Clinician-authored health information
This article supports informed conversations with your clinician. It does not replace an examination, diagnosis or emergency care.
Importance of Karyotyping in an Infertile Couple
Infertility is generally defined as the inability to achieve a clinical pregnancy after 12 months or more of regular, unprotected sexual intercourse. It may result from factors affecting the female partner, male partner, both partners, or may remain unexplained despite conventional evaluation. Although most cases are attributable to non-genetic causes, genetic abnormalities, particularly chromosomal abnormalities, are an important and potentially identifiable cause of infertility and adverse reproductive outcomes.
Karyotyping is a cytogenetic test that examines the number, size, and structural appearance of an individual's chromosomes. Normal human somatic cells contain 46 chromosomes arranged in pairs, including 22 pairs of autosomes and one pair of sex chromosomes. Karyotyping can therefore identify numerical abnormalities, such as an extra or missing chromosome, as well as structural abnormalities, including translocations, inversions, deletions, and duplications. Importantly, some structural chromosomal abnormalities may be present in a balanced form; however, there is no significant loss or gain of genetic material. Individuals carrying such abnormalities may be completely healthy and phenotypically normal but can have impaired fertility or an increased risk of miscarriage or chromosomally abnormal offspring.
Couple karyotyping, in which both partners undergo chromosomal analysis, is particularly relevant when infertility is associated with recurrent pregnancy loss, repeated implantation failure, severe oligospermia or azoospermia, a history of congenital anomalies, or a previous pregnancy or child affected by a chromosomal abnormality. In such circumstances, either partner may be an apparently healthy carrier of a balanced chromosomal rearrangement. During gamete formation, these rearrangements can result in chromosomally unbalanced sperm or ova, leading to failure of conception, early embryonic loss, recurrent miscarriage, implantation failure, or, in some cases, the birth of a child with a chromosomal disorder.
One of the important abnormalities identified through couple karyotyping is a balanced reciprocal translocation, in which segments of two different chromosomes exchange places without an overall gain or loss of genetic material. Similarly, Robertsonian translocations, which involve the fusion of specific acrocentric chromosomes, may be associated with recurrent miscarriage and abnormal reproductive outcomes. In men, chromosomal abnormalities such as Klinefelter syndrome (47, XXY) may be associated with severe oligospermia or azoospermia. In women, chromosomal abnormalities or mosaicism involving the sex chromosomes may be associated with ovarian dysfunction, premature ovarian insufficiency, or reproductive failure.
The identification of a chromosomal abnormality has important implications beyond establishing a possible cause of infertility. It enables genetic counselling, allowing the couple to understand the nature of the abnormality, its potential reproductive consequences, and the likelihood of recurrence. Depending on the specific finding and clinical circumstances, reproductive options may include natural conception with appropriate counselling, prenatal diagnostic testing, in vitro fertilization (IVF) with preimplantation genetic testing for structural chromosomal rearrangements (PGT-SR), or the use of donor gametes. Thus, couple karyotyping can provide valuable diagnostic information, guide further reproductive evaluation, and facilitate informed reproductive decision-making.
However, a normal karyotype does not exclude all genetic causes of infertility, as conventional karyotyping has limited resolution and cannot detect many sub-microscopic genetic abnormalities. Additional investigations, such as Y-chromosome microdeletion testing, testing for pathogenic variants in selected infertility-associated genes, or chromosomal microarray, may be indicated according to the clinical presentation. Therefore, karyotyping should be considered as part of a broader, clinically guided genetic evaluation rather than as an isolated test.
Overall, couple karyotyping provides an opportunity to identify clinically silent chromosomal abnormalities that may otherwise remain undiagnosed until infertility, recurrent pregnancy loss, or an affected pregnancy occurs. Early identification allows appropriate genetic counselling and helps couples understand their reproductive options, making it a valuable investigation in appropriately selected infertile couples.