Cerclage position, cervical length and preterm delivery in women undergoing ultrasound indicated cervical cerclage: A retrospective cohort study

Abstract

ObjectiveThe objectives were to assess whether anatomical location of ultrasound (USS) indicated cervical cerclage and/or the degree of cervical shortening (cervical length; CL) prior to and following cerclage affects the risk of preterm birth (PTB).MethodA retrospective cohort study of 179 women receiving cerclage for short cervix (≤25mm) was performed. Demographic data, CL before and after cerclage insertion, height of cerclage (distance from external os) and gestation at delivery were collected. Relative risk (RR) and odds ratio (OR) of preterm delivery were calculated according to the anatomical location of the cerclage within the cervix and the CL before and after cerclage as categorical and continuous variables. Partition tree analysis was used to identify the threshold cerclage height that best predicts PTB.Results25% (n = 45) delivered <34 weeks and 36% (n = 65) delivered <37 weeks. Risk of PTB was greater with cerclage in the distal 10mm (RR2.37, 95% CI 1.45–3.87) or the distal half of a closed cervix (RR2.16, 95% CI 1.45–3.87). Increasing absolute cerclage height was associated with a reduction in PTB (OR 0.87, 95% CI 0.82–0.94). A cerclage height <14.5 mm best predicts PTB (70.8%). Increasing CL following cerclage was associated with a reduction in PTB (OR0.87, 95% CI 0.82–0.94). Conversely, the risk of PTB was increased where CL remained static or shortened further following cerclage (RR2.34, 95% CI 1.04–5.25).ConclusionThe higher a cerclage was placed within a shortened cervix, the lower the subsequent odds of PTB. Women whose cerclage is placed in the distal 10mm of closed cervix or whose cervix fails to elongate subsequently, should remain under close surveillance as they have the highest risk of PTB.

Indicaciones para la realización de cerclaje profiláctico en la prevención de parto pretérmino del embarazo de feto único.

“…En la Tabla 1 se exponen los principales estudios analizados, dentro de los cuales, trece artículos respaldaron la idea del requerimiento de un antecedente obstétrico sugestivo de incompetencia cervical como indicación para tratar con cerclaje cervical la incompetencia cervical y así prevenir el parto pretérmino; de estos artículos se encontraron siete (5,12,13,14,15,19,20) que consideran este antecedente suficiente como indicación única, y seis artículos (3,17,18,21,23,24) que consideran que este antecedente deber estar asociado a disminución de la longitud cervical para ser considerado como indicación de cerclaje cervical profiláctico. Por otra parte, los catorce artículos restantes (1,2,4,6,7,8,9,10,11,16,22,25,26,27), resaltan la importancia de no exponer a un riesgo precipitado a la gestante y no someterla a un procedimiento quirúrgico con probabilidades de complicaciones derivados del mismo, sin un sustento soportado por valoraciones seriadas de la longitud cervical con disminución progresiva de la misma demostrada.…”

Beyond Cervical Length: Association between Postcerclage Transvaginal Ultrasound Parameters and Preterm Birth

“…Approximately half of women who had cervical cerclage placement delivered at less than 37 weeks and almost one-third delivered at less than 34 weeks, consistent with prior studies. 6,8,10,16 On the first ultrasound after cerclage, women with short cervical length between cerclage stitch and external os, cerclage stitch located in the inner third of cervical stroma, funneling membranes to or past the cerclage, presence of intra-amniotic sludge, and a straight endocervical canal have the highest risk of preterm birth less than 34 weeks and less than 37 weeks. Obstetric characteristics that are also important to consider when assessing a woman's risk of preterm birth after cerclage include indication for cerclage placement as women with exam-indicated cerclage are at higher risk for preterm birth than those with history or ultrasound indication as well as use of vaginal progesterone.…”

“…Sonographic measurements associated with preterm birth have included postcerclage cervical length, cerclage height (defined as distance from external os to cerclage suture), and anterior uterocervical angle (defined as angle formed by intersecting lines drawn from internal to external os and second line parallel to the lower aspect of the anterior uterine wall). [8][9][10][11][12] These associations, however, have not been consistent across studies. [13][14][15] Furthermore, the value of assessing other sonographic measurements delineating the stitch position is also unknown.…”

Controversies in the prevention of spontaneous preterm birth in asymptomatic women: an evidence summary and expert opinion

“…Small studies have evaluated the ability of ultrasound examination after cerclage placement to prognosticate for the continuing risk of PTB. 64,65 A cerclage placed within the distal 10 mm of a closed cervix or the absence of cervical elongation after cerclage were highlighted as predictors of PTB and could be used to determine the frequency of follow-up. 65 Within trials of cervical pessary, Goya et al performed monthly cervical assessments after the placement of a cervical pessary but no details of interventions based on this assessment are given.…”

“…64,65 A cerclage placed within the distal 10 mm of a closed cervix or the absence of cervical elongation after cerclage were highlighted as predictors of PTB and could be used to determine the frequency of follow-up. 65 Within trials of cervical pessary, Goya et al performed monthly cervical assessments after the placement of a cervical pessary but no details of interventions based on this assessment are given. 66 Nicolaides et al randomised women with a cervix of <25 mm to cervical pessary or expectant management, and women subsequently had 4-weekly cervical assessment until 34 weeks of gestation, with supplementary vaginal progesterone for all women with a CL of <15 mm.…”