Если десна кровоточит, стоит пойти к врачу.

Here стоит does not mean costs.

In the pattern стоит + infinitive, it means something like:

• it is worth doing
• it would be a good idea to do
• one should do

So стоит пойти к врачу means it’s worth going to the doctor or more naturally you should go to the doctor.

This is a fairly soft, natural way to give advice. It is less direct than нужно пойти к врачу or надо пойти к врачу.

Russian often leaves out a specific subject when making a general recommendation.

In стоит пойти к врачу, there is no explicit you, but the meaning is understood as:

• you should go to the doctor
• one should go to the doctor

This is an impersonal construction. Russian uses these very often, especially for advice, rules, and general statements.

This is about aspect.

• идти = imperfective, to be going / to go in an ongoing or general sense
• пойти = perfective, to go as a single completed action, often with the sense of set off / go once

Here the sentence is recommending a single concrete action: make a visit to the doctor. That is why пойти fits better.

So:

• стоит пойти к врачу = it would be a good idea to go see a doctor
• стоит идти к врачу would sound less natural in this context

К takes the dative case, so:

• врач = nominative
• врачу = dative

So к врачу literally means to the doctor.

In Russian, идти/пойти к врачу is the normal way to say go to the doctor in the sense of go see a doctor.

Because the idea here is movement toward a person, and Russian normally uses к + dative for that.

• пойти к врачу = go to the doctor / go see the doctor

Just врачу by itself would not express that meaning.

So the preposition к is necessary.

Кровоточить means to bleed, often in a somewhat medical or descriptive sense.

It is commonly used for things like:

• gums bleeding
• wounds bleeding
• ulcers bleeding

So десна кровоточит means the gum is bleeding.

There is also the verb кровить, but кровоточить often sounds more standard in medical-style phrasing.

Yes, that is a very natural question.

• десна = gum (singular)
• дёсны / десны = gums (plural)

So this sentence literally refers to one gum: If a gum is bleeding...

In many everyday situations, if you mean your gums are bleeding in general, Russian would more often use the plural:

• Если дёсны кровоточат, стоит пойти к врачу.

So the singular sentence is grammatically fine, but it sounds more like:

• one part of the gum is bleeding
• a particular gum is bleeding
• a simplified example sentence

Because Если десна кровоточит is a subordinate clause introduced by если (if).

Russian normally puts a comma between the if-clause and the main clause:

• Если десна кровоточит, стоит пойти к врачу.

This is standard punctuation.

Yes. Russian word order is more flexible than English.

For example, you can also say:

• Стоит пойти к врачу, если десна кровоточит.

This means the same thing: If the gum is bleeding, you should go to the doctor.

The original version starts with the condition first, which is very natural.

They are close, but not identical in tone.

• стоит пойти к врачу = it would be a good idea to go to the doctor / you should go
• нужно пойти к врачу = it is necessary to go to the doctor
• надо пойти к врачу = you need to go to the doctor

So стоит sounds a bit softer and more like advice, while нужно and надо sound stronger.

It is mostly neutral.

• кровоточит gives it a slightly medical or health-advice feel
• стоит пойти к врачу sounds polite and natural

So it would fit well in:

• health advice
• a doctor’s recommendation
• a textbook example
• ordinary conversation

It is not especially formal, but it is a bit more polished than very casual speech.