Today we’re going to be speaking very briefly on imaging modalities to diagnose appendicitis. So we’re going to go over which options are ideal, for which populations of people.
So very quickly, if you have a patient that comes in with a classic presentation of appendicitis, you don’t need any type of imaging modalities. You go straight to surgery. If they have the classic right lower quadrant pain, they have positive Psoas, Obturator, Rovsings, whatever it may be; if it presents classically, you do not do imaging modalities. You call the surgeon and they go straight to the OR.
Imaging modalities are used when the clinical presentation isn’t as clear cut or you’re unsure of the diagnosis. Then you go ahead and order an imaging modality. So which is going to be preferred? Well hands down the best imaging modality is still going to be CT scan. CT scan with IV contrast. CT scan has the best sensitivity, the best specificity for diagnosing appendicitis.
If you have a child that walks in, the initial choice is going to be ultrasound, because you want to prevent them from exposure to radiation. So the initial modality for children is going to be ultrasound. If ultrasound is positive, they go straight to the OR. If ultrasound is negative, the next best step is going to be CT scan with IV contrast.
If you have a pregnant woman that comes in and you’re not sure, the initial test of choice is going to be ultrasound. If the ultrasound is negative, you’re going to do MRI and this is because you want to prevent exposure to the fetus, so ultrasound is going to save them from that exposure. You don’t want to jump to CT scan even thought it’s the most accurate because CT scan is going to expose them to radiation. So MRI is the next best step in a pregnant female.
Now, as far as ultrasound goes, ultrasound has great specificity just like CT scan; it’s almost comparable. This means that if ultrasound picks up the diagnosis of appendicitis, we have appendicitis. However it can miss appendicitis as well. Which means the sensitivity isn’t that great. Right? So it’s really good at diagnosing, but it’s not as good as excluding the diagnosis.
It’s for that reason that if we have a negative or unequivocal ultrasound exam, you’re going to then do CT scan or you’re going to do an MRI, depending if this is an adult, a child, or a pregnant woman.
Alright guys hope that cleared up some confusion for you guys. Generally speaking, ultrasound is going to be done first line. Now if you have an adult, who is non-pregnant, then you’re going to do a CT scan with IV contrast because that is hands down, the best imaging modality for diagnosis of appendicitis.