In simple words: This code is for digestive problems a mother has during the last part of her pregnancy (after 28 weeks). It only applies to the mother's health, not the baby's.If the doctor knows exactly how many weeks pregnant the mother is, they might add another code along with this one.

O99.613, Diseases of the digestive system complicating pregnancy, third trimester, is an ICD-10-CM code used to classify digestive system disorders that arise during or are exacerbated by pregnancy in the third trimester (28 weeks 0 days to delivery).This code is specifically for maternal records and should not be used for newborn records.It's crucial to use additional codes from category Z3A (Weeks of gestation) if the specific week of gestation is known.The code excludes conditions such as hemorrhoids (O22.4-), liver and biliary tract disorders (O26.6-), and situations where the fetal condition is the primary reason for maternal care (O35-O36).

Example 1: A 35-year-old pregnant woman at 32 weeks gestation presents with severe nausea, vomiting, and abdominal pain consistent with hyperemesis gravidarum. The diagnosis of hyperemesis gravidarum complicated by pregnancy in the third trimester is coded as O99.613., A 28-year-old patient at 36 weeks gestation experiences worsening gastroesophageal reflux disease (GERD) symptoms.The physician documents GERD complicating the pregnancy, making O99.613 appropriate. The specific GERD diagnosis should also be coded., A 40-year-old woman at 30 weeks gestation is admitted for acute pancreatitis. Her pancreatitis is determined to be complicated by her pregnancy.O99.613 is used along with the specific pancreatitis code.

Complete obstetric history, including gestational age. Detailed description of digestive symptoms, physical examination findings, laboratory results (e.g., complete blood count, liver function tests), and imaging studies (if performed) are essential for proper coding.

** The age range specified for this code in some sources (12-55 years) is likely a data limitation or filter and not an inherent restriction of the code itself.It is appropriate to use for women of childbearing age.