Gas in the Endometrial Cavity: Pneumometra
The term for gas in the endometrial cavity is "pneumometra," though in clinical imaging reports, it should be described simply as "gas in the endometrial cavity" or "endometrial gas" to avoid confusion and ensure clear communication. 1, 2
Clinical Context and Terminology
- Pneumometra is the formal medical term referring to gas distending or present within the uterine cavity 1, 2
- In imaging reports, particularly ultrasound, the preferred descriptive terminology is "gas in the endometrial cavity" or "endometrial gas" rather than using the Latin term 3
- This straightforward descriptive approach prevents misinterpretation and clearly communicates the imaging finding to clinicians 3
Clinical Significance: When Gas is Normal vs. Pathologic
Normal Postpartum Finding
- Gas in the endometrial cavity is a normal finding after uncomplicated spontaneous vaginal delivery and should NOT automatically suggest endometritis 4
- Gas appears in 19% of healthy women within the first 3 postpartum days (mean 37 hours, range 25-59 hours) 4
- Gas persists in 7% of healthy women at 3 weeks postpartum (mean 2.4 weeks, range 2.1-2.9 weeks) 4
- Overall, 21% of apparently healthy postpartum women show gas in the endometrial cavity at some point during the first 3 postpartum weeks without developing clinical endometritis 4
- Gas detected within the endometrial cavity is not, by itself, suggestive of endometritis and should be considered normal until the end of the 3rd postpartum week 4
Pathologic Context
- When evaluating for postpartum endometritis, the diagnosis is clinical, not radiologic 3
- On CT imaging, endometritis appears as a thickened heterogeneous endometrium with fluid, gas, AND debris within the cavity—the combination of findings matters, not gas alone 3
- Gas in the myometrial defect extending from the endometrium to the parametrial tissue along with hemoperitoneum suggests uterine rupture, which is a surgical emergency 3
- Gas can become entrapped in the uterine cavity with severe cervical stenosis, creating significant pneumometra 1
Common Pitfall to Avoid
Critical Error: Do not diagnose endometritis based solely on the presence of gas in the endometrial cavity on imaging, especially in the postpartum period 4, 3
- Endometritis is a clinical diagnosis requiring fever, uterine tenderness, and purulent discharge 3
- Imaging findings must be interpreted in clinical context—gas alone is nonspecific and frequently normal postpartum 4
- The presence of gas with other findings (thickened heterogeneous endometrium, debris, parametrial extension) increases concern for infection 3