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Three-dimensional Rendering and Analysis of Immunolabeled, Clarified Human Placental Villous Vascular Networks
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The Difference Between Unfixed and Postfixation Placental Weight.

Rosemary Tambouret1, William R Jeck1, Drucilla J Roberts1

  • 1Department of Pathology, Massachusetts General Hospital, Boston.

American Journal of Clinical Pathology
|May 23, 2019
PubMed
Summary
This summary is machine-generated.

Formalin fixation of placentas results in a small, statistically significant weight gain. This weight change is clinically negligible, ensuring accuracy for surgical pathology reference values.

Keywords:
Formalin fixationPlacentaWeight

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Area of Science:

  • Obstetrics and Gynecology
  • Pathology
  • Medical Research

Background:

  • Placental weight reference values are crucial for surgical pathology and correlate with gestational age.
  • Established reference values primarily use fresh placentas, raising concerns about accuracy with routinely fixed specimens.

Purpose of the Study:

  • To investigate the impact of formalin fixation on placental weight.
  • To determine if fixation affects the accuracy of placental weight reference values.

Main Methods:

  • One hundred placentas from uncomplicated pregnancies were weighed fresh, then after 1 and 5 days of formalin fixation.
  • Weight changes were analyzed using a two-tailed paired t-test.

Main Results:

  • A statistically significant weight gain of 3.7% was observed after 24 hours of fixation (P << .001).
  • No significant weight change occurred between 24 hours and 5 days of fixation (P = .51).
  • A minority of placentas (9%) lost weight, and some (4%) remained unchanged.

Conclusions:

  • Formalin fixation introduces a statistically significant but clinically negligible increase in placental weight.
  • The findings suggest that current reference values remain largely accurate despite routine formalin fixation.