O tipo sanguíneo está no cadastro.

Portuguese uses definite articles much more often than English does.

In a normal full sentence, o tipo sanguíneo sounds natural because you are referring to a specific piece of information: the blood type.

English often says simply blood type, but Portuguese usually prefers o tipo sanguíneo in this kind of sentence.

You may see the article omitted in labels, headings, or forms, for example:

• Tipo sanguíneo:
• Nome:
• Data de nascimento:

But in a complete sentence, O tipo sanguíneo está no cadastro is the natural version.

Because adjectives usually come after the noun in Portuguese.

So:

• tipo = type
• sanguíneo = blood-related / sanguine

Together, tipo sanguíneo is the standard way to say blood type.

This noun + adjective order is very common in Portuguese. English often does the opposite:

• English: blood type
• Portuguese: tipo sanguíneo

Because estar is used here to talk about location or where something is found.

The sentence means that the blood type information is in the record/system/file. That is a location idea, so Portuguese uses estar:

• O tipo sanguíneo está no cadastro.

If you were identifying what the blood type actually is, you would normally use ser:

• O tipo sanguíneo é O positivo.

So a simple contrast is:

• está = is located / is found
• é = is by identity/classification

In Brazilian Portuguese, cadastro is a very common word that can mean something like:

• a registration
• a record
• a file
• a database entry
• information stored in a system

In this sentence, no cadastro most naturally means something like:

• in the record
• on file
• in the system
• in the registration data

The exact English translation depends on context. In Brazil, cadastro is used a lot in administrative, medical, business, and customer-service contexts.

Because Portuguese normally contracts em + o into no.

So:

• em + o = no
• em + a = na
• em + os = nos
• em + as = nas

That means:

• no cadastro = in the record/system

Using em o cadastro would sound unnatural in standard Portuguese.

The accents show important pronunciation and stress information, and they are part of the correct spelling.

• está has stress on the last syllable
• sanguíneo has stress on the syllable with í

The accent can also distinguish words:

• esta = this, feminine
• está = is

So the accent is not optional decoration. It changes how the word is read and sometimes helps distinguish meaning.

Yes. O tipo de sangue is also very common and natural in Brazilian Portuguese.

Both mean blood type:

• o tipo sanguíneo
• o tipo de sangue

A rough difference is:

• tipo sanguíneo can sound a little more formal or technical
• tipo de sangue can sound a little more everyday and conversational

In most situations, both are perfectly understandable.

Usually not in a normal sentence. That sounds incomplete or telegraphic.

The full sentence normally needs the article:

• O tipo sanguíneo está no cadastro.

But without the article, Tipo sanguíneo works very well as a label or heading, such as on a form or in a table.

So:

• Tipo sanguíneo → good as a field name
• O tipo sanguíneo está no cadastro. → good as a full sentence

Yes, if the context already makes it clear what it is.

Portuguese often leaves out the subject when it is understood from context. So if everyone already knows you are talking about the blood type, Está no cadastro can be natural.

But if you want the sentence to stand alone clearly, O tipo sanguíneo está no cadastro is better.

It would become:

Os tipos sanguíneos estão no cadastro.

Notice that several words change:

• o → os
• tipo → tipos
• sanguíneo → sanguíneos
• está → estão

This is a good example of agreement in Portuguese:

• article agrees with the noun
• adjective agrees with the noun
• verb agrees with the subject

It can be either.

Cadastro can refer to information stored:

• in a computer system
• in a database
• in an official file
• in a paper-based record

What matters is the idea of an organized record or registration, not the format. So in real Brazilian usage, cadastro may refer to digital or non-digital records depending on the situation.