Diagnose complete or partial molar pregnancy.
- Patient Preparation
- Products of conception.
- Specimen Preparation
- Formalin fix and paraffin embed tissue containing areas of villi and of decidua. In some cases, decidua may not be present in sufficient amounts, and a maternal blood sample may be requested. Transport tissue block.
- Storage/Transport Temperature
- Room temperature. Ship in a cooled container during the summer months.
- Unacceptable Conditions
- Paraffin block with no tissue remaining. Specimens fixed in formalin substitute.
- Include surgical pathology report.
- Ambient: Indefinitely; Refrigerated: Indefinitely; Frozen: Unacceptable
Characteristics of Complete Mole: Typically presents with vaginal bleeding, markedly elevated beta hCG, and ultrasound showing enlarged placenta. Histologic examination shows marked trophoblastic hyperplasia and hydropic villi.
Characteristics of Partial Mole: Typically presents as an enlarged placenta with hydropic change of some villi and a growth restricted fetus. Histologic examination shows a mixture of normal and abnormal villi with trophoblastic hyperplasia and hydropic change.
Incidence of Complete and Partial Moles: Approximately 1 in 1500 and 1 in 700 pregnancies respectively, with regional and ethnic variation observed.
Inheritance: The majority of cases are de novo; rare recurrences may be due to heritable mutations.
Cause of Complete Mole: Typically due to fertilization of an anucleate ovum by one endoreduplicated sperm or two separate sperm; karyotype is 46, N.
Cause of Partial Mole: Typically due to a normal ovum fertilized by two sperm; karyotype 69, N.
Clinical Sensitivity: Estimated to be 99 percent.
Clinical Specificity: Greater than 99 percent.
Methodology: PCR followed by capillary electrophoresis. Specimens are analyzed using 15 short tandem repeat (STR) markers (D8S1179, D21S11, D7S820, CSF1PO, D3S1358, TH01, D13S317, D16S539, D2S1338, D19S433, vWa, TPOX, D18S51, D5S818 and FGA) and one gender marker (amelogenin).
Analytical sensitivity and specificity: 99 percent.
Limitations: Contamination of villi / decidua may occur. Inhibitors present in the specimen can interfere with the polymerase chain reaction. Rare case of heritable molar pregnancy may appear normal by STR analysis.
|Component Test Code*||Component Chart Name||LOINC|
|0051757||Molar Pregnancy, 16 DNA Markers|
|2001366||MOL PREG Specimen|
- Hyatid form testing
- Product of conception PCR assay