The effect of immersion formaldehyde fixation on human placental weight.

The prevalence of the human immunodeficiency and hepatitis viruses has led to considerable concern by health care workers about safer means of examining surgical pathological specimens. The human placenta needs to be examined when there are complications during pregnancy, labor, and delivery; when the fetus is born with apparent problems; and when the delivered placenta is abnormal. Placentas are routinely immersion fixed with neutral buffered 3.7% to 4.0% formaldehyde solution before examination and without obtaining a fresh weight. This study was undertaken to determine if there was a significant change in weight between a fresh and fixed placenta. The results show a 7.67% increase in placental weight after formaldehyde fixation for 24 hours. Thus, the practice of formaldehyde fixation prior to weighing and examination can be continued and still allow for accurate estimation of fresh placental weight.