Tubal patency test

The Fallopian Tubes: A Vital Path to Fertility 

The fallopian tubes are integral organs connected directly to the uterus, divided into the left and right tubes. They play a pivotal role in reproduction, including capturing the egg released from the ovary, facilitating the sperm's journey to the egg, aiding in fertilization, supporting embryo development for the initial 4-5 days post ovulation, and then transporting the embryo into the uterus for implantation. One might draw a parallel between fallopian tubes and the incubators we use in labs for in vitro fertilization.

Any malfunction in the fallopian tubes, whether due to blockages (nonpatent tubes), fluid-filled tubes (hydrosalpinges), or inflammation, can hamper the initial stages of conception, leading to tubal factor infertility. This condition accounts for 15-30% of infertility cases. Moreover, the functioning of the fallopian tubes also influences the choice of infertility treatments. For instance, intrauterine insemination (IUI) is not recommended if there are fallopian tube abnormalities, as it does not offer an optimal environment for the sperm to fertilize the egg. Those with tube-related issues typically need to opt for in vitro fertilization (IVF or ICSI) as their primary treatment.

The study and evaluation of the fallopian tubes have a long-standing history (1). Reports tracing the assessment of the fallopian tubes using hysterosalpingography (HSG) date back to as early as 1895. Since then, numerous testing methods have emerged, while some have phased out, others remain, and new techniques continue to be developed. As of now, it's worth discussing the available methods, their merits, and their drawbacks. Let's delve into this topic today.

Tubal Patency Assessment Technologies

Various modalities currently exist (2) for evaluating fallopian tube patency. Among the most commonly utilized methods are:

1. Hysterosalpingography (HSG): 

This is one of the earliest reported techniques for fallopian tube assessment, employing low-dose radiography. It involves the injection of a radiopaque contrast medium through the cervix, which allows for the evaluation of the uterine cavity and both fallopian tubes by examining the dispersion of the contrast medium from the tubes. There are two types of contrast media: water-soluble contrast media (WSCM) and oil-soluble contrast media (OSCM). Notably, the use of OSCM might also have therapeutic effects, especially in cases where there's mucus blockage in the tubes. However, limitations of HSG include discomfort during the procedure, radiation exposure to the pelvic region, and reduced accuracy, especially in detecting proximal tubal occlusion, with reported accuracy rates around 40%.

2. Laparoscopic Chromopertubation: 

This is considered the gold standard for evaluating tubal patency. It involves injecting dye through the cervix during a laparoscopic procedure under general anesthesia. While it offers high accuracy, it is invasive, requiring general anesthesia, endotracheal intubation, and possibly a hospital stay. Thus, it's typically reserved for cases where additional laparoscopic interventions are also required.

3. Hysterosalpingo-contrast Sonography (HyCoSy): 

This is an ultrasound-guided technique where saline infused with microbubbles is injected into the uterine cavity. The dispersion of this saline can be visualized as it emerges from the fimbrial end of the tubes and surrounds the ovarian periphery, producing an "ovarian rim sign". Benefits of HyCoSy include minimal discomfort, cost-effectiveness, and convenience, as it can be conducted in most infertility clinics already equipped with ultrasound technology. Additionally, the procedure can be enhanced using three-dimensional transvaginal ultrasound (3D-TVUS) to simultaneously visualize the contrast dispersion from both tubes, similar to HSG.

Figure 4 Hysterosalpingo-contrast Sonography (HyCoSy); Left explains air-saline technique HyCoSy, and Right explains microbubble contrast. 

4. Hysterosalpingo-foam Sonography (HyFoSy): 

Similar to HyCoSy, this method utilizes ultrasound but differs in the use of a foam-based contrast agent (with more air bubbles than the saline used in HyCoSy). This leads to a brighter and clearer visualization.

Both HyCoSy and HyFoSy have a high diagnostic accuracy that closely approximates that of laparoscopic chromopertubation.

5. MR HSG and CT HSG 

They are more complicated, with limited availability of the necessary equipment and a higher cost, making them less cost-effective for routine screening.

Conclusion:

The choice of modality for assessing fallopian tube function largely depends on the expertise and proficiency of the institution, the patient's condition, and their comfort level with the procedure.