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 77904-1: Left atrial End-systolic volume by US.2D+Calculated by modified Simpson method

Name: LOINC Code 77904-1: Left atrial End-systolic volume by US.2D+Calculated by modified Simpson method
Creator: HealthAssure Clinical Team
Published: 2026-05-21T08:59:58.755Z

77904-1 is a LOINC code used to identify Left atrial End-systolic volume by US.2D+Calculated by modified Simpson 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 End-systolic volume. It is commonly used with the system or sample type Heart.atrium.left.

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 End-systolic volume. It is commonly used with the system or sample type Heart.atrium.left.

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.2D+Calculated by modified Simpson method

What it does not mean

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

Key facts

Left atrial End-systolic volume by US.2D+Calculated by modified Simpson method

End-systolic volume

The modified Simpson method is commonly used for volume measurements in 2D cardiac imaging. It uses the biplane method of disks, meaning that the total volume is calculated by adding together the two-dimensional area measurements of the series of circular or elliptical slices that, taken as a whole, represent the chamber being measured. [PMID16376782]

2D US; Atrial; Calc; Calculation; CARD.US; Cardiac; Cardio; Cardiology; Echography; ES vol; Heart Disease; Hrt; L; LA; LT; Point in time; QNT; Quan; Quant; Quantitative; Random; Sonogram; Sonograph; Sonography; ULS; Ultrasound; Ultrasound - 2-dimensional; US.2D+mod Simpson; Vol; Volume

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

Left atrial End-systolic volume by US.2D+Calculated by modified Simpson methodLA ES vol US.2D+mod SimpsonEnd-systolic volumeCARD.USVolPtHeart.atrium.left

Frequently asked questions

Code details

Code77904-1

SystemLOINC

Display nameLeft atrial End-systolic volume by US.2D+Calculated by modified Simpson method

DescriptionEnd-systolic volume

Short nameLA ES vol US.2D+mod Simpson

ComponentEnd-systolic volume

PropertyVol

TimingPt

System (specimen)Heart.atrium.left

ScaleQn

MethodUS.2D+Calculated by modified Simpson method

ClassCARD.US

Example unitsmL

StatusACTIVE

Order/ObservationObservation

Flags

BillableNo

Valid clinical useNo

Source

SourceLOINC

Version2.82

Releasemain

First released2.52

Last changed2.52

Part names

End-systolic volumeVolPtHeart.atrium.leftQnUS.2D+Calculated by modified Simpson methodVolumePoint in time (spot)Heart.atrium Left

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.