What does this LOINC code represent?

This LOINC code identifies a lab observation, measurement, question, or clinical concept in a standardized format.

Is this enough to understand my test result?

No. The code identifies the test or observation, but the interpretation depends on the actual result, reference range, and clinical context.

LOINCActiveObservation

LOINC Code 11821-6: Fetal Head Mean biparietal diameter Estimated from gestational age

Name: LOINC Code 11821-6: Fetal Head Mean biparietal diameter Estimated from gestational age
Creator: HealthAssure Clinical Team
Published: 2026-05-21T11:17:22.973Z

11821-6 is a LOINC code used to identify Fetal Head Mean biparietal diameter Estimated from gestational age in laboratory and clinical observation data. You may see this code in lab systems, lab reports, EHR exports, interoperability feeds, or other structured clinical data exchanges. LOINC codes identify tests, measurements, observations, survey items, and clinical questions in a standardized way. It is associated with the component Diameter.biparietal.mean. It is commonly used with the system or sample type Head^Fetus.

Reviewed by HealthAssure Clinical TeamUpdated 21 May 2026

What is this code?

LOINC codes identify tests, measurements, observations, survey items, and clinical questions in a standardized way. It is associated with the component Diameter.biparietal.mean. It is commonly used with the system or sample type Head^Fetus.

When is it used?

Used in lab systems, EHRs, and clinical data exchange.
May identify a test, observation, survey item, or clinical document request rather than a diagnosis.
Status: ACTIVE
Order vs observation: Observation
Method: Estimated from gestational age

What it does not mean

The code identifies the observation or test, not the actual result.

Key facts

Fetal Head Mean biparietal diameter Estimated from gestational age
Diameter.biparietal.mean
See Table II this reference for variance
Average; Avg; BPD; BPD by GA; BPD predicted from gestational age; BPD.mean; Brain; Cranial; Cranium; DIA; Diam; Echoencephalogram; Echoencephalography; Est; Est from GA; estimation; Fetal; Gest; Gestation; Gyn; Gynecology; Intracranial; Length; OB; ObGyn; OBSTERICAL; OBSTERICAL.ULTRASOUND; Obstetrical; Obstetrics; Point in time; predicted; Prenatal; QNT; Quan; Quant; Quantitative; Random; Skull

Where you may see this code

You may see this code in lab systems, lab reports, EHR exports, interoperability feeds, or other structured clinical data exchanges.

Common synonyms

Fetal Head Mean biparietal diameter Estimated from gestational ageFet BPD.mean Est from GADiameter.biparietal.meanOB.USLenPtHead^fetus

Frequently asked questions

Code details

Code11821-6

SystemLOINC

Display nameFetal Head Mean biparietal diameter Estimated from gestational age

DescriptionDiameter.biparietal.mean

Short nameFet BPD.mean Est from GA

ComponentDiameter.biparietal.mean

PropertyLen

TimingPt

System (specimen)Head^Fetus

ScaleQn

MethodEstimated from gestational age

ClassOB.US

Example unitsmm

StatusACTIVE

Order/ObservationObservation

Flags

BillableNo

Valid clinical useNo

Source

SourceLOINC

Version2.82

Releasemain

First released1.0j-a

Last changed2.48

Part names

Diameter.biparietal.meanLenPtHead^fetusQnEstimated from gestational ageLengthPoint in time (spot)

About this content

This page is prepared by HealthAssure's clinical team using official coding standards from LOINC. AI tools assist with drafting explanations, which are then reviewed and verified by healthcare professionals for accuracy. This content is for informational purposes and does not replace professional medical advice. Meet our team.