Use of the nitrazine yellow swab test in the diagnosis of ruptured membranes.

Throat swabs impregnated with nitrazine yellow have been used to detect pH change in the vagina before and after amniotomy. The effect of infection on the test has been examined. A negative result is of use in excluding the diagnosis of ruptured membranes. A positive result is highly suggestive of the presence of amniotic fluid.