When couples struggle to get pregnant, a doctor who specializes in fertility can perform a saline infusion sonogram, or SIS, to check for blockage in the fallopian tubes. The ovary releases an egg for fertilization. Tiny finger-like structures called fimbriae help guide the egg through the fallopian tube to the uterus. The egg can get fertilized during the journey along the fallopian tube. Once fertilized, the egg implants and grows in the uterus.

The doctor uses a syringe, filled with a mixture of saline and air bubbles,* and injects the mixture into the uterine cavity through a small catheter with a small balloon near the tip that is inflated to stop the fluid from running back through the cervix.

The mixture flows into the fallopian tubes.

Under ultrasound, the doctor can see if the saline-bubble mixture is able to flow through the fallopian tubes. If the tubes are open, or not blocked, the liquid will fill the tubes and spill out the end. This is known as “fill and spill.”

Once the procedure is finished, the saline mixture ultimately flows into the peritoneal cavity, or abdominal cavity, which contains the liver, stomach, small and large intestines, and in women, the peritoneal cavity also includes the uterus, fallopian tubes and ovaries. A small bit of the liquid also will flow back through the cervix into the vagina.

*In this case, the syringe was mistakenly filled with trichloroacetic acid, which the doctor injected into the uterine cavity, causing internal and external chemical burns. Saline and trichloroacetic acid are both clear fluids that are indistinguishable once poured from a labeled bottle.

When couples struggle to get pregnant, a doctor who specializes in fertility can perform a saline infusion sonogram, or SIS, to check for blockage in the fallopian tubes. The ovary releases an egg for fertilization. Tiny finger-like structures called fimbriae help guide the egg through the fallopian tube to the uterus. The egg can get fertilized during the journey along the fallopian tube. Once fertilized, the egg implants and grows in the uterus.

The doctor

uses a

syringe,

filled with a

mixture of

saline and

air bubbles,*

and injects

the mixture

into the uterine cavity through a small catheter with a small balloon near the tip that is inflated to stop the fluid from running back through the cervix.

The mixture flows into the fallopian tubes.

Under ultrasound, the doctor can see if the saline-bubble mixture is able to flow through the fallopian tubes. If the tubes are open, or not blocked, the liquid will fill the tubes and spill out the end. This is known as “fill and spill.”

Once the procedure is finished, the saline mixture ultimately flows into the peritoneal cavity, or abdominal cavity, which contains the liver, stomach, small and large intestines, and in women, the peritoneal cavity also includes the uterus, fallopian tubes and ovaries. A small bit of the liquid also will flow back through the cervix into the vagina.

*In this case, the syringe was mistakenly filled with trichloroacetic acid, which the doctor injected into the uterine cavity, causing internal and external chemical burns. Saline and trichloroacetic acid are both clear fluids that are indistinguishable once poured from a labeled bottle.