CT abdomen IV contrast vs IV & oral contrast

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What percent of the ED patients with acute gastroenteritis has air under the diaphragm?
What percentage of pneumoperitoneum patients have visible free air under the diaphragm on upright CXR?

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What percentage of pneumoperitoneum patients have visible free air under the diaphragm on upright CXR?
J Comput Assist Tomogr. 1992 Sep-Oct;16(5):713-6.

Diagnosis of pneumoperitoneum: abdominal CT vs. upright chest film.
Stapakis JC1, Thickman D.
Author information
Abstract

To compare the sensitivity of CT with upright chest radiography for the detection of free intraperitoneal air, we compared the results of these examinations performed on trauma patients who had introduction of intraperitoneal air from diagnostic peritoneal lavage (DPL). Thirteen patients were studied by abdominal CT within 24 h after DPL. Upright chest radiography was performed prior to abdominal CT or less than 4 h after abdominal CT. All patients demonstrated free air on abdominal CT. Only 5 of 13 (38%) patients demonstrated free air on plain radiography. The amount of free air demonstrated on CT was quantified into three groups. Upright chest radiography in the minimal group (less than three 1 mm pockets of air) was totally insensitive (0 of 2) in detecting free air. Upright chest radiography in the moderate group (greater than three 1 mm pockets, but less than 13 mm diameter collection of air) was 33% sensitive (3 of 9). Upright chest radiography in the large group (greater than 13 mm collection of air) was 100% sensitive (2 of 2). Abdominal CT is clearly superior to upright chest radiography in demonstrating free intraperitoneal air in this clinical setting.
 
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J Comput Assist Tomogr. 1992 Sep-Oct;16(5):713-6.

Diagnosis of pneumoperitoneum: abdominal CT vs. upright chest film.
Stapakis JC1, Thickman D.
Author information
Abstract

To compare the sensitivity of CT with upright chest radiography for the detection of free intraperitoneal air, we compared the results of these examinations performed on trauma patients who had introduction of intraperitoneal air from diagnostic peritoneal lavage (DPL). Thirteen patients were studied by abdominal CT within 24 h after DPL. Upright chest radiography was performed prior to abdominal CT or less than 4 h after abdominal CT. All patients demonstrated free air on abdominal CT. Only 5 of 13 (38%) patients demonstrated free air on plain radiography. The amount of free air demonstrated on CT was quantified into three groups. Upright chest radiography in the minimal group (less than three 1 mm pockets of air) was totally insensitive (0 of 2) in detecting free air. Upright chest radiography in the moderate group (greater than three 1 mm pockets, but less than 13 mm diameter collection of air) was 33% sensitive (3 of 9). Upright chest radiography in the large group (greater than 13 mm collection of air) was 100% sensitive (2 of 2). Abdominal CT is clearly superior to upright chest radiography in demonstrating free intraperitoneal air in this clinical setting.
I already knew the answer, was just hoping our IM colleague would look for the answer himself.
 
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The newer agents definitively cause less reactions but they do exist. The ACR contrast manual is the best resource for information on this. Part of the issue is poor documentation of prior allergies such as those with the mythical iodine allergy.
The ACR manual says they exist, but no pretreatment or prior evidence is relevant, because they're anaphylactoid. Getting the radiologists to agree to this is impossible, even though it's in their own manual.
 
What exactly are you advocating?

Pretreatment has only ever been shown to modestly reduce mild reactions. Pretreatment has not been found to impact rates of severe reactions.

In this study of nearly 500,000 scans only one death was observed, and the attribution of that death to contrast was debatable.

I won't speak for McNinja, but what I'm suggesting is that emergent scans not be delayed for pretreatment. If the indication for the scan is a potential emergency, then the benefit of pretreatment is eclipsed by the potential delay in diagnosis of an emergent condition.

Now, if you want to pretreat in scans that get scheduled 2 weeks ahead of time, then I have nothing to say about that.
 
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The ACR manual says they exist, but no pretreatment or prior evidence is relevant, because they're anaphylactoid. Getting the radiologists to agree to this is impossible, even though it's in their own manual.

I've worked at 1 hospital that does these. The rest say they cost too much and don't do them. So it's not exactly the same.

I'm a bit disappointed that these were the two snippets of my posts you decided to respond to.

How many patients have documented anaphylactic reactions to contrast vs. hx of contrast reaction that may be mild and not even related to the contrast?

If a scan is truly emergent (unstable vitals and clinically rapid deterioration) and contrast is absolutely needed with a history of anaphylaxis then I'll do it with a physician in the control room with appropriate MDM documentation of Benefits outweighs risk.

Most scans from the ER however are not truly emergent and alternatives such as MRI or even non contrast can be used to screen if contrast must be given for definitive diagnosis in the anaphylactic cases.

If a mild allergic reaction was documented, pre meds help. If it was a physiologic reaction then they get nothing.

Problem is people rarely document the reaction correctly or completely.

As for your second point, what percent of belly pain pts get CTs without you ever ordering labs that visit and how long does a BMP take to come back?
 
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I'm a bit disappointed that these were the two snippets of my posts you decided to respond to.
How many patients have documented anaphylactic reactions to contrast vs. hx of contrast reaction that may be mild and not even related to the contrast?
If a scan is truly emergent (unstable vitals and clinically rapid deterioration) and contrast is absolutely needed with a history of anaphylaxis then I'll do it with a physician in the control room with appropriate MDM documentation of risk outweighs benefit.
Most scans from the ER however are not truly emergent and alternatives such as MRI or even non contrast can be used to screen if contrast must be given for definitive diagnosis in the anaphylactic cases.
If a mild allergic reaction was documented, pre meds help. If it was a physiologic reaction then they get nothing.
Problem is people rarely document the reaction correctly or completely.
For the record, I don't disagree about not every scan being emergent. All the scans I order are. However, many of the scans are basically dictated to us by the admitting physician to be ordered before the patient can be admitted. So we are stuck, as getting an emergent MRI is out of the question for anything short of cauda equina, and getting a patient admitted for a diagnostic routine MRI is also impossible as they don't have any criteria for admission.
Of note, where I work, it isn't a documented contrast allergy about 95% of the time. It's either "shrimp", "shellfish", or "iodine". And even though the last isn't compatible with life, it's given dogmatic status for future imaging studies.
From the ACR
The mortality incidence related to intravascular ICM is unknown. In a large Japanese study by Katayama et al, no fatal reactions were attributed to LOCM despite greater than 170,000 injections. The conservative estimate of 1 fatality per 170,000 contrast media administrations is thus often quoted. Fatal reactions to LOCM have been reported. A meta-analysis performed by Caro et al documented a fatality rate of 0.9 per 100,000 injections of LOCM. A review of U.S. FDA and drug manufacturer data from 1990 to 1994 demonstrated 2.1 fatalities per 1 million contrast-enhanced studies using LOCM.
...
A prior allergic-like reaction to ICM is the most substantial risk factor for a recurrent allergic-like adverse event. Such a history is not an absolute predictor, and the incidence of recurrent allergic-like reactions in high-risk nonpremedicated patients is unknown.
So yeah, there's no reason to pretreat anyone in the emergency department. The data is spurious and anecdotal at best, but those are the battles we fight. Just like the PO contrast battle.

As for your second point, what percent of belly pain pts get CTs without you ever ordering labs that visit and how long does a BMP take to come back?
Zero belly pain patients get imaging without labs. Not that the labs always mean a whole lot, as CBC and Chemistries aren't sensitive enough to rule out pathology. A BMP takes at least an hour from the time the blood is collected, which may be another 30 minutes to an hour after they make the room or get triaged.

Of note, from your ACR manual on contrast media pertaining to CIN
At the current time, it is the position of ACR Committee on Drugs and Contrast Media that CIN is a real, albeit rare, entity. Published studies on CIN have been heavily contaminated by bias and conflation. Future investigations building on recent methodological advancements, are necessary to clarify the incidence and significance of this disease.
...
There is no agreed-upon threshold of serum creatinine elevation or eGFR declination beyond which the risk of CIN is considered so great that intravascular iodinated contrast medium should never be administered. In fact, since each contrast medium administration always implies a risk-benefit analysis for the patient, contrast medium administration for all patients should always be taken in the clinical context, considering all risks, benefits and alternatives.
All of us emergency physicians love the added "Study limited by lack of contrast" at the beginning of the report after we ordered for it to be given, spoke to the radiology tech, then spoke to the radiologist, and still couldn't get it done that way. But hey, keep on doing it your way.
 
For the record, I don't disagree about not every scan being emergent. All the scans I order are. However, many of the scans are basically dictated to us by the admitting physician to be ordered before the patient can be admitted. So we are stuck, as getting an emergent MRI is out of the question for anything short of cauda equina, and getting a patient admitted for a diagnostic routine MRI is also impossible as they don't have any criteria for admission.
Of note, where I work, it isn't a documented contrast allergy about 95% of the time. It's either "shrimp", "shellfish", or "iodine". And even though the last isn't compatible with life, it's given dogmatic status for future imaging studies.
You are trying to equate medically emergent with systemically emergent.
The unstable pt with suspected RP bleed and hgb of 5 is medically emergent.
The three days of belly pain with normal exam, vitals and labs is highly likely not medically emergent however it's systemically emergent because you need to dispo the patient.

Why are you trying patient getting a "diagnostic routine MRI" from the ER or by admission? It's either needed for the diagnosis/management of an admittable dx or it's an outpt issue. The pt is actually less likely to get a subspecialty radiologist read on their routine outpt problem when done through the ER during off hours.

Again the contrast allergy documentation is a systemic issue. Perhaps each time it comes up, clarify with the patient and correct it in the chart if necessary otherwise each time the pt comes back it's going to be unknown contrast allergy and protocols are followed.

So yeah, there's no reason to pretreat anyone in the emergency department. The data is spurious and anecdotal at best, but those are the battles we fight. Just like the PO contrast battle.

Zero belly pain patients get imaging without labs. Not that the labs always mean a whole lot, as CBC and Chemistries aren't sensitive enough to rule out pathology. A BMP takes at least an hour from the time the blood is collected, which may be another 30 minutes to an hour after they make the room or get triaged.

All of us emergency physicians love the added "Study limited by lack of contrast" at the beginning of the report after we ordered for it to be given, spoke to the radiology tech, then spoke to the radiologist, and still couldn't get it done that way. But hey, keep on doing it your way.

There is no reason to pretreat the "medically emergent" patient described above I agree.

If there is a history of mild allergic rxn then pretreatment helps but it takes 4 hours for the steroids to be effective and I'm guessing you don't want to wait that long in the "systemically emergent" patient described above, but you're already waiting 90 minutes for labs.

My point with the BMP was that perhaps that can be the focus of your fight with administration to decrease LOS because it's purely an economic tradeoff vs POC labs. If you get the Cr. back faster, we can scan faster using IV contrast which is more appropriate for abdominal pain (except stones). Foregoing contrast so you don't have to wait for labs is a disservice to the patient and makes both of us more likely to miss a diagnosis.

Study limited by lack of contrast is a factual medical statement. Sorry it annoys you so much but when you can't evaluate the vasculature or organ enhancement, the evaluation of those structures is indeed limited.

Seemingly a lot of your frustrations are with your local radiologists and systemic issues. Things disseminate slower into community practice than at academic centers and similarly at places with fewer interdisciplinary committees.

The whole point I was trying to drive home was that IV contrast is helpful in almost all abdominal CTs except stones and ordering 80% non contrast as quoted was not optimal care.
 
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What percentage of pneumoperitoneum patients have visible free air under the diaphragm on upright CXR?
Are you suggesting that either 1. You're going to forgo a chest xray? (I can get a portable chest generally quicker than a CT...) or 2. You're going to ignore free air on a CXR and get a CT anyways? Maybe I should have revised my comment to say it's the initial x-ray of choice. Regardless, as I mentioned earlier, if there's free air, no one is going to delay the stat surgery consult to wait for a CT.

Now, mind you, on the floor (including the unit) at my hospital getting a CT is harder because any ED CT, regardless of how minor, is generally placed before any floor CT regardless of how critical.
 
For the record, I don't disagree about not every scan being emergent. All the scans I order are. However, many of the scans are basically dictated to us by the admitting physician to be ordered before the patient can be admitted. So we are stuck, as getting an emergent MRI is out of the question for anything short of cauda equina, and getting a patient admitted for a diagnostic routine MRI is also impossible as they don't have any criteria for admission.
Of note, where I work, it isn't a documented contrast allergy about 95% of the time. It's either "shrimp", "shellfish", or "iodine". And even though the last isn't compatible with life, it's given dogmatic status for future imaging studies.
From the ACR

So yeah, there's no reason to pretreat anyone in the emergency department. The data is spurious and anecdotal at best, but those are the battles we fight. Just like the PO contrast battle.


Zero belly pain patients get imaging without labs. Not that the labs always mean a whole lot, as CBC and Chemistries aren't sensitive enough to rule out pathology. A BMP takes at least an hour from the time the blood is collected, which may be another 30 minutes to an hour after they make the room or get triaged.

Of note, from your ACR manual on contrast media pertaining to CIN

All of us emergency physicians love the added "Study limited by lack of contrast" at the beginning of the report after we ordered for it to be given, spoke to the radiology tech, then spoke to the radiologist, and still couldn't get it done that way. But hey, keep on doing it your way.
Dude, I'm not arguing with your points, but, man, do you sound pugnacious. Well, to me, at least.

I am my radiologist's favorite doctor, simply because I'm not a **** up. I just stand there, and my colleagues shoot the bed on their own accord. But, I always defer to my rads buddy. Maybe that's just me.
 
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I'm going to have to address this in parts.
You are trying to equate medically emergent with systemically emergent.
The unstable pt with suspected RP bleed and hgb of 5 is medically emergent.
No argument
The three days of belly pain with normal exam, vitals and labs is highly likely not medically emergent however it's systemically emergent because you need to dispo the patient.
I don't scan that patient. I know you probably see a fair number of these scans, it's not my routine.

Why are you trying patient getting a "diagnostic routine MRI" from the ER or by admission? It's either needed for the diagnosis/management of an admittable dx or it's an outpt issue. The pt is actually less likely to get a subspecialty radiologist read on their routine outpt problem when done through the ER during off hours.
Because you mentioned MRI as an option in your post. I was merely stating why that was a nonstarter in the ED.

Again the contrast allergy documentation is a systemic issue. Perhaps each time it comes up, clarify with the patient and correct it in the chart if necessary otherwise each time the pt comes back it's going to be unknown contrast allergy and protocols are followed.
Yep. But even if I change it in the chart, if the patient tells the tech anything along the lines of iodine and allergy, it never happens. Maybe your system is more progressive. Mine sadly isn't.

There is no reason to pretreat the "medically emergent" patient described above I agree.
Still no disagreement.

If there is a history of mild allergic rxn then pretreatment helps but it takes 4 hours for the steroids to be effective and I'm guessing you don't want to wait that long in the "systemically emergent" patient described above, but you're already waiting 90 minutes for labs.
4 hours is more than twice as long as 90 minutes. Also, the metric coming down the pipeline from CMS is dispo in 4 hours, so there's no chance of meeting that metric with pretreatment. Also, since literally nobody dies of allergy-like reactions, and only 10-35% have them on repeat scan, I would rather simply treat it if it happens. It's not a never event or anything?

My point with the BMP was that perhaps that can be the focus of your fight with administration to decrease LOS because it's purely an economic tradeoff vs POC labs. If you get the Cr. back faster, we can scan faster using IV contrast which is more appropriate for abdominal pain (except stones).
I think many if not most of us have fought that fight. And it makes even more sense for the patients not getting CTs, since at best its only 10% of a normal department. We would save scads of time. Admin literally gives zero ****s.
Foregoing contrast so you don't have to wait for labs is a disservice to the patient and makes both of us more likely to miss a diagnosis.
Except that all those studies, most of them done by radiologists, say it doesn't. In a perfect world I wouldn't mind giving it to everyone in the absence of labs. Since that world doesn't exist, I'm stuck with waiting or getting what is equivocal in the literature.

Study limited by lack of contrast is a factual medical statement. Sorry it annoys you so much but when you can't evaluate the vasculature or organ enhancement, the evaluation of those structures is indeed limited.
The comment was pertaining to the fact that the statement is in there even though we in the ED made every attempt to give the contrast, but that part isn't put in the report.

Seemingly a lot of your frustrations are with your local radiologists and systemic issues. Things disseminate slower into community practice than at academic centers and similarly at places with fewer interdisciplinary committees.
It's a problem at the 3 academic centers I work at as well, but I agree it's less of a problem.

The whole point I was trying to drive home was that IV contrast is helpful in almost all abdominal CTs except stones and ordering 80% non contrast as quoted was not optimal care.
I guess we will have to disagree based on the literature I've read.
 
Dude, I'm not arguing with your points, but, man, do you sound pugnacious. Well, to me, at least.

I am my radiologist's favorite doctor, simply because I'm not a **** up. I just stand there, and my colleagues shoot the bed on their own accord. But, I always defer to my rads buddy. Maybe that's just me.
Maybe yours are nicer. I'm not fighting, we are having an academic discussion. I've yet to see him quote a paper that says IV contrast is important. Or, you know, the ACR points I copied and pasted from their manual. My goal is to improve emergency care. Some discussions need to happen. I never defer to someone because "it's their specialty" because everything we do is someone else's specialty.
 
Are you suggesting that either 1. You're going to forgo a chest xray? (I can get a portable chest generally quicker than a CT...) or 2. You're going to ignore free air on a CXR and get a CT anyways? Maybe I should have revised my comment to say it's the initial x-ray of choice. Regardless, as I mentioned earlier, if there's free air, no one is going to delay the stat surgery consult to wait for a CT.

Now, mind you, on the floor (including the unit) at my hospital getting a CT is harder because any ED CT, regardless of how minor, is generally placed before any floor CT regardless of how critical.
If the patient isn't unstable, my surgeons want CT, so if the patient isn't unstable they go for CT and no x-ray.
 
I guess we will have to disagree based on the literature I've read.
I can see your point of view on everything but this. Your literature that you quoted about appendicitis has been less than convincing in applying it to an abdominal pain case.

Please read the ACR appropriateness criteria papers on various conditions and scenarios. These are highly researched and evidence based recommendations. I can guarantee that they've wrote more literature than youve read on the topics. They may even influence your ordering patterns.

You will likely be seeing these implemented into your EMR as clinical decision support as quality metrics on appropriate imaging use.
 
Maybe yours are nicer. I'm not fighting, we are having an academic discussion. I've yet to see him quote a paper that says IV contrast is important. Or, you know, the ACR points I copied and pasted from their manual. My goal is to improve emergency care. Some discussions need to happen. I never defer to someone because "it's their specialty" because everything we do is someone else's specialty.

Appropriateness Criteria: Appropriateness Criteria

Right Lower Quadrant Pain - Suspected Appendicitis
Summary https://acsearch.acr.org/docs/69357/Narrative/
 In general, CT is the most accurate imaging study for evaluating suspected appendicitis and alternative etiologies of RLQ abdominal pain. Data favor the use of IV contrast for CT, but the need for enteric contrast when IV contrast is used is not favored.
Evidence table with summary of each of the 73 studies they used to make the conclusions that they did. https://acsearch.acr.org/docs/69357/EvidenceTable/

Acute Non Localized Abdominal Pain - https://acsearch.acr.org/docs/69467/Narrative/
Abdominal CT without the use of oral or IV contrast has been advocated as an alternative to abdominal radiographs for evaluating appendicitis [23,38]. However, the use of contrast agents increases the spectrum of detectable pathology [45,50].
 
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I can see your point of view on everything but this. Your literature that you quoted about appendicitis has been less than convincing in applying it to an abdominal pain case.

Please read the ACR appropriateness criteria papers on various conditions and scenarios. These are highly researched and evidence based recommendations. I can guarantee that they've wrote more literature than youve read on the topics. They may even influence your ordering patterns.

You will likely be seeing these implemented into your EMR as clinical decision support as quality metrics on appropriate imaging use.
That's reasonable. Although I will say you've clearly not seen anything nearly as terrible as the EMR at my hospital. One day I hope you get to experience the hell that is Meditech.
I mean, I frequently talk to my radiologist about what is the most appropriate test for what I'm looking for. I don't dislike any of them. I actually wish my local group would help us give contrast more often by pushing back against some of the silly rules. I mean, hell, I have to sign a form for trauma patients saying it's ok to give contrast in the trauma setting without the BMP coming back.
 
No IV and no PO? Ok, fine. If it's early in my shift. Late in my shift? Please give long drink PO and pretreat that allergy for 13 hours.
 
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If the patient isn't unstable, my surgeons want CT, so if the patient isn't unstable they go for CT and no x-ray.

@Siggy

This.

"Oh, there's free air, eh? K. Go to CT while I queue up your admit labs and such. I'll call the gen.surgeon when I can look at your pics."

Here's the rub; you need not await the official declaration from the darkwalkers to make the call; 'cause the surgeon is gonna look at the CT images his/herself and "see where the hole is". You should probably look, too. I don't always do, but I mostly do. Mostly.

They mostly come out at night. Mostly.

As an aside; this is also my perpetual argument as to why I turn the goddamned overhead lights off in the ER...

"Radiology looks at their pictures in the dark because its easier and better. I look at all my own pictures. Turn off the effing lights, nurse manager."
 
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@Siggy
Here's the rub; you need not await the official declaration from the darkwalkers to make the call; 'cause the surgeon is gonna look at the CT images his/herself and "see where the hole is". You should probably look, too. I don't always do, but I mostly do. Mostly.

For the record, I always make a habit of looking at my own films. The radiologist has the advantage of specializing in radiology... but I have the advantage of knowing the patient.
 
For the record, I always make a habit of looking at my own films. The radiologist has the advantage of specializing in radiology... but I have the advantage of knowing the patient.

So yeah, the acute abd. series is kinda obviated in this case.
 
I wouldn't consider 25% of patients requiring a second CT scan a desirable outcome.
It's not ideal, no. But you can identify the people that needed the contrast, and give it to them.
Really it's more about the time it takes to get the BMP back more than anything.
 
It's not ideal, no. But you can identify the people that needed the contrast, and give it to them.
Really it's more about the time it takes to get the BMP back more than anything.
I get that. That is one of the reasons why if it is a kid (especially a skinny one) with a longer time since onset (plus high wbc and crp if you have them back) who is having enough pain they ought to stay in house to be watched anyway, I advise peds admit and taking the time for a CT with IV and po. Solves your guys's dispo issue and my issue of whether to rescan the kid or just guess at what is really going on.
 
I get that. That is one of the reasons why if it is a kid (especially a skinny one) with a longer time since onset (plus high wbc and crp if you have them back) who is having enough pain they ought to stay in house to be watched anyway, I advise peds admit and taking the time for a CT with IV and po. Solves your guys's dispo issue and my issue of whether to rescan the kid or just guess at what is really going on.
My pediatric surgeons will actually admit based on exam still, even without the CT.
The peds residents are pretty terrible. About 50% of the time, I read their H&P will say something about gastroenteritis but they scan in AM anyway, and the appendicitis is still there.
 
My pediatric surgeons will actually admit based on exam still, even without the CT.
The peds residents are pretty terrible. About 50% of the time, I read their H&P will say something about gastroenteritis but they scan in AM anyway, and the appendicitis is still there.
I have operated without a scan on a kid with the right story and wbc not too high and not too low. But usually I am getting consulted after everything is done because some of my colleagues are not like minded. Because I know they are getting jerked in a bunch of different directions by us I generally try to acknowledge that the others may want this but I am ok with that in the future (or just roll with what they give me without comment). I know a lot of them from residency which I think helps us have a good relationship.
 
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