The liver doesn't produce the bile from scratch much of it is recycled from the entrohepatic cycle. However, there is tendency for recycled bile to clump more easily that freshly synthesised bile. It is important to ensure that a regular good proportion of bile is expelled so that new bile is synthesised.
It is now believed that more bile is lost that the 5% that older theory books report. Also, many more substances that we consume cause bile secreted through the biliary tract.
There are two distinct types of bile, hepatic bile and gallbladder bile the main difference being that hepatic bile contains bicarbonate and gallbladder bile is concentrated having water and bicarbonate removed. Both types in slightly different proportion are secreted by demand of different foods.
Many people survive perfectly well without a gallbladder and I have a friend whose diseased gallbladder was removed and his life has been unaffected. So it could be concluded that either he is lucky or in you circumstance and that of about 40% of people without a gallbladder that there is another factor.
The major problem with cholesterol is its inherently high melting point of 150 deg C. This is way above body temperature. When the essential fatty acids linoleic and linolenic are present in sufficient quantity with lecithin, cholesterol becomes liquid below normal body temperature.
'Normal' Bile is a critically stable (Metastable) material. It is a mixture of 3 compounds:
Cholesterol
Bile Salts
Lecithin
They need to exist together in certain proportion and any imbalance in any of the 3 substances can lead to anomalies in the bile. Too much cholesterol and crystals of cholesterol and clumps of fatty material form. A drop in lecithin and crystals of cholesterol, clumps of fatty material and cluster of plastic like material form. A drop in bile salts and clumps of fatty material and cluster of plastic like material form.
It can be seen that bile has the potential to make a wide variety of different types of 'stones' in the liver, ducts or gallbladder. It is also possibly that bile falling within normal concentrations may under certain condition form gall stones, Eg if the bile isn't replenished regularly or the gallbladder doesn't contract properly among other things.
Experiments in a laboratory have demonstrated that bile from people without
Gallstones takes about 15 days to form the nucleus of a gallstone. Bile of people with cholesterol gallstones, which, usually already contains cholesterol crystals has a nucleation time of about 3 days. Nucleation of cholesterol occurs far more rapidly from gallbladder bile of people with cholesterol
Gallstones than from hepatic bile in the same person, even when hepatic bile samples are supersaturated with cholesterol. The addition of even small amounts of gallbladder bile to the hepatic bile samples causes rapid nucleation. These observations have led to the isolation of proteins in the gallbladder that promote or retard the nucleation of cholesterol crystals. At least five proteins have been identified as nucleation promoters, in addition to gallbladder mucoprotein.
During the normal inter-digestive period the gallbladder partially contracts, thus potentially evacuating any small crystals that might have formed. This cleansing function of the gallbladder should in theory prevent bile stasis and prevent crystals from growing into stones. However, interruption in the normal biliary cycles can lead to the formation of cholesterol gallstones. This condition is sometimes called biliary stasis or gallbladder stasis. Stasis means the state in which the normal flow of a body stops.
Cholesterol re-absorption in the intestines can be blocked with an essential fatty acid "alpha-olefin maleic acid". This may be way of expelling excess bile, mainly cholesterol, and facilitating the biliary equivalent of an oil change but the evidence is not sufficiently robust at this point in time.