This is the current release of the guideline.

This guideline updates a previous version: Sandler CM, Francis IR, Baumgarten DA, Bluth EI, Bush WH Jr, Casalino DD, Curry NS, Israel GM, Jafri SZ, Kawashima A, Papanicolaou N, Remer EM, Spring DB, Fulgham P, Expert Panel on Urologic Imaging. Renal trauma. [online publication]. Reston (VA): American College of Radiology (ACR); 2007. 4 p. [24 references]

The appropriateness criteria are reviewed biennially and updated by the panels as needed, depending on introduction of new and highly significant scientific evidence.

Renal trauma

To evaluate the appropriateness of radiologic procedures in the differential diagnosis and evaluation of renal trauma

Patients with renal trauma

Utility of radiologic procedures in evaluation of renal trauma

Literature Search Procedure

The Medline literature search is based on keywords provided by the topic author. The two general classes of keywords are those related to the condition (e.g., ankle pain, fever) and those that describe the diagnostic or therapeutic intervention of interest (e.g., mammography, MRI).

The search terms and parameters are manipulated to produce the most relevant, current evidence to address the American College of Radiology Appropriateness Criteria (ACR AC) topic being reviewed or developed. Combining the clinical conditions and diagnostic modalities or therapeutic procedures narrows the search to be relevant to the topic. Exploding the term "diagnostic imaging" captures relevant results for diagnostic topics.

The following criteria/limits are used in the searches.

1. Articles that have abstracts available and are concerned with humans.
2. Restrict the search to the year prior to the last topic update or in some cases the author of the topic may specify which year range to use in the search. For new topics, the year range is restricted to the last 5 years unless the topic author provides other instructions.
3. May restrict the search to Adults only or Pediatrics only.
4. Articles consisting of only summaries or case reports are often excluded from final results.

The search strategy may be revised to improve the output as needed.

The total number of source documents identified as the result of the literature search is not known.

Strength of Evidence Key

Category 1 - The conclusions of the study are valid and strongly supported by study design, analysis, and results.

Category 2 - The conclusions of the study are likely valid, but study design does not permit certainty.

Category 3 - The conclusions of the study may be valid, but the evidence supporting the conclusions is inconclusive or equivocal.

Category 4 - The conclusions of the study may not be valid because the evidence may not be reliable given the study design or analysis.

The topic author drafts or revises the narrative text summarizing the evidence found in the literature. American College of Radiology (ACR) staff draft an evidence table based on the analysis of the selected literature. These tables rate the strength of the evidence for all articles included in the narrative text.

The expert panel reviews the narrative text, evidence table, and the supporting literature for each of the topic-variant combinations and assigns an appropriateness rating for each procedure listed in the table. Each individual panel member forms his/her own opinion based on his/her interpretation of the available evidence.

More information about the evidence table development process can be found in the American College of Radiology (ACR) Appropriateness Criteria® Evidence Table Development document (see the "Availability of Companion Documents" field).

Modified Delphi Technique

When the data available from existing scientific studies are insufficient, the American College of Radiology Appropriateness Criteria (ACR AC) employs systematic consensus techniques to determine appropriateness. The ACR AC panels use a modified Delphi technique to determine the rating for a specific procedure. A series of surveys are conducted to elicit each individual panelist's expert opinion of the appropriateness of an imaging or therapeutic procedure for a specific clinical scenario based on the available data. ACR staff distributes surveys to the panelists along with the evidence table and narrative. Each panelist interprets the available evidence and rates each procedure. Voting surveys are completed by panelists without consulting other panelists. The ratings are integers on a scale between 1 and 9, where 1 means the panel member feels the procedure is "least appropriate" and 9 means the panel member feels the procedure is "most appropriate." Each panel member has one vote per round to assign a rating. The surveys are collected and de-identified and the results are tabulated and redistributed after each round. A maximum of three rounds are conducted. The modified Delphi technique enables each panelist to express individual interpretations of the evidence and his or her expert opinion without excessive bias from fellow panelists in a simple, standardized, and economical process.

Consensus among the panel members must be achieved to determine the final rating for each procedure. If eighty percent (80%) of the panel members agree on a single rating or one of two consecutive ratings, the final rating is determined by the rating that is closest to the median of all the ratings. Up to three voting rounds are conducted to achieve consensus.

If consensus is not reached through the modified Delphi technique, the panel is convened by conference call. The strengths and weaknesses of each imaging examination or procedure are discussed and a final rating is proposed. If the panelists on the call agree, the rating is accepted as the panel's consensus. The document is circulated to all the panelists to make the final determination. If consensus cannot be reached, "No consensus" appears in the rating column and the reasons for this decision are added to the comment sections.

Not applicable

A formal cost analysis was not performed and published cost analyses were not reviewed.

Criteria developed by the Expert Panels are reviewed by the American College of Radiology (ACR) Committee on Appropriateness Criteria.

Note from the American College of Radiology (ACR) and the National Guideline Clearinghouse (NGC): ACR has updated its Relative Radiation Level categories and Rating Scale. The Rating Scale now includes categories (1,2,3 = Usually not appropriate; 4,5,6 = May be appropriate; 7,8,9 = Usually appropriate). See the original guideline document for details.

ACR Appropriateness Criteria®

Clinical Condition: Renal Trauma

Variant 1: Blunt abdominal trauma with microscopic hematuria; no suspicion of associated abdominal injury.

Note: Abbreviations used in the tables are listed at the end of the "Major Recommendations" field.

Variant 2: Blunt abdominal injury; suspicion of multisystem trauma, with hematuria.

Note: Abbreviations used in the tables are listed at the end of the "Major Recommendations" field.

Variant 3: Penetrating abdominal injury; suspicion of multisystem trauma, with or without hematuria.

Note: Abbreviations used in the tables are listed at the end of the "Major Recommendations" field.

Summary of Literature Review

No single method of imaging evaluation can be uniformly applied to all patients suspected of suffering abdominal trauma. The exact approach depends not only on the types of injuries the patient has likely suffered, but also on the philosophy of the attending physicians, local practice, and the type of equipment and support available. Moreover, the evaluation of a suspected renal injury cannot be isolated from the evaluation of other suspected intra-abdominal injuries. A variety of different approaches to a given patient may therefore be acceptable.

Most closed upper urinary tract injury occurs after wide-impact blunt abdominal trauma, usually after sudden deceleration (motor vehicle accident) or crash injury (fall from height). The incidence of penetrating injuries from either a gunshot wound or a stab wound is variable but may be associated with more severe renal injuries. Regardless of the mechanism, the majority of serious renal injuries are associated with injuries to other organs that may dominate the clinical picture. Isolated renal injuries after blunt trauma are rare, and the majority are relatively minor in most published series. In a series by a group of researchers, 241 of 831 patients had what were considered to be solitary renal injuries; however, the vast majority (98%) were minor injuries. Therefore, only five patients in the entire series suffered significant isolated renal injury, but there were 33 significant renal injuries in the group of 590 patients with hematuria who suffered multisystem trauma.

Other injuries associated with injury of the kidneys following multisystem blunt trauma include (in order of decreasing frequency) fractures of the extremities, thoracic injury, pelvic fracture, intra-abdominal injury, head injuries, and diaphragmatic rupture. In the abdomen, injuries to the liver and spleen are most commonly associated with renal injury, followed by injury to the pancreas, the colon, and the small bowel.

Renal injuries are classified into grades 1 to 5 based on the severity of the injury according to the American Association for the Surgery of Trauma organ injury severity scale.

Hematuria is a characteristic sign of renal trauma. However, there is no correlation between the degree of hematuria and the severity of the renal injury. The amount of hematuria that should trigger radiologic investigation of the urinary tract after localized blunt trauma is controversial.

One group of investigators found that significant renal injury was limited to the group of patients in whom shock and either gross or microscopic hematuria was present among 306 individuals analyzed retrospectively following blunt trauma. There were no significant renal injuries among the 221 patients who had microscopic hematuria but were not suffering from shock. In patients in the same series who suffered penetrating injuries, however, no such discrimination was possible, and the authors suggest radiologic evaluation of all patients suffering penetrating injury and any degree of hematuria. These observations have now been confirmed in multiple additional studies, both retrospectively and prospectively. It can therefore be concluded that investigation of hematuria is warranted in patients with suspected isolated renal injury who 1) have penetrating injury, 2) have gross hematuria, 3) have microscopic hematuria with shock (systolic pressure less than 90 mm Hg in the field or during resuscitation), or 4) are suspected of having major associated intra-abdominal injury.

On the other hand, the absence of hematuria does not exclude the presence of a significant renal injury. In a series of 396 patients suffering renal injury after falling from a height, 20.8% (5 out of 24) of patients with grade 2 to 4 renal injuries had no hematuria. In another study of patients with renovascular injuries, the authors reported that hematuria was absent in 18% of cases.

Computed Tomography

It is now well established that computed tomography (CT) of the abdomen is the screening study of choice for suspected intra-abdominal injury. Multidetector CT (MDCT) has been shown to be a rapid and accurate method for detecting the presence of and grading the extent of abdominal injuries, and it allows for optimal treatment planning. When available, CT is the examination of choice to evaluate the hemodynamically stable patient with blunt or penetrating trauma to the abdomen. Many trauma surgeons still regard diagnostic peritoneal lavage (DPL) as a viable method for detecting intraperitoneal hemorrhage. DPL is sensitive, easy to perform, and universally available; however, it does not differentiate inconsequential bleeding from that which requires laparotomy and, more importantly, cannot detect the site of the bleeding or retroperitoneal injuries. It is now considered an adjunct diagnostic method, particularly if intestinal and mesenteric injuries are suspected or if CT or ultrasound (US) is not available. CT is much more specific than DPL for both intraperitoneal and retroperitoneal injuries.

CT is now playing a major role in guiding management of patients with renal trauma. One study reported that early CT evaluation allowed confident nonoperative management in 17 of 22 patients with renal injuries. Another study found nonoperative management was effective in 50% of patients with grade 4 or 5 injuries who were hemodynamically stable. Another group of researchers reviewed outcomes in 517 patients with renal artery injuries and reported shorter hospital stays in patients who were observed compared to those treated with nephrectomy or surgical revascularization. Additionally, expectant management has been shown to decrease the number of iatrogenic nephrectomies. Many authorities now believe that with accurate preoperative CT, renal exploration need not be performed unless there are major devitalized fragments with associated bowel or pancreatic injury or unless the patient becomes hemodynamically unstable from a major renal laceration and is not manageable by angiographic embolization.

Ultrasound

Because CT is expensive, not universally available on an immediate basis, and exposes many young patients to ionizing radiation, focused abdominal sonography for trauma (FAST) has been touted by some as an alternative to CT. This method, originally pioneered in Europe, has now been advocated by many in the United States. One potential limitation of FAST is that it requires the presence of a qualified sonographer and/or physician to perform and interpret the study. A sensitivity of 98% for detecting free fluid with a specificity of 99% has been reported for US; this same study reported 100% sensitivity and specificity and a positive predictive value for US in detecting renal injuries. The series, however, included only three patients with renal injuries.

The value of FAST in screening abdominal trauma patients has been recently confirmed by several large studies. One study reported that among 3,679 patients with negative findings on US, 99.9% were confirmed as true negative by clinical or radiographic follow-up. In another series of 4,029 patients suffering from blunt abdominal trauma, the accuracy of FAST was reported to be 95%. The authors concluded that hypotensive patients with positive FAST could be triaged directly to laparotomy, without need for CT. However, there is a statistically significant correlation between the presence of a falsely negative FAST US and an underlying pelvic fracture or a renal injury.

A significant limitation of US for imaging of renal trauma is that no functional information is provided. A review of the role of US in patients with renal trauma showed that only 22% of renal parenchymal abnormalities were identified prospectively and that abnormalities were detected more commonly with severe injuries. A more recent study of the role of US in diagnosing solid abdominal organ injuries reported a sensitivity of 45.7% and specificity of 64.1%. These numbers improve significantly if contrast-enhanced US is used; however, this technique is not available in the United States. There is little information concerning the use of color Doppler for assessing renal blood flow after trauma.

Intravenous Urography

In patients who are hemodynamically unstable, only limited information about the status of the urinary tract can generally be obtained. A single view of the abdomen following a large dose of intravenously administered contrast material ("one-shot" intravenous urography [IVU]) is generally all that can be obtained; such a study is insufficient to diagnose a renal injury but can give information about the location and status of the uninjured kidney(s). The value of these limited "one-shot" studies in unstable patients has been questioned; a retrospective review of 239 such studies showed that the preoperative urographic assessment of contralateral renal function played no role in the management of a renal injury. The authors of this study felt that delaying definitive therapy merely to obtain the urographic study was not justified.

Penetrating Injury

In patients who are suspected to have suffered a penetrating renal injury, CT is also the method of choice for assessment. In patients with limited posterior stab wounds, however, CT should be performed for assessment, since exploratory surgery is not mandatory.

In recent years, there has been a growing trend towards nonoperative management of renal injuries in the hemodynamically stable adult and pediatric patient. This practice is well established for managing blunt abdominal trauma and even after penetrating injuries in selective cases. CT thus becomes critically important for precise delineation of the nature and extent of injuries. The management of patients with penetrating renal injuries remains more controversial, although even in these cases there is a developing trend towards conservative management. This paradigm shift can be in large part attributed to the accurate staging of such injuries that is provided by CT.

Renal Angiography and Embolization

Another important trend is the use of arteriography and embolotherapy for nonoperative management of persistent or life-threatening traumatic renovascular injuries. Although arteriography has a high degree of specificity in detecting the bleeder, it is usually performed as part of a therapeutic embolization and directed towards a suspected abnormality detected on contrast-enhanced CT.

Both the Société Internationale d'Urologie and the European Association of Urology have published a consensus document on issues concerning the diagnosis and management of renal injuries. Its recommendations are not substantially different from those in this summary.

Summary

• Assessment of the nature and extent of the renal injury is most important in those patients in whom there will be an attempt to avoid exploratory surgery.
• In hemodynamically stable patients being assessed for wide-impact blunt injury in a major trauma center where CT is available immediately on a 24-hour basis, CT is the imaging method of choice and gold standard.
• In institutions where there would be a significant delay in obtaining high-quality CT, it is acceptable to use DPL or FAST to look for the presence of intraperitoneal fluid and "one-shot" IVU to assess the kidneys.
• In patients who suffer suspected anterior penetrating renal injury, CT should be used as a first-line study if radiographic assessment is desired. Similarly, CT is the study of choice to evaluate the effect of limited posterior stab wounds.
• The preferred treatment of patients with suspected isolated blunt renal injury is perhaps the most controversial issue. Most such patients do not have evidence of multisystem trauma but are suspected of renal injury because of hematuria. Studies have demonstrated that the incidence of significant renal injury in this group of patients is low; those with microscopic hematuria alone do not need any radiologic evaluation.

Anticipated Exceptions

In pregnant patients, US should be considered as a first-line study.

Abbreviations

• CT, computed tomography
• FAST, focused abdominal sonography for trauma
• Med, medium
• US, ultrasound

None provided

The recommendations are based on analysis of the current literature and expert panel consensus.

Selection of appropriate radiologic imaging procedures for evaluation of patients with renal trauma

There is a statistically significant correlation between the presence of a falsely negative focused abdominal sonography for trauma ultrasound (FAST US) and an underlying pelvic fracture or a renal injury.

Relative Radiation Level (RRL)

Potential adverse health effects associated with radiation exposure are an important factor to consider when selecting the appropriate imaging procedure. Because there is a wide range of radiation exposures associated with different diagnostic procedures, an RRL indication has been included for each imaging examination. The RRLs are based on effective dose, which is a radiation dose quantity that is used to estimate population total radiation risk associated with an imaging procedure. Additional information regarding radiation dose assessment for imaging examinations can be found in the American College of Radiology (ACR) Appropriateness Criteria® Radiation Dose Assessment Introduction document (see the "Availability of Companion Documents" field).

The American College of Radiology (ACR) Committee on Appropriateness Criteria and its expert panels have developed criteria for determining appropriate imaging examinations for diagnosis and treatment of specified medical condition(s). These criteria are intended to guide radiologists, radiation oncologists, and referring physicians in making decisions regarding radiologic imaging and treatment. Generally, the complexity and severity of a patient's clinical condition should dictate the selection of appropriate imaging procedures or treatments. Only those exams generally used for evaluation of the patient's condition are ranked. Other imaging studies necessary to evaluate other co-existent diseases or other medical consequences of this condition are not considered in this document. The availability of equipment or personnel may influence the selection of appropriate imaging procedures or treatments. Imaging techniques classified as investigational by the U.S. Food and Drug Administration (FDA) have not been considered in developing these criteria; however, study of new equipment and applications should be encouraged. The ultimate decision regarding the appropriateness of any specific radiologic examination or treatment must be made by the referring physician and radiologist in light of all the circumstances presented in an individual examination.

An implementation strategy was not provided.

Not applicable: The guideline was not adapted from another source.

The American College of Radiology (ACR) provided the funding and the resources for these ACR Appropriateness Criteria®.

Committee on Appropriateness Criteria, Expert Panel on Urologic Imaging

Panel Members: Sheila Sheth, MD (Principal Author); Isaac R. Francis, MD (Panel Chair); David D. Casalino, MD (Panel Vice-Chair); Ronald S. Arellano, MD; Deborah A. Baumgarten, MD, MPH; Nancy S. Curry, MD; Manjiri Dighe, MD; Pat Fulgham, MD; Gary M. Israel, MD; John R. Leyendecker, MD; Nicholas Papanicolaou, MD; Srinivasa Prasad, MD; Parvati Ramchandani, MD; Erick M. Remer, MD

Not stated

This is the current release of the guideline.

This guideline updates a previous version: Sandler CM, Francis IR, Baumgarten DA, Bluth EI, Bush WH Jr, Casalino DD, Curry NS, Israel GM, Jafri SZ, Kawashima A, Papanicolaou N, Remer EM, Spring DB, Fulgham P, Expert Panel on Urologic Imaging. Renal trauma. [online publication]. Reston (VA): American College of Radiology (ACR); 2007. 4 p. [24 references]

The appropriateness criteria are reviewed biennially and updated by the panels as needed, depending on introduction of new and highly significant scientific evidence.

Electronic copies: Available in Portable Document Format (PDF) from the American College of Radiology (ACR) Web site.

Print copies: Available from the American College of Radiology, 1891 Preston White Drive, Reston, VA 20191. Telephone: (703) 648-8900.

The following are available:

• ACR Appropriateness Criteria®. Overview. Reston (VA): American College of Radiology; 2 p. Electronic copies: Available in Portable Document Format (PDF) from the American College of Radiology (ACR) Web site.
• ACR Appropriateness Criteria®. Literature search process. Reston (VA): American College of Radiology; 1 p. Electronic copies: Available in Portable Document Format (PDF) from the ACR Web site.
• ACR Appropriateness Criteria®. Evidence table development. Reston (VA): American College of Radiology; 4 p. Electronic copies: Available in Portable Document Format (PDF) from the ACR Web site.
• ACR Appropriateness Criteria®. Radiation dose assessment introduction. Reston (VA): American College of Radiology; 2 p. Electronic copies: Available in Portable Document Format (PDF) from the ACR Web site.
• ACR Appropriateness Criteria® Manual on contrast media. Reston (VA): American College of Radiology; 90 p. Electronic copies: Available in PDF from the ACR Web site.

None available

This summary was completed by ECRI on March 25, 1999. The information was verified by the guideline developer on September 9, 1999. This summary was updated by ECRI on February 12, 2002. It was verified again by the guideline developer on March 25, 2002. This summary was updated by ECRI on March 8, 2006. This NGC summary was updated by ECRI Institute on December 4, 2007. This NGC summary was updated by ECRI Institute on June 18, 2010.

Instructions for downloading, use, and reproduction of the American College of Radiology (ACR) Appropriateness Criteria® may be found on the ACR Web site .