A patient undergoing dialysis for chronic kidney disease has a positive quad screen for trisomy 21. A subsequent amniocentesis with karyotype is normal. What is the most likely reason for the false positive aneuploidy screen?
Low Human chorionic gonadotropin (hCG)
Low Alpha-fetoprotein (AFP)
Serum beta-hCG is renally excreted so serum levels can be increased even in the absence of pregnancy in women with end-stage renal disease. False positive tests can occur with first-trimester or second-trimester aneuploidy screening.