The patients affected were among 15 who underwent routine colonoscopies at the University Nursing Centre of the hospital at the Paul Brien site in Schaarbeek. The procedure involves the introduction of a camera into the colon via the rectum, and it is used to detect the presence of abnormalities within the large intestine.

In normal circumstances, the “eye” of the camera is constantly laved with distilled water to keep it free of debris while it transmits pictures to the computer where staff can watch what is going on. However, in the Paul Brien case, the water was replaced with glutaraldehyde, a colourless liquid used to sterilise medical equipment, which is toxic and a severe irritant to skin, eyes and lungs.

Two patients came back to the hospital two days after the procedure complaining of severe pain. The other patients who had been treated at the same time were interviewed and admitted for tests, when it emerged that four in all had suffered damage to the colon. According to one report, one of the patients, a young woman, has had a colostomy put in place.

The hospital is now investigating how the glutaraldehyde came to be used instead of distilled water. At the same time, a complaint has been filed with the Brussels prosecutor’s office against persons unknown, in the event that it turns out to be an act of sabotage. Meanwhile, the hospital has promised both treatment and compensation to those affected, none of whom has so far lodged a complaint.