Awaiting biopsy results

Hi I'm waiting my biopsy results had abnormal smear result was then sent for colposcopy doctor said that it was serious and that she would be treating me that day with loop treatment  then she took a biopsy  it's now 4wks still no biopsy result my mind is working over time as I'm thinking the worse . They said I'd get a letter but nothing yet in the post does anyone know how long it will take for these results as my anxiety is through the roof