The Maternal-Fetal Medicine Unit Network is an NIH trial that is currently examining how pessaries work for twin pregnancies
Pessaries are medical devices that have long been used as a method of delivering medication or to provide internal structural support for women. There is some indication that in cases of women with twin pregnancies, the use of a vaginal pessary reduces the chances of premature birth. Currently, definitive evidence is lacking and therefore this issue requires further investigation.
How can a pessary work to prevent preterm delivery in twin pregnancies?
While the exact mechanism(s) of pessaries for mothers carrying twins is unclear, there are several theories that support its effectiveness.
One hypothesis follows that the pessary is worn every day to alter the axis of the cervical canal, thereby displacing the weight of the uterine contents away from the cervix. By changing the angle of the cervix in relation to the uterus, the pessary also obstructs the internal orifice of the uterus. It is, therefore, possible that the weight of the uterus and the fetuses are thereby directed towards the lower anterior uterine segment.
A second interpretation is that the pessary simply protects the cervical mucus plug. There is a possibility of vaginal discharge and it is due to the collection of fluid behind the pessary, which is released incidentally.
The Maternal-Fetal Medicine Unit Network is an NIH trial that is currently examining how pessaries work for twin pregnancies at this time.
Contraindications to pessary placement have been reviewed, including: presence of a lethal fetal abnormality; suspicion of chorioamnionitis (infection in the uterus); ballooning of membranes outside the cervix into the vagina; and painful, regular uterine contractions.
How is a pessary placed?
Pessaries are placed with the patient having an empty bladder and in stirrups. She will be asked to give a urine sample in advance to test for signs of infection. A urogynecologist will perform a digital examination to measure the number of fingerbreadths accommodated across the vagina. The pessary will be inserted into the vagina with one hand, while the other hand separates the introitus and pushes down on the posterior vaginal wall.
A small amount of lubricant will be applied to the leading edge of the pessary. After the pessary is inserted into the vagina, the patient will be asked to gently strain and cough repeatedly on the examination table, walk around in the office and empty her bladder while sitting on a toilet.
She should bring the pessary back in a plastic bag if it falls out so that it can be replaced with another size. Please be reassured that it is not an emergency if the pessary is expelled; simply bring the pessary back to the office and a different type or size of pessary will likely be effective.
There are a few indications for removal and reinsertion of the pessary. If a woman complains of discomfort or minor bleeding, a speculum examination should be performed to exclude erosions and lacerations. Routinely, the pessary is removed around 37 weeks. The pessary should always be removed when there are signs of imminent delivery, and removal must not be forgotten if you are admitted in labor or undergoing cesarean delivery.
Your doctor should be made aware if you have a pessary in place before vaginal examinations, ultrasounds and when you go into labor.
Please see your obstetrician in case of discomfort, painful contractions, vaginal bleeding or suspicion of ruptured membranes.
* CU Urogynecology doctors do not care for pregnant patients, however, they do place pessaries for pregnant women.
More about Pessary
University of Colorado Urogynecology is a specialty women’s health practice focused on female pelvic health and surgery. Our physicians are also professors & researchers for the CU School of Medicine, one of the top-ranked medical schools in the nation.