In 80 pregnancies with clinical and ultrasonic signs of cervical incompetency, the length of the cervix and the thickness of the anterior wall of a lower uterine segment have been evaluated ultrasonically. We have also measured the width of the endocervical canal and studied the prolapse of fetal membranes (with fetal parts) into the endocervical canal. We evaluated these same parameters in 80 healthy pregnancies. The length of the cervix, the thickness of the anterior wall of a lower uterine segment, and the width of the endocervical canal were followed longitudinally in the patients from the 10th to the 36th gestation week. No statistically significant differences between age groups were found. In four age groups at risk for cervical incompetency, cervical lengths and wall thickness were significantly different (p < 0.001) from those in comparable controls. Forty-five percent of the patients in the at-risk group, with cervical cerclage, delivered at 37.3 (range: 32 to 41) weeks and 6.25% of pregnancies ended in abortion when the amniotic membrane herniated into the cervical canal, with or without some part of the fetus. Indexing Words: Ultrasound Cervix incompetence Anterior wall of the lower uterine segment Endocervical canal Prolapsus of fetal membranes Preterm birth Normal pregnancy Cervical incompetency is characterized by painless dilatation of the incompetent cervix resulting in preterm delivery after the second trimester. Very often premature rupture of membranes or prolapse of fetal membranes with fetal parts into the endocervical canal of vagina can also be found.
The incidence of cervical incompetency according to Sarti is 0.2% to 2%,l Varma 0.05% to 1%,2 and Feingold 1.83%.3 Fetal mortality rates of 45% to 89% have been reported in pregnancies complicated by incompetent ~e r v i x . ~
The diagnosis is commonly made retrospectively but occasionally physical examination may lead to the correct diagnosis.
The improvements in ultrasound techniques provide a more effective approach to the diagnosis of cervical incompetency during pregnancy.