Hysterosalpingogram Technique

Usually completed in about 3-5 minutes, HSG is performed by instilling radio opaque contrast into the uterine cavity while using fluoroscopy with intermittent still images for documentation. Proper technique is important to enhance patient comfort and ensure the highest quality images. Having the patient empty her bladder prior to positioning may ease discomfort from the speculum, which should be warmed prior to insertion. Supporting the patient’s hips on a short stack of towels or an overturned bed pan often aids in visualization of the cervix. As with any pelvic examination, the operator should attempt to drape as much of the patient’s lower body as possible, have a female chaperone, and explain to the patient each step of the procedure.

Very few items are necessary to perform an HSG (see image below). Instillation devices include instruments that fit into the cervix such as a Cohen cannula or a 5-F catheter that has a balloon to prevent efflux of contrast from the cervix. An open-sided speculum is optimal since it is easier to remove with instruments in place.

Instruments required for hysterosalpingogram (HSG) include an open-sided speculum, tenaculum, sponge stick, antiseptic, contrast medium, and an acorn (Cohen) cannula (A) or a balloon-tip catheter (B).

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The cervix is prepared with an antiseptic and grasped with a single-toothed tenaculum. Gentle, slow placement of the tenaculum, grasping only enough tissue for adequate stabilization of the cannula, is recommended. Distress experienced by the patient because of poor tenaculum placement is often a predictor of a negative patient experience. Cohen cannulas come with a narrow acorn tip for use in nulliparous patients or a wider acorn tip for multiparous patients. All air should be removed from the cannula by priming it in the vertical position. Holding the Cohen and applied tenaculum in one hand to occlude the cervix is preferable to attaching the cannula to the tenaculum since it usually causes less pain. A balloon catheter may be more suitable for patients with cervical stenosis since it has a smaller diameter than the tip of the Cohen cannula. Some patients experience discomfort during inflation of the balloon. Other methods such as using a balloon catheter are also frequently employed and avoid the useof the tenaculum.

For patients planning to undergo in-vitro fertilization, documenting how the catheter traverses the cervical canal may provide valuable information for the embryo transfer. The speculum should be removed both for patient comfort and to prevent nonvisualization of portions of the pelvis. Failure to remove the speculum is one of the most common errors made when performing an HSG. Gentle traction on the cervix is necessary so that the uterine body is perpendicular to the x-ray beam. Failure to properly position the uterus is another common mistake that may result in the inability to identify significant intrauterine filling defects or fundal contour abnormalities (see the image below). When using an intrauterine catheter, deflating the balloon at the end of the procedure and continuing to inject dye in order to visualize the uterine isthmus and cervix is very important.

Positioning the uterus parallel to the x-ray beam is critical for evaluation. In panel A, the uterus is not positioned correctly, obscuring the uterine septum seen in panel B when the uterus is repositioned.

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To decrease uterine spasm, the media should be warmed to body temperature and injected slowly. A 1995 meta-analysis on the accuracy of HSG reported that proximal tubal occlusion can occur secondary to transient tubal spasm or obstructive endometrial debris in up to 20% and 40% of cases, respectively. ^[13] False-negative results can occur from excessively rapid or overinstillation of contrast, obscuring subtle filling defects. In fact, in one study, approximately 10-35% of women with a reportedly normal HSG were then found to have abnormal findings on hysteroscopy. ^[4] Historically, administration of glucagon and selective tubal catheterization have been performed in an attempt to combat proximal tubal occlusion. However, increased cost and technical complexity have caused these methods to become less popular. ^[11]

A scout radiograph is taken prior to the instillation of contrast. Then a series of at least 4 more images should be captured as the contrast spreads through the genital tract. The first image after the scout film documents initial cavity fill and is best for visualizing small filling defects. ^[3] The subsequent image should be obtained when the cavity is fully distended to assess uterine shape. The third and fourth images after the scout are obtained as the fallopian tubes are filling and after dye has spilled into the pelvis, respectively. Additional images may be required to better document any pathology that is seen.

Occasionally, the patient may need to be positioned obliquely or laterally to obtain optimal orientation of anatomy or to clarify pathology from artifact. As with all radiography procedures, the goal is to obtain an adequate study using as low as reasonably achievable (ALARA) radiation dose. Strategies include adjusting the dose for body mass index, shielding of other body areas, and using the smallest radiation field needed.

Both oil-based and water-based iodinated contrasts are used for HSG. The advantages and disadvantages of each have been debated for years. Most studies ultimately fail to show a difference in the diagnostic accuracy of uterine or tubal pathology with either of these media.

However, water-soluble dyes have been found to provide better detail of the uterine cavity and mucosal folds of the ampullary portion of the tube and are more quickly eliminated. ^[26] Oil-based dyes have been associated with less postprocedure vaginal bleeding, but in animal models oil-based dyes are reported to cause temporary granulomatous formation of the pelvic peritoneum. ^{[26, 27]}

Other studies have confirmed a higher incidence of lipogranulomas in women, as well as a higher rate of allergic reaction with oil-based media, prompting most practitioners to prefer the use of water-based media. ^{[26, 28]}  A meta-analysis showed that the most common complication after an HSG with oil-based contrast is intravasation, which was reported in 2.7% of procedures. ^[29]

Air polymer type A (ExEm Foam) is a water-soluble ultrasound contrast gel indicated for sonohysterosalpingography to assess fallopian tube patency in women with known or suspected infertility. 

Approval of air polymer type A was based on 2 studies that compared 2D or 3D imaging to detect fallopian tube patency in women with infertility which was confirmed by laparoscopy with chromotubation as the reference standard. For 2D-sonohysterosalpingography imaging, the proportion of fallopian tubes correctly identified as occluded was 80% and the proportion of tubes that were correctly identified as patent was 92%. For 3D imaging, the proportion of tubes correctly identified as occluded was 98% and the proportion of tubes that were correctly identified as patent was 91%. ^[30]

Nonetheless, a Cochrane review from 2007 demonstrated a significantly higher post-HSG pregnancy rate (PR) when using oil-based contrast. In this meta-analysis, PR varied from 17-23% with water-soluble contrast to 24-38% with oil-based contrast, compared to 8-21% without the HSG. ^[31] These authors pointed to an improvement in endometrial receptivity after oil-based contrast exposure as a possible explanation for this. Another theory suggests a reduction in peritoneal macrophage function after oil-based media as a potential mechanism. ^{[32, 33]}

Complications from HSG are rare. The most common adverse event is a vasovagal reaction with bradycardia and hypotension, potentially resulting in syncope. This may occur anytime during the procedure such as with tenaculum placement, dye instillation, or shortly after completion. Most cases resolve with simple maneuvers including termination of the procedure and placement of the patient in a Trendelenburg position, if possible.

Extravasation of dye is also an indication to discontinue the procedure. Unabated extravasation may increase the risk of systemic reaction to the contrast, increase the risk of infection, and result in embolism with an oil contrast agent. Allergic reactions to contrast dye are much less common than with intravenous administration but have been reported. Most cases demonstrate urticaria. One case of angioedema with bronchospasm after extravasation requiring systemic administration of epinephrine and Benadryl was reported in a patient with asthma. ^[34]

The videos below further illustrate the procedure of hysterosalpingogram: