"A Stitch in Time..."
Recently, we helped care for a woman carrying twins conceived by in vitro fertilization. She had a long history of infertility associated with polycystic ovary syndrome (PCOS) and at age 38 had all but given up hope of ever carrying a pregnancy. Our infertility group, and her primary obstetrician, had sent her to us for consultation at 12 weeks’ because of her age and the multiple gestation. She had no other significant medical problems and the discussion was very straightforward. We talked about PCOS-associated risks of hypertensive disorders and gestational diabetes and we also talked about the age-related risks of fetal chromosomal abnormalities and her options for prenatal diagnosis. She was well-educated and there was little new information I could provide her with on these topics.
We then talked about fetal complications specific to twin pregnancies and finally we got around to the subject of preterm labor. In brief, I informed her that she was at greater risk for PTB, not only because of the twins, and this being her first pregnancy, but also because of her underlying PCOS for reasons that are poorly understood and unrelated to any other medical complications either she or the twins might develop during the pregnancy. My specific concern was related to a condition called “cervical incompetence” that seems to haunt infertility patients with PCOS. Of all the things we discussed, this worried her the most. After all the time (and money) it had taken to conceive, the last thing she wanted was “to deliver too early and at my age have children who have problems resulting from prematurity.” When she left that day, I scheduled her to return at about 20 weeks’ for ultrasound evaluation of the babies and her cervix.
Cervical incompetence represents loss of integrity at the internal cervical os (the junction of the cervix and the uterus) that results in progressive cervical change from the inside out. Lots of factors can contribute to cervical incompetence and we will save that discussion for another day. Before the availability of ultrasound, however, the diagnosis was almost never made before a woman had delivered prematurely, or lost one or more pregnancies, with a history of 'silent' cervical dilation, usually presenting in the advanced stages of labor, preceded by minimal painful contractions. Over the last 10 years, we have learned that ultrasound evaluation of cervical length and configuration can help to identify cervical incompetence and certain women at increased risk for premature delivery.
When our patient came back at 20 weeks,’ her baby girl and boy looked fine. Her cervix measured 42 mm in length (very good!) but “slight funneling is noted at the internal cervical os.” No cause for immediate concern or action, but with that finding, she did buy herself a follow up ultrasound. Although scheduled for the next week, she could not keep that appointment. When she did return two weeks later, she now had “U-shaped funneling of membranes in the cervical canal to within 3 mm of the external cervical os” (very BAD!). To make a long story short, she was admitted to the hospital that day and underwent placement of an emergency (“rescue”) cervical cerclage (stitch around the cervix). At the time of the surgery, “the cervix was 1-2 cm dilated and membranes were clearly visible just within the cervix.” If something had not been done at that point, she surely would have delivered extremely prematurely, probably within days. Although the surgery went well, she understood that she still wasn’t out of the woods for early delivery and complications, especially those related to infection.
There is a happy ending to this story. She eventually carried the babies to 36 weeks’ before spontaneously rupturing membranes, having the cerclage removed, and delivering two beautiful healthy children who got to leave the hospital with her two days later. Technically, she had two “near term” births, but that was so much better than losing two babies at 22 weeks or, perhaps even worse, having two babies survive at 23-24 weeks with severe sequelae secondary to their prematurity. Like I said before, in the case of PTB, every little bit helps. Multiple factors contribute to PTB, but the key to reducing rates is to successfully anticipate risks and identify specific factors in individuals that might lend themselves to timely intervention.