Sonohysterogram Test: Purpose, Test Details & Results

A sonohysterogram, also known as saline infusion sonohysterography (SIS or SHG), is a minimally invasive ultrasound procedure designed to provide detailed images of the uterus. This test plays a crucial role in diagnosing uterine conditions that might not be visible with standard ultrasound alone. Whether you are experiencing abnormal uterine bleeding, infertility, or are at risk for certain uterine diseases, understanding the purpose, process, and outcomes of a sonohysterogram can help you make informed decisions about your health.

Purpose of Sonohysterogram Test

Sonohysterography is a specialized imaging procedure that helps physicians evaluate the uterine cavity more precisely than conventional ultrasound. Its main goal is to detect abnormalities that might cause symptoms such as abnormal bleeding, infertility, or recurrent pregnancy loss.

Table 1: Primary Purposes and Beneficiaries of Sonohysterogram

Understanding the Role of a Sonohysterogram

A sonohysterogram is not a first-line imaging test. Instead, it’s used when conventional transvaginal ultrasound (TVS) reveals a suspicious or unclear finding or when more anatomical detail is needed. The procedure involves infusing sterile saline into the uterus during an ultrasound, which provides a clearer picture of the uterine lining and cavity.

Key Reasons for Ordering a Sonohysterogram:

• Abnormal Uterine Bleeding: SHG is highly effective for determining whether bleeding is caused by focal lesions like polyps or fibroids, or by diffuse conditions such as endometrial hyperplasia 2 6 8.
• Infertility Investigation: For women struggling to conceive, SHG helps identify intrauterine abnormalities (like adhesions or septum) that may interfere with implantation or pregnancy maintenance 1 5 7.
• Recurrent Pregnancy Loss: In women with repeated miscarriages, SHG can identify subtle uterine defects that might otherwise go unnoticed 3.
• Monitoring High-Risk Groups: Postmenopausal women on tamoxifen, a medication used in breast cancer, are at increased risk for uterine abnormalities. SHG allows for targeted assessment, even when routine ultrasounds are inconclusive 9 10.

Advantages Over Other Imaging Techniques

Compared to traditional ultrasound or x-ray-based methods (like hysterosalpingography), SHG offers several benefits:

• Improved Accuracy: SHG has higher sensitivity and specificity for detecting polyps, submucosal fibroids, and focal lesions compared to TVS and HSG 1 5 7.
• Guides Treatment: By distinguishing between focal and diffuse disease, SHG helps doctors choose the best treatment strategy — such as whether a biopsy or hysteroscopic surgery is needed 2 8.
• Reduces Unnecessary Surgery: A normal SHG can obviate the need for invasive procedures in some women 2 10.

Sonohysterogram Test Details

Knowing what to expect from a sonohysterogram can ease concerns and help you prepare for the procedure. This section covers the step-by-step process, preparation tips, and an overview of safety.

Table 2: Summary of Sonohysterogram Procedure Details

How the Test Works

A sonohysterogram is usually performed in a gynecologist’s or radiologist’s office and involves several well-defined steps:

Scheduling and Preparation

• Timing: The test is typically scheduled after menstruation but before ovulation to minimize infection risk and avoid disrupting a possible early pregnancy 4 6.
• Preparation: Patients may be advised to take an over-the-counter pain reliever before the procedure. No special fasting is required, and a urine pregnancy test may be performed to confirm non-pregnancy 4 6 8.
• Informed Consent: The clinician explains the procedure, including potential risks, and obtains informed consent.

The Procedure

1. Positioning: The patient lies on an exam table, similar to a pelvic exam or Pap smear.
2. Insertion of Speculum and Catheter: A speculum is inserted into the vagina to visualize the cervix. A thin catheter is gently threaded through the cervical canal into the uterus 8.
3. Saline Infusion: Sterile saline is slowly infused through the catheter, expanding the uterine cavity and separating the walls.
4. Ultrasound Imaging: While the uterus is distended, a transvaginal ultrasound probe is used to obtain images of the uterine cavity. The saline acts as a contrast agent, highlighting abnormalities 8 10.
5. Completion: The catheter and speculum are removed. The entire process typically takes 10–20 minutes 4 8.

Patient Experience and Safety

• Discomfort: Most women report only mild to moderate cramping, similar to menstrual cramps, during saline infusion. The procedure is generally well-tolerated 4 6 8.
• Complications: Serious complications are rare but can include infection (endometritis), pelvic pain, or procedure failure due to cervical stenosis 4.
• Failure Rate: Procedure failure is uncommon, most often due to difficulties in catheter insertion in women with cervical stenosis 4.
• Recovery: Most patients can resume normal activities immediately after the test.

Who Performs the Test?

The test is typically performed by a gynecologist, radiologist, or a trained sonographer with experience in women’s imaging 6 7.

Sonohysterogram Test Results & Follow-Up

After the procedure, your healthcare provider will interpret the images, discuss the findings, and recommend next steps. Understanding what your results mean and the possible follow-up actions is essential for your care.

Table 3: Typical Sonohysterogram Findings and Recommended Follow-Up

Understanding Your Results

What Can a Sonohysterogram Detect?

• Endometrial Polyps: These small, benign growths are a common cause of abnormal uterine bleeding and infertility. SHG is highly accurate for identifying their size and location, often matching the accuracy of hysteroscopy (the gold standard) 1 6 7.
• Submucosal Fibroids: These fibroids grow just beneath the lining of the uterus and can distort the uterine cavity. SHG provides clear images, helping to plan appropriate surgical intervention if necessary 2 4 6.
• Endometrial Hyperplasia: A thickened uterine lining, which can be a precursor to cancer. SHG distinguishes between focal and diffuse thickening, guiding whether a biopsy is required 1 6 8.
• Intrauterine Adhesions (Synechiae): Scar tissue inside the uterus, often from prior surgery or infection, can cause infertility or menstrual problems. SHG is helpful but may have limited sensitivity for small adhesions 1 5 7.
• Uterine Malformations: Congenital anomalies, such as septate uterus, can be diagnosed accurately with SHG, especially in cases of infertility or recurrent pregnancy loss 1 3 5.

Accuracy and Limitations

• Sensitivity and Specificity: SHG has demonstrated sensitivity and specificity rates as high as 98% and 94%, respectively, compared to diagnostic hysteroscopy 7. Its accuracy is particularly high for polyps and fibroids, although it is less reliable for detecting small adhesions 1 7.
• Comparisons to Other Tests: In multiple studies, SHG outperformed both transvaginal sonography and hysterosalpingography in diagnosing most intrauterine pathologies 1 3 5 7.
• False Positives/Negatives: Rare, but possible—especially for subtle adhesions or when technical difficulties arise 1 4.
• Impact on Management: SHG findings often change the treatment plan, sometimes reducing unnecessary surgery or helping target biopsies more accurately 2 8 10.

What Happens After the Test?

• Normal Results: If no abnormalities are found, further invasive testing or treatment is usually not required 4 10.
• Abnormal Results: If the test reveals polyps, fibroids, hyperplasia, or other abnormalities, your provider will discuss options. These might include:
  • Hysteroscopic surgery to remove polyps or fibroids 2 6 7
  • Endometrial biopsy to assess for hyperplasia or malignancy 1 6 8
  • Further imaging or specialist referral for congenital anomalies 3 5

In some cases, the findings may mean that less invasive management is possible, or that surgery can be carefully planned to address the specific issue identified 2 8 10.

Conclusion

A sonohysterogram is a safe, effective, and minimally invasive test for evaluating various uterine conditions. Its ability to provide detailed images of the uterine cavity makes it a valuable tool in diagnosing the causes of abnormal bleeding, infertility, and recurrent pregnancy loss, as well as monitoring at-risk populations.

Key Takeaways:

• Purpose: SHG is used for evaluating abnormal uterine bleeding, infertility, recurrent pregnancy loss, and uterine monitoring in high-risk groups 1 2 3 9 10.
• Test Details: The procedure is quick, mostly well-tolerated, and rarely associated with complications 4 6 8.
• Results: SHG offers superior accuracy for detecting polyps, fibroids, and other uterine abnormalities compared to traditional ultrasound or x-ray methods; results guide further management and can reduce unnecessary surgery 1 2 6 7 8 10.
• Follow-Up: Abnormal findings may require biopsy, surgery, or further imaging, while normal results usually mean no further invasive procedures are necessary.

Understanding the purpose, process, and potential outcomes of a sonohysterogram empowers patients to engage confidently in their gynecologic care.