Hysterosalpingography
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Direct answer
Hysterosalpingography is a contrast X-ray study in which iodinated dye is injected through the cervix under fluoroscopy to outline the uterine cavity and fallopian tubes. It is done soon after menstruation ends and before ovulation, and its main purpose is to test tubal patency and check the shape of the uterine cavity.
What you must remember
- Timing: Perform it in the early follicular phase, after menses and before ovulation, which also lowers the chance of an unrecognised early pregnancy being exposed.
- Contraindications: Pregnancy, active pelvic infection, unexplained uterine bleeding and known iodine or contrast sensitivity.
- Free spill: Contrast passing into the peritoneal cavity proves the tube is patent, so spill is the most reliable sign of patency.
- Proximal block: Occlusion at the cornual end, often from salpingitis isthmica nodosa or past infection.
- Hydrosalpinx: A dilated, fluid-filled tube that fills with contrast but does not spill, usually after chlamydial pelvic inflammatory disease.
- Septate uterus: The commonest major congenital anomaly, showing two narrow, closely set cavities with an acute intercornual angle (below about 75 degrees); HSG cannot show the external fundal contour.
- Bicornuate uterus: Two widely divergent horns with a wide intercornual angle (above about 105 degrees), giving a Y or heart-shaped cavity.
- Filling defects: Polyps, submucosal fibroids and endometrial synechiae appear as cavity irregularities or missing areas of the cavity.
A reading sequence for the HSG film
The vignette gives a film description, and the reading follows a fixed order.
- Confirm the study is safe: Check for pregnancy, pelvic infection and contrast allergy before the cannula is placed.
- Assess the cavity: A regular cavity is normal. An irregular outline suggests a polyp, fibroid or synechiae, and the intercornual angle separates a septate (narrow) from a bicornuate (wide) uterus.
- Look at each tube: Note whether contrast fills the tube fully, stops at the cornua (proximal block) or dilates a distal segment (hydrosalpinx).
- Check for spill: Free spill into the pouch of Douglas confirms patency. A tube that fills without spilling raises the question of distal occlusion.
- Repeat if in doubt: Tubal spasm can mimic occlusion, so a delayed film or a repeat study is needed before diagnosing a block.
Film findings are described in terms the examiner expects, such as proximal block, free spill and filling defect, so use those words when explaining the answer.
Where the exam tries to catch you
A single film is easy to misread, and most traps come from over-reading one image.
- Trap: Diagnosing bilateral tubal block from one unremarkable film. Correct: Tubal spasm can mimic occlusion, so a delayed film or repeat study is needed before accepting a block.
- Trap: Calling any divided cavity a bicornuate uterus. Correct: HSG shows only the cavity, so a narrow intercornual angle suggests a septate uterus and a wide angle suggests a bicornuate uterus; MRI or 3D ultrasound shows the fundal contour.
- Trap: Performing the study during a suspected early pregnancy. Correct: Pregnancy is a contraindication, so a pregnancy test precedes the study.
Frequently asked questions
When is hysterosalpingography performed in the menstrual cycle?
Hysterosalpingography is performed soon after menstruation ends and before ovulation, in the early follicular phase. This timing lowers the risk of exposing an unrecognised early pregnancy to radiation and contrast.
What does free spill of contrast on hysterosalpingography indicate?
Free spill of contrast into the peritoneal cavity indicates that the fallopian tube is patent. It is the most reliable sign of tubal patency, whereas a tube that fills but does not spill raises suspicion of a distal block or hydrosalpinx.
Which uterine anomaly shows a heart-shaped cavity on hysterosalpingography?
A bicornuate uterus shows two widely divergent horns forming a Y or heart-shaped cavity on hysterosalpingography. A septate uterus, by contrast, shows a narrow intercornual angle, and the two are commonly confused in vignettes.
Why is hysterosalpingography avoided in active pelvic infection?
Hysterosalpingography is avoided in active pelvic infection because injecting contrast can spread infection into the upper genital tract and peritoneal cavity. Infection must be treated and excluded before the study is performed.