Cervical incompetence
RECURRENT miscarriages in the second trimester of pregnancy can be a result of cervical incompetence or weakness.
Dr Daryl Daley, obstetrician-gynaecologist at Gynae Associates, said during normal pregnancy, the cervix, which is the lower part of the uterus that protrudes in the vagina, remains closed and maintains the pregnancy until labour approaches around 37 weeks of gestation or later when the labour process begins.
“During the labour process, the cervix gradually shortens and dilates until becoming of minimal length and of full dilatation. At this point, with additional contractions of the uterus, the baby is delivered through the vagina,” he explained. “Recurrent miscarriages occur when the cervix is unable to maintain its structural integrity and this results in it prematurely dilating and shortening, resulting in loss of the pregnancy. This usually occurs in the middle of the second trimester. Patients normally present with painless vaginal spotting and then progress to a complete loss of the pregnancy.”
Dr Daley said it is quite difficult to ascertain definitive causative factors for cervical incompetence, but in a lot of instances the diagnosis is made based on past history. He said some risk factors include :
1. Three or more miscarriages.
2. Previous surgery to the cervix such as a cone biopsy, which is treatment of precancerous cells of the cervix.
3. Congenital malformations of the uterus.
4. Multiple pregnancies.
Unfortunately, Dr Daley said there is truly no pre-pregnancy test to determine if the cervix is incompetent; however, most of the time the diagnosis is made after a history of recurrent miscarriages or in miscarriages in patients with previous cervical surgery.
The ObGyn said high-risk patients such as those with uterine malformations, multiple pregnancies, one or more second trimester miscarriages, may benefit from frequent ultrasounds of the cervix.
“The cervix and its length is monitored every two weeks in high-risk patients. If the length goes below 2.5 cm in high-risk patients then intervention is required,” Dr Daley said.
He said intervention is in the form of placing a stitch or a suture around the cervix.
“This suture adds extra support to the cervix and prevents it from prematurely dilating,” he explained.
He said the procedure is usually done at the end of the first trimester and in the operating theatre.
“It is usually a very quick procedure with minimal complications and can be done through the vagina or through the abdomen. Most obstetricians prefer the vaginal route. An ultrasound is done to confirm that the foetus is well and alive prior to doing the procedure,” Dr Daley said.
The ObGyn explained that intervention can be done in one of three ways —
1. Electively. Dr Daley said this is done in a patient who is known to have incompetence, for example, someone who has had three or more mid-second trimester miscarriages.
2. In a high-risk patient whose cervix is short on ultrasound (less than 2.5 cm).
3. In an emergency setting, when the patient is found to be miscarrying and the cervix has not fully dilated (usually 4 cm and below).
With regards to adjusting to life with the suture in place, Dr Daley said patients are encouraged to avoid strenuous activity such as lifting, and rest when necessary. He said a common question asked from patients and their spouses is that of sexual intercourse. Dr Daley explained that historically it was thought that sex should be avoided with the suture in place, but recent international studies state that it is safe to have sex with it in place.
Sutures are removed at 37 weeks and this can be done in the office and causes minimal discomfort. However, patients are observed for four hours to see if spontaneous labour will occur.
Dr Daley said while there is no real way to diagnose a weak cervix in pre-natal care, and the diagnosis is usually made retrospectively, risk factors exist and these should be identified.
“Preventative measures can be put in place to prevent incompetence in patients known to be incompetent,” he said.
–Kimberley Hibbert
