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 11891-9: Gestational age estimated from Abdominal circumference on US by Hadlock 1982 method

Name: LOINC Code 11891-9: Gestational age estimated from Abdominal circumference on US by Hadlock 1982 method
Creator: HealthAssure Clinical Team
Published: 2026-05-21T11:17:22.973Z

11891-9 is a LOINC code used to identify Gestational age estimated from Abdominal circumference on US by Hadlock 1982 method 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 Gestational age. It is commonly used with the system or sample type ^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 Gestational age. It is commonly used with the system or sample type ^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 AC.Hadlock 1982

What it does not mean

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

Key facts

Gestational age estimated from Abdominal circumference on US by Hadlock 1982 method
Gestational age
range 10.0 cm (15.6 weeks) to 36.5 cm (40.8 weeks)
82; Abdominal circumference; AC chart; Echography; Est; estimation; Fetal; from AC.Hadlock82; GA; Gest; Gestation; Gyn; Gynecology; OB; ObGyn; OBSTERICAL; OBSTERICAL.ULTRASOUND; Obstetrical; Obstetrics; Point in time; predicted; Prenatal; QNT; Quan; Quant; Quantitative; Random; Sonogram; Sonograph; Sonography; ULS; Ultrasound

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

Gestational age estimated from Abdominal circumference on US by Hadlock 1982 methodGA from AC.Hadlock82Gestational ageOB.USTimePt^Fetus

Frequently asked questions

Code details

Code11891-9

SystemLOINC

Display nameGestational age estimated from Abdominal circumference on US by Hadlock 1982 method

DescriptionGestational age

Short nameGA from AC.Hadlock82

ComponentGestational age

PropertyTime

TimingPt

System (specimen)^Fetus

ScaleQn

MethodUS+Estimated from AC.Hadlock 1982

ClassOB.US

Example unitsdays

StatusACTIVE

Order/ObservationObservation

Flags

BillableNo

Valid clinical useNo

Source

SourceLOINC

Version2.82

Releasemain

First released1.0j-a

Last changed2.52

Part names

Gestational ageTimePt^FetusQnUS+Estimated from AC.Hadlock 1982Time (e.g. seconds)Point in time (spot)Ultrasound+Estimated from AC.Hadlock 1982

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.