Detectives are worried a woman may be hurt after blood was discovered in a toilet cubicle at The Warehouse.
Police were initially told a fetus had been found in the public block at the The Base shopping centre in Hamilton, but found no evidence to confirm that.
A staff member is thought to have discovered the blood on Tuesday and informed the cleaners, who called police on Wednesday afternoon.
Hamilton police said a young girl with a bleeding nose had also been seen in the area and they were attempting to identify the child to see if there was a connection to the incident.
"At this stage we are working to gain certainty about the events, and clarify if in fact a fetus was found, as physical searches have not found any evidence consistent with a fetus," said Detective Inspector Chris Page.