The Principles of Clinical Cytogenetics - Extra Materials - Springer

274 Linda Marie Randolph
Table 6
Frequency of Autosomal Trisomy for Each
Human Chromosome Among Aborted Specimens
Trisomy
chromosome No. of trisomies (%)
1 0
2 34 (5.2)
3 6 (0.93)
4 15 (2.3)
5 5 (0.78)
6 5 (0.78)
7 27 (4.2)
8 23 (3.6)
9 18 (2.8)
10 11 (1.7)
11 0
12 2 (0.31)
13 53 (8.2)
14 32 (5.0)
15 52 (8.1)
16 202 (31.3)
17 4 (0.62)
18 23 (3.6)
19 0
20 18 (2.8)
21 54 (8.4)
22 55 (8.5)
Total 645 (100)
Source: Data from ref. 37.
Table 7
Frequencies of Chromosome Abnormalities in Stillbirths and Neonatal Deaths;
Combined Data from Three Studies
Macerated stillbirths Nonmacerated stillbirths Neonatal deaths Total
No. No. No. No.
karyotyped Abnormal karyotyped Abnormal karyotyped Abnormal karyotyped Abnormal
59 7 (11.86%) 215 9 (4.18%) 549 33 (6.0%) 823 52 (6.31%)
Source: Date from ref. 30.
related to practitioner experience, number of needle insertions, size of the needle and other factors
(52). The appropriate risk figure to provide patients is still debated. In spite of the millions of amniocentesis
procedures performed and the importance of an accurate risk figure to provide patients, there
has been only one large prospective controlled study performed regarding the risks of amniocentesis.
In this paper, known as “the Danish study,” 4606 women comprised the final study population (53).
Of these, half were randomized to have amniocentesis, and the other half were randomly assigned to
the control, nonamniocentesis group. At the conclusion of the study, it was found that the total rate of
spontaneous abortion was 1.7% in the study group and 0.7% in the control group (p