* The classic triad of the<unk>  is: membrane rupture, painless vaginal bleeding and fetal bradycardia or fetal death. * Prior to the advent of ultrasound, this diagnosis was most often made after a stillbirth or neonatal death in which the mother had ruptured her membranes, had some bleeding, and delivered an exsanguinated baby. In these cases, examination of the placenta and membranes after delivery would show evidence of a velamentous cord insertion with rupture of the vessels. However, with almost universal use of ultrasound in the developed world, many cases are now detected during pregnancy, giving the opportunity to deliver the baby before this catastrophic rupture of the membranes occurs.<unk>  is diagnosed with ultrasound when echolucent linear or tubular structures are found overlying the cervix or in close proximity to it. Transvaginal ultrasound is the preferred modality. Color, power and pulsed wave Doppler should be used to confirm that the structures are fetal vessels. The vessels will demonstrate a fetal arterial or venous waveform. *Alkali denaturation test detects the presence of fetal hemoglobin in vaginal blood, as fetal hemoglobin is resistant to denaturation in presence of 1% NaOH. Tests such as the Ogita Test, Apt test or Londersloot test were previously used to attempt to detect fetal blood in the vaginal blood, to help make the diagnosis. These tests are no longer widely used in the US, but are sometimes used in other parts of the world. * Also detection of fetal hemoglobin in vaginal bleeding is diagnostic.
Vasa praevia
Uremic fetor
Breus' mole
Aposthia
Arbor vitae 
Placenta praevia
Wandering womb
Abortion in Brunei