CT Cystography For Bladder Trauma

Bladder injury after blunt trauma is relatively uncommon, but needs to be identified promptly. Nearly every patient (97%+) with a bladder injury will have hematuria that is visible to the naked eye. This should prompt the trauma professional to obtain a CT of the abdomen/pelvis and a CT cystogram.

The CT of the abdomen and pelvis will identify any renal or ureteral (extremely rare!) source for the hematuria. The CT cystogram will demonstrate a bladder injury, but only if done properly!

During most trauma CT scanning of the abdomen and pelvis, the bladder is allowed to passively fill, either by having no urinary catheter and having the patient hold it, or by clamping the catheter if it is present. Unfortunately, this does not provide enough pressure to demonstrate small intraperitoneal bladder injuries and most extraperitoneal injuries.

The proper technique involves infusing contrast into the bladder through a urinary catheter. At least 350cc of dilute contrast solution must be instilled for proper distension and accurate diagnosis. This can be done prior to the abdominal scan. Once the initial scan has been obtained, the bladder must be emptied and a focused scan of just the bladder should be performed (post-void images). Several papers have shown that this technique is as accurate as conventional retrograde cystography, with 100% sensitivity and specificity for intraperitoneal ruptures. The sensitivity for extraperitoneal injury was slightly less at 93%.

Bottom line: Gross hematuria equals CT of the abdomen/pelvis and a proper CT cystogram, as described above. Don’t try to cheat and passively fill the bladder. You will miss about half of these injuries!

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Reference: CT cystography with multiplanar reformation for suspected bladder rupture: experience in 234 cases. Am J Roentgenol 187(5):1296-302, 2006.

Intraperitoneal bladder injury

Intraperitoneal bladder rupture

Extraperitoneal bladder

Extraperitoneal bladder injury

Consequences of Using O+ Blood For Initial Transfusion In Trauma Patients

Blood transfusion is one of those potentially life-saving procedures that we take for granted in major trauma patients. Even the ATLS course recommends it for patients presenting in hemorrhagic shock. Unfortunately, it took quite a bit of work in the late 1800’s and early 1900’s to figure out how to keep from killing people when giving them someone else’s blood.

We now have very good systems for making sure that blood is safe, and that the appropriate antigens and antibodies are compatible in order to avoid serious transfusion reactions. Unfortunately, a lot of that goes out the door when a trauma professional needs blood now! A crossmatch takes about 45 minutes, and even making sure the major blood types match (ABO and Rh) takes about 15 minutes once you factor in paperwork and transport times.

All trauma centers now have access to “universal donor” blood. In the purest sense, this is O- blood, since it has no antigens that can activate the recipient’s immune system. However, O- comprises only 6.6% of the US blood supply, and it is frequently in short supply in smaller hospitals. An alternative is to use O+ blood, which is much more readily available (37.4% of the US supply).

But doesn’t this pose a risk of hemolytic transfusion reaction to patients who are Rh-? And what about women of childbearing age developing Rh antibodies that could cause hemolytic disease of the newborn? The Maryland Shocktrauma Center published a paper that showed some interesting results. It was a retrospective review of the 5,623 patients they saw in the year 2000 (!). A total of 480 of those patients received 5,203 units of blood.

Here are the interesting factoids:

  • 161 received uncrossmatched O blood
  • There were no acute transfusion reactions 
  • 14 patients lived to receive full crossmatch with Rh
  • 4 females received O- and none developed antibodies
  • Of the 10 males who received O+ blood, only 1 developed persistent Rh antibodies. One other had transient antibodies that disappeared at later testing.

Bottom line: Although it looks big, this is really just a small series. However, it does agree with other similar studies (listed in the bibliography of this paper). The use of uncrossmatched blood in general, and O+ blood specificially for males does appear to be safe. The low number of Rh antibody conversions may be due to the immunosuppression that goes along with both major trauma and blood transfusion. Consideration should still be given to administering RhoGam to males who are found to be Rh- after receiving Rh+ blood.

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Reference: Safety of Uncrossmatched Type-O Red Cells for Resuscitation from Hemorrhagic Shock. J Trauma 59(6):1445-1449, 2005.

To Probe or Not To Probe: Penetrating Wounds

There is considerable variability in the way that penetrating wounds are approached. Some are located over areas of lesser importance (distal extremities) or are so superficial that they obviously don’t fully penetrate the skin.

Unfortunately, some involve high-value structures (much of the neck and torso), or are too small to tell if they penetrate (ice pick injury). How should these injuries be approached?

Too often, someone just probes the wound and makes a pronouncement based on that assessment. Unfortunately, there are major problems with this technique:

  • The tract may be too small to appreciate with a finger or even a cotton-tip swab
  • The tract may be oriented in an unexpected direction, or the soft tissues may have moved after the penetration occurred. In this case, the examiner may not appreciate any significant depth to the wound.
  • Inserting an object may violate a structure that you wish it hadn’t (resulting in a hissing sound after probing a chest wound, or a column of blood after probing the neck)

A better way to approach these wounds is as follows:

  • Is the patient unstable? If so, you know the penetration caused the problem and the patient belongs in the OR.
  • Is there other evidence of deep injury, such as peritonitis with a penetrating abdominal wound? If so, the patient still needs to go to the OR.
  • Do a legitimate local wound exploration. This entails making the hole bigger with a knife, and using surgical instruments and your eyes to find the bottom of the tract. Obviously, there are some parts of the body where this cannot be done, such as the face, but they probably don’t need this kind of workup anyway.

As one of my mentors, John Weigelt, used to say, “Doctor, do you have an eye on the end of your finger?” In general, don’t use anything that doesn’t involve an eyeball in your local wound explorations!

Taking X-Rays Through A Backboard

Most major trauma patients are transported to the trauma center on a backboard. And nearly all of them get at least a chest x-ray, and possibly a pelvis x-ray. But do the backboard and x-rays mix?

There seems to be a debate in our ED about the quality of x-rays obtained through a backboard. This has led to a push to hold the x-ray until the patient has been rolled and the board removed. Unfortunately, since we must wait and actually view the image before transporting the patient, this can lead to a delay in leaving the resuscitation room.

So what’s the problem? Most backboards are made of plastic these days, with very few metal parts. Even the strap buckles are usually plastic. And plastic is, for the most part, transparent to x-rays. Yes, if the board is thick it may lighten the image a bit. And if there are cutouts in it, they may show as darker areas. However, they tend to have smooth and regular borders that are easily distinguished from structures in the human body.

Bottom line: The densities and irregularities in backboards do not significantly degrade x-ray images. Remember, you are looking for large collections of air (pneumothorax) or fluid (hemothorax) in the chest, and major bony disruption in the pelvis. These are easily seen through a backboard, or even if parts of the body are off the edge of the image. Don’t wait to get those x-rays, have them done as early as possible so you can view them and move on to the next phase of care.

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