Back to Basics: Is that Amniotic Fluid?

Case:  A pregnant female presents with "damp" underwear upon wakening.  She has a history of intermittent urinary incontinence, however she is concerned for spontaenous rupture of membranes (amniorrhexis).

How to evaluate if vaginal fluid contains amniotic fluid:


  1. Sterile speculum exam

  • No lubricating jelly (affects pH)

  • Is there fluid pooling in posterior fornix or flowing from os?


  1. Nitrazine paper

  • Collect sample and apply to Nitrazine paper

  • Turns BLUE in the presence of alkaline amniotic fluid


  1. Ferning

  • Collect sample and apply to clean dry glass slide

  • Allow 10 minutes to fully dry

  • Ferning is a positive sign of amniotic fluid