If a history of surgery were not provided, the mass might be mistaken for an angiomyolipoma. (c) Sagittal gadolinium-enhanced T1-weighted fat-suppressed image, obtained at the same time as b, shows an area of low signal intensity consistent with fat surgically packed into a wedge-shaped postoperative defect. This finding corresponds to the apparently round mass in b. Extensive postoperative reactive changes (arrows) in the retroperitoneum also are visible.
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Figure 4a. Fat-filled postoperative defect at CT in a 45-year-old man after an open left partial nephrectomy for renal cell carcinoma. (a) Preoperative axial contrast-enhanced image demonstrates a 3-cm-diameter solid mass in the left kidney. (b) Axial contrast-enhanced image, obtained 6 months after surgery, depicts an area of fatty tissue within a wedge-shaped defect at the postoperative site in the left kidney. This finding was due to fat packing at surgery. The posterior location of the left kidney, adjacent to the posterior abdominal wall, is typical of previous renal surgery.
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Figure 4b. Fat-filled postoperative defect at CT in a 45-year-old man after an open left partial nephrectomy for renal cell carcinoma. (a) Preoperative axial contrast-enhanced image demonstrates a 3-cm-diameter solid mass in the left kidney. (b) Axial contrast-enhanced image, obtained 6 months after surgery, depicts an area of fatty tissue within a wedge-shaped defect at the postoperative site in the left kidney. This finding was due to fat packing at surgery. The posterior location of the left kidney, adjacent to the posterior abdominal wall, is typical of previous renal surgery.
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Over time, the volume of fat used for surgical packing may decrease or remain unchanged. Biologically absorbable hemostatic agents also may be used to help control intraoperative bleeding (9). Such materials may contain air pockets or bubbles that on early postoperative images may resemble a focal abscess (10,11) (Fig 5). The possible presence of a hemostatic agent should be considered if a linear arrangement of air bubbles is noted or if air bubbles maintain the same position on subsequent images. In most cases, the air in a hemostatic agent is rapidly resorbed during the 1st postsurgical week. However, in some cases, air bubbles can be identified on images even 1 month after surgery (9). The presence of an abscess should be suspected if a localized fluid collection that has an enhanced rim and contains gas bubbles or a gas-fluid level is seen (9). In addition, decreased intensity of the nephrogram because of edema in the surrounding renal parenchyma supports the diagnosis of an abscess.
To differentiate between a collection that consists of a hemostatic agent containing air bubbles and one that consists of infected fluid containing gas bubbles, it is necessary to consider the imaging findings in combination with the patient’s clinical history and symptoms.
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Figure 5a. Bioabsorbable hemostatic material at CT in a 53-year-old woman who presented with fever after an open right partial nephrectomy. The fever developed within the 1st week after surgery but was subsequently determined to be due to pneumonia. (a) Preoperative axial contrast-enhanced image demonstrates a solid mass in the anterior portion of the upper pole of the right kidney, a finding that represents a renal cell carcinoma. (b) Axial unenhanced image, obtained 1 week after surgery, demonstrates small bubbles of air, some of which are in linear configurations, in the postoperative bed. Considerable perirenal reactive changes also are depicted, but no fluid collection is seen. The findings are consistent with air pockets within a bioabsorbable agent that was used to control intraoperative bleeding. Images obtained at a follow-up CT examination (not shown) 6 months after surgery showed residual postoperative changes and total resorption of the air bubbles.
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Figure 5b. Bioabsorbable hemostatic material at CT in a 53-year-old woman who presented with fever after an open right partial nephrectomy. The fever developed within the 1st week after surgery but was subsequently determined to be due to pneumonia. (a) Preoperative axial contrast-enhanced image demonstrates a solid mass in the anterior portion of the upper pole of the right kidney, a finding that represents a renal cell carcinoma. (b) Axial unenhanced image, obtained 1 week after surgery, demonstrates small bubbles of air, some of which are in linear configurations, in the postoperative bed. Considerable perirenal reactive changes also are depicted, but no fluid collection is seen. The findings are consistent with air pockets within a bioabsorbable agent that was used to control intraoperative bleeding. Images obtained at a follow-up CT examination (not shown) 6 months after surgery showed residual postoperative changes and total resorption of the air bubbles.
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Accurate differentiation is important to avoid unnecessary aggressive therapy.
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Vascular Complications
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During partial nephrectomy, clear visualization of the tumor bed is necessary to ensure that surgical margins are adequate and to identify and control transected intrarenal blood vessels (12). For this reason, the renal hilar vessels must be temporarily clamped to ensure a bloodless surgical field; however, clamping may injure the arterial intima and lead to thrombosis (13). If that complication is not recognized at the time of surgery or in the immediate postoperative period, renal infarction and atrophy will occur (Fig 6). Because clamping of the artery for more than 2 hours may result in a complete loss of renal function and atrophy of the kidney, urologists try to limit renal artery clamping to 30 minutes or less (12). Complications related to injury of the intrarenal arteries in the surgical bed also may occur. A hematoma may result if the suturing of transected blood vessels is inadequate (Fig 7). A pseudoaneurysm may result from injury to an intrarenal artery at the surgical site or to the main renal artery or one of its major branches (Fig 8) (14,15).
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Figure 6a. Renal atrophy in a 76-year-old man after an open left partial nephrectomy for renal cell carcinoma. (a, b) Preoperative coronal T2-weighted MR image (a) and axial gadolinium-enhanced T1-weighted fat-suppressed MR image (b) demonstrate a complex cystic mass that extends to the renal sinus in a left kidney 9 cm long. Nodular enhancement is visible along the septa (arrows in b). (c) Coronal T2-weighted MR image, obtained 5 months after surgery, depicts atrophy of the left kidney (large arrow), which is now only 6 cm long, and a small fluid collection (small arrow) in the postoperative bed. (d) Axial gadolinium-enhanced T1-weighted fat-suppressed MR image shows an avascular, atrophic left kidney (short arrows) and a small high-signal-intensity fluid collection (long arrow) that likely represents residual blood in the postoperative bed. It was assumed that the left renal artery was injured during surgery and became thrombosed, with resultant left renal infarction.
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Figure 6b. Renal atrophy in a 76-year-old man after an open left partial nephrectomy for renal cell carcinoma. (a, b) Preoperative coronal T2-weighted MR image (a) and axial gadolinium-enhanced T1-weighted fat-suppressed MR image (b) demonstrate a complex cystic mass that extends to the renal sinus in a left kidney 9 cm long. Nodular enhancement is visible along the septa (arrows in b). (c) Coronal T2-weighted MR image, obtained 5 months after surgery, depicts atrophy of the left kidney (large arrow), which is now only 6 cm long, and a small fluid collection (small arrow) in the postoperative bed. (d) Axial gadolinium-enhanced T1-weighted fat-suppressed MR image shows an avascular, atrophic left kidney (short arrows) and a small high-signal-intensity fluid collection (long arrow) that likely represents residual blood in the postoperative bed. It was assumed that the left renal artery was injured during surgery and became thrombosed, with resultant left renal infarction.
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Figure 6c. Renal atrophy in a 76-year-old man after an open left partial nephrectomy for renal cell carcinoma. (a, b) Preoperative coronal T2-weighted MR image (a) and axial gadolinium-enhanced T1-weighted fat-suppressed MR image (b) demonstrate a complex cystic mass that extends to the renal sinus in a left kidney 9 cm long. Nodular enhancement is visible along the septa (arrows in b). (c) Coronal T2-weighted MR image, obtained 5 months after surgery, depicts atrophy of the left kidney (large arrow), which is now only 6 cm long, and a small fluid collection (small arrow) in the postoperative bed. (d) Axial gadolinium-enhanced T1-weighted fat-suppressed MR image shows an avascular, atrophic left kidney (short arrows) and a small high-signal-intensity fluid collection (long arrow) that likely represents residual blood in the postoperative bed. It was assumed that the left renal artery was injured during surgery and became thrombosed, with resultant left renal infarction.
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Figure 6d. Renal atrophy in a 76-year-old man after an open left partial nephrectomy for renal cell carcinoma. (a, b) Preoperative coronal T2-weighted MR image (a) and axial gadolinium-enhanced T1-weighted fat-suppressed MR image (b) demonstrate a complex cystic mass that extends to the renal sinus in a left kidney 9 cm long. Nodular enhancement is visible along the septa (arrows in b). (c) Coronal T2-weighted MR image, obtained 5 months after surgery, depicts atrophy of the left kidney (large arrow), which is now only 6 cm long, and a small fluid collection (small arrow) in the postoperative bed. (d) Axial gadolinium-enhanced T1-weighted fat-suppressed MR image shows an avascular, atrophic left kidney (short arrows) and a small high-signal-intensity fluid collection (long arrow) that likely represents residual blood in the postoperative bed. It was assumed that the left renal artery was injured during surgery and became thrombosed, with resultant left renal infarction.
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Figure 7a. Hematoma in a 41-year-old man who presented with hematuria 4 days after an open left partial nephrectomy for renal cell carcinoma. (a) Preoperative axial contrast-enhanced CT image demonstrates a solid enhanced mass (arrow) in the posterolateral aspect of the left kidney. (b) Axial contrast-enhanced CT image, obtained 4 days after surgery, depicts a homogeneous mass (arrow) with attenuation of 55 HU, a finding consistent with a hematoma. The mass extends from the postoperative bed to the perinephric space and subcutaneous tissues of the flank. When unenhanced images (not shown) were compared with contrast-enhanced images, no enhancement was seen in the postoperative bed on the contrast-enhanced images. This finding helped to confirm the diagnosis of hematoma and to exclude residual neoplasm and active bleeding.
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Figure 7b. Hematoma in a 41-year-old man who presented with hematuria 4 days after an open left partial nephrectomy for renal cell carcinoma. (a) Preoperative axial contrast-enhanced CT image demonstrates a solid enhanced mass (arrow) in the posterolateral aspect of the left kidney. (b) Axial contrast-enhanced CT image, obtained 4 days after surgery, depicts a homogeneous mass (arrow) with attenuation of 55 HU, a finding consistent with a hematoma. The mass extends from the postoperative bed to the perinephric space and subcutaneous tissues of the flank. When unenhanced images (not shown) were compared with contrast-enhanced images, no enhancement was seen in the postoperative bed on the contrast-enhanced images. This finding helped to confirm the diagnosis of hematoma and to exclude residual neoplasm and active bleeding.
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Figure 8a. Pseudoaneurysm in a 63-year-old woman after a laparoscopic left partial nephrectomy for renal cell carcinoma. (a) Preoperative coronal T2-weighted MR image demonstrates a predominantly low-signal-intensity mass (arrow) at the lower pole of the left kidney. The mass appeared solid and enhanced at gadolinium-enhanced MR imaging. (b) Coronal oblique maximum intensity projection image obtained with MR angiography 3 weeks after surgery shows a 3-cm-diameter well-defined collection of contrast material (arrows) in the postoperative bed at the lower pole of the left kidney. The signal intensity in the collection is similar to that in the aorta, a finding consistent with a pseudoaneurysm of a lower polar branch of the left renal artery. (c) Conventional selective angiogram of the left renal artery depicts the pseudoaneurysm (arrows). (d) Conventional selective angiogram of the left renal artery, obtained after embolization, shows complete thrombosis of the pseudoaneurysm.
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Figure 8b. Pseudoaneurysm in a 63-year-old woman after a laparoscopic left partial nephrectomy for renal cell carcinoma. (a) Preoperative coronal T2-weighted MR image demonstrates a predominantly low-signal-intensity mass (arrow) at the lower pole of the left kidney. The mass appeared solid and enhanced at gadolinium-enhanced MR imaging. (b) Coronal oblique maximum intensity projection image obtained with MR angiography 3 weeks after surgery shows a 3-cm-diameter well-defined collection of contrast material (arrows) in the postoperative bed at the lower pole of the left kidney. The signal intensity in the collection is similar to that in the aorta, a finding consistent with a pseudoaneurysm of a lower polar branch of the left renal artery. (c) Conventional selective angiogram of the left renal artery depicts the pseudoaneurysm (arrows). (d) Conventional selective angiogram of the left renal artery, obtained after embolization, shows complete thrombosis of the pseudoaneurysm.
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Figure 8c. Pseudoaneurysm in a 63-year-old woman after a laparoscopic left partial nephrectomy for renal cell carcinoma. (a) Preoperative coronal T2-weighted MR image demonstrates a predominantly low-signal-intensity mass (arrow) at the lower pole of the left kidney. The mass appeared solid and enhanced at gadolinium-enhanced MR imaging. (b) Coronal oblique maximum intensity projection image obtained with MR angiography 3 weeks after surgery shows a 3-cm-diameter well-defined collection of contrast material (arrows) in the postoperative bed at the lower pole of the left kidney. The signal intensity in the collection is similar to that in the aorta, a finding consistent with a pseudoaneurysm of a lower polar branch of the left renal artery. (c) Conventional selective angiogram of the left renal artery depicts the pseudoaneurysm (arrows). (d) Conventional selective angiogram of the left renal artery, obtained after embolization, shows complete thrombosis of the pseudoaneurysm.
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Figure 8d. Pseudoaneurysm in a 63-year-old woman after a laparoscopic left partial nephrectomy for renal cell carcinoma. (a) Preoperative coronal T2-weighted MR image demonstrates a predominantly low-signal-intensity mass (arrow) at the lower pole of the left kidney. The mass appeared solid and enhanced at gadolinium-enhanced MR imaging. (b) Coronal oblique maximum intensity projection image obtained with MR angiography 3 weeks after surgery shows a 3-cm-diameter well-defined collection of contrast material (arrows) in the postoperative bed at the lower pole of the left kidney. The signal intensity in the collection is similar to that in the aorta, a finding consistent with a pseudoaneurysm of a lower polar branch of the left renal artery. (c) Conventional selective angiogram of the left renal artery depicts the pseudoaneurysm (arrows). (d) Conventional selective angiogram of the left renal artery, obtained after embolization, shows complete thrombosis of the pseudoaneurysm.
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Complications in the Collecting System
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To ensure an adequate margin of resection for tumors that extend deep into the renal parenchyma, calyceal entry is often necessary. Calyceal repair then would be required, to avoid urinary leakage. If the repair is not watertight, urine may leak into the surgical bed. Such leakage may have the appearance of a simple fluid collection in the perirenal space (12), or it may have a more heterogeneous appearance if it contains blood products. This complication can be diagnosed on the basis of contrast-enhanced CT and MR images acquired during the excretory phase, with the observation of contrast material leakage from the collecting system into the surgical bed (Fig 9). In most cases, the fluid collection resolves either spontaneously or after placement of a ureteral stent or nephrostomy catheter. Less commonly, urinary leakage persists and a urinoma forms (Fig 10).
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Figure 9a. Urinary leak at the incision site in a 68-year-old man after an open left partial nephrectomy. (a) Preop-erative axial contrast-enhanced CT image demonstrates a solid enhanced mass (arrow), which was surgically proved to be a renal cell carcinoma, in the left kidney. (b) Axial contrast-enhanced CT image obtained during the nephrographic phase of enhancement, 5 days after surgery, demonstrates a postoperative defect in the renal parenchyma (long arrow) that contains fluid (urine) and that extends into the perirenal space. Mild dilatation of the proximal ureter (short arrow), which contains a small amount of air, likely is due to recent surgery. (c) Axial contrast-enhanced CT image obtained during the excretory phase of the examination shows an accumulation of contrast material in the perinephric space, a finding that established the presence of a urinary leak. Leakage ceased after placement of a ureteral stent.
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Figure 9b. Urinary leak at the incision site in a 68-year-old man after an open left partial nephrectomy. (a) Preoperative axial contrast-enhanced CT image demonstrates a solid enhanced mass (arrow), which was surgically proved to be a renal cell carcinoma, in the left kidney. (b) Axial contrast-enhanced CT image obtained during the nephrographic phase of enhancement, 5 days after surgery, demonstrates a postoperative defect in the renal parenchyma (long arrow) that contains fluid (urine) and that extends into the perirenal space. Mild dilatation of the proximal ureter (short arrow), which contains a small amount of air, likely is due to recent surgery. (c) Axial contrast-enhanced CT image obtained during the excretory phase of the examination shows an accumulation of contrast material in the perinephric space, a finding that established the presence of a urinary leak. Leakage ceased after placement of a ureteral stent.
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Figure 9c. Urinary leak at the incision site in a 68-year-old man after an open left partial nephrectomy. (a) Preoperative axial contrast-enhanced CT image demonstrates a solid enhanced mass (arrow), which was surgically proved to be a renal cell carcinoma, in the left kidney. (b) Axial contrast-enhanced CT image obtained during the nephro-graphic phase of enhancement, 5 days after surgery, demonstrates a postoperative defect in the renal parenchyma (long arrow) that contains fluid (urine) and that extends into the perirenal space. Mild dilatation of the proximal ureter (short arrow), which contains a small amount of air, likely is due to recent surgery. (c) Axial contrast-enhanced CT image obtained during the excretory phase of the examination shows an accumulation of contrast material in the perinephric space, a finding that established the presence of a urinary leak. Leakage ceased after placement of a ureteral stent.
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Figure 10a. Urinoma in a 56-year-old man 1 year after an open left partial nephrectomy. (a) Coronal reformatted CT image shows a fluid collection (arrows) superior to the left kidney, at the partial nephrectomy site. (b) Axial contrast-enhanced CT image obtained during the nephrographic phase of enhancement depicts a fluid collection in the left renal fossa, as well as several surgical clips (arrows). (c) Axial contrast-enhanced CT image, obtained 45 minutes after the injection of contrast material, shows higher overall attenuation in the fluid collection and a fluid-contrast level (arrow) indicative of a communication with the collecting system. These features are diagnostic of a urinoma.
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Figure 10b. Urinoma in a 56-year-old man 1 year after an open left partial nephrectomy. (a) Coronal reformatted CT image shows a fluid collection (arrows) superior to the left kidney, at the partial nephrectomy site. (b) Axial contrast-enhanced CT image obtained during the nephrographic phase of enhancement depicts a fluid collection in the left renal fossa, as well as several surgical clips (arrows). (c) Axial contrast-enhanced CT image, obtained 45 minutes after the injection of contrast material, shows higher overall attenuation in the fluid collection and a fluid-contrast level (arrow) indicative of a communication with the collecting system. These features are diagnostic of a urinoma.
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Figure 10c. Urinoma in a 56-year-old man 1 year after an open left partial nephrectomy. (a) Coronal reformatted CT image shows a fluid collection (arrows) superior to the left kidney, at the partial nephrectomy site. (b) Axial contrast-enhanced CT image obtained during the nephrographic phase of enhancement depicts a fluid collection in the left renal fossa, as well as several surgical clips (arrows). (c) Axial contrast-enhanced CT image, obtained 45 minutes after the injection of contrast material, shows higher overall attenuation in the fluid collection and a fluid-contrast level (arrow) indicative of a communication with the collecting system. These features are diagnostic of a urinoma.
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Recurrent Tumor
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At partial nephrectomy, a small portion of the normal renal parenchyma is excised with the tumor to ensure an adequate resection and a tumor-free margin. If an adequate margin is not obtained and surgical excision is incomplete, the growth of any remaining neoplastic cells at the resection site over time may result in tumor recurrence in the surgical bed. Even if a tumor is completely excised, it may recur if tumor cells are spilled into the surgical field at the time of resection (Fig 11). Alternatively, in a patient with multiple foci of disease, an apparent tumor recurrence may actually be an additional preexistent renal cell carcinoma that either was not depicted at preoperative imaging or was not identified intraoperatively (13).
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Figure 11a. Recurrent neoplasm in a 65-year-old man after a laparoscopic left partial nephrectomy. (a) Preoperative axial gadolinium-enhanced T1-weighted fat-suppressed MR image demonstrates a 2-cm-diameter solid heterogeneously enhanced mass in the left kidney. Pathologic analysis of the surgical specimen revealed a renal cell carcinoma with surgical margins free of tumor cells. (b) Axial contrast-enhanced CT image, obtained 11 months after surgery, reveals a 2.2-cm-diameter solid enhanced mass (small arrow) at the postoperative site in the lateral aspect of the left kidney, a finding consistent with a recurrent neoplasm, as well as a tumor implant (large arrow) in the perinephric space. The patient subsequently underwent a radical nephrectomy, at which the imaging findings were confirmed.
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Figure 11b. Recurrent neoplasm in a 65-year-old man after a laparoscopic left partial nephrectomy. (a) Preoperative axial gadolinium-enhanced T1-weighted fat-suppressed MR image demonstrates a 2-cm-diameter solid heterogeneously enhanced mass in the left kidney. Pathologic analysis of the surgical specimen revealed a renal cell carcinoma with surgical margins free of tumor cells. (b) Axial contrast-enhanced CT image, obtained 11 months after surgery, reveals a 2.2-cm-diameter solid enhanced mass (small arrow) at the postoperative site in the lateral aspect of the left kidney, a finding consistent with a recurrent neoplasm, as well as a tumor implant (large arrow) in the perinephric space. The patient subsequently underwent a radical nephrectomy, at which the imaging findings were confirmed.
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The surgical field of view during laparoscopic partial nephrectomy is limited, and the surgeon can see only a small portion of the kidney. This limitation may lead to a failure to identify a specific small renal tumor if there is more than one small lesion in the vicinity. In this situation, a tiny incidental lesion that was not detected on preoperative images might be surgically resected, and the small tumor that was detected at imaging may not be seen; it may be left in place and subsequently discovered at the follow-up examination. Unless previous imaging studies are carefully reviewed, the latter then might be misidentified as a recurrent lesion (Fig 12).
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Figure 12a. Misidentification of a lesion in a 62-year-old woman after a laparoscopic partial nephrectomy. (a) Preoperative axial contrast-enhanced CT image demonstrates a 1-cm-diameter solid enhanced mass (arrow) that protrudes from the posterior aspect of the left kidney. (b) Axial gadolinium-enhanced T1-weighted fat-suppressed MR image, obtained a few months after surgery, depicts a renal mass (arrow), apparently the same lesion as in a, in the posterior aspect of the left kidney. (c) Axial gadolinium-enhanced T1-weighted fat-suppressed MR image, at a level 2 cm below that in b, demonstrates postoperative changes (arrow) in the lateral aspect of the left kidney. (d) Preoperative CT scan, evaluated retrospectively, shows a nonspecific minimal bump (arrow) in the same location as the postoperative changes in c. The bump is believed to have been mistaken for the 1-cm-diameter lesion and resected at laparoscopic surgery. Pathologic analysis of the surgical specimen showed that it was a benign fibroma. The patient decided against further surgery and is undergoing regular follow-up examinations.
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Figure 12b. Misidentification of a lesion in a 62-year-old woman after a laparoscopic partial nephrectomy. (a) Preoperative axial contrast-enhanced CT image demonstrates a 1-cm-diameter solid enhanced mass (arrow) that protrudes from the posterior aspect of the left kidney. (b) Axial gadolinium-enhanced T1-weighted fat-suppressed MR image, obtained a few months after surgery, depicts a renal mass (arrow), apparently the same lesion as in a, in the posterior aspect of the left kidney. (c) Axial gadolinium-enhanced T1-weighted fat-suppressed MR image, at a level 2 cm below that in b, demonstrates postoperative changes (arrow) in the lateral aspect of the left kidney. (d) Preoperative CT scan, evaluated retrospectively, shows a nonspecific minimal bump (arrow) in the same location as the postoperative changes in c. The bump is believed to have been mistaken for the 1-cm-diameter lesion and resected at laparoscopic surgery. Pathologic analysis of the surgical specimen showed that it was a benign fibroma. The patient decided against further surgery and is undergoing regular follow-up examinations.
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Figure 12c. Misidentification of a lesion in a 62-year-old woman after a laparoscopic partial nephrectomy. (a) Preoperative axial contrast-enhanced CT image demonstrates a 1-cm-diameter solid enhanced mass (arrow) that protrudes from the posterior aspect of the left kidney. (b) Axial gadolinium-enhanced T1-weighted fat-suppressed MR image, obtained a few months after surgery, depicts a renal mass (arrow), apparently the same lesion as in a, in the posterior aspect of the left kidney. (c) Axial gadolinium-enhanced T1-weighted fat-suppressed MR image, at a level 2 cm below that in b, demonstrates postoperative changes (arrow) in the lateral aspect of the left kidney. (d) Preoperative CT scan, evaluated retrospectively, shows a nonspecific minimal bump (arrow) in the same location as the postoperative changes in c. The bump is believed to have been mistaken for the 1-cm-diameter lesion and resected at laparoscopic surgery. Pathologic analysis of the surgical specimen showed that it was a benign fibroma. The patient decided against further surgery and is undergoing regular follow-up examinations.
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Figure 12d. Misidentification of a lesion in a 62-year-old woman after a laparoscopic partial nephrectomy. (a) Preoperative axial contrast-enhanced CT image demonstrates a 1-cm-diameter solid enhanced mass (arrow) that protrudes from the posterior aspect of the left kidney. (b) Axial gadolinium-enhanced T1-weighted fat-suppressed MR image, obtained a few months after surgery, depicts a renal mass (arrow), apparently the same lesion as in a, in the posterior aspect of the left kidney. (c) Axial gadolinium-enhanced T1-weighted fat-suppressed MR image, at a level 2 cm below that in b, demonstrates postoperative changes (arrow) in the lateral aspect of the left kidney. (d) Preoperative CT scan, evaluated retrospectively, shows a nonspecific minimal bump (arrow) in the same location as the postoperative changes in c. The bump is believed to have been mistaken for the 1-cm-diameter lesion and resected at laparoscopic surgery. Pathologic analysis of the surgical specimen showed that it was a benign fibroma. The patient decided against further surgery and is undergoing regular follow-up examinations.
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Infection
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A fluid collection (urinoma or hematoma) in the surgical bed may become infected, and an abscess may develop as a result (Fig 13). With imaging alone, it may be difficult to differentiate an infected fluid collection from an uninfected one. Moreover, as mentioned earlier, the presence of air bubbles in a bioabsorbable hemostatic agent may further complicate the interpretation of imaging studies. However, patients with a postoperative abscess are likely to manifest clinical symptoms and signs (eg, fever and an elevated white blood cell count) suggestive of infection; in such cases, a needle aspiration is performed for laboratory analysis, followed by drainage if necessary. In addition, patients who have undergone a partial nephrectomy may present with pyelonephritis, which may appear as a striated or heterogeneous nephrogram and may be difficult to differentiate from renal infarction on images alone (Fig 14b).
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Figure 13a. Abscess in a 64-year-old man after an open left partial nephrectomy. (a) Preoperative axial gadolinium-enhanced fat-suppressed MR image shows a solid enhanced mass that abuts a calyx of the left kidney. The mass proved to be an oncocytoma. (b) Axial contrast-enhanced CT image, obtained 3 weeks after surgery, depicts a fluid and gas collection, which has a thickened wall, in the left perinephric space just inferior to the surgical bed. This finding was consistent with a postoperative abscess. The abscess was drained percutaneously.
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Figure 13b. Abscess in a 64-year-old man after an open left partial nephrectomy. (a) Preoperative axial gadolinium-enhanced fat-suppressed MR image shows a solid enhanced mass that abuts a calyx of the left kidney. The mass proved to be an oncocytoma. (b) Axial contrast-enhanced CT image, obtained 3 weeks after surgery, depicts a fluid and gas collection, which has a thickened wall, in the left perinephric space just inferior to the surgical bed. This finding was consistent with a postoperative abscess. The abscess was drained percutaneously.
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Figure 14a. Laceration of the liver and pyelonephritis in a 45-year-old woman after a laparoscopic right partial nephrectomy. (a) Preoperative coronal multiplanar reformatted CT image demonstrates a renal neoplasm at the lower pole of the right kidney, in close proximity to the liver. (b) Axial contrast-enhanced CT image, obtained 5 days after surgery because of fever and flank pain, depicts a heterogeneous right nephrogram with multiple areas of decreased attenuation (arrows). In conjunction with the symptoms of fever and flank pain, these findings are consistent with pyelonephritis, although small areas of infarction might have a similar CT appearance. (c) Axial contrast-enhanced CT image obtained during the same examination, at a level inferior to that in b, shows a laceration of the inferior right lobe of the liver and a small hematoma. The laceration is presumably secondary to inadvertent trauma to the liver at the time of surgery. The low-attenuation regions in the kidney are consistent with pyelonephritis.
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Figure 14b. Laceration of the liver and pyelonephritis in a 45-year-old woman after a laparoscopic right partial nephrectomy. (a) Preoperative coronal multiplanar reformatted CT image demonstrates a renal neoplasm at the lower pole of the right kidney, in close proximity to the liver. (b) Axial contrast-enhanced CT image, obtained 5 days after surgery because of fever and flank pain, depicts a heterogeneous right nephrogram with multiple areas of decreased attenuation (arrows). In conjunction with the symptoms of fever and flank pain, these findings are consistent with pyelonephritis, although small areas of infarction might have a similar CT appearance. (c) Axial contrast-enhanced CT image obtained during the same examination, at a level inferior to that in b, shows a laceration of the inferior right lobe of the liver and a small hematoma. The laceration is presumably secondary to inadvertent trauma to the liver at the time of surgery. The low-attenuation regions in the kidney are consistent with pyelonephritis.
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Figure 14c. Laceration of the liver and pyelonephritis in a 45-year-old woman after a laparoscopic right partial nephrectomy. (a) Preoperative coronal multiplanar reformatted CT image demonstrates a renal neoplasm at the lower pole of the right kidney, in close proximity to the liver. (b) Axial contrast-enhanced CT image, obtained 5 days after surgery because of fever and flank pain, depicts a heterogeneous right nephrogram with multiple areas of decreased attenuation (arrows). In conjunction with the symptoms of fever and flank pain, these findings are consistent with pyelonephritis, although small areas of infarction might have a similar CT appearance. (c) Axial contrast-enhanced CT image obtained during the same examination, at a level inferior to that in b, shows a laceration of the inferior right lobe of the liver and a small hematoma. The laceration is presumably secondary to inadvertent trauma to the liver at the time of surgery. The low-attenuation regions in the kidney are consistent with pyelonephritis.
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Technical Factors
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During partial nephrectomy, the liver or spleen may be inadvertently lacerated or contused by retractors and other surgical instruments used to keep adjacent organs away from the surgical field. Such injuries may be detected with CT and MR imaging (Fig 14a, 14c). In addition, hernias may occur at the incision site and may contain portions of the bowel or other abdominal organs (12) (Fig 15).
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Figure 15. Right flank hernia in a 63-year-old man 1 year after an open right partial nephrectomy. Gadolinium-enhanced T1-weighted fat-suppressed MR image demonstrates a right flank hernia (arrow), secondary to the surgical procedure, that contains part of the colon. The right kidney is posteriorly located in the retroperitoneum. Atrophy of the kidneys, of unknown cause, is present.
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Conclusion
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Partial nephrectomy with either an open or a laparoscopic approach has become an accepted method of treatment in selected cases of renal cell carcinoma.
Familiarity with the normal postoperative imaging features as well as the features that are indicative of complications is important for appropriate postoperative management.
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References
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- Rassweiler JJ, Abbou C, Janetschek G, Jeschke K. Laparoscopic partial nephrectomy: the European experience. Urol Clin North Am 2000;27:721–736.[CrossRef][Medline]
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Abstract
Introduction
