Sem a anestesia, a injeção teria sido muito pior.

Sem means without.

So Sem a anestesia means Without the anaesthetic or Without the anesthesia.

Portuguese often begins a sentence with this kind of phrase to set the condition first. In English, we can do the same:

• Without the anesthesia, the injection would have been much worse.

The comma helps separate that introductory phrase from the rest of the sentence.

In Portuguese, definite articles like o / a / os / as are used more often than in English.

So a anestesia literally means the anesthesia / the anaesthetic, but in natural English we might simply say without anesthesia.

Portuguese often prefers the article here because it is referring to the specific anesthesia involved in that situation.

Compare:

• Sem anestesia = without anesthesia, in a more general sense
• Sem a anestesia = without the anesthesia, referring to the one that was actually used

Both can be possible, but Sem a anestesia sounds more specific.

Yes. Injeção is a feminine noun, so it takes the feminine article a:

• a injeção = the injection

In Portuguese, nouns have grammatical gender, and the article must match the noun.

Some examples:

• a injeção
• a anestesia
• a operação

Even though grammatical gender does not always feel logical to an English speaker, it is something you simply learn with each noun.

Teria sido means would have been.

It is made up of:

• teria = would have
• sido = been

This is a common way to form the conditional perfect in Portuguese, used for hypothetical past situations.

So:

• teria sido muito pior = would have been much worse

This tells us the speaker is talking about something that did not happen, because the anesthesia was in fact used.

Because the sentence refers to a hypothetical result in the past.

• seria muito pior = would be much worse
• teria sido muito pior = would have been much worse

In this sentence, the injection already happened, so Portuguese uses the equivalent of would have been.

That is why teria sido is the best choice here.

You might hear something like that in some contexts, but it changes the meaning slightly.

• teria sido muito pior = it would have been much worse
  This clearly refers to a completed past event.
• seria muito pior = it would be much worse
  This sounds more general, less tied to a specific finished event.

Since the sentence is about an injection that already took place, teria sido muito pior is the most accurate form.

Pior means worse.

Adding muito means much:

• pior = worse
• muito pior = much worse

So:

• a injeção teria sido pior = the injection would have been worse
• a injeção teria sido muito pior = the injection would have been much worse

This simply adds emphasis.

Yes, absolutely.

• Sem anestesia = without anesthesia
• Sem a anestesia = without the anesthesia

The version without the article is often more general or more abstract. The version with the article sounds more tied to the specific situation.

In real Portuguese, both may appear, depending on context and style.

Because Sem a anestesia is an introductory phrase.

Portuguese, like English, often uses a comma after a phrase placed at the beginning of a sentence, especially when it gives background or a condition.

So the sentence is structured like this:

• Sem a anestesia, = without the anesthesia
• a injeção teria sido muito pior. = the injection would have been much worse

The comma makes the sentence easier to read.

In European Portuguese, injeção is pronounced approximately like:

• in-zheh-SOUNG

A few helpful points:

• the j sounds like the s in measure
• the final -ão is a nasal sound, not a full English ow
• the stress is on the last syllable: -ção

If you know IPA, it is roughly [ĩʒɛˈsɐ̃w̃] in European Portuguese.

Both spellings may be encountered, but injeção is the modern standard spelling.

Before the spelling reform, European Portuguese commonly used:

• injecção

After the reform, the silent c was removed:

• injeção

So if you see injecção, it is older spelling, not a different word.

Anestesia is completely normal and natural here.

It usually refers to the anesthesia itself, the numbing process, or the anesthetic effect.

Anestésico usually refers more specifically to the anesthetic substance or agent.

So in this sentence:

• Sem a anestesia = Without the anesthesia

That is the most natural choice if the idea is that the numbing treatment made the injection less bad.

Grammatically, a injeção is the subject, so literally it says the injection would have been much worse.

But in natural meaning, this usually refers to the experience of receiving the injection, especially the pain or discomfort.

Portuguese often allows this kind of wording, just as English does:

• The injection was bad
• The injection would have been worse without anesthesia

So the sentence is really about how unpleasant the injection would have felt.