Diagnosed WITH vs Diagnosed AS vs Presenting WITH: The Clinical Preposition Traps

Diagnosed with, diagnosed as, and presenting with all appear in nearly every OET referral, discharge, and advice letter, and candidates use all three constantly — every letter reports at least one condition and at least one symptom the patient showed on examination. The problem isn’t unfamiliarity with the words. It’s that “diagnosed” pairs with two different prepositions depending on what follows it, “presenting” pairs with two different prepositions that mean genuinely different things, and mixing up which preposition goes where produces sentences that read as confidently wrong rather than simply informal.

Watch the full breakdown: Diagnosed WITH vs AS works through both preposition traps using real OET case-note sentences.

This post goes deeper on one specific family than our broader prepositions after clinical verbs guide, which surveys four collocation groups across referral, medication, admission, and description verbs. That guide flags “diagnosed with” as one line in a wider table; this one works through the full diagnosed WITH / diagnosed AS / presenting WITH / presenting AS system in detail, because it’s dense enough with its own internal traps to deserve separate treatment.

Why do diagnosed and presenting cause so many preposition errors in OET writing?

Both verbs describe a clinical judgement being reached, and in most candidates’ first languages, a single flexible preposition covers the whole idea — there’s no separate grammatical form for “the condition itself” versus “the category the patient was placed in.” English splits that distinction across two different prepositions for each verb, and neither split maps onto a rule a candidate can reason out from first principles. You either know the pairing or you guess, and under exam time pressure, the guess defaults to whichever preposition felt most recently correct — which is exactly how “diagnosed as diabetes” and “presented with a routine infection” (meaning the opposite of what the writer intended) end up in finished scripts.

Case notes make this worse because they hand the pattern to the candidate in fragments — “dx: T2DM,” “c/o chest pain 3/7” — and expanding a fragment into a full clinical sentence means supplying the connecting preposition from memory, in real time, while thinking about content rather than grammar.

Diagnosed WITH: the default pattern in OET writing

Diagnosed with is the pattern to reach for by default in almost every OET letter, because it’s the one that takes a condition noun directly.

The rule that covers all four rows: if the word after “diagnosed” names the condition itself as a noun, WITH is correct and OF is never correct, no matter how natural “of” might feel by analogy with “suffering of” or “accused of.” Diagnose simply doesn’t take “of” in any of its forms.

When is it diagnosed AS, not diagnosed WITH?

Diagnosed AS exists, but it does a different grammatical job: it introduces an adjective, a category label, or the word “having” plus a noun — never a bare condition noun on its own.

Compare the two errors this creates in practice. Writing “diagnosed as diabetes” is wrong because “diabetes” is a bare noun, not an adjective and not preceded by “having” — it needs WITH instead (“diagnosed with diabetes”). Writing “diagnosed with diabetic” is the mirror error — “diabetic” is an adjective, so it needs AS, or it needs to become a noun (“diagnosed with diabetes”). The safest exam-day habit: if the condition only exists as a noun and has no natural adjective form (most conditions), default to WITH. Reach for AS only when you’re specifically using an adjective, a label, or “having.”

Presenting WITH vs presenting AS — a different pair entirely

Presenting follows its own two-way split, and unlike diagnosed with/as, the two forms don’t just differ grammatically — they can change the clinical claim the sentence makes.

Presenting WITH names the specific symptom, sign, or complaint a patient showed on examination. It’s the pattern you’ll use constantly in the opening line of a referral or discharge letter.

• Mr Chen presented with severe lower back pain radiating to the left leg.
• She presented with a two-day history of fever and productive cough.

Presenting AS describes how the whole case appeared, was categorised, or was initially read — often, though not always, before a different or more specific diagnosis was reached. It answers “what did this look like?” rather than “what did the patient show?”

• The case initially presented as a straightforward urinary tract infection but was later diagnosed with pyelonephritis.
• The referral was flagged and presented as an emergency given the rapid onset of symptoms.

Swapping the two changes what the sentence claims, not just its grammar. “The patient presented as chest pain” is a genre error that also confuses the claim — a patient can present with chest pain (the symptom) but cannot present as chest pain (a symptom isn’t a category the whole case gets read as). Reading the sentence back and asking “am I naming a symptom, or describing how the case as a whole looked?” resolves almost every WITH/AS choice for both diagnosed and presenting.

Quick reference: all four forms side by side

Worked examples from real OET letter contexts

A quick self-check before you submit

Find every instance of “diagnosed” and “presented” in your draft and ask two questions in order. First: does the word immediately after it name the condition or symptom itself as a noun? If so, it needs WITH, and OF is never an option. Second: are you instead describing an adjective, a label, “having” plus a noun, or how the whole case looked rather than what it contained? If so, it needs AS. Running this check across a full letter usually catches every instance in under a minute, because the same handful of patterns repeat in almost every script.

This pairs well with the broader prepositions after clinical verbs guide, which covers referral, medication, and admission collocations alongside this one, and with the Language criterion breakdown, which explains how grammatical range and control are weighted at each band — exactly where a diagnosed-as-diabetes slip does its damage even when the sentence is still understandable. If you want a fast first check on a specific letter, our free OET Grammar Checker will flag many preposition errors automatically, though it won’t always catch a presenting AS used where presenting WITH changes the clinical claim.

Why this is worth fixing as a habit

Diagnosed and presented aren’t occasional verbs in OET writing — between them, they appear in almost every referral and discharge letter, often more than once, which means a candidate who hasn’t fixed the WITH/AS distinction repeats the same error pattern three or four times across a single script. Examiners marking Language read for exactly this kind of repeated pattern, not an isolated slip, and a letter with “diagnosed of” or “presented as chest pain” running through it reads as a genuine control gap even when every sentence still communicates its intended meaning. Our OET writing correction service checks collocation patterns like this across a full letter alongside the other five criteria, so a repeated preposition error gets caught and corrected before it costs you a band.