USMLE (United States Medical Licensing Examination) Step 1 Practice Exam

What is the primary cause of Chorioamnionitis?

1. Viral infection

2. Bacterial infection

3. Fungal infection

4. Protozoal infection

The correct answer is: Bacterial infection

Chorioamnionitis, an infection of the amniotic fluid, membranes, and placenta, is predominantly caused by bacterial infections. This condition typically occurs when bacteria ascend from the lower genital tract into the cervix and uterus during pregnancy. The presence of bacteria is significant as it can lead to inflammatory processes that may result in complications for both the mother and the fetus, including preterm labor, sepsis, and increased morbidity. Bacterial infections commonly responsible for chorioamnionitis include species such as Group B Streptococcus, Escherichia coli, and various anaerobes. The infectious process can be exacerbated by risk factors such as prolonged rupture of membranes and invasive procedures during labor. While viral, fungal, and protozoal infections can occur in pregnant individuals, they are not recognized as the primary causes of chorioamnionitis. Thus, the clarity on bacterial infection being the main contributor underscores the importance of vigilance in monitoring maternal health during pregnancy to prevent and manage such infections effectively.