CBC's in Pediatrics

[Makati2008]

I am just wondering what the group thinks about doing CBCs in the little ones?

I have seen two trains of thought from two attendings both boarded in EM:
1.)EM MD and Director-cbc should be done to know what you could possibly be dealing with viral vs bacterial
2.)EM MD a year or so out of residency-No need to do CBCs, and he said kind of nicely a waste of time and $.
3.)My current attending here in TX-If you don't do CBCs I will smack you(He was only joking but was saying they are important)
Which Doctor is right in this discussion?
I know in 36month old patients or less CBC,UA,CXR, and Spinal Tap(if deemed to be needed) used to be done where I worked last.

Just wondering been wanting to ask the question on the board for a while and don't want to poke my head in hear too much until I get through school and start EM residency if I am lucky but I like to learn.

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[kungfufishing]

Kind of a broad question. I get them as part of a septic workup and in some abdominal complaints. Most of the time I don't get one, in that it is probably going to be high, and then what do I do with that information?

 

[Stitch]

I find CBCs to be greatly overrated and contain much less information about what's going on than people think. There used to be a school of thought that a CBC could identify those kids with 'occult bacteremia' who would then go on to be septic. This view is no longer well supported in the data, and neither is the idea that you can tell the difference between 'viral' and bacterial illnesses. Especially in the era of the Hib and pneumococcal vaccines, where the incidence of bacteremia is much lower than it was even in the 90s. If the kid is unvaccinated however, I could see where using a CBC might be helpful. But I suspect even then, you'd be using it to justify giving the kid a dose of Rocephin and kicking them out the door.

You might say "well if the WBC is normal and without shift, I feel better about whatever is going on." All fine and good, but what do you do with a slightly elevated or slightly low count? Is it viral suppression of the bone marrow or is it something else going on? What do you do with that number? If it's 25, do you launch into a full septic workup? Where do you stop?

I mainly use my CBCs for looking at 'emias.' Leukemia, anemia, thrombocytopenia. So a younger kid with fever for 5-6 days, you may want to screen them for leukemia. If it's particularly high and the kid is fussy, you may want to consider osteo and get them a bone scan. It's helpful in evaluating Kawasaki disease since often platelets are high. But these are fairly specific "I'm looking for something in particular" cases.

Kids who are sick enough to be admitted with something infectious, I get a CBC mainly for the in patient team. I don't know what they do with them, though I have seen a case of atypical HUS with severely depressed counts that changed our disposition and landed the kid in the unit. In general I try to identify sepsis, even early sepsis clinically and not by a CBC.

As to the 36 month full work up comment: you did all that up to three years? Even the most conservative centers stop at 3 months. Most of us have moved to stopping the LP/meningitis work up around 6 weeks.

 

[Makati2008]

I meant 90 days(I don't know where I got 3yrs old from). It was late when I was writing that. Thanks for the indepth answer and I apologize about the typo.

 

[Homunculus]

Kind of a broad question. I get them as part of a septic workup and in some abdominal complaints. Most of the time I don't get one, in that it is probably going to be high, and then what do I do with that information?

agree

I find CBCs to be greatly overrated and contain much less information about what's going on than people think. .

i agree with your "emias" philosophy. a targeted CBC for a specific reason is what i've gradually adopted as my practice in non-sepsis workups. "left shift", as much as it gets thrown to me as something significant, i find depends on the practitioner. some people define it as simply neutrophil shifted, whereas i define it as significant bands. i've also seen early slam dunk viral kids with neutrophilic predominance shift over to leukocytes (eventually), which gives me much less of a neut = bacterial philosophy. probably something for the Allergy/Immunology "i escaped peds" folks to chime in on, lol.

the "outpatient rule out" has pretty much been my go between on those wishy-washy kids that don't have a good source, aren't really sick enough for admission but still are actually "sick". ceftriaxone q24 hrs IM x2 while cultures cook (and whatever likely viral thing burns itself out or declares itself) is a nice compromise between admitting or watchful waiting. so many of these kids back in our attendings day used to be admitted, which is one reason peds is so much more complicated for us. no one faulted them for admitting everything that sneezed or fevered. we're expected (rightfully so, in my opinon) to now be able to think a bit and manage these kids outpatient, or in the case of the trainwreck complicated ex preeemie, know how to manage them outpatient to hopefully avoid those admissions. due to NP's and PA's that's what "pediatrics" is going to become-- less well baby, more complex medical issues and sick kids. but i digress. anyway, similar to the CBC/culture/CRP that for some reason is the norm in our newborn rule outs, i think the CBC is just there because people are drawing blood anyway, gives a snapshot in time of what things look like, and until we have definitive (ie, medicolegal) evidence we don't *have* to get one, we will be getting them. i have no issues sending a 25k home if they look good and have a followup plan, (or responsible parents), likewise i'm not going to be falsely reassured and send a sick kid home with a 13k if they look bad. at least with the 25k i can pre-empt the attorney, which i would have a hard time doing if a kid came in, didn't get a CBC, and later came in in sepsis.

it's a great question, and even though relatively unhelpful i think because they are currently "standard of care" i should get them. anytime i get a blood culture, i get a cbc. not because i think it will guide me (it may) but because without it there's too much of a hole/target for badne$$ later. we spend much more money on defensive medical practices in other areas, i figure a cbc is pennies on the dollar cheaper than some of the MRI's i've ordered . . .

--your friendly neighborhood back to wart freezing and weight checks caveman