However, the techniques available so far possess several
pitfalls when applied to casework samples with unknown origin
and possibly unfavourable storage conditions. Visualization of
amplification products from small-sized or degraded samples
with ethidium bromide-stained agarose gels may be ambiguous
due to background fluorescence and to the low sensitivity of
ethidium bromide which interacts with every double-stranded
nucleic acid. Furthermore, negative results are of limited value
and do not prove the absence of menstrual blood because the
method is not quantitative and does not allow any conclusion as
to the amount and quality of RNA present in the sample.