Objective: To determine if maternal blood contamination falsely elevates the lamellar body count fetal lung maturity test.
Study design: Fifty mothers undergoing amniocentesis for fetal lung maturity consented to participation in the study. For each participant a blood-contaminated sample using the patient's own blood was run in tandem with the noncontaminated sample used for clinical practice.
Results: Of the 50 study patient samples the lamellar body count decreased by ≥ 3,000/μL in 33 (66%) and remained unchanged in 16 (32%). In only 1 case did the value increase--the actual result of 37,000/μL increased to 44,000/μL, both of which exceeded the mature level in our institution.
Conclusion: Maternal blood contamination of amniotic fluid does not falsely increase the lamellar body count in 98% of cases. The result was falsely lowered in 2 out of 3 cases. Therefore, a mature lamellar body count test result in a blood-contaminated sample is reliable