Some drops come out of him after urinating, but if he waits he may miss the prayer in congregation

Firstly: 

What comes out following urination is usually wadiy, which is
a thick, white liquid that comes out in the form of drops. As for madhiy
(prostatic fluid), it is what comes out following provocation of desire. 

Both of them invalidate wudoo’, but they do not necessitate
ghusl. When you say, “When it comes out I do ghusl”, perhaps you mean that
you wash it. As for ghusl (full ablution), you do not have to do it; rather
you have to do wudoo’. 

An-Nawawi (may Allah have mercy on him) said, explaining the
difference between madhiy and wadiy: As for madhiy, it is a sticky, thin,
clear fluid that is emitted with or without desire; it does not gush out in
spurts, and it is not followed by exhaustion; and one may not feel it coming
out. It happens to both men and women. 

As for wadiy, it is a thick, darkish fluid that resembles
maniy (semen) in its thickness, but differs from it in colour, and it has no
smell. It comes out following urination, when one is constipated, or when
carrying something heavy, and it comes out in the form of one or two drops
and the like. The scholars are unanimously agreed that it is not required to
do ghusl when madhiy and wadiy are emitted.

End quote from al-Majmoo‘, 2/160 

Shaykh Ibn Jibreen (may Allah preserve him) was asked: At the
end of urination, I notice some seminal fluid (maniy) coming out, and I do
not know whether I have to do ghusl every time I urinate, or what should I
do? Because I am not sure whether it has the same effect as intercourse? 

He replied: This “maniy” that comes out after urination is
wadiy, which is well known (and is not actually maniy). As it comes out
after urination and comes out in a stream (as opposed to gushing out), it
does not necessitate ghusl. However it does invalidate wudoo’, so the penis
should be washed after that, then one should do wudoo’, but it is not
necessary to do ghusl. Ghusl is only required when maniy gushes out in
spurts accompanied by feelings of pleasure, and is not required otherwise.
As gushing out in spurts forcefully is not like the emission of urine, which
comes out in a stream or in drops, it does not matter if it comes out like
that.

End quote from Fataawa Islamiyyah, 1/226 

Secondly: 

When you have relieved yourself, you have to wait until you
are certain that the flow has stopped, then clean yourself and do wudoo’. If
that leads to you missing the prayer in congregation, there is no blame on
you. But you should get ready for the prayer before the time comes, so long
as you know that you need a long time to relieve yourself. 

The Standing Committee for Issuing Fatwas were asked: There
is a man who suffers from urinary incontinence. He purifies himself some
time after urinating, but if he were to wait until the incontinence ends,
the time for the prayer in congregation would be over. What is the ruling? 

They replied: If he knows that the incontinence will end, it
is not permissible for him to pray when it is still affecting him, seeking
the virtue of praying in congregation. Rather he has to wait until it ends,
then he should clean himself after that, then do wudoo’ and offer his
prayer, even if he misses the prayer in congregation. However he should
hasten to clean himself and do wudoo’ once the time for the prayer has
begun, in the hope that he will be able to pray in congregation. End quote. 

Fataawa al-Lajnah ad-Daa’imah,
5/408 

Shaykh Ibn Jibreen (may Allah preserve him) said concerning
the one who is faced with that problem: 

First of all you have to take precautions with regard to
purification. So do wudoo’ half an hour or so before the time for prayer
begins, after you have urinated and the effects of urination have ceased, in
the hope that it will stop before the time for prayer comes. 

Secondly, after urinating you have to wash your private part
with cold water that will stop urination and prevent drops coming out. 

If these drops are the result of waswaas (whispers from the
Shaytaan) or something imaginary, then after cleaning yourself you should
sprinkle water on your pants or thobe, so that the Shaytaan cannot make you
imagine, if you see dampness, that it is urine, because you will know that
it is water that you put on your garment.

End quote from Fataawa Islamiyyah, 1/196 

Thirdly: 

You should beware of waswasah (whispers from the Shaytaan),
for it is a disease and an evil that can cause a person to worry and
generate doubt in his mind, making worship burdensome for him. So beware of
that. When you have relieved yourself, done wudoo’ and prayed, do not pay
any attention to doubts, because the basic principle is that one is pure and
that prayers are valid. 

Shaykh Ibn ‘Uthaymeen (may Allah have mercy on him) was
asked: When I have finished wudoo’ and am going to pray, I feel a drop of
urine coming out of the penis; what should I do? 

He replied:

The one who is affected with that should ignore it, as
enjoined by the leading scholars of the Muslims. He should not pay any
attention to it or go and check whether anything came out or not. By Allah’s
leave, if he seeks refuge with Allah from the accursed Shaytaan and ignores
it, it will go away. But if he is utterly certain about it, then it is
essential to wash whatever the urine has gotten onto, then repeat his wudoo’
because some people, if they feel coldness at the tip of the penis, think
that something has come out. But if you are certain, you should do what I
told you. What you have mentioned is not incontinence, because it stops,
whereas incontinence is ongoing. As for this, it is one or two drops that
come out after moving; this is not incontinence because two drops come out
then it stops. In this case you should wash yourself and do wudoo’ again.
You should always do this, and be patient and seek reward with Allah.

End quote from Liqa’ al-Baab al-Maftooh, 184/15 

And Allah knows best.