AFP, reflex to AChe & Fetal Hb, Amniotic Fluid (Sendout)

Ordering Recommendation: Evaluate possibility of a fetal open neural tube defect (ONTD) at 13-36 weeks of gestation.

Test Description: When a fetus has an ONTD, such as meningomyelocele or anencephaly, the amniotic fluid has an elevated alpha-fetoprotein (AFP) concentration and acetylcholinesterase (AChE) activity. The best option for testing is reflexive and involves measuring AFP from amniotic fluid first. If the amniotic fluid AFP is elevated, then reflexive testing is performed to determine if AChE activity is present.

Reflexive testing increases the specificity for ONTD detection because elevated AFP without the presence of AChE activity can be caused by other conditions and pregnancy complications, such as fetal renal disease and intrauterine bleeding. This reflex pattern offers a sensitivity and specificity for anencephaly of 98% and <1%, respectively, and 96% and <1% for open spina bifida.¹ Alternatively, spina bifida and anencephaly in a fetus may be confirmed by targeted ultrasound exam.

Test Algorithm: If the AFP (amniotic fluid) is elevated, then Acetylcholinesterase & Fetal Hb, Amniotic Fluid (Sendout) [RAACH] will be added at additional charge.

Patient Preparation: Specimen must be drawn between 13 weeks, 0 days and 36 weeks, 6 days gestation.

Ordering Requirements:

• For orders not placed in Epic, an ARUP Prenatal Cytogenetics Patient History Form is required.

Outside Laboratories:

• Store and transport amniotic fluid at ambient temperature. If other tests are requested, submit a separate aliquot for each test.
• Submit a completed ARUP Prenatal Cytogenetics Patient History Form along with the DLMP requisition.* Failure to provide mandatory information may result in test delays.
  • *Use client-specific requisition when available. To obtain a client-specific requisition, contact Client Support Services via email at: commserv@uw.edu.

Vancouver Clinic: Complete the Ask-at-Order-Entry Question below.

• RAMFG: Multifetal Gestation:
  • For Singleton Pregnancies, enter N (No)
  • For Multi-fetal Pregnancies, indicate which fetus (Twin A, Twin B, etc.) the sample is for.

Store and transport amniotic fluid at ambient temperature.

Sendouts:

• Order ARUP Test: 3000142
• Interfaced: Yes. [Interface: 602; Department: ARPA]
• For orders placed in Epic: The answers to the order questions will file from Epic to ARUP via the interface.
• For outside orders not placed in Epic: A completed ARUP Patient History Form is required. If not provided, send an HC1 Task to CSS asking them to follow up with the client to obtain the form.

Stability: Ambient (preferred): 1 month; Refrigerated: 3 months; Frozen: 3 months.