Learn Spanish (Latin America): Estas puntadas son pequeñas pequeñas.

Repeating an adjective is a very common, natural way in spoken Latin American Spanish to emphasize the maximum degree of that quality. Saying pequeñas pequeñas means the stitches are 'extremely small' or 'tiny.' It does the exact same job as adding 'very, very' in English.

Do both words in pequeñas pequeñas need to agree with the noun?

Yes. Because they are both adjectives describing the feminine plural noun puntadas, both copies of the word must take the feminine plural ending -as.

Could I just say pequeñísimas instead?

Absolutely. Pequeñísimas uses the absolute superlative suffix -ísimo to mean 'extremely small.' Both are perfectly natural, but repeating the word (pequeñas pequeñas) can feel a bit more conversational and spontaneous.

Why do we use son instead of están for stitches?

We use son (from the verb ser) because size is an inherent, defining characteristic of these specific stitches. Even though someone created them, they are not going to change size—being tiny is just what they are.

Would I use puntadas for medical stitches at a hospital?