Indications

Infertility workup — tubal patency assessment
Recurrent pregnancy loss — uterine cavity evaluation
Müllerian anomaly characterization
Suspected intrauterine synechiae (Asherman's syndrome)
Pre-ESSURE or post-tubal ligation confirmation
Suspected tubal obstruction (prior PID, ectopic pregnancy, tubal ligation)

Normal Anatomy and Findings

Structure	Normal Finding
Uterine cavity	Triangular; smooth, symmetric margins; fundus slightly concave or flat; no filling defects
Cornua	Symmetric bilateral entry into fallopian tubes
Interstitial segment	Intramural portion of tube within uterine wall; 1–2 cm; narrow caliber
Isthmic segment	Narrow; straight; 2–3 cm
Ampullary segment	Widest portion; gently curved; rugated inner folds
Fimbrial end	Feathery fimbrial folds; opens to peritoneum
Peritoneal spill	Free spill of contrast around ovary and into cul-de-sac = patent tube

Bilateral free peritoneal spillage confirms tubal patency on both sides. Unilateral spill with no filling of the contralateral tube = likely occlusion, but may represent tubal spasm — document position and consider repeat imaging after antispasmodic or on a separate occasion.

Key Findings — Uterine

Finding	Features
Submucosal fibroid	Smooth, rounded filling defect within cavity; broad base; may distort cavity or cornua
Endometrial polyp	Smooth, sessile filling defect; may be sessile or polypoid; difficult to distinguish from fibroid on HSG alone — sonohysterography or hysteroscopy for confirmation
Intrauterine synechiae (Asherman's)	Irregular filling defects; may be small or large; can obliterate portions of cavity; history of uterine curettage or infection
T-shaped uterus	Narrow, elongated cavity; constricted lateral walls; associated with in utero DES exposure

Müllerian Anomalies

Anomaly	HSG Appearance
Septate uterus	Two horns with narrow intervening septum; external fundal contour normal or minimally indented; septum extends variable distance into cavity
Bicornuate uterus	Two separate horns; divergent angle >105°; external fundal indentation >1 cm (diagnosed on MRI/3D US — HSG cannot assess external contour)
Arcuate uterus	Mild fundal indentation <1 cm; normal variant; no clinical significance
Unicornuate uterus	Single banana-shaped cavity; no contralateral horn; rudimentary horn may be present
Uterus didelphys	Two completely separate uterine horns and cervices; two cavities fill separately

HSG cannot reliably distinguish septate from bicornuate uterus — this distinction requires external fundal contour assessment (MRI or 3D ultrasound). This distinction is clinically critical: septate uterus is correctable hysteroscopically; bicornuate is not. Always recommend MRI or 3D US when a uterine anomaly is identified.

Key Findings — Tubal

Finding	Features
Cornual occlusion	No filling of tube; contrast pools at cornua; may represent tubal spasm (see pitfall below)
Proximal tubal occlusion	Contrast fills interstitial and proximal isthmic segment only; abrupt cutoff
Hydrosalpinx	Dilated, fluid-filled tube; smooth walls; ballooned ampullary segment without fimbrial spill; may fill with contrast
Peritubal adhesions	Tube fills but contrast does not spill freely; loculated contrast pooling around tube
Salpingitis isthmica nodosa (SIN)	Multiple small diverticula in the isthmic segment of the tube; nodular, irregular; associated with PID and ectopic pregnancy risk
Tubal occlusion post-ligation	No filling beyond ligation site; clip artifact visible

Reporting Checklist

Uterine cavity: normal / filling defect (location, morphology) / synechiae / Müllerian anomaly
Müllerian anomaly: type — recommend MRI for external contour if anomaly identified
Right tube: fills to fimbrial end / occluded (level) / hydrosalpinx / SIN
Left tube: fills to fimbrial end / occluded (level) / hydrosalpinx / SIN
Bilateral peritoneal spill: present / unilateral / absent
Tubal spasm considered: if cornual occlusion, document and recommend antispasmodic or repeat
Contrast used: water-soluble (Omnipaque) / oil-based (Lipiodol)

Common Pitfalls

Pitfall	How to Avoid
Cornual spasm mimicking occlusion	Cornual spasm is common — causes false positive occlusion. If cornua do not fill: administer glucagon or butylscopolamine; wait 5–10 min; repeat; prone positioning may help; refer for repeat HSG or office hysteroscopy before diagnosing occlusion
Underfilling of uterine cavity	Inject slowly with small volume first; insufficient contrast → missed filling defects; cavity should be fully outlined before evaluating tubes
Venous intravasation	Contrast entering myometrial veins = "feathery" pattern extending outside cavity at myometrium; stop injection; does not represent perforation; reposition and reattempt if needed
Septate vs. bicornuate	HSG cannot assess external contour — always recommend MRI or 3D US when any uterine cavity anomaly is found
Lipiodol oil embolism	Oil-based contrast (Lipiodol) is contraindicated if there is concern for tubal obstruction and venous intravasation risk — use water-soluble contrast (Omnipaque) instead

Step-by-step fluoroscopy technique and systematic search patterns available in RadCall Pro.

Hysterosalpingogram — Interpretation and Findings