- 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 and ultrasound showing enlarged placenta, marked trophoblastic hyperplasia and swollen villi. If diagnosed in the first trimester, embryonic tissue may be present; by the second trimester, no fetal tissue is evident.
Characteristics of Partial Mole: Typically presents as a threatened or missed abortion at the end of the first trimester; if still viable in the second trimester, a large placenta with hydropic change of some villi and a growth restricted fetus is usually observed.
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 doubling of chromosome content of a normal 23,X sperm fertilizing an egg lacking a maternal set of chromosomes; occasionally results from two sperm fertilizing an egg lacking maternal chromosomes; karyotype is 46,N.
Cause of Partial Mole: Typically due to a normal ovum fertilized by two sperm resulting in a 69,XXX or 69,XXY chromosome complement.
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. Diagnostic errors can occur due to rare sequence variations.
See Compliance Statement B: www.aruplab.com/CS
|Component Test Code*||Component Chart Name|
|0051757||Molar Pregnancy, 16 DNA Markers|
|2001366||MOL PREG Specimen|