O41.129 Chorioamnionitis, unspecified trimester

Name of the Condition

• Chorioamnionitis, Unspecified Trimester (ICD Code: O41.129)

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, often combined with gentamicin. Delivery is usually recommended if the pregnancy is at or near term, or if the infection is severe. Supportive care, including hydration and monitoring, is also provided.

Prognosis and Follow-Up

With prompt treatment, outcomes for both mother and baby can improve, though complications may still occur. Follow-up care includes monitoring for signs of infection resolution and assessing fetal well-being. Long-term follow-up may be needed for infants exposed to infection in utero.

Complications

• Preterm birth
• Neonatal sepsis or pneumonia
• Maternal postpartum infection
• Chorioamnionitis recurrence in future pregnancies
• Increased risk of cesarean delivery

Lifestyle & Prevention

• Attend regular prenatal care to monitor for infections
• Avoid unnecessary vaginal examinations during pregnancy
• Seek prompt treatment for genitourinary infections
• Follow guidelines for membrane rupture management

When to Seek Professional Help

Seek immediate medical attention if experiencing fever, uterine tenderness, or foul-smelling vaginal discharge during pregnancy. Early evaluation is critical to prevent complications.

Tips for Medical Coders

Document the trimester when chorioamnionitis is diagnosed, if known, to assign the appropriate code. If the trimester is unspecified, use O41.129. Ensure clinical documentation supports the diagnosis, including symptoms, lab results, or imaging findings.