Placenta
Nonneoplastic placental conditions and abnormalities
Placental findings in specific conditions
Abortion subtypes


Topic Completed: 1 November 2011

Minor changes: 5 October 2020

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PubMed Search: abortion spontaneous septic missed

Mandolin S. Ziadie, M.D.
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Cite this page: Ziadie MS. Abortion subtypes. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/placentaspontaneousab.html. Accessed May 15th, 2021.
Definition / general
  • Spontaneous abortion:
    • Naturally occurring intrauterine loss is observed in 10 - 15% of clinically recognized pregnancies and 22% of pregnancies detected via hCG levels
    • May be due to fetal factors (e.g. genetic abnormalities) or maternal factors (e.g. anatomic, infectious or autoimmune)
    • Fetal loss with normal karyotype is associated with maternal age < 20 years, chronic intervillositis, increased perivillous fibrin deposition with intermediate trophoblast and decidual plasma cells (Hum Pathol 1999;30:93)
    • Fetal loss with abnormal karyotype is associated with developmental stage < 6 weeks, hydropic villi > 1 mm and villi with 2+ dysmorphic features
  • Missed abortion:
    • Fetal death with delayed abortion resulting in passage of placental tissue without an embryo
  • Septic abortion:
    • Placental bacteremia due to coliforms or anaerobic streptococci
Treatment
  • D&C to remove residual trophoblastic tissue to confirm intrauterine pregnancy and rule out gestational trophoblastic disease
  • To diagnose intrauterine pregnancy with certainty, should see fetal parts, villi and trophoblasts in sections of intrauterine contents
  • Enlarged hyalinized spiral arteries and fibrinoid matrix are suggestive
  • Decidual reaction, gestational hyperplasia (glandular secretion, stromal edema) and Arias-Stella reaction are suggestive of pregnancy (not necessarily intrauterine) but are nonspecific (also occur with hormones)
Gross description
  • Spontaneous abortion:
    • Soft hemorrhagic mass of spongy tissue (villi) and soft tissue (decidua) that may be attached to membranes as an intact or ruptured gestational sac
    • Report should indicate presence of sac, state of rupture and presence of umbilical cord
    • Fetal parts should be documented and closely examined for anomalies
    • Cytogenetics should be obtained in cases of recurrent spontaneous abortion or malformed fetuses
  • Missed abortion:
    • Placental tissue including a gestational sac and villi are present in the absence of a fetus
Microscopic (histologic) description
  • Spontaneous abortion:
    • Early abortions show decidual necrosis and decidual blood vessel thrombi, neutrophilic infiltrate, old / recent hemorrhage and edematous avascular villi
    • Dysmorphic villi and villous trophoblastic hyperplasia are suggestive of an abnormal karyotype (Mod Pathol 1998;11:762)
    • Second trimester abortions show focal decidual necrosis, intradecidual hemorrhage, congestion / thrombosis of maternal vessels and avascular villi
  • Missed abortion:
    • Normal or hydropic villi, sometimes with cisterns and without trophoblastic hyperplasia
    • Dysmorphic villi suggest a chromosomal abnormality
    • Other features may reveal a cause of fetal death including vasculitis, infarction, perivillous fibrin, deciduitis and intervillositis
  • Septic abortion:
    • Must demonstrate infectious organisms in placental parenchyma or membranes; the presence of neutrophils is insufficient because they may be a reaction to necrotic decidua
Differential diagnosis
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