Laboratory Studies
Laboratory evaluation should include the following:
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Urinalysis
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Urine culture
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Complete blood count
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Creatinine determination from the serum and drainage
Interestingly, hematuria is not a reliable finding in ureteral injuries. [33] Only 74% of cases involve gross or microscopic hematuria. [13] Absence of hematuria may occur with a completely transected ureter or partial transection of an adynamic segment.
Imaging Studies
Computed tomography
Computed tomography (CT) scanning is the criterion standard for evaluating abdominal injuries due to blunt trauma in stable patients. Contrast-enhanced CT scanning is highly sensitive in detecting urine extravasation and thus can be considered the primary imaging modality to evaluate for ureteral integrity in the stable patient. However, delayed imaging at least 10-15 minutes after contrast injection must be performed to adequately evaluate for urine extravasation.
Delayed images must be obtained if the clinician has an index of suspicion because subtle findings on initial CT scanning can suggest ureteral or ureteropelvic junction injury. Findings on early or noncontrast images that may raise suspicion of ureteral or renal pelvis injury include the following [34] :
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Perinephric stranding
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Low-density fluid around the kidney and ureters
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Perinephric hematomas
Excretory urography or intravenous pyelography
Formal intravenous pyelography (IVP) is not appropriate in the acute setting. However, in patients who must undergo immediate exploratory laparotomy for a penetrating injury to the abdomen, the ureters may be evaluated with a one-shot IVP. This is performed by obtaining a single anterior-posterior abdominal film on the gurney or operating room table 10 minutes after the intravenous injection of a 2 mL/kg (maximum of 150 mL) bolus of contrast medium. The advantage of this study is that, when performed correctly, surgical intervention is not delayed, allowing for concurrent assessment of renal function and staging of upper urinary tract injuries.
Findings suggestive of an injury include the following:
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Delayed renal function or excretion
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Ureteral dilatation or deviation
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Extravasation of contrast
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Nonvisualization of the ureter
Unfortunately, this study yields a wide range of sensitivity, from 0% to 100%, with an average of 61%. [13] As a result, negative findings do not preclude the surgical exploration of the ureter if damage is suspected, but completely normal findings indicate that significant ureteral injury is unlikely. Intraoperative single-shot IVP cannot reliably exclude ureteral injury and should not be used solely for this purpose. [35]
Retrograde pyelography
Retrograde pyelography (RPG) is the most sensitive radiographic study for the diagnosis of ureteral injury. It is not always appropriate for use in the acute setting but may be used in the stable patient as an adjunct to other imaging modalities when other clinical information is needed. It has the added advantage of facilitating the placement of a ureteral stent in the same session, if indicated.
Antegrade ureterography
Antegrade ureterography is not routinely used in diagnosing ureteral injuries. It is useful in conjunction with percutaneous nephrostomy tube placement, or placement of an antegrade ureteral stent.
Magnetic resonance imaging
Cost and time has precluded the widespread use of magnetic resonance imaging (MRI) in the acute, particularly, traumatic situation. MR urography (MRU) is a more recent imaging concept in evaluating the urinary tract. In MRU, a low-dose diuretic injection is used to enhance excretion of the contrast agent gadopentetate dimeglumine. MRU sequences are generally repeated 5 and 15 min after contrast agent injection. T2-weighted sequences have been shown to be rapid, safe, and noninvasive for reliable depiction of the urinary tract while avoiding exposure to ionizing radiation and iodinated contrast agents. [36, 37]
Delayed imaging
Delayed presentation of ureteral injuries or those missed on initial presentation may be suggested by signs such as fever, leukocytosis, local peritoneal irritation, and leakage of urine from the wound. These should be evaluated with CT scanning, but RPG may ultimately be necessary.
Diagnostic Procedures
Surgical exploration of the retroperitoneum with direct visualization of the ureter is the best method of diagnosing ureteral injury. An average of 89.3% of ureteral injuries are detected with intraoperative inspection. [38]
Inspection of the ureter involves mobilization of the ureter and visualization of the entire wall for evidence of contusion, hemorrhage, or disruption. Neither blind palpation nor observation of ureteral peristalsis is a reliable indicator of a healthy ureter.
Intravenous indigo carmine or methylene blue injection is a useful adjunct with simultaneous inspection for ureteral dye leakage. Alternately, 1-2 mL can be injected directly in the renal pelvis with a 27-gauge needle and the ureter examined for leakage. This is particularly helpful in patients with hypotension in whom intravenous dye may not be excreted efficiently. The lack of dye extravasation is only guardedly reassuring, as a damaged ureteral wall may not leak immediately but may leak or extravasate later. This indicates the importance of visualization of the entire ureteral segment in question. In some cases, the dye itself may hinder diagnosis by staining local tissues and impeding visualization of the specific leakage points.
Injection of indocyanine green with fluorescence under near-infrared light can be used in assessment of the ureter. The indocyanine green can be instilled intralumenally in the ureter via an antegrade or retrograde approach to identify the source of an injury. It may also be injected intravenously to assess the viability and vascular supply of the ureter. [39, 40, 41, 42]
Gunshot wounds near the ureter warrant careful inspection of the entire ureteral wall for continuity, hemorrhage, and contusion. Indigo carmine or methylene blue may administered, as described above. If the bladder is already open, the dye may be injected in a retrograde fashion; otherwise, ureteral catheters may be passed up the ureter. If the catheter passes easily and no obvious defect in the continuity of the ureter is observed, a ureteral injury is unlikely.
Cystoscopy with retrograde pyelography is the best procedure for detecting ureteral injuries in the stable patient. In addition, it allows for ureteral stent placement in the same session, as indicated.
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Psoas hitch in ureteral trauma.
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Boari flap procedure in ureteral trauma.
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Ureteroureterostomy in ureteral trauma.
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Transureteroureterostomy in ureteral trauma.
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Complete ureteral replacement utilizing ileum in ureteral trauma.
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Ileovesical anastomosis. Bladder to the left, ileum to the right.
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Dual injury during hysterectomy. Combination transection of the right ureter with extravasation and left ureter ligation. Image from combined intraoperative intravenous pyelogram IVP and retrograde pyelogram.
