By Melody W. Mulaik, MSHS, CPC, CPC-H, RCC, PCS, FCS
Many coders have struggled with ICD-9-
CM’s confusing system for classifying
pregnancy-related conditions. An ICD- 9
pregnancy code’s fifth digit is selected
based on the “episode of care,” a concept
that was developed back in the 1970s for
inpatient billing and is not well suited to
coding for hospital outpatient and physician services.
ICD-10-CM uses a much more logical
system in which the code’s last character is
determined by the patient’s trimester. The
code should always reflect the trimester at
the time of the current encounter, even if
the condition began earlier in pregnancy.
For example, if a patient undergoes an OB
ultrasound during her third trimester due
to pregnancy-induced hypertension
(PIH) that began in the second trimester,
you would assign code O13.3 [Gestational
(pregnancy-induced) hypertension without significant proteinuria, third trimes-ter]. There are other codes for PIH if the
patient is currently in her first trimester
(O13.1), second trimester (O13.2), or an
unspecified trimester (O13.9).
ICD- 10 defines the trimesters as
follows, counting from the first day of the
last menstrual period:
• First: Less than 14 weeks 0 days
• Second: 14 weeks 0 days to less than 28
weeks 0 days
• Third: 28 weeks 0 days until delivery
The ICD- 10 guidelines allow coders to
select the trimester based on the physician’s
documentation of weeks of gestation, if the
trimester is not specifically documented.
Melody W. Mulaik is president and co-founder of
Coding Strategies, Inc. She is a nationally recognized
speaker and has delivered numerous presentations at
AHRA annual meetings and conferences. Melody is a
member of AHRA, has published extensively, and may
be contacted at firstname.lastname@example.org.