A fall in cervical resistance to dilatation for first-trimester-induced abortions has been observed in previous studies and considered a sign of tearing of the cervical tissue. In a study of 104 patients undergoing first-trimester abortion a fall in resistance was found in 12.5% of women in whom the cervix was dilated to 9 mm, and in 66.7% when dilatation reached 11 mm. No difference between parous and nulliparous women was found.
PIP: Physicians used as electronic force monitor to measure cervical resistance to dilatation in 104 pregnant women (gestation = or 12 weeks) who came to Danderyd Hospital in Danderyd, Sweden to undergo vacuum aspiration to induce abortion. They used straight, tapered Pratt dilators (metal rods of increasing diameter). 61 women had children and 43 women had no children. Patients who dilated to 11 mm had a significantly higher risk of fall in resistance (indicative of a cervical tear of more than 2 mm) than those dilated to 9 mm (66.7% vs. 12.5%). The frequency of fall in resistance was essentially the same for both nulliparous and parous women. This high risk of a fall in resistance when dilatation is greater than 9 mm, regardless of the parity of the woman, suggests that physicians should preoperatively treat the cervix to soften and/or dilate it. Leading methods for preoperative treatment include prostaglandins or laminaria tents. The researchers did not know the clinical significance of a tear in the cervix, but some studies showed that women with a previous first-trimester abortion were at increased risk of second-trimester miscarriage and preterm delivery. Other studies have found the internal cervical of women who have undergone consecutive induced abortions to be wider than that of women with full-time pregnancies. A wide cervical os has been linked to cervical incompetence.