- Tubal Insufflation (Rubin’s Test):
Carbon dioxide is injected into the uterus via a catheter at a rate of 60 ml/min, with pressure not exceeding 2.7 kPa. If the fallopian tubes are patent, gas bubbles can be heard passing into the abdominal cavity, and the pressure rapidly decreases. If blocked, no bubbles are detected, and the pressure remains elevated. - Ultrasonographic Contrast Imaging (Sonohysterography):
A contrast agent (e.g., saline) is injected under ultrasound guidance to visualize flow through the uterus and fallopian tubes. However, since saline is hypoechoic, direct visualization of tubal patency is limited. Instead, indirect signs, such as fluid accumulation in the rectouterine pouch (cul-de-sac), are used to infer tubal status. This method cannot determine the exact location or nature of blockages. - Laparoscopy:
A dye (e.g., methylene blue) is injected into the uterus, and laparoscopy is used to observe whether the dye flows through the fallopian tubes into the pelvic cavity, indicating patency. Blockages prevent dye passage, but this method cannot pinpoint the exact site or cause of obstruction. Laparoscopy primarily assesses tubal patency, fimbrial occlusion, and peri-tubal adhesions. - Hysterosalpingography (HSG):
A radiocontrast agent is injected into the uterus, and X-ray imaging captures the uterine and tubal morphology. Spill of contrast into the peritoneal cavity confirms tubal patency. However, artifacts from contrast type, imaging timing, or air bubbles may yield false results. - Saline Infusion Sonography (Hydrotubation):
Sterile saline is injected into the uterus, and ease of fluid passage is assessed. While large volumes suggest patency, this method has ~70% accuracy. False negatives may arise from tubal spasm (e.g., due to patient anxiety), while hydrosalpinx (fluid-filled tubes) can produce false positives.
Note: Each test has limitations, and a combination of methods or clinical correlation is often required for accurate diagnosis.
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