Meconium generally present after used of drugs, Demerol and/or Oxytocin

Meconium staining

Full Report at:  http://www.pathologyoutlines.com/placenta.html

Passage of meconium in utero is due to bowel peristalsis and relaxation of anal sphincter; may indicate fetal distress; associated with meconium aspiration

Must differentiate between deposition of slimy green meconium across placental surface that is washed off with a gentle rinse (normal fetus that pases meconium shortly after delivery) and true mecomium staining (exposure to meconium for several hours)

Damage to fetus increases with length of exposure to meconium; over time, soluble meconium components diffuse into placenta and cord, induce vasoconstriction and cause fetal hypoperfusion

Present in cord macrophages; causes necrosis of individual myoctes; may cause funisitis without chorioamnionitis

Before 34 weeks, pigment present is usually hemoglobin   Meconium associated vasculopathy: avascular fetal vasculopathy secondary to remote thrombus   Gross:  initially slimy green membranes, later muddy brown; flattened segment of umbilical cord, slimy green to muddy brown membranes and cord surface

Gross images:  {HYPERLINK "http://medlib.med.utah.edu/WebPath/PLACHTML/PLAC015.html"} image1

Micro:

pigmented macrophages with apoptotic like nuclei

mild -superficial necrotic or sloughed amniotic epithelium with meconium containing macrophages confined to the surface

moderate -ballooning of vacuolated amniotic epithelium with obvious meconium containing macrophages adjacent to chorionic tissue; indicates meconium discharge at least 2-3 hours before delivery

severe -moderate histologic findings but with more macrophages; may have meconium induced necrosis of umbilical vessels with myocyte necrosis; indicates fetal meconium discharge 6-12 hours before delivery

Micro images: {HYPERLINK "http://medlib.med.utah.edu/WebPath/PLACHTML/PLAC016.html"} image1

_____________________________