KEY FACTS
Imaging
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Thin-walled, distended tube; tube wall < 3 mm
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Convoluted or S-shaped, oval or pear-shaped, more dilated at fimbriated end
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Separate from uterus and ovaries
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Content anechoic; low-level echoes suggest acute pelvic inflammatory disease (PID)
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Thin endosalpingeal folds (~ 2-3 mm) protrude into lumen
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Incomplete septa: Short, linear echogenic projections into lumen from tubal kinking
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Waist sign: Indentation of opposing walls of dilated tubal structure resulting in appearance of waist
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Beads on string sign: Small hyperechoic mural nodules on transverse imaging
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Cogwheel sign: Thicker endosalpingeal folds in acute PID
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No color flow in endosalpingeal folds or wall
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Color flow in thickened tube suggests acute infection (as well as internal debris)
Top Differential Diagnoses
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Pyosalpinx (acute PID)/tuboovarian complex
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Cystic ovarian neoplasm
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Paraovarian cyst/peritoneal inclusion cyst
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Dilated bowel, acute appendicitis
Pathology
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Tubal obstruction from PID, endometriosis, appendicitis, or postpelvic surgery
Clinical Issues
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Usually asymptomatic, can present with pelvic or lower abdominal pain, severe pain may indicate adnexal torsion
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Must be distinguished from pyosalpinx or hematosalpinx based on tubal content and clinical picture
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Can result in infertility or ectopic pregnancy
Scanning Tips
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Cine clips are very useful for confirmation of tubular configuration
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Look for incomplete septa and mural nodules in tubular, fluid-filled structure separate from uterus and ovaries
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3D-rendered US can help see tortuous structure, which is difficult to follow with 2D imaging