No, cerebrospinal fluid is not normally found in the sinuses.
It means there is fluid in that sinus. You have a right & a left maxillary sinus. Sometimes one can be worse than the other or only one can be infected.
superior sagittal sinus
It is reabsorbed through arachnoid granulations and goes into the venous sinus system.
One way to treat sinus drainage is to keep mucus thin rather than thick. Another way is to clean the nasal by flooding with fluid and this is a quick method to unclog the nose.
Pregnancy and fluid in the ears are unrelated to the best of my knowledge. The fluid is caused by a build up in the sinuses, after a cold or sinus allergy. It can cause dizziness, pain and infection if it does not drain on it's own.
paranasal sinus include frontal sinus, the maxillary sinus, the ethmodial sinuses, and the spheniodal sinus.
The maxillary sinus
The Cerebrospinal Fluid is absorbed into the venous blood in the dural sinuses through the arachnoid villi. Arachnoid villi connect the subarachnoid space to the superior sagittal sinus.
paranasal sinus include frontal sinus, the maxillary sinus, the ethmodial sinuses, and the spheniodal sinus.
Some words with the root sinus include sinusitis (inflammation of the sinuses), sinusoid (having a sinus-like curve), and sinusoidal (relating to a sinus).
In health, be sure you are talking about the correct "sinus" The heart has a sinus, so please be specific about which sinus you are referring to.