What is a Hysterosalpingogram (HSG) Scan?
A hysterosalpingogram (HSG) is an X-ray imaging procedure that evaluates the uterine cavity and fallopian tube patency by injecting contrast material through the cervix to visualize the internal reproductive anatomy. 1, 2
Primary Purpose and Clinical Applications
HSG serves as a first-line diagnostic test for evaluating tubal patency in infertility workups, recommended by the American College of Radiology due to its less invasive nature and good diagnostic accuracy 1
The procedure demonstrates the morphology of the uterine cavity, the lumina of the fallopian tubes, and whether the tubes are open (patent) or blocked 2
HSG has 65% sensitivity and 85% specificity for diagnosing tubal patency when compared with the gold standard of laparoscopy 1, 3
What the Procedure Detects
Tubal abnormalities: HSG can identify tubal patency, tubal size, tubal irregularity, peritubal disease, and conditions like hydrosalpinx and salpingitis isthmica nodosa 1, 4
Uterine cavity abnormalities: The test can detect intrauterine synechiae (adhesions), which appear as irregular endometrial filling defects 1
Post-surgical evaluation: HSG is useful for assessment after sterilization procedures or before fallopian tube recanalization 4
Important Clinical Considerations
Therapeutic benefit: Tubal flushing during HSG has been shown to increase pregnancy rates up to 38% compared to 21% in women who did not undergo HSG, suggesting the procedure itself may have fertility-enhancing effects 1
Contrast medium selection: HSG can utilize either water-soluble contrast medium (WSCM) or oil-soluble contrast medium (OSCM), with OSCM resulting in higher incidence of non-IVF pregnancies and therefore preferred in women younger than 38 years with unexplained subfertility 4
Antibiotic prophylaxis: Should be considered at the discretion of the referring physician, particularly in patients with history of pelvic inflammatory disease or if hydrosalpinx is noted during the procedure 1, 5
Limitations to Be Aware Of
Structural but not functional information: HSG provides anatomical details about tubal patency but does not assess functional transport capability of the fallopian tubes 3
Limited accuracy for certain conditions: HSG has only 16.7% accuracy in categorizing Müllerian duct anomalies compared to MRI's 100% accuracy 1
Radiation exposure: Unlike ultrasound-based alternatives (HyCoSy), HSG involves ionizing radiation, though it remains widely available and serves as a reference standard 4
Alternative Testing Options
Hysterosalpingo-contrast sonography (HyCoSy) is an ultrasound-based alternative that involves instilling echogenic contrast with real-time ultrasound imaging, offering similar accuracy to HSG (91% accuracy for tubal patency in women with endometriosis) without radiation exposure 1, 4
HyCoSy can be performed as part of a comprehensive infertility examination in one session when combined with transvaginal ultrasound with 3D imaging 1