Canon vs. Fanon, part 13: Infirmary Fanon
Welcome to a new edition of Canon vs. Fanon! And hello to the newcomers to my flist. :) I hope you’ll join the discussion - agreements and arguments are always welcome.
This time, we’re taking a look at the Little Doc’s domain: the infirmary, a favorite setting for drama, hurt/comfort, and angst. Certain basic staples of story-telling appear in nearly every fic that includes a scene in the infirmary, but how many of those are actually based on canon?
Recap: Canon is anything shown onscreen in the movie or show; show supersedes movie, when necessary. (The rebellion against Ra took place five thousand years ago, not ten thousand.) Fanon is defined as popular concepts that occur regularly in fanfic, but have little or no actual canon basis to defend them.
We begin with common fanon concepts, compare and contrast them to the reality of canon, and form a conclusion regarding the fanon’s validity. If I’ve missed something, whether it confirms or contradicts my analyses, please comment and let me know! And please remember that I'm not deliberately trying to mock any specific writer, or even whole groups of writers; I'm only pointing out what's fanon, and what's actually canon.
When SG-1 returns from a mission, someone is invariably hurt (usually Daniel). When SG-1’s IDC code shows up on the computer, the medical team immediately starts prepping for surgery.
It is true that whumping, of one kind or another, is a frequent occurrence on off-world missions. However, it is a gross exaggeration to suggest that any time SG-1 goes on a mission, the medical staff automatically preps the OR room - or that SG-1 is the only team that ends up hurt. (Siler, of course, has the largest medical file at the SGC.)
Some of this was detailed in an earlier post; but in the first eight seasons of the show - that is, one hundred seventy-eight episodes - the individual members of SG-1 required medical attention of various degrees during an average of ten percent of those episodes:
Daniel's totals: 17 medical treatments on-world, including 8 infirmary stays. (An “infirmary stay” is any incident in which the patient is put to bed, rather than being monitored or receiving out-patient treatment.)
Jack's totals: 19 medical treatments on-world, including 8 infirmary stays.
Sam's totals: 16 medical treatments on-world, including 8 infirmary stays.
Teal’c’s totals: 11 medical treatments on-world, including seven - possibly eight, if you include Avatar - infirmary stays. (Bloodlines [voluntary], Solitudes, Bane, Out of Mind, Legacy, Urgo, Threshold, The Fifth Man, Changeling, Orpheus, and Avatar. Episodes like New Ground and The Serpent’s Venom, where Teal’c is badly wounded off-world, are not included; we don’t know that Junior didn’t repair the damage on its own.) You will note that Teal’c has a much higher percentage of overnight infirmary stays than the other members of SG-1, but this is because Teal’c has Junior for the little things. When Teal’c is sick or wounded, it tends to be serious.
Obviously, post-mission exams are routine (more on this below!). But considering the totals listed here, the typical fanfic musings from Hammond or Janet that “it’s always SG-1" are a lot more fanon than canon.
Conclusion: While all the members of SG-1 have required medical attention multiple times during the course of the show, it is not inevitable that they will always be injured during their missions through the Stargate.
Janet keeps her patients in line with threats of using “big” or “specially dulled” needles.
While this entertaining bit of fanon fits nicely with what we know of Janet’s mischievous personality (and even more, I suspect, with Teryl Rothery’s), there is no canon basis whatsoever for what would actually be hugely unprofessional behavior on Janet's part.
We have a direct reference to needles in the infirmary once only, in Foothold. In that episode, the people in the infirmary are actually aliens masquerading as the medical staff, but since they are behaving completely in character, thanks to the little gadgets they’re wearing, we can accept that behavior as canon. (For further discussion on when canon should and shouldn’t be accepted as regular canonical behavior, you might want to wander over here.)
SG-1 returns from a mission in a rather waterlogged state. Janet instructs Jack to loosen his belt to prepare for an injection.
“How is a needle in the butt going to get water out of my ears?” Jack complains.
Janet’s smile does seem to indicate that this is a rather common gripe, as she replies, “It isn’t. Come on, sir, you know this is standard procedure.”
“We should rethink this procedure,” Jack snipes. Then, as a (never seen again) nurse approaches with a rather large syringe, he turns to her and says, “Listen, really jam it in this time, okay?”
The nurse’s grin as she nods does suggest, once again, that the medical staff is used to Jack’s grousing about injections. (Jack’s behavior as a patient is a different topic entirely, and one that I might tackle in the future.) But there is no mention of the size of the needle, or how blunt it might be.
Conclusion: there is no canon basis for the common fanon trope of Janet threatening to use the “big needles” if her patients don’t behave.
Injured teammates off-world are comforted with promises of “happy juice” once they get to the sanctuary of the infirmary; once they are back at the SGC, the other members of the team stand ready to offer ice chips when the patient awakens.
The charm of these bits of fanon, to me, is how often they appear in fanfics, despite the absence of any canon to support them.
There is actually plenty of canonical evidence of team members parking themselves at a victim’s bedside, although not necessarily in shifts and for hours at a time. In Season One alone, we have:
COTG. Kawalsky stays at Ferretti’s bedside while he is recovering from surgery.
Enemy Within. Jack spends time with Kawalsky before the failed surgery to remove the Goa’uld, and the team watches the surgery itself.
The Broca Divide. Teal’c sits at Daniel’s side in “The Circle” while they wait for him to recover from his antihistamine tranq shot.
Bloodlines. The team watches Janet’s attempt to remove Junior.
Singularity. Sam stays with Cassie, with Daniel as back-up.
Solitudes. Teal’c is there when Daniel awakens from his head-first landing on the ramp.
However, there is never a single instance when a wounded teammate is promised “lots of happy juice” (otherwise known as “sedatives,” or possibly morphine) when they get back to the safety of “Janet’s needles,” and the only time ice is ever featured on SG-1 is when they’re in Antarctica. (Off-world, there’s Touchstone and Beneath the Surface.)
Conclusion: While there is plenty of canonical evidence for the team rallying around wounded teammates, we never see them referring to “happy juice” (or, in fact, ever promising that Janet will take away the pain) or spooning ice chips into the mouths of just-awakened patients.
MRIs are a routine part of the post-mission exams - a mandatory check that no one has been infested with a Goa’uld while off-world.
To be fair, it’s relatively easy to trace just how this came to be accepted as fanon. The problem is that both instances take place within the first season of the show - and there isn’t a single other mention of using the MRI to detect a Goa’uld after that, much less as a routine check-up.
Let’s take a look at the various MRIs performed (or not performed) on SG-1, and the reasons for them:
Enemy Within. Warner performs an MRI on Kawalsky and discovers the immature Goa’uld attached to Kowalsky’s brainstem. This is the first canon reference to using the MRI to detect the presence of a symbiote.
Cold Lazarus. When a “second” Jack comes back to the SGC, Janet performs an MRI on the real Jack to determine his identity. I’m unclear on how the MRI was supposed to do this. She also performed a DNA test.
Fire and Water. When Sam, Teal’c, and Jack continue to profess their disbelief of Daniel’s death, Janet performs MRIs and uncovers evidence of tampering with their memories.
ETA: Singularity. caladria strikes again! Janet reports about Cassie, "No sign of the infection, and as a precaution, I did an ultrasound to make sure she wasn't parasitically infested with a Goa'uld." This is doubly interesting, because while they know that Cassie has naquadah in her blood at this point, they don't know that a Goa'uld releases naquadah into the host's system. This is the only canon reference to using ultrasound to detect the presence of a symbiote.
TBFTGOG. In the SGA, Daniel is handcuffed and sedated so the doctors can perform an MRI, specifically, as Katherine states later, for the purpose of detecting the possible presence of a symbiote. Daniel clearly recognizes this, as he shouts, “I am not a Goa’uld!" while they slam him down. This is the second canon reference to using the MRI to detect the presence of a symbiote, albeit in an alternate universe; Daniel understands the purpose immediately.
In the Line of Duty. Janet’s post-mission inspection for possible Goa’uld infestation is apparently limited to inspecting the neck for possible scars. No MRI is performed, which is why Jolinar is able to remain in Sam until Cassie senses the symbiote.
Serpent’s Song. Janet uses progressive MRIs to monitor Apophis-the-symbiote during the time he is imprisoned in the infirmary.
One False Step. Janet performs an MRI on one of the aliens to try and determine what is causing them all to collapse.
Legacy. Janet tells Daniel that she performed, among other things, an MRI on Teal’c, but that she could not find any sign of the organism that Daniel insists he saw go inside him.
Learning Curve. Janet uses an MRI to find out why Merrin has “abnormally high neural-peptide levels” and discover the nanites in Merrin’s brain.
Past and Present. Janet uses MRIs on the victims of the Vorlix to determine how their memories are affected.
ETA: Urgo. Thanks, aurora_novarum! This one really was on my list, I just watched it...! Ah, well. The type of medical scan isn't specified, but Janet probably used an MRI to detect Urgo's physical presence in SG-1's brains. It's only "an errant pixel" until she enhances it with an "electron resonance scan" which, magnified ten thousand times, gives them a picture of Urgo itself (himself?). Someone who knows a bit more about medical equipment can clarify for me whether or not MRIs were actually involved here.
The Curse. Janet and Sam use an MRI to discover the dead Isis trapped in her canopic jar.
Rite of Passage. Because of the EM fields that Cassie keeps generating, Janet cannot perform an MRI to find out what’s wrong.
Prophecy. Janet uses a series of MRIs to detect the growing tumor in Jonas’ brain.
Lifeboat. McKenzie performs an MRI and EEG on Daniel when he returns from the Stromos and determines that while Daniel’s consciousness has retreated to a comatose state for safety, there are as many as twelve distinct personalities renting space in Daniel’s brain.
Evolution. Sam and Jacob try to perform an MRI on the captured Kull warrior, but the armor doesn’t allow it.
Full Alert. The Russian authorities take a blood sample from Daniel to determine whether or not he is infested with a Goa’uld. This is the first canon suggestion that a simple blood test can be used to detect a symbiote. ETA: An interesting suggestion in the comments has prompted the theory that the blood test might, in fact, have been useless. Since it was the Goa'uld himself who ordered the blood work done, it might very well have been a smokescreen to mask its own presence by convincing the Russian authorities to use blood tests, rather than ultrasounds or MRIs, to detect a Goa'uld symbiote. Daniel didn't argue that the blood test was useless, but he might have been wary of kicking up too much of a fuss.
So Warner first uses the MRI to spot the immature Goa’uld taking up residence in Kawalsky. The alternate universe uses the MRI to determine that the floppy-haired kid that insists he's part of SG-1 isn't hosting a Goa’uld. But while Daniel instantly recognizes why they’re performing the MRI, that isn’t proof that he’s used to the routine; it only means that he remembers Warner’s test and what it might mean under his present circumstances. It might even be possible that he’d overhead specific instructions that clarified their intentions.
In the Line of Duty is ample proof that MRIs aren’t part of the routine post-mission check-up. Jolinar did try to duck the exam; but since she eventually did go, and Janet only found evidence of some abrasions in the back of Sam’s throat, it wasn’t because Jolinar had searched Sam’s mind and discovered the risk of the MRI.
There is no canonical reference to Janet or Hammond or anyone suggesting that after the disaster of Jolinar, MRIs had better be instituted as a mandatory exam to ensure that no other Goa’uld/Tok’ra tried to smuggle themselves to Earth.
ETA: Yes, there is! Thanks to caladria, who points out that Janet does, in fact, make the following statement in In the Line of Duty: "If a Goa'uld can infest a human being with no detectible physical signs, we're going to have to start giving all personnel who go through the Gate an ultrasound or an MRI." I'm going to assume this statement of Janet's is actually the canonical reference for the mandatory MRI. Consider this, though: after that single statement at the beginning of Season Two, MRIs are not associated with the Goa’uld at all - with the sole exception of Janet using multiple MRIs to track Apophis’ weakening condition in Serpent’s Song. And by the time the eighth season rolls around, it is evident that a simple blood test - for naquadah, perhaps? - is enough to determine the presence of the Goa’uld. (Or not, if that theory about the blood test being a false trail is true.) There might be reasons why MRIs are preferable to blood work, or vice versa - time constraints, or naquadah only appearing in the blood after the Goa’uld is fully integrated with the host, or who knows what else. And ultrasounds - also on Janet's list of suggestions, and actually appearing once in canon! - are a lot less time consuming (and cheaper!) than an MRI, but no one seems to suggest that for routine post-mission examinations, even though Janet uses ultrasound to check out Cassie in Singularity. At the very least, Full Alert suggests that there are probably multiple ways to detect a symbiote.
Conclusion: There is a single canon instance in our universe, and a single canon reference in an alternate universe, in which an MRI is specifically performed for the purpose of detecting the presence of a symbiote. Both of these references take place in Season One, before Jolinar in Sam does not undergo an MRI in Season Two. Therefore, despite the suggestion Janet makes in In the Line of Duty, there is no canonical proof for the common fanon assertion that MRIs are a mandatory, routine part of the post-mission exam for any person who goes off-world.
If you’re interested in other common infirmary fanon tropes, previous discussions have included a more detailed comparison of visits to the infirmary (cited above) and Janet’s fangirl nurses.
My personal fanon opinion? The infirmary is a truly wonderful setting for fanfic. You've got all the props Jack needs to play with, the Little Doc (who brightens up any story), and the opportunity for the whole range of emotional drama, from angst to humor and back again. But while team whumping is often too tempting to resist, and will always be part of the fannish consciousness, authors should be aware that it’s not quite as common as many writers would suggest. Janet’s wicked sense of humor is certainly canon, but dire threats of big, dulled needles are not. Ice chips and happy juice are clichés that a writer might wish to avoid. And quite frankly, the MRI fanon bothers me a lot, because I was convinced it was true until I actually did some research. Bad fanon! No biscuit!
"Anyway, I'm sorry, but that just happens to be how I feel about it. What do you think?"
ETA August 29th: Whee! Aurora got inspired by this discussion in the comments and came up with this: Trauma Confusion!
This time, we’re taking a look at the Little Doc’s domain: the infirmary, a favorite setting for drama, hurt/comfort, and angst. Certain basic staples of story-telling appear in nearly every fic that includes a scene in the infirmary, but how many of those are actually based on canon?
Recap: Canon is anything shown onscreen in the movie or show; show supersedes movie, when necessary. (The rebellion against Ra took place five thousand years ago, not ten thousand.) Fanon is defined as popular concepts that occur regularly in fanfic, but have little or no actual canon basis to defend them.
We begin with common fanon concepts, compare and contrast them to the reality of canon, and form a conclusion regarding the fanon’s validity. If I’ve missed something, whether it confirms or contradicts my analyses, please comment and let me know! And please remember that I'm not deliberately trying to mock any specific writer, or even whole groups of writers; I'm only pointing out what's fanon, and what's actually canon.
When SG-1 returns from a mission, someone is invariably hurt (usually Daniel). When SG-1’s IDC code shows up on the computer, the medical team immediately starts prepping for surgery.
It is true that whumping, of one kind or another, is a frequent occurrence on off-world missions. However, it is a gross exaggeration to suggest that any time SG-1 goes on a mission, the medical staff automatically preps the OR room - or that SG-1 is the only team that ends up hurt. (Siler, of course, has the largest medical file at the SGC.)
Some of this was detailed in an earlier post; but in the first eight seasons of the show - that is, one hundred seventy-eight episodes - the individual members of SG-1 required medical attention of various degrees during an average of ten percent of those episodes:
Daniel's totals: 17 medical treatments on-world, including 8 infirmary stays. (An “infirmary stay” is any incident in which the patient is put to bed, rather than being monitored or receiving out-patient treatment.)
Jack's totals: 19 medical treatments on-world, including 8 infirmary stays.
Sam's totals: 16 medical treatments on-world, including 8 infirmary stays.
Teal’c’s totals: 11 medical treatments on-world, including seven - possibly eight, if you include Avatar - infirmary stays. (Bloodlines [voluntary], Solitudes, Bane, Out of Mind, Legacy, Urgo, Threshold, The Fifth Man, Changeling, Orpheus, and Avatar. Episodes like New Ground and The Serpent’s Venom, where Teal’c is badly wounded off-world, are not included; we don’t know that Junior didn’t repair the damage on its own.) You will note that Teal’c has a much higher percentage of overnight infirmary stays than the other members of SG-1, but this is because Teal’c has Junior for the little things. When Teal’c is sick or wounded, it tends to be serious.
Obviously, post-mission exams are routine (more on this below!). But considering the totals listed here, the typical fanfic musings from Hammond or Janet that “it’s always SG-1" are a lot more fanon than canon.
Conclusion: While all the members of SG-1 have required medical attention multiple times during the course of the show, it is not inevitable that they will always be injured during their missions through the Stargate.
Janet keeps her patients in line with threats of using “big” or “specially dulled” needles.
While this entertaining bit of fanon fits nicely with what we know of Janet’s mischievous personality (and even more, I suspect, with Teryl Rothery’s), there is no canon basis whatsoever for what would actually be hugely unprofessional behavior on Janet's part.
We have a direct reference to needles in the infirmary once only, in Foothold. In that episode, the people in the infirmary are actually aliens masquerading as the medical staff, but since they are behaving completely in character, thanks to the little gadgets they’re wearing, we can accept that behavior as canon. (For further discussion on when canon should and shouldn’t be accepted as regular canonical behavior, you might want to wander over here.)
SG-1 returns from a mission in a rather waterlogged state. Janet instructs Jack to loosen his belt to prepare for an injection.
“How is a needle in the butt going to get water out of my ears?” Jack complains.
Janet’s smile does seem to indicate that this is a rather common gripe, as she replies, “It isn’t. Come on, sir, you know this is standard procedure.”
“We should rethink this procedure,” Jack snipes. Then, as a (never seen again) nurse approaches with a rather large syringe, he turns to her and says, “Listen, really jam it in this time, okay?”
The nurse’s grin as she nods does suggest, once again, that the medical staff is used to Jack’s grousing about injections. (Jack’s behavior as a patient is a different topic entirely, and one that I might tackle in the future.) But there is no mention of the size of the needle, or how blunt it might be.
Conclusion: there is no canon basis for the common fanon trope of Janet threatening to use the “big needles” if her patients don’t behave.
Injured teammates off-world are comforted with promises of “happy juice” once they get to the sanctuary of the infirmary; once they are back at the SGC, the other members of the team stand ready to offer ice chips when the patient awakens.
The charm of these bits of fanon, to me, is how often they appear in fanfics, despite the absence of any canon to support them.
There is actually plenty of canonical evidence of team members parking themselves at a victim’s bedside, although not necessarily in shifts and for hours at a time. In Season One alone, we have:
COTG. Kawalsky stays at Ferretti’s bedside while he is recovering from surgery.
Enemy Within. Jack spends time with Kawalsky before the failed surgery to remove the Goa’uld, and the team watches the surgery itself.
The Broca Divide. Teal’c sits at Daniel’s side in “The Circle” while they wait for him to recover from his antihistamine tranq shot.
Bloodlines. The team watches Janet’s attempt to remove Junior.
Singularity. Sam stays with Cassie, with Daniel as back-up.
Solitudes. Teal’c is there when Daniel awakens from his head-first landing on the ramp.
However, there is never a single instance when a wounded teammate is promised “lots of happy juice” (otherwise known as “sedatives,” or possibly morphine) when they get back to the safety of “Janet’s needles,” and the only time ice is ever featured on SG-1 is when they’re in Antarctica. (Off-world, there’s Touchstone and Beneath the Surface.)
Conclusion: While there is plenty of canonical evidence for the team rallying around wounded teammates, we never see them referring to “happy juice” (or, in fact, ever promising that Janet will take away the pain) or spooning ice chips into the mouths of just-awakened patients.
MRIs are a routine part of the post-mission exams - a mandatory check that no one has been infested with a Goa’uld while off-world.
To be fair, it’s relatively easy to trace just how this came to be accepted as fanon. The problem is that both instances take place within the first season of the show - and there isn’t a single other mention of using the MRI to detect a Goa’uld after that, much less as a routine check-up.
Let’s take a look at the various MRIs performed (or not performed) on SG-1, and the reasons for them:
Enemy Within. Warner performs an MRI on Kawalsky and discovers the immature Goa’uld attached to Kowalsky’s brainstem. This is the first canon reference to using the MRI to detect the presence of a symbiote.
Cold Lazarus. When a “second” Jack comes back to the SGC, Janet performs an MRI on the real Jack to determine his identity. I’m unclear on how the MRI was supposed to do this. She also performed a DNA test.
Fire and Water. When Sam, Teal’c, and Jack continue to profess their disbelief of Daniel’s death, Janet performs MRIs and uncovers evidence of tampering with their memories.
ETA: Singularity. caladria strikes again! Janet reports about Cassie, "No sign of the infection, and as a precaution, I did an ultrasound to make sure she wasn't parasitically infested with a Goa'uld." This is doubly interesting, because while they know that Cassie has naquadah in her blood at this point, they don't know that a Goa'uld releases naquadah into the host's system. This is the only canon reference to using ultrasound to detect the presence of a symbiote.
TBFTGOG. In the SGA, Daniel is handcuffed and sedated so the doctors can perform an MRI, specifically, as Katherine states later, for the purpose of detecting the possible presence of a symbiote. Daniel clearly recognizes this, as he shouts, “I am not a Goa’uld!" while they slam him down. This is the second canon reference to using the MRI to detect the presence of a symbiote, albeit in an alternate universe; Daniel understands the purpose immediately.
In the Line of Duty. Janet’s post-mission inspection for possible Goa’uld infestation is apparently limited to inspecting the neck for possible scars. No MRI is performed, which is why Jolinar is able to remain in Sam until Cassie senses the symbiote.
Serpent’s Song. Janet uses progressive MRIs to monitor Apophis-the-symbiote during the time he is imprisoned in the infirmary.
One False Step. Janet performs an MRI on one of the aliens to try and determine what is causing them all to collapse.
Legacy. Janet tells Daniel that she performed, among other things, an MRI on Teal’c, but that she could not find any sign of the organism that Daniel insists he saw go inside him.
Learning Curve. Janet uses an MRI to find out why Merrin has “abnormally high neural-peptide levels” and discover the nanites in Merrin’s brain.
Past and Present. Janet uses MRIs on the victims of the Vorlix to determine how their memories are affected.
ETA: Urgo. Thanks, aurora_novarum! This one really was on my list, I just watched it...! Ah, well. The type of medical scan isn't specified, but Janet probably used an MRI to detect Urgo's physical presence in SG-1's brains. It's only "an errant pixel" until she enhances it with an "electron resonance scan" which, magnified ten thousand times, gives them a picture of Urgo itself (himself?). Someone who knows a bit more about medical equipment can clarify for me whether or not MRIs were actually involved here.
The Curse. Janet and Sam use an MRI to discover the dead Isis trapped in her canopic jar.
Rite of Passage. Because of the EM fields that Cassie keeps generating, Janet cannot perform an MRI to find out what’s wrong.
Prophecy. Janet uses a series of MRIs to detect the growing tumor in Jonas’ brain.
Lifeboat. McKenzie performs an MRI and EEG on Daniel when he returns from the Stromos and determines that while Daniel’s consciousness has retreated to a comatose state for safety, there are as many as twelve distinct personalities renting space in Daniel’s brain.
Evolution. Sam and Jacob try to perform an MRI on the captured Kull warrior, but the armor doesn’t allow it.
Full Alert. The Russian authorities take a blood sample from Daniel to determine whether or not he is infested with a Goa’uld. This is the first canon suggestion that a simple blood test can be used to detect a symbiote. ETA: An interesting suggestion in the comments has prompted the theory that the blood test might, in fact, have been useless. Since it was the Goa'uld himself who ordered the blood work done, it might very well have been a smokescreen to mask its own presence by convincing the Russian authorities to use blood tests, rather than ultrasounds or MRIs, to detect a Goa'uld symbiote. Daniel didn't argue that the blood test was useless, but he might have been wary of kicking up too much of a fuss.
So Warner first uses the MRI to spot the immature Goa’uld taking up residence in Kawalsky. The alternate universe uses the MRI to determine that the floppy-haired kid that insists he's part of SG-1 isn't hosting a Goa’uld. But while Daniel instantly recognizes why they’re performing the MRI, that isn’t proof that he’s used to the routine; it only means that he remembers Warner’s test and what it might mean under his present circumstances. It might even be possible that he’d overhead specific instructions that clarified their intentions.
In the Line of Duty is ample proof that MRIs aren’t part of the routine post-mission check-up. Jolinar did try to duck the exam; but since she eventually did go, and Janet only found evidence of some abrasions in the back of Sam’s throat, it wasn’t because Jolinar had searched Sam’s mind and discovered the risk of the MRI.
There is no canonical reference to Janet or Hammond or anyone suggesting that after the disaster of Jolinar, MRIs had better be instituted as a mandatory exam to ensure that no other Goa’uld/Tok’ra tried to smuggle themselves to Earth.
ETA: Yes, there is! Thanks to caladria, who points out that Janet does, in fact, make the following statement in In the Line of Duty: "If a Goa'uld can infest a human being with no detectible physical signs, we're going to have to start giving all personnel who go through the Gate an ultrasound or an MRI." I'm going to assume this statement of Janet's is actually the canonical reference for the mandatory MRI. Consider this, though: after that single statement at the beginning of Season Two, MRIs are not associated with the Goa’uld at all - with the sole exception of Janet using multiple MRIs to track Apophis’ weakening condition in Serpent’s Song. And by the time the eighth season rolls around, it is evident that a simple blood test - for naquadah, perhaps? - is enough to determine the presence of the Goa’uld. (Or not, if that theory about the blood test being a false trail is true.) There might be reasons why MRIs are preferable to blood work, or vice versa - time constraints, or naquadah only appearing in the blood after the Goa’uld is fully integrated with the host, or who knows what else. And ultrasounds - also on Janet's list of suggestions, and actually appearing once in canon! - are a lot less time consuming (and cheaper!) than an MRI, but no one seems to suggest that for routine post-mission examinations, even though Janet uses ultrasound to check out Cassie in Singularity. At the very least, Full Alert suggests that there are probably multiple ways to detect a symbiote.
Conclusion: There is a single canon instance in our universe, and a single canon reference in an alternate universe, in which an MRI is specifically performed for the purpose of detecting the presence of a symbiote. Both of these references take place in Season One, before Jolinar in Sam does not undergo an MRI in Season Two. Therefore, despite the suggestion Janet makes in In the Line of Duty, there is no canonical proof for the common fanon assertion that MRIs are a mandatory, routine part of the post-mission exam for any person who goes off-world.
If you’re interested in other common infirmary fanon tropes, previous discussions have included a more detailed comparison of visits to the infirmary (cited above) and Janet’s fangirl nurses.
My personal fanon opinion? The infirmary is a truly wonderful setting for fanfic. You've got all the props Jack needs to play with, the Little Doc (who brightens up any story), and the opportunity for the whole range of emotional drama, from angst to humor and back again. But while team whumping is often too tempting to resist, and will always be part of the fannish consciousness, authors should be aware that it’s not quite as common as many writers would suggest. Janet’s wicked sense of humor is certainly canon, but dire threats of big, dulled needles are not. Ice chips and happy juice are clichés that a writer might wish to avoid. And quite frankly, the MRI fanon bothers me a lot, because I was convinced it was true until I actually did some research. Bad fanon! No biscuit!
"Anyway, I'm sorry, but that just happens to be how I feel about it. What do you think?"
ETA August 29th: Whee! Aurora got inspired by this discussion in the comments and came up with this: Trauma Confusion!