PGD FISH 9 vs PGT-A 24-chromosome — which test is right for you?

Choosing between PGD FISH 9 and PGT-A 24-chromosome testing is one of the most consequential decisions in a surrogacy journey. Both screen embryos for chromosomal abnormalities before transfer — but they do so with very different technologies, levels of detail, and price points.

If you're considering surrogacy in Ukraine, Georgia, or Armenia, your clinic will likely offer both options. Understanding what each test actually does — and what it can't do — will help you have a more informed conversation with your reproductive specialist.

What is preimplantation genetic testing?

Preimplantation genetic testing (PGT) is a laboratory procedure performed on embryos created through IVF, before they are transferred into a surrogate's uterus. The goal is straightforward: identify embryos with the correct number of chromosomes and exclude those with abnormalities that would result in failed implantation, miscarriage, or a child born with a genetic condition.

The procedure itself is the same regardless of which test is used. On day 5 or 6 after fertilization, the embryologist performs a trophectoderm biopsy — removing 5-10 cells from the outer layer of the embryo (which will later become the placenta), without touching the inner cells that develop into the baby. These cells are then sent for genetic analysis.

PGD FISH 9 — the established method

PGD FISH 9 (Preimplantation Genetic Diagnosis using Fluorescence In Situ Hybridization) has been the workhorse of preimplantation genetic testing since the late 1990s. The technique uses fluorescent DNA probes that bind to specific chromosomes, making them visible under a microscope and countable.

The "9" refers to the number of chromosome pairs analysed: 13, 15, 16, 17, 18, 21, 22, X, and Y. These nine were chosen because they represent the chromosomes most commonly involved in viable abnormalities — meaning the ones that can result in a born child with a genetic condition, rather than causing very early miscarriage.

Syndromes detected by PGD FISH 9

• Down syndrome (trisomy 21) — the most common chromosomal disorder at birth
• Edwards syndrome (trisomy 18)
• Patau syndrome (trisomy 13)
• Klinefelter syndrome (47,XXY)
• Turner syndrome (45,X)
• Triple X syndrome (47,XXX)
• Jacobs syndrome (47,XYY)
• Trisomies of chromosomes 15, 16, 17, and 22

PGD FISH 9 also identifies the embryo's sex chromosomes (XX or XY), enabling sex selection — also known as gender selection or family balancing — where legally permitted.

PGT-A 24-chromosome — the comprehensive option

PGT-A 24-chromosome (Preimplantation Genetic Testing for Aneuploidy, performed via Next Generation Sequencing) is the modern standard. Instead of looking at nine chromosome pairs through a microscope, NGS reads the actual DNA sequence of all 24 chromosomes — that is, all 22 autosomes plus the X and Y sex chromosomes.

This is performed in a sophisticated embryology laboratory using high-throughput DNA sequencers. The process takes longer than FISH (typically 1-2 weeks for results) but produces far more comprehensive data.

You may also see PGT-A referred to by older or alternative names: PGS (preimplantation genetic screening), PGT-A by NGS, or simply 24-chromosome aneuploidy testing. They all describe the same modern technique.

What PGT-A 24-chromosome detects beyond FISH 9

• All aneuploidies — trisomies and monosomies of every chromosome, not just nine
• Microdeletions and microduplications — small segments of missing or extra DNA invisible to FISH
• Mosaicism — embryos with mixed normal and abnormal cells
• Sex chromosome abnormalities — same as FISH
• Sex identification for sex selection where legally permitted

Side-by-side comparison

Which test should you choose?

The honest answer is: it depends on your situation. Here are the most common decision factors.

PGD FISH 9 may be appropriate if:

• You are under 35 and have no family history of chromosomal disorders
• You have produced multiple high-quality embryos and want a faster, more affordable screen
• Your primary concern is identifying viable trisomies (Down syndrome being the most common)
• Time is a factor and you'd prefer faster results

PGT-A 24-chromosome is generally recommended if:

• You are over 35 (advanced maternal age increases risk of all aneuploidies, not just nine)
• You have a history of recurrent miscarriage or failed IVF cycles
• There is a family history of chromosomal rearrangements or microdeletion syndromes
• You have produced fewer embryos and want maximum information from each one
• You want the most comprehensive screen available

What about sex selection (also called gender selection)?

Both PGD FISH 9 and PGT-A 24-chromosome reveal the embryo's sex chromosomes (XX or XY), so both enable sex selection — sometimes called gender selection or family balancing.

However, the legality of non-medical sex selection varies significantly:

• Permitted in the United States, Mexico, Cyprus, and some other countries
• Prohibited in most of Western Europe (UK, Germany, France, Spain), Canada, India, and China
• Variable depending on circumstances in Ukraine, Georgia, and Armenia — your destination country's regulations apply

If sex selection is important to you, this should be discussed early in your consultation, as it may influence which destination country your coordinator recommends.

This article is for educational purposes only and does not constitute medical advice. Genetic testing options, success rates, and legal availability of sex selection vary by clinic and country. Always discuss your specific situation with a qualified reproductive specialist before making decisions. Novaparent Surrogacy provides coordination services and works with licensed partner clinics in Ukraine, Georgia, and Armenia — your medical care is provided by the clinic's specialists.