Imaging techniques for assessment of tubal status

Fallopian tubes make a vital portal for transfer of gametes and embryo. Tubal factor is responsible for infertility in 25-35% of cases. Hysterosalpingography (HSG) has been used to evaluate the uterine cavity and the tubal status since decades. It uses iodinated contrast and X-rays and is painful and inconvenient for patient. Laparoscopy is considered to be the gold standard for tubal evaluation, but is an operative procedure and needs anesthesia. Though ultrasound is a modality of choice for assessment of uterus and ovaries, it does not allow assessment of the fallopian tube unless there is any fluid surrounding it or inside the lumen. This fluid interface can be created artificially by introducing saline in the uterine cavity and fallopian tubes and scanning simultaneously. The procedure is named Saline infusion HSG. Saline infusion sonohysterosalpingography (SIS) can be done with B mode US and Doppler. SIS can demonstrate a patent tube but if blocked, the site of block cannot be demonstrated. Ultrasound contrast agents can be used for tubal assessment using contrast mode on the scanners. This procedure is known as hystero-contrast sonography (HyCoSy). This actually shows the passage of hyperechoic contrast agent through tubal lumen and delineates it and locates the site of block. Using the volume ultrasound may even make the demonstration of tubal status and fimbriae better. Results of HyCoSy have been found to correlate well with laparoscopic findings, which are a gold standard. It is recommended by National Institute for Health and Clinical Excellence as a primary investigation for tubal assessment in patients without any positive history of tubal damage and also can replace a second look laparoscopy.