Placental meconium

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Placental meconium
Diagnosis in short

Meconium-laden macrophages. H&E stain.

LM macrophages with brown fine granular pigment in the amnion +/- chorion
LM DDx hemorrhage
Stains PASD +ve, Prussian blue -ve
Gross green discolourization of fetal membranes
Site placental membranes

Associated Dx +/-chorioamnionitis
Clinical history +/-non-reassuring fetal heart rate
Prevalence uncommon
Prognosis benign

Placental meconium, also known as meconium staining, is associated with fetal distress.

General

  • Associated with fetal distress.
  • Small amount - at term - is considered to be normal.

Other meconium-related pathology:

Gross

  • Fetal membranes with a green discolourization.

Microscopic

Features:[1]

  • Meconium histiocytes - key feature.
    • Macrophages with brown fine granular pigment.
  • Pseudostratified epithelium (amnion) - low power.
  • Amnion - columnar morphology (normally cuboidal).
  • "Drop-out" of individual amnion cells / loss of individual cells.

Time of meconium passage:[2]

  • <1 h - no staining of membranes.
  • 1-3 h - amnion is stained.
  • >3 h - chorion is stained.

DDx:

  • Hemosiderin-laden macrophages.
    • This is sorted-out with an iron stain -- see below.
  • Chorioamnionitis - apoptotic cells may be mistaken for neutrophils.

Notes:

  • The above time course is disputed - in vitro experiments suggest it is considerably longer.[3]

Images

Special stains

  • Hemosiderin +ve in hemosiderin-laden macrophages.
  • PAS +ve in meconium-laden macrophages.[4]

Useful to differentiate hemosiderin-laden macrophages and meconium laden macrophages:

  • Hemosiderin stain -- +ve for old blood.
    • Prussian-blue stain = hemosiderin stain.[5]

Notes:

  • PAS-D -- +ve in meconium... though may rarely stain hemosiderin.
  • Meconium contains bile.[6]

Sign out

PLACENTA, UMBILICAL CORD AND FETAL MEMBRANES, BIRTH:
- FETAL MEMBRANES WITH MECONIUM-LADEN MACROPHAGES, NEGATIVE FOR CHORIOAMNIONITIS.
- THREE VESSEL UMBILICAL CORD WITHIN NORMAL LIMITS.
- PLACENTAL DISC WITH THIRD TRIMESTER VILLI WITHIN NORMAL LIMITS.
COMMENT:
A PAS-D stain and Prussian blue stain were used to confirm the presence of meconium.

Degenerative changes present

PLACENTA, UMBILICAL CORD AND FETAL MEMBRANES, BIRTH:
- FETAL MEMBRANES WITH MECONIUM-LADEN MACROPHAGES AND DEGENERATIVE CHANGES, 
  NEGATIVE FOR CHORIOAMNIONITIS.
- THREE VESSEL UMBILICAL CORD WITHIN NORMAL LIMITS.
- PLACENTAL DISC WITH THIRD TRIMESTER VILLI WITHIN NORMAL LIMITS.

Not definite

PLACENTA, UMBILICAL CORD AND FETAL MEMBRANES, BIRTH:
- EARLY CHORIOAMNIONITIS.
- FETAL MEMBRANES WITH FOCAL AMNION CELL DROP-OUT AND RARE PIGMENTED
  CELLS SUGGESTIVE OF MECONIUM.
- THREE VESSEL UMBILICAL CORD WITHIN NORMAL LIMITS.
- PLACENTAL DISC WITH THIRD TRIMESTER VILLI.

See also

References

  1. ALS. 6 Febraury 2009.
  2. Miller PW, Coen RW, Benirschke K (October 1985). "Dating the time interval from meconium passage to birth". Obstet Gynecol 66 (4): 459–62. PMID 2413412.
  3. Funai EF, Labowsky AT, Drewes CE, Kliman HJ (January 2009). "Timing of fetal meconium absorption by amnionic macrophages". Am J Perinatol 26 (1): 93–7. doi:10.1055/s-0028-1103028. PMID 19031358.
  4. Povýsil C, Bennett R, Povýsilová V (January 2001). "CD 68 positivity of the so-called meconium corpuscles in human foetal intestine". Cesk Patol 37 (1): 7–9. PMID 11268705.
  5. Sienko A, Altshuler G (September 1999). "Meconium-induced umbilical vascular necrosis in abortuses and fetuses: a histopathologic study for cytokines". Obstet Gynecol 94 (3): 415?0. PMID 10472870.
  6. Sienko A, Altshuler G (September 1999). "Meconium-induced umbilical vascular necrosis in abortuses and fetuses: a histopathologic study for cytokines". Obstet Gynecol 94 (3): 415?0. PMID 10472870.