Extravasation After Injection of Methylene Blue into the Ureter or Collecting System
Direct injection of diluted methylene blue into an exposed segment of normal ureter (or directly into the renal pelvis if this has been exposed) can be used to demonstrate the integrity of the ureter, leakage of dye from a more distant section of ureter confirming the presence of an injury. Be careful, however, not to spill any of the dye, because if this occurs it stains the surrounding tissues, making it impossible to see a leak. There will be no leak of dye in a ligation injury so the methylene blue method will 'miss' such injuries.
On-Table Intravenous Urography and Retrograde Ureterography The conditions for performing on-table x-rays are not always ideal. The patient may be on an operating table through which x-rays cannot pass! The hospital portable x-ray C-arm may be in use or the radiographer may be busy elsewhere. In a shocked patient, possibly with a ureter obstructed by a ligature, contrast may not be excreted from the affected kidney in sufficient con-
5. TRAUMATIC UROLOGICAL EMERGENCIES 69
centration to allow interpretation of the IVU. The results of on-table intravenous urography have been reported in the context of renal trauma management (Morey et al. 1999). While not strictly comparable with iatrogenic ureteric injury, the results from the San Francisco General Hospital experience demonstrate the difficulty of determining the presence or absence of ureteric injuries using intravenous urography. In 50 patients undergoing on-table IVU, complete radiologic demonstration of one or both ureters was possible in only 36% of cases.
The technique of on-table IVU has been discussed elsewhere (p. 58).
Retrograde ureterography can be performed via an incision made in the bladder, or via a cystoscope. This is a very accurate method of establishing the presence or absence of a ureteric injury, and the contralateral ureter can easily be examined using this technique to exclude a bilateral injury. However, similar logistical problems can be encountered to those with on-table IVU. We use a 4 or 6 cm ureteric catheter, with a hole at the distal end but no side-holes, so that contrast flows up the ureter rather than leaking out of the ureter and into the bladder.