Fern Test

Test Code

FERN

Alias/See Also

ROM, Rupture of Membranes

CPT Codes
89060

Preferred Specimen

Vaginal Secretions smeared on a glass labeled slide
Amniotic Fluid

Reference Range

Negative: No crystallization seen (membranes are not ruptured)
Positive: Crystallization seen (membranes are ruptured)

Clinical Significance

The correct diagnosis of rupture of the membranes (PROM) during pregnancy is of great importance. A false-positive diagnosis may lead to a non-indicated intervention such as early delivery or a surgical delivery. A false-negative diagnosis may place the infant and mother at increased risk of infection which may be life threatening to one or both. Therefore, every attempt should be made to diagnose this condition as quickly and accurately as possible.
The Fern Test is one of several tests used to detect rupture of the membranes. Vaginal secretions are inspected under a microscope for crystallization or a ferning pattern. The crystallization is due to an increased concentration of protein and electrolytes within the fluid.

Vaginal secretions do not show the ferning pattern during pregnancy, but if amniotic fluid is present, the fern pattern is seen.

Performing Laboratory
CRMC Laboratory
CCMC Laboratory

The CPT Codes provided in this document are based on AMA guidelines and are for informational purposes only. CPT coding is the sole responsibility of the billing party. Please direct any questions regarding coding to the payor being billed. Any Profile/panel component may be ordered separately. Reflex tests are performed at an additional charge.