Brief Answer:
Dark substance in semen is known as hematospermia.

Detailed Answer:
Hi,
Welcome to health care magic.
Dark substance in semen could be your blood ,the condition is known as hematospermia.
The causes could be infection of prostate or seminal vesicles,vigorous sexual activity, trauma to small blood vessel or rarely urethral stricture or trauma.
If it has come spontaneously without pain then it could be due to injury small blood vessel or capillary and in majority of cases it subsides automatically.
You must need further evaluation like complete physical examination, prostate examination, urine and semen analysis,ultrasound of pelvis with urethroscopy to rule out infective or any other pathology of prostate, seminal vesicles and testis.
You should consult urologist for complete medical history and thoroughly examination for proper diagnosis.
Thanks and Regards,
Dr.sandipkabra

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Brief Answer:
It would be advisable to go for urologist check-up at least once.

Detailed Answer:
Hi,
Thanks for follow-up query.

As you had not any history of pain,so chances of injury would be very rare.

Now,as I said earlier if it has come spontaneously without any pain or injury then it should subside automatically in majority of cases by itself.

Here, considering your age, I would suggest you to go at least once for urologist consultation for complete medical history and thoroughly examination of pelvis and genitals to clear any doubt.

Regards,
Dr.SandipKabra.

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Brief Answer:
My pleasure

Detailed Answer:
Hi,

you are welcome,

Hope you have received helpful and satisfactory answer.

Regards,

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