There are concerns that women may be facing more delays in getting smear test results under Cervical Check.
Irish-based MedLab Pathology has cleared 55,000 from the backlog but is no longer carrying out work for the screening programme.
It has led to fears the US-based lab Quest Diagnostics might not have enough capacity to clear the remaining backlog.
Sinn Féin's health spokesperson, Louise O'Reilly, said women may be faced with longer waiting times for their results.
She said: "We know that there is an issue regarding capacity. This latest revelation, I think, is going to put additional pressure on a system that's already under pressure and indeed additional pressure on women, who want their results in timely manner."