LOINCActive

LOINC Code 8665-2: Last menstrual period start date

8665-2 is a LOINC code used to identify Last menstrual period start date 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 Date last menstrual period. It is commonly used with the system or sample type ^Patient.

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 Date last menstrual period. It is commonly used with the system or sample type ^Patient.

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

What it does not mean

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

Key facts

  • Last menstrual period start date
  • Date last menstrual period
  • AOEObservation; Gyn; Gynecology; H+P; H+P.HX; LMP; LMP Start date; OB; ObGyn; Obstetrics; P prime; Past; Point in time; QNT; Quan; Quant; Quantitative; Random

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

Last menstrual period start dateLMP Start dateDate last menstrual periodH&P.HXDatePt^Patient

Frequently asked questions

Code details

Code8665-2
SystemLOINC
Display nameLast menstrual period start date
DescriptionDate last menstrual period
Short nameLMP Start date
ComponentDate last menstrual period
PropertyDate
TimingPt
System (specimen)^Patient
ScaleQn
ClassH&P.HX
Example unitsMMDDYY
StatusACTIVE

Flags

BillableNo
Valid clinical useNo

Source

SourceLOINC
Version2.82
Releasemain
First released1.0h(3)
Last changed2.73

Part names

Date last menstrual periodDatePt^PatientQnLast menstrual period start datePoint 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.

LOINC Code 8665-2 | HealthAssure