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HelpTest Code ACHE_ Acetylcholinesterase, Amniotic Fluid
Performing Laboratory
Mayo Clinic Laboratories in Rochester
Reporting Name
Acetylcholinesterase, AFSpecimen Type
Amniotic FldAdditional Testing Requirements
If chromosome studies are also requested, see CHRAF / Chromosome Analysis, Amniotic Fluid for specimen requirements. When requested with chromosome analysis, the specimen cannot be frozen.
Necessary Information
1. Gestational age at amniocentesis is required.
2. If not ordering electronically, provide gestational age on Second Trimester Maternal Screening Alpha-Fetoprotein / Quad Screen Patient Information (T595) and send with specimen.
Specimen Required
Container/Tube: Amniotic fluid container
Specimen Volume: 1 mL
Collection Instructions: Specimen must be collected between 14 to 21 weeks gestation; 14 to 18 weeks is preferred.
Reject Due To
| Gross hemolysis | OK |
| Gross icterus | OK |
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Amniotic Fld | Refrigerated (preferred) | 365 days | |
| Frozen | 365 days | ||
| Ambient | 14 days |
Specimen Minimum Volume
0.3 mL
Special Instructions
Day(s) Performed
Tuesday, Thursday
Specimen Retention Time
60 daysReport Available
3 to 7 daysReference Values
Negative (reported as negative [normal] or positive [abnormal] for inhibitable acetylcholinesterase)
Reference values were established in conjunction with alpha-fetoprotein testing and include only amniotic fluids from pregnancies between 14- and 21-weeks gestation.
Useful For
Diagnosing open neural tube defects and, to a lesser degree, ventral wall defects
CPT Code Information
82013
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| ACHE_ | Acetylcholinesterase, AF | 30106-9 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| 9287 | Acetylcholinesterase, AF | 30106-9 |
| GACHE | Gestational Age (ACHE) | 18185-9 |
Method Description
Acetylcholinesterase (AChE) and pseudocholinesterase (PChE) catalyze the deesterification of acetylthiocholine iodide to form a white copper thiocholine precipitate. The white precipitate is acted upon by dithiooxamide to provide a dark-green color. If 1,5 bis (4-allyldimethylammoniumphenyl) pentane-3-1 dibromide is present, it will inhibit the action of AChE on acetylthiocholine iodide but will not inhibit the activity of PChE. AChE and PChE are separated by polyacrylamide gel electrophoresis and then reacted with the inhibitor and substrate while remaining in the gel.(Barlow RD, Cuckle HS, Wald NJ. A simple method for amniotic fluid gel-acetylcholinesterase determination, suitable for routine use in the antenatal diagnosis of open neural tube defects. Clin Chim Acta. 1982;119:137-142); Cowan T, Pasquali M. Laboratory Investigations of Inborn Errors of Metabolism. In: Sarafoglou K, Hoffman GF, Roth KS, eds. Pediatric Endocrinology and Inborn Errors of Metabolism. 2nd ed. McGraw Hill; 2017:1139-1158)