Sonographic Features of Septic Abortion
Ultrasound is the first-line imaging modality for evaluating suspected septic abortion, focusing on identifying retained products of conception, intrauterine fluid collections, and associated pelvic complications such as tubo-ovarian abscess or pelvic peritonitis. 1
Primary Ultrasound Findings
Intrauterine Abnormalities
- Retained products of conception appear as heterogeneous echogenic material within the endometrial cavity, though distinguishing normal postabortion changes from pathologic retained tissue remains challenging 2
- Intrauterine fluid collections may represent infected material, blood, or pus within the uterine cavity 1
- Endometrial thickening with irregular borders and heterogeneous echotexture suggests endometritis 1
- The uterus should be systematically examined in both long and short axis from fundus to cervix to avoid missing pathology 1
Pelvic Complications
- Tubo-ovarian abscess presents as complex adnexal masses with thick irregular walls, internal septations, and debris 1
- Pelvic peritonitis manifests as complex free fluid in the cul-de-sac (pouch of Douglas) 1
- Echogenic fluid in the pelvis suggests either pus or blood, which in the context of septic abortion raises concern for uterine perforation or rupture 1
- Large amounts of free fluid are abnormal and warrant concern for serious complications 1
Adnexal Evaluation
- Both ovaries must be scanned in two orthogonal planes to identify masses, abscesses, or other pathology 1
- Salpingitis may show distended, fluid-filled fallopian tubes (hydrosalpinx) when visible 1
- Oophoritis appears as enlarged ovaries with heterogeneous echotexture 1
Technical Approach
Systematic Scanning Protocol
- Perform both transabdominal and transvaginal ultrasound when clinically appropriate, as transvaginal provides superior detail of pelvic structures 1
- Scan the uterus completely in sagittal and transverse planes, measuring from the fundus to cervix 1
- Evaluate both adnexa systematically for masses or fluid collections 1
- Assess the cul-de-sac for free fluid, noting quantity and echogenicity 1
Key Measurements and Observations
- Document endometrial thickness and echotexture 2
- Measure any fluid collections or masses identified 1
- Use color Doppler to assess vascularity and hyperemia without requiring IV contrast 3
- Evaluate for gas within tissues, which may indicate gas-forming organisms 1
Important Caveats and Pitfalls
Diagnostic Limitations
- Overlap between normal and abnormal findings is substantial in the postabortion period, making definitive diagnosis challenging 2
- Normal postabortion changes can mimic retained products of conception 2
- Operator dependence significantly affects sensitivity and accuracy 3
- Bowel gas may obscure pelvic structures and limit visualization 1
When to Escalate Imaging
- If ultrasound is non-diagnostic or equivocal, CT abdomen and pelvis with IV contrast should be obtained, as it has superior sensitivity for detecting abscesses, gas-forming infections, and complications 1
- CT demonstrates a positive predictive value of 81.82% for identifying septic foci in the pelvis 1
- CT is superior for visualizing perirenal abscesses, gas-forming infections, and bowel complications that may be missed on ultrasound 1
Clinical Context
Gynecologic Causes of Sepsis
Ultrasound can assess multiple gynecologic sources of sepsis including endometritis, salpingitis, oophoritis, tubo-ovarian abscess, and pelvic peritonitis 1
Role in Management
- Ultrasound guidance significantly improves success rates for diagnostic aspiration and therapeutic drainage of collections 3
- Allows accurate needle placement while reducing procedural complications 3
- Portable nature permits bedside evaluation in critically ill patients 1
Non-Gynecologic Considerations
While evaluating for septic abortion, remain alert for non-gynecologic causes of pelvic sepsis including appendicitis, diverticulitis, and urological sources, which ultrasound can assess to varying degrees 1