Pediatric emergency medicine trisk 3317 3317
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Medial extravasation of contrast is often seen with UPJ ruptures and no
contrast will be seen in the distal ureter on delayed images of complete UPJ
avulsion. Historically, diagnosis of UPJ injuries was delayed in 50% of cases but
routine evaluation of trauma with CT, especially when delayed images are
obtained, has increased the initial detection rate to almost 90%.
Ultrasound
The focused assessment by sonography for trauma (FAST) is often used to
evaluate trauma patients for abdominal injuries and intra-abdominal fluid
collections. Despite the availability and low risk nature of sonography, this
modality has a low sensitivity (48%) for detecting renal injuries and often
overlooks significant damages.
The use of contrast-enhanced ultrasound has recently been reported to increase
the sensitivity to 69%, which is still inferior to the >90% sensitivity of CT.
Extravasation is also more difficult to visualize on ultrasound. Currently used
contrast preparations are not well excreted into the collecting system, limiting
evaluation in the trauma setting. This study is being utilized more often for
follow-up of parenchymal injuries, especially in stable patients.
Intravenous Urography
Although almost completely replaced by CT for evaluating stable trauma patients,
the intravenous urogram or pyelogram still maintains a role in evaluating the
unstable trauma patient taken directly to the operating room. The main utility of
this modality is to verify the presence of a functioning contralateral kidney. The
one-shot urogram is performed by giving a 2 mL/kg body weight contrast bolus
followed by plain film 10 minutes later. Identifying a functional contralateral
kidney is important first because every possible attempt should be made to save
the injured kidney if it is the only one. The injured kidney may lack contrast
uptake if there is a major vascular injury or demonstrate a delayed nephrogram
due to significant compression from a contained hematoma. An abnormal renal
outline, displacement of the bowel or ureter, and loss of the psoas margin are all
suggestive of renal injury and hematoma. Distinctive patterns of contrast
extravasation that raise concern of a possible UPJ injury include extravasation
medial or circumferential (circumferential urinoma) to the kidney. Also, with a
complete UPJ disruption, the ipsilateral ureter will lack intraluminal contrast. The
study is not particularly sensitive for picking up ureteral injuries.
