Products of conception

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Author: Mikael Häggström [note 1]

Comprehensiveness

On this resource, the following formatting is used for comprehensiveness:

  • Minimal depth
  • (Moderate depth)
  • ((Comprehensive))

Gross processing

Look up the gestational age of the pregnancy.

  • Look for fetal tissue (fetus, fetal membranes or chorionic villi). They are generally easier to distinguish from decidua (which is maternal tissue) when fragments are put in clear fluid and shaken, with chorionic villi having a consistency like orange pulp, whereas decidua is more rubbery. The fluid may be formalin if no sample for genetic workup is needed. If chorionic villi are found, no lengthy search is needed for other kinds of fetal tissue, just a quick look for obvious ones. Membranous material is less reliable, and may still indicate further sampling. Inspect any found fetal tissue for gross anomalies. If found, submit one piece of the fetus and one piece of the placenta.[1]
  • If fetal parts are not visually found, search for diagnostic placental tissue, which is soft and shaggy or spongy (as opposed to membranous, which is likely to be decidua or blood clots).[1]
  • If no fetal or placental tissue is found, all presented tissue generally needs to be submitted.

(If transported or processed together with other cases, put any chorionic villi in thin-mesh cassettes or tissue bags to limit contamination).[note 2]

Gross report

(Labeled - products of conception.) The specimen (is received <<fresh / in formalin>>) and consists of multiple fragments of soft tan-pink decidua, blood clots and amniotic sac measuring about 5 cc in aggregate. The intact amniotic sac measures 2.3 cm in greatest dimension. Fetal tissue is identified within the amniotic sac, measuring 1.0 cm in crown-rump length. Representative sections are submitted for microscopic examination (in 1 cassette).

Microscopy

The most important is to detect the presence of chorionic villi.

In the absence of chorionic villi, look for implantation site intermediate trophoblasts (ISITs):

  • In the absence of both chorionic villi and ISITs, preferably perform cytokeratin immunostaining of each tissue sample, such as CAM5.2.[2]
  • In the absence of chorionic villi and ISITs even after staining, call the clinician, since there may be an ectopic pregnancy.

Microscopy report

Examples:

Histopathology of chorionic villi at gestational age of 9 weeks.jpg

((Products of conception:)) Products of conception, including immature chorionic villi, corresponding to first trimester pregnancy. ((Spontaneous abortion, clinically.))

Histology of implantation site intermediate trophoblasts.jpg

((Products of conception:)) Fragments of focally necrotic decidua and implantation site, consistent with intrauterine products of conception. Negative for chorionic villi.

Notes

  1. For a full list of contributors, see article history. Creators of images are attributed at the image description pages, seen by clicking on the images. See Patholines:Authorship for details.
  2. Chorionic villi are promiscuous contaminants of other tissues, and may cause a false positive finding for another cassette containing products of conception.
    - Carll T, Fuja C, Antic T, Lastra R, Pytel P (2022). "Tissue Contamination During Transportation of Formalin-Fixed, Paraffin-Embedded Blocks. ". Am J Clin Pathol 158 (1): 96-104. doi:10.1093/ajcp/aqac014. PMID 35195717. Archived from the original. . 

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References

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