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7-Dehydrocholesterol, Amniotic Fluid — Qualitative

Published: August 9, 2026Updated: August 16, 2026

A qualitative amniotic-fluid test for 7-dehydrocholesterol, used in selected prenatal evaluations for Smith-Lemli-Opitz syndrome.

Quick summary

["This specialized prenatal test can help evaluate a fetus for a cholesterol-synthesis disorder called Smith-Lemli-Opitz syndrome."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
40597-7
Short code
7-DHC Amn Ql
Synonyms
7-DHC Amn Ql
Category
lipid
Sample
fluid
Container
Sterile tube
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Specimen volume
2-5 mL
Stability
Room temperature: 2h, Refrigerated: 24h
Hemolysis max
300
TAT
4–24 hours
Order
routine

What is this test?

This test evaluates 7-dehydrocholesterol in amniotic fluid, the fluid surrounding a fetus. It is a specialized test rather than part of routine prenatal screening.

Why might I need this test?

It may be recommended when a fetus has findings that raise concern for Smith-Lemli-Opitz syndrome, when there is a relevant family history, or when a genetic counselor or obstetric clinician recommends further evaluation.

How is the test performed?

A clinician obtains amniotic fluid through amniocentesis. The laboratory then uses a validated assay to evaluate 7-dehydrocholesterol and reports a qualitative result. The assay method is not specified by this test code.

How do I prepare for the test?

No special laboratory preparation is required. If amniocentesis is recommended, your obstetric clinician will explain the procedure, its risks and benefits, and any preparation instructions before it is performed.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

An abnormal 7-dehydrocholesterol result may indicate a problem with fetal cholesterol synthesis, including Smith-Lemli-Opitz syndrome. Results should be interpreted with ultrasound findings, genetic testing, and other clinical information. A qualitative result alone may not establish or exclude a diagnosis.

Short name

Amniotic Fluid 7-Dehydrocholesterol

Frequently asked questions

What does an abnormal result mean?
It may suggest impaired cholesterol synthesis, including Smith-Lemli-Opitz syndrome. Additional genetic or clinical testing is usually needed to confirm the diagnosis.
Is this the same as a routine prenatal screening test?
No. This is a specialized test performed on amniotic fluid and is generally considered only when there is a specific clinical reason.
Do I need to fast before this test?
No special fasting instructions apply to the laboratory analysis. Any preparation for the amniocentesis procedure should follow your clinician's instructions.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy