Fern test: A sterile cotton swab is used to collect fluid from the vagina and place it on a microscope slide. After drying, amniotic fluid will form a crystallization pattern called arborization which resembles leaves of a fern plant when viewed under a microscope. Fibronectin and alpha-fetoprotein blood tests

Classification
Prelabor rupture of membranes (PROM): when the fetal membranes rupture early, at least one hour before labor has started. Prolonged PROM: a case of prelabor rupture of membranes in which more than 18 hours has passed between the rupture and the onset of labor. Preterm prelabor rupture of membranes (PPROM): prelabor rupture of membranes that occurs before 37 weeks gestation. Midtrimester PPROM or pre-viable PPROM: prelabor rupture of membranes that occurs before 24 weeks gestation. Before this age, the fetus cannot survive outside of the mothers womb. Additional tests
The following tests should only be used if the diagnosis is still unclear after the standard tests above. Ultrasound: Ultrasound can measure the amount of fluid still in the uterus surrounding the fetus. If the fluid levels are low, PROM is more likely. This is helpful in cases when the diagnosis is not certain, but is not, by itself, definitive. Immune-chromatological tests are helpful, if negative, to rule out PROM, but are not that helpful if positive since the false-positive rate is relatively high (19–30%). Indigo carmine dye test: a needle is used to inject indigo carmine dye (blue) into the amniotic fluid that remains in the uterus through the abdominal wall.
The risk of infection was noted to be increasing with age, especially in people older than 40 years and it was greater in men than women. Most cases were acquired in Bavaria (46%) and Baden-Württemberg (37%), much less in Saxony, Hesse, Lower Saxony and other states. Altogether 164 Landkreise are designated TBE-risk areas, including all of Baden-Württemberg except for the city of Heilbronn.In Sweden, most cases of TBE occur in a band running from Stockholm to the west, especially around lakes and the nearby region of the Baltic sea. It reflects the greater population involved in outdoor activities in these areas. Overall, for Europe, the estimated risk is roughly 1 case per 10,000 human-months of woodland activity. Although in some regions of Russia and Slovenia, the prevalence of cases can be as high as 70 cases per 100,000 people per year. Travelers to endemic regions do not often become cases, with only 5 cases reported among U.S. travelers returning from Eurasia between 2000 and 2011, a rate so low that as of 2016 the U.S. Centers for Disease Control and Prevention recommended vaccination only for those who will be extensively exposed in high risk areas. References
External links

Tickborne encephalitis at Centers for Disease Control and Prevention (CDC)
Factsheet from Viral Special Pathogens Branch at the CDC