Uterine size-date discrepancy, first trimester

This code signifies a discrepancy between the estimated gestational age based on the last menstrual period and the actual uterine size observed during a first-trimester examination. This can indicate either a smaller-than-expected uterus (suggesting a dating error, early pregnancy loss, or ectopic pregnancy) or a larger-than-expected uterus (suggesting multiple gestation, fibroids, or hydatidiform mole).

Apply this code when a clinician documents a uterine size that is inconsistent with the expected gestational age during the first trimester of pregnancy. Documentation should clearly state the discrepancy and the trimester. This code is often used when further investigation (e.g., ultrasound) is warranted to determine the cause of the size discrepancy.

• Ensure the documentation explicitly states "first trimester" for accurate code assignment.
• This code is for the discrepancy itself, not the underlying cause once identified. Code the definitive diagnosis (e.g., multiple gestation, blighted ovum) once confirmed.
• Do not confuse with codes for abnormal fetal growth (e.g., intrauterine growth restriction), which typically apply later in pregnancy.