The effects of loop excision of the transformation zone on cervical length: Implications for pregnancy

OBJECTIVE: This study was undertaken to determine whether previously described significant and quantitative cervical shortening caused by loop excision of the transformation zone persists after 3 months of healing. STUDY DESIGN: A prospective study was designed in which 20 patients were enrolled. Each underwent transvaginal ultrasonography for determination of cervical length before the loop excision of the transformation zone and greater than or equal to 3 months after the loop excision of the transformation zone. Simple regression analysis and the Student paired t test was performed to determine whether the length of the cervix had changed significantly between the measurements. RESULTS: The mean cervical lengths as measured by transvaginal ultrasonography before and after loop excision of the transformation zone were 3.1 +/- 0.8 cm and 3.1 +/- 0.7 cml respectively. The correlation between ultrasonographic measurements before and after loop excision of the transformation zone was r = 0.88 (P < .0001). A paired t test resulted in a P value of 1.0000, which indicates that the ultrasonographic measurement after loop excision of the transformation zone was not different from the ultrasonographic measurement before loop excision of the transformation zone. The mean difference between measurements was 0.0 +/- 0.4 cm. CONCLUSION: After adequate healing time after loop excision of the transformation zone, the length of the cervix, as measured by transvaginal ultrasonography, does not appear to remain shortened.