Assessing Second-Trimester Ferning in Diagnosing Preterm Prelabor Rupture of Membranes.

Area of Science:

• Obstetrics and Gynecology
• Maternal-Fetal Medicine
• Diagnostic Cytology

Background:

• Preterm prelabor rupture of membranes (PPROM) diagnosis relies on methods including microscopic detection of amniotic fluid ferning.
• Existing data on ferning detection sensitivity and specificity have not specifically focused on the second trimester of pregnancy.

Purpose of the Study:

• To evaluate the presence of ferning in transvaginally collected amniotic fluid in pregnancies with known second-trimester PPROM.
• To determine if ferning detection differs based on gestational age and amniotic fluid sample drying time.

Main Methods:

• Prospective study involving amniotic fluid analysis in individuals undergoing pregnancy termination between 15 and 24 weeks gestation.
• Collection of vaginal swabs before and at the time of membrane rupture, alongside amniotic fluid samples.
• Microscopic examination of centrifuged and uncentrifuged samples for ferning at various drying time intervals (up to 10 minutes) by blinded investigators.

Main Results:

• A significant increase in ferning detection was observed with longer drying times, particularly up to 10 minutes (p < 0.001).
• Gestational age did not significantly impact the detection rates of ferning (p = 0.09).
• Centrifuging the amniotic fluid to remove blood improved ferning detection by 15% at 10 minutes compared to vaginal swabs.

Conclusions:

• Ferning detection in second-trimester PPROM cases is enhanced by allowing samples to dry for at least 10 minutes.
• Centrifugation of amniotic fluid samples to remove blood improves the ability to detect ferning.
• Gestational age within the second trimester does not appear to influence ferning detection rates.