Risk factors for preterm delivery in patients demonstrating sonographic evidence of premature dilation of the internal os, prolapse of the membranes in the endocervical canal and shortening of the distal cervical segment by second trimester ultrasound.
OBJECTIVE
To investigate the outcomes and risk factors associated with the second trimester sonographic findings of premature dilation of the internal cervical os, prolapse of the membranes into the endocervical canal and shortening of the distal segment.


METHODS
Retrospective chart review to identify patients who met the following criteria: (i) gestational age between 16 and 24 weeks; (ii) a vaginal probe ultrasound documenting dilatation of the internal os, prolapsed membranes into the endocervical canal but not extending beyond the external os, and a shortened distal cervix; and (iii) no evidence of increased uterine activity


METHODS
Sonographic measurements obtained included: (i) the width of the internal os dilation; (ii) the depth of membranes prolapsed into endocervix (funneling); (iii) the distal cervical length; and (iv) the total cervical length. Patients were stratified into two groups according to gestational age at delivery: the preterm group (< 34 weeks) and the near-term group (> or = 34 weeks).


RESULTS
Thirty-seven patients had complete records for analysis and their pregnancies resulted in 47 live births. Eighteen patients were stratified to the near term group and 19 were stratified to the preterm group. There were no stillborn infants and 10 neonatal deaths. Ten patients received cerclage and seven patients delivered at < 34 weeks gestational age. Risk factors found to be significant for preterm delivery included a gestational age at diagnosis of < or = 20 weeks gestation (p = 0.03), dilatation of the internal os > 1.3 cm (p = 0.04), and a composite Benham score > or = 1.0 (p = 0.02).


CONCLUSIONS
The sonographic findings of premature dilatation of the internal os, prolapse of the membranes into the endocervical canal and shortening of the distal cervix are associated with a high rate of delivery < 34 weeks (51%) and neonatal death (27%).
Benham
Brady N
BN
Lehigh Valley Hospital, Department of Obstetrics and Gynecology, Allentown, Pennsylvania 18105, United States of America.
Balducci
James
J
Atlas
Robert O
RO
Rust
Orion A
OA
D000328:Adult; D020070:Cervical Ripening / Q000502:physiology*; D005260:Female; D005322:Premature Rupture of Fetal Membranes / Q000000981:diagnostic imaging*; D006801:Humans; D007231:Infant, Newborn; D007234:Infant, Premature; D008875:Middle Aged; D007752:Obstetric Labor, Premature / Q000000981:diagnostic imaging* / Q000453:epidemiology*; D010923:Placenta Previa / Q000000981:diagnostic imaging*; D011237:Predictive Value of Tests; D011247:Pregnancy; D011256:Pregnancy Outcome; D011262:Pregnancy Trimester, Second; D015995:Prevalence; D012189:Retrospective Studies; D012307:Risk Factors; D012680:Sensitivity and Specificity; D016216:Ultrasonography, Prenatal; D014590:Uterine Contraction / Q000502:physiology