O41.123 Chorioamnionitis, third trimester

Name of the Condition

• Chorioamnionitis, Third Trimester (ICD Code: O41.123)

Summary

Chorioamnionitis is an infection of the fetal membranes (chorion and amnion) and amniotic fluid during pregnancy. This condition involves microbial invasion, typically bacterial, and can affect both maternal and fetal health. It is often associated with inflammation and may lead to complications if not managed promptly. The infection can occur at any stage of pregnancy but is more common in the second or third trimester.

Causes

The infection usually results from bacteria ascending from the vaginal tract into the uterus, though hematogenous spread (via the bloodstream) or direct contamination can also occur. Common pathogens include group B streptococcus, Escherichia coli, and other vaginal flora. Risk increases with prolonged rupture of membranes or invasive procedures during pregnancy.

Risk Factors

• Prolonged rupture of membranes (especially >18 hours)
• Multiple vaginal examinations during labor
• Preterm labor or delivery
• Maternal infections (e.g., urinary tract infections)
• Low socioeconomic status or limited prenatal care
• History of prior intrauterine infections

Symptoms

• Maternal fever (≥38°C or 100.4°F)
• Maternal tachycardia (≥100 beats per minute)
• Fetal tachycardia (≥160 beats per minute)
• Uterine tenderness
• Foul-smelling amniotic fluid (if membranes are ruptured)

Diagnosis

Diagnosis relies on clinical evaluation of maternal symptoms, laboratory testing for infection markers (e.g., elevated white blood cell count), and ultrasound to assess amniotic fluid and fetal status. Amniocentesis may be used for culture if membranes are ruptured.

Treatment Options

Treatment typically involves intravenous antibiotics to target common pathogens, such as penicillin or clindamycin. Delivery is often recommended if the infection is severe or if the fetus is at risk, especially in the third trimester. Supportive care, including monitoring of maternal and fetal vital signs, is also provided.

Prognosis and Follow-Up

With prompt treatment, outcomes for both mother and fetus can improve, though complications may still occur. Follow-up care includes monitoring for postpartum infections and assessing neonatal health, as infants may require antibiotics or intensive care.

Complications

• Maternal sepsis or septic shock
• Preterm birth
• Neonatal sepsis or pneumonia
• Fetal distress or stillbirth
• Postpartum endometritis

Lifestyle & Prevention

• Attend regular prenatal care to monitor for infections
• Avoid unnecessary vaginal examinations during pregnancy
• Treat any genitourinary infections promptly
• Follow guidelines for membrane rupture management

When to Seek Professional Help

Seek immediate medical attention if experiencing fever, uterine tenderness, or fetal movement changes during the third trimester, as these may indicate chorioamnionitis.

Tips for Medical Coders

Document the trimester (third trimester) and clinical findings supporting the diagnosis. Ensure the code O41.123 is used when the infection is specifically identified in the third trimester. Include details on maternal symptoms, fetal status, and any interventions performed.