How do hysterosalpingography catheter work

Hysterosalpingography catheter is also abbreviated as HSG catheter. It can be simply understood as a precisely positioned fluid delivery channel. Its core task is to accurately place the catheter tip in the appropriate position in the uterus while ensuring the patient's comfort, and then safely and adequately inject contrast agent into the uterine cavity and fallopian tubes to achieve clear medical imaging diagnosis.

This process mainly consists of two parts: precise positioning and a smooth contrast agent pathway.

Step 1: Precise Positioning to Ensure No Deviation
This is crucial for a successful procedure. The catheter needs to be skillfully secured within the body to prevent slippage during contrast agent injection, while simultaneously ensuring it is aligned with the target.

• Fixation and Sealing: To prevent contrast agent leakage from the cervix, the catheter is designed with a balloon or a conical rubber tip. A common practice is to inflate a small balloon after the catheter is inserted into the internal cervical os, anchoring it to the os for fixation and sealing. Some patented designs even include two balloons, one supporting the cervix and the other the uterine horn, providing more stable fixation and allowing for more precise alignment of the contrast agent outlet with the fallopian tube opening.

• Flexible Alignment: The shape and position of the uterus vary from person to person. To facilitate doctor's operation, some catheters have an elastic flap at the tip. After entering the uterine cavity, it naturally bends, helping the catheter tip to more easily turn and approach the uterine horn (i.e., the location of the fallopian tube opening), ensuring precise entry of the contrast agent into the fallopian tube.

Step 2: Inject contrast agent and illuminate the channel
After securing the catheter, the doctor can begin injecting the contrast agent for imaging.

• Establishing the pathway: The catheter is hollow, with a special interface at its rear end for connecting a syringe. The doctor slowly injects the contrast agent (usually iodine solution or iodized oil) through this interface.

• Dynamic imaging: Under X-ray fluoroscopy, the contrast agent sequentially fills the uterine cavity -> flows into both fallopian tubes -> overflows from the fimbriae of the fallopian tubes -> diffuses into the pelvic cavity. By observing this process, the doctor can determine whether the fallopian tubes are open, the location of any blockage, and whether the uterus is of normal shape.

• Additional functions: In some cases, the injected contrast agent itself has a flushing effect, which may help to clear slightly adhered fallopian tubes. For completely blocked fallopian tubes, the doctor can also introduce a very thin guide wire through the catheter for direct unblocking treatment.

In general, the hysterosalpingography (HSG) catheter is like a miniature syringe with positioning and aiming functions. It is fixed in the body by a balloon or special structure and aimed at the target. Then, the contrast agent is precisely delivered to the area to be examined through a hollow tube, helping doctors to see whether the fallopian tubes are open.