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 33154-6: Fetal Head Diameter.biparietal estimated from gestational age by method of Merz 1988 (US)

Name: LOINC Code 33154-6: Fetal Head Diameter.biparietal estimated from gestational age by method of Merz 1988 (US)
Creator: HealthAssure Clinical Team
Published: 2026-05-21T08:59:20.067Z

33154-6 is a LOINC code used to identify Fetal Head Diameter.biparietal estimated from gestational age by method of Merz 1988 (US) 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. 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. 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: US.estimated from Merz 1988

What it does not mean

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

Key facts

Fetal Head Diameter.biparietal estimated from gestational age by method of Merz 1988 (US)
Diameter.biparietal
88; BPD; BPD by GA; BPD predicted from gestational age; Brain; Cranial; Cranium; DIA; Diam; Echoencephalogram; Echoencephalography; Echography; Est; estimation; Fetal; from GA.Merz88; Gyn; Gynecology; Intracranial; Length; OB; ObGyn; OBSTERICAL; OBSTERICAL.ULTRASOUND; Obstetrical; Obstetrics; Point in time; predicted; QNT; Quan; Quant; Quantitative; Random; Skull; Sonogram; Sonograph; Sonography; ULS; Ultrasound; US+est

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 Diameter.biparietal estimated from gestational age by method of Merz 1988 (US)Fet BPD from GA.Merz88Diameter.biparietalOB.USLenPtHead^fetus

Frequently asked questions

Code details

Code33154-6

SystemLOINC

Display nameFetal Head Diameter.biparietal estimated from gestational age by method of Merz 1988 (US)

DescriptionDiameter.biparietal

Short nameFet BPD from GA.Merz88

ComponentDiameter.biparietal

PropertyLen

TimingPt

System (specimen)Head^Fetus

ScaleQn

MethodUS.estimated from Merz 1988

ClassOB.US

Example unitsmm

StatusACTIVE

Order/ObservationObservation

Flags

BillableNo

Valid clinical useNo

Source

SourceLOINC

Version2.82

Releasemain

First released2.09

Last changed2.70

Part names

Diameter.biparietalLenPtHead^fetusQnUS.estimated from Merz 1988LengthPoint in time (spot)Ultrasound.estimated from Merz 1988

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.