PICTURE THIS: The black stones that can lie hidden inside us!

WHEN this 3 cm gallstone was surgically removed from a patient’s gallbladder, even the medics were shocked by its size. But just as interesting, arguably, is the colour. Typically, gallstones are yellow, but this is what’s known as a pigmented gallstone, which account for around a fifth of cases.

As many as one in ten adults is thought to have gallstones, which are usually formed as a result of high levels of cholesterol inside the gallbladder, explains Dr Simon Campbell, a consultant gastroenterologist at the BMI Alexandra Hospital in Cheadle, Cheshire.

Black or heavily pigmented stones such as this one are due to high levels of a waste product called bilirubin inside the gallbladder or the bile duct (which runs from the liver to the gallbladder).

Bilirubin is the by-product of broken down, old red blood cells. This goes into the liver, where it forms bile, which flows

down the bile duct to the gallbladder, where it’s stored as an aid to digestion.

Black gallstones can form when there is too much bilirubin due to excess red blood cells — perhaps as a result of excess drinking or sickle cell anaemia.

With all types of gallstones, symptoms usually only occur when a gallstone dislodges from the gallbladder and then gets stuck — for instance in the bile duct,

which is about 6mm wide. As well as triggering pain, muscle spasms and vomiting, the blockage means bile cannot leave the body, which may cause jaundice.

This image was posted on Figure 1, an app and website where doctors around the world share medical images.

The nurse from North America who posted the picture said the operating team were shocked the patient’s gallbladder had not ruptured, given the number and size of the gallstones.

The patient underwent surgery to remove the gallbladder. However, the bad news is that whereas cholesterol gallstones will not recur after this surgery, bilirubin stones can reappear as they form in the bile duct as well as the gallbladder.