CYTOGENETICS

In the WiSSP series, nearly 5% of all stillborn infants have had chromosomal abnormalities that were the underlying cause of death. In a majority of these infants the specific reason for their stillbirth would not have been determined had samples not been obtained for chromosome analysis. That is, clinical assessment alone is often insufficient to allow recognition of cytogenetic anomalies in stillborn infants. In part this is true because of our collective ignorance about the fetal phenotype of even common cytogenetic aberrations. In part this is because many stillborn infants are sufficiently macerated that recognizing the external manifestations of a chromosomal abnormality is quite difficult.

Others have recommended that macerated infants not be sampled because of low yield of successful cultures. While success is less (and can be anticipated to be only perhaps 30-40% in macerated babies), our own experience shows that many diagnoses would have been missed had that approach been used:

Success of Attempted Cytogenetic Assessment Versis Degree of Maceration

							No growth/
	Growth		Abnormal		Normal		contamination
	N	%	N	%	N	%	N	%
Degree of maceration
None [N = 120]	96	80.0	10	8.3	86	71.7	24	20.0
Slight [N = 73]	40	54.8	2	2.7	38	52.1	33	45.2
Mild [N = 120]	37	30.8	3	2.5	34	28.3	83	69.2
Moderate [N = 203]	63	31.0	10	4.9	53	26.1	140	69.0
Advanced [N = 165]	51	30.9	10	6.1	41	24.8	114	69.1

Some have also suggested that chromosomal assessment need not be completed if there are no obvious external anomalies. This selectivity, too, will result in certain diagnoses being missed. In the WiSSP series, 2 infants with trisomy 21, one with triploidy and one with mosaic trisomy 6 would not have been diagnosed had this criterion been used.

Therefore we recommend that chromosomal assessment be attempted on every stillborn baby.

In order to maximize yield, appropriate sampling has to be done. We have generated an Algorithm for Chromosomal Studies which can be found on the following pages. In addition, specific instructions regarding Fetal Tissue Sampling and Placental Sampling may be of considerable help for those without experience in obtaining materials for cytogenetic assessment. Additional information concerning chromosomal evaluations in stillborn babies can be found in WiSSPers Vol 3, number 2 and Vol 3, number 3.

Radiographs < == > Placental and Cord Examination

Protocol
WiSSP home page