QF-PCR test, in Visit Clinic

QF‑PCR (Quantitative Fluorescent PCR) is a rapid prenatal genetic test that detects common fetal chromosomal aneuploidies—mainly trisomies 21, 18 and 13 and sex‑chromosome abnormalities. It uses fetal DNA from amniotic fluid, chorionic villus sampling or fetal blood and typically returns results within 1–2 days. It’s quick and sensitive for common aneuploidies but won’t detect all chromosomal changes, so follow-up testing may be needed.

A QF‑PCR (rapid aneuploidy) test usually yields results within 24–72 hours after the laboratory receives the sample. The process—DNA extraction, PCR amplification and data analysis—can sometimes be completed same day in urgent cases, but typical turnaround is one to three working days depending on local lab capacity and sample logistics. Your clinic will advise specific timing.

A PCR test detects specific genetic material (DNA or RNA) of an organism in a sample. For viruses like SARS‑CoV‑2, reverse transcription PCR first converts viral RNA to DNA, then amplifies target sequences to identify presence of the pathogen. PCR is highly sensitive and can detect small amounts of genetic material, indicating current or recent infection, though it doesn't distinguish live from non‑infectious fragments.

QF‑PCR is highly accurate for rapid detection of common fetal aneuploidies: sensitivity and specificity are generally around 98–99% for trisomy 21 and similarly high for trisomies 13 and 18. It reliably detects full aneuploidies but may miss low‑level mosaicism, structural rearrangements, or rare variants, and cannot identify microdeletions — abnormal or equivocal results usually need confirmatory testing.

Noninvasive prenatal testing (NIPT) screens maternal blood for fetal cell‑free DNA to detect common chromosomal aneuploidies—trisomy 21 (Down), trisomy 18 (Edwards) and trisomy 13 (Patau)—and sex chromosome abnormalities (e.g., Turner, Klinefelter) and can determine fetal sex. Some panels screen for selected microdeletions (e.g., 22q11.2) but with lower accuracy. NIPT is a screening, not diagnostic, test; it does not reliably detect neural tube defects or most single‑gene disorders.

Trisomy 18 most often arises from spontaneous chromosomal nondisjunction; the main risk factor is advanced maternal age. Other risks include a prior pregnancy or child with trisomy 18 and parental chromosomal rearrangements (balanced translocations or mosaicism), which raise recurrence risk. Paternal age has little effect, and most cases occur sporadically without a family history.