Late Trimester Miscarriages
While miscarriages are common in the first trimester (the first three months of pregnancy), they are more infrequent in the second and third trimesters. However, late trimester miscarriages unfortunately can and do occur. One such incidence is known as an "incompetent cervix."
What is an Incompetent Cervix?
Also called a weak cervix or cervical insufficiency, this refers a condition in which a woman's cervix dilates before it should during pregnancy. While the cervix normally stays closed until a woman goes into labor, thereby holding the fetus in place, when a woman has a weak cervix the pressure the growing baby puts on the membranes of the amniotic sac that the fetus stretch, weaken, and break. This can result in a miscarriage, stillbirth, or a premature baby.
It is estimated that one out of one hundred, or 20-25% of all second-trimester losses are due to an incompetent cervix.
Unfortunately, there are often no warning signs or symptoms for this condition. An incompetent cervix dilates without contractions, the water breaks, and the baby is born or lost. Therefore until a late trimester miscarriage has occurred, the condition is generally not diagnosed.
If a woman has already experienced the loss of a baby due to a weak cervix, however, it generally assumed that she is at risk for this condition and she should be checked regularly throughout her pregnancy.
Diagnosis and Treatment
The good news is that if cervical incompetence is detected early, it is possible to prevent these types of late trimester miscarriages. Diagnosis can be made by a manual pelvic exam or by an ultrasound. A pelvic exam determines whether the cervix is dilating. An ultrasound measures the cervical opening and the length of the cervix.
To treat an incompetent cervix, a procedure called cerclage is performed, wherein the cervix is stitched closed to reinforce the weak cervix while the baby develops. Cerclage is performed under a local or general anesthetic, most often between weeks 14 and 16 of pregnancy. Later the stitches are removed (between weeks 36 to 38) to allow for a regular birth process. Sometimes medications are prescribed in conjunction with cerclage.
The treatment combination of cerclage and drug therapy boasts a high success rate of 85-90%, where women carry to term and give birth to healthy babies.
Rare but possible complications associated with cervical cerclage include:
Cervical laceration; rupture of the uterus or bladder; maternal hemorrhage; preterm labor; premature rupture of the membranes.
Women with the following conditions are not candidates for the cervical cerclage procedure:
•· Cervix is dilated 4cm or more
•· Cervix is irritated
•· The amniotic membranes have ruptured and water has broken
•· The fetus has already died
After experiencing a late trimester miscarriage, women should consult with a high-risk pregnancy specialist before conception and early on during pregnancy.
If you have suffered from an incompetent cervix, you are at risk for a re-occurrence of similar complications in your next pregnancies. In addition to careful monitoring of your cervix and frequent prenatal checkups, your doctor may give you other special instructions, such as avoiding sexual intercourse or reducing strenuous exercise.