Products of conception

Products of conception, abbreviated POC, is stuff formed from the union of egg and sperm. This article covers POC superficially.

There are separate articles for chorionic villi and gestational trophoblastic disease.

General

Clinical

• Therapeutic abortions - may be abbreviated "MVC" (manual vacuum aspiration).

• Diagnosis of pregnancy: beta-hCG > 10 mIU/mL.
  • Beta-hCG calculator: http://www.countdowntopregnancy.com/tools/beta_doubling_calculator.php.
  • If the beta-hCG is >1500 mIU/mL -- there is a good chance an ultrasound is diagnostic.

Screening tests

First trimester screen

• PAPP-A.
• Nuchal translucency.
• Beta-hCG.

Maternal serum screen

• Alpha-fetoprotein.
• Beta-hCG.
• Estriol.

Diagnostic tests

• Chorionic villus sampling (10-12 weeks???).
• Amniocentesis (15-16 weeks+).

Gross

Fetal parts absent:

• Minimum of five cassettes.

Microscopic

Features:

• Chorionic villi are need to call POC - key feature.
  • Cytotrophoblast.
  • Centre of villi often have fetal red blood cells (which have nuclei) -- not required for diagnosis of POC.
• +/-Endometrium (intrauterine pregnancy):
  • Should have decidual changes -- mnemonic NEW:
    • Nucleus central.
    • Eosinophilic cytoplasm.
    • Well-defined cell borders.
• +/-Uterine tube +/- decidualization (tubal pregnancy).
• +/-Hyaline globules.
• +/-Embryo or fetus - a bonus.
  • Cartilage - common.
  • Primitive neuroepithelium.
  • Gastrointestinal epithelium.

Aside:

• Embryo = conceptus before 8 weeks.
• Fetus = conceptus 8th weeks 'til birth.

DDx:

• Partial hydatidiform mole.

Images

• 

  Chorionic villi - intermed. mag. (WC)

• 

  Chorionic villi and fetal parts - low mag. (WC)

• 

  Intermediate trophoblast reaction - low mag. (WC)

• 

  Intermediate trophoblast - high mag. (WC)

www:

• Tubal pregnancy - several images (gfmer.ch).

Specific conditions

Arias-Stella reaction

General

• Benign atypical endometrial changes associated with chorionic tissue.
  • May be seen in a normal pregnancy, hydatidiform moles, others.
• Historically it was diagnosed as endometrial cancer.

Note:

• To the novice... the nuclei look really scary, i.e. they look like cancer.

Microscopic

Features:

• Epithelial component of endometrium with large nuclei - key feature.
  • +/-Nuclear hyperchromasia, i.e. dark nuclei.
  • +/-Irregular nuclear membrane.
  • +/-Nuclear clearing.
  • +/-Nuclear pseudoinclusions.
• NC ratio is preserved.
• Usually a focal change.
• +/-Mitoses - uncommon.

Notes:

• No decidual reaction in the stroma.

DDx:

• Choriocarcinoma.
• Herpetic endometritis.
• Clear cell carcinoma.

Images

• Arias-Stella reaction (odn.ne.jp)

Subtypes

There are five subtypes:

1. Minimal atypia.
   • Usually early gestation.
2. Early secretory pattern.
   • Mimics secretory endometrium: cytoplasmic vacuoles, central nucleus, palisading architecture.
3. Secretory or hypersecretory pattern.
4. Regenerative, proliferative or nonsecretory pattern.
5. Monstrous cell pattern.

Ectopic pregnancy

General

• Chorionic villi have to be identified (in some location, e.g. Fallopian tube) to Dx a pregnancy.
• Endometrium: decidual reaction, as seen in any pregnancy.

Clinical:

• Abdominal pain in woman of childbearing age.
  • Every woman of childbearing age should be assumed pregnant until proven otherwise!
• Typical gestational age (GA) for a tubal pregnancy ~ 5-9 weeks.
  • Beta-hCG elevated but may be relatively low (<100 IU/L) even in the context of (uterine tube) rupture.

Microscopic

See Microscopic section above.

DDx:

• Hydropic abortus.
• Complete hydatidiform mole.
• Partial hydatidiform mole.

Images

• 

  EP - low mag. (WC)

• 

  EP - intermed. mag. (WC)

• 

  EP - high mag. (WC)

• 

  EP - intermed. mag. (WC)

Sign out

Fallopian Tube, Right Salpingectomy:
     - Fallopian tube with chorionic villi (tubal pregnancy).

Submitted as "Left Fallopian Tube and Ectopic Pregnancy", Excision:
     - Tubal pregnancy; Fallopian tube with chorionic villi and fetal parts.

Block letters

FALLOPIAN TUBE, RIGHT, SALPINGECTOMY:
- FALLOPIAN TUBE WITH CHORIONIC VILLI (TUBAL PREGNANCY).

Micro

The sections show fallopian tube wall with chorionic villi.

Nucleated red blood cells are present. No other fetal components are identified.

The chorionic villi do not show a Norwegian fjord-like periphery. Central cisterns are not apparent. There is no trophoblastic proliferation.

Retained products of conception

General

• May occur in a number of contexts, e.g. therapeutic abortion, sponatenous abortion.

Microscopic

See Microscopic section above.

DDx:

• Complete hydatidiform mole.
• Partial hydatidiform mole.
• Choriocarcinoma.

Sign out

Submitted as "Products of Conception":
- Chorionic villi present with degenerative changes, NEGATIVE for 
  proliferation or significant atypia. 
- Benign decidual tissue present.
- Necro-inflammatory debris and fibrin.

Variants

Submitted as "Products of Conception":
- Fetal tissue present.
- Benign decidual tissue present.
- Chorionic villi present, NEGATIVE for proliferation or significant atypia.

Submitted as "Products of Conception":
- Chorionic villi present with degenerative changes, negative for proliferation 
  or significant atypia.
- Benign decidual tissue present.
- Negative for fetal tissue.

Products of Conception, Curettage:
- Chorionic villi present without proliferation or significant atypia.
- Decidua present.
- Negative for malignancy.

No chorionic villi

Submitted as "Products of Conception", Curettage:
- Blood and fibrin.
- Scant benign squamous epithelium and scant benign endocervical epithelium.
- NEGATIVE for decidua.
- NEGATIVE for chorionic villi, see comment.

Comment:
The tissue was submitted in total. Clinical correlation is suggested.

The above was communicated to the on call gynecologist.

Notes:

• The above is considered a critical diagnosis.
• It should be communicated to the on call gynecologist and this communication should be documented.

Submitted as "Products of Conception":
     - Decidualized endometrium with necro-inflammatory changes/degeneration, 
       blood and fibrin.
     - NEGATIVE for chorionic villi, see comment.

Comment:
The tissue was submitted in total. 

The ultrasound impression (intrauterine gestational sac present) is noted. The decrease in serum beta-hCG is noted.

The lack of chorionic villi on pathology is a discordance with the clinical findings. 
A non-exhaustive list of possible explanations includes: non-removal/retention and prior spontaneous passing. Clinical correlation is required.

Block letters

ENDOMETRIUM, CURETTAGE:
- OUTLINES CONSISTENT WITH NON-VIABLE CHORIONIC VILLI WITH FIBRIN AND FOCAL 
  CALCIFICATIONS (COMPATIBLE WITH RETAINED PRODUCTS OF CONCEPTION).
- ENDOCERVICITIS, CHRONIC.
- NO DEFINITE ENDOMETRIUM.
- NO VIABLE CHORIONIC VILLI IDENTIFIED.
- NO EVIDENCE OF MALIGNANCY.

See also

• Gynecologic pathology.
• Chorionic villi.
• Gestational trophoblastic disease.
• Pregnancy luteoma.

External links

• Crown-rump length calculator (perinatology.com).