References for: Causes, evaluation, and treatment.

Medscape Women’s Health 1998 May;3(3):2 (ISSN: 1521-2076) Bick RL; Madden J; Heller KB; Toofanian A

Thrombosis Clinical Center, Department of Medicine (Hematology & Oncology), Presbyterian Hospital of Dallas, Tex., USA.

Impact and Implications of Chromosomal Abnormalities

Cytogenetic Studies of Abortuses

In determining the cause of fetal loss, it is useful to conduct a chromosome study on the abortus. Chromosome analysis is indicated in the case of a stillbirth or neonatal death because chromosomal anomalies are found in approximately 6% of these cases.[8] Tissues for cytogenetic studies should be obtained using sterile technique, and they should be delivered immediately to the cytogenetics laboratory in transport medium provided by the laboratory. If such medium is not available, a laboratory technician can provide information regarding the suitability of sterile saline or other solutions, although culture success is compromised. To avoid this problem, it is important to have tubes of frozen, unexpired transport medium onsite.

Tissue specimens that have been frozen or placed in formalin may not be cultured. Tissues suitable for cytogenetic study include placental villi, chorion, amnion, skin, or internal organs such as liver, lung, kidney, or spleen. For early gestation, the entire abortus may be submitted. For later gestation, blood in a sodium heparin tube is also suitable. Submitting several specimen types increases the culture success rate which, even in laboratories with the most experienced staff, is usually no more than 85%.

Cytogenetic Studies of Parents

When a couple has had 2 or more spontaneous abortions or a child with a structural chromosomal anomaly, chromosomal analysis on both partners should be considered. Analysis requires a 5mL to 10mL blood sample in a tube with sodium heparin.

The chance of a balanced chromosome rearrangement in 1 partner of a couple with 2 or more spontaneous abortions is about 7%.[5] Determining the presence of such a rearrangement in a parent is useful because it provides: (1) an explanation for the miscarriages; (2) information about the risk for a live-born child with potentially serious anomalies, as well as the risk for future miscarriages; (3) availability of prenatal diagnosis in a future pregnancy; and (4) information for members of the extended family who may be at risk and may wish to undergo chromosome testing.

References for: Causes, evaluation, and treatment.

Medscape Women’s Health 1998 May;3(3):2 (ISSN: 1521-2076) Bick RL; Madden J; Heller KB; Toofanian A

Thrombosis Clinical Center, Department of Medicine (Hematology & Oncology), Presbyterian Hospital of Dallas, Tex., USA.

Impact and Implications of Chromosomal Abnormalities

Relevance of Family History

When a patient presents having had recurrent spontaneous abortions, a detailed family history should be obtained, including information about the partner’s family. The family history may provide a clue to the presence of a familial chromosome rearrangement. A history of any congenital anomaly, mental retardation, infertility, spontaneous abortion, or perinatal death is significant because each is characteristic of chromosomal anomaly (see Fig. 4).

Figure 4. Family pedigree showing typical features of familial chromosome rearrangement. In this family, husband had mentally retarded sister and brother whose wife suffered 2 spontaneous abortions. Family history is noteworthy, particularly in view of couple’s experience having spontaneous abortion and stillbirth with growth retardation. Blood chromosome study of both partners is necessary to rule out translocation or other chromosomal anomaly.

References for: Causes, evaluation, and treatment.

Medscape Women’s Health 1998 May;3(3):2 (ISSN: 1521-2076) Bick RL; Madden J; Heller KB; Toofanian A

Thrombosis Clinical Center, Department of Medicine (Hematology & Oncology), Presbyterian Hospital of Dallas, Tex., USA.

Impact and Implications of Chromosomal Abnormalities

Role of Chromosomal Anomalies in Recurrent Spontaneous Abortion

In up to 7% of couples with at least 2 spontaneous abortions, one partner carries a balanced chromosome rearrangement.[5] The most common of these is a reciprocal translocation in which a segment of chromosome has exchanged places with a segment of a nonhomologous chromosome. When such a rearrangement is present, the chromosomes have difficulty pairing up and dividing evenly during meiosis. As a result, gametes frequently possess an unbalanced amount of chromosomal material (duplications and/or deficiencies). These imbalances are usually lethal to the developing embryo or fetus, causing spontaneous abortion. Sometimes, the pregnancy continues to term, producing an infant with significant congenital anomalies and mental retardation.

When a parent carries a balanced chromosome rearrangement, the chance of having a live birth with an unbalanced chromosome complement is usually about 1% to 15%. The exact risk depends on the specific chromosomes involved, size of the segment(s) involved in the rearrangement, sex of the transmitting parent, family history, and mode of ascertainment. Therefore, it is quite possible that the couple will have healthy children. In fact, Coulam[6] found a higher incidence of chromosome rearrangement in couples who had experienced both recurrent spontaneous abortion and viable pregnancies than in couples with recurrent spontaneous abortion and no viable pregnancies. When 1 parent carries a chromosome rearrangement, the chance of spontaneous abortion is usually 25% to 50%. Empirical and/or hypothetical data are available for predicting the chance of adverse pregnancy outcome for various rearrangements.[1,7]