The Impact of Routine Transvaginal Ultrasound Measurement of the Cervical Length on the Prediction of Preterm Birth: A Retrospective Study in a Tertiary Hospital

Almeida, Joana Patricia Rodrigues Félix Peixoto de; Bartosch, Carla Maria Magno; Macedo, Alexandra Matias Pereira Cunha Coelho

doi:10.1055/s-0041-1726053

Acessibilidade / Reportar erro

Brasil

Revista Brasileira de Ginecologia e Obstetrícia

Español English

Brasil

Español English

sumário « anterior atual seguinte »

Sumário

Original Article • Rev. Bras. Ginecol. Obstet. 43 (04) • Apr 2021 • https://doi.org/10.1055/s-0041-1726053 copy

The Impact of Routine Transvaginal Ultrasound Measurement of the Cervical Length on the Prediction of Preterm Birth: A Retrospective Study in a Tertiary Hospital

O impacto da medição por rotina do comprimento cervical por ecografia transvaginal na predição de parto pré-termo: Um estudo retrospetivo num hospital terciário

Authorship SCIMAGO INSTITUTIONS RANKINGS

Abstract

Pretermbirth (PTB) is a major obstetric problem associated with high rates of neonatal morbidity and mortality. The prevalence of PTB has not changed in the last decade; thus, the establishment of a screening test and effective treatment are warranted. Transvaginal ultrasoundmeasurement of the cervical length (TUCL) has been proposed as an effective method to screen pregnant women at a higher risk of experiencing PTB.

Objective

To evaluate the applicability and usefulness of second-trimester TUCL to predict PTB in a cohort of Portuguese pregnant women.

Methods

Retrospective cross-sectional cohort study including all singleton pregnant women who performed their second-trimester ultrasound (between weeks 18 and 22þ6 days) from January 2013 to October 2017 at Centro Hospitalar Universitário São João.

Results

Our cohort included 4,481 women. The prevalence of spontaneous PTB was of 4.0%, with 0.7% occurring before the 34th week of gestation. The mean TUCL was of 33.8mm,and percentiles 3, 5 and 10 corresponded toTUCLs of 25.0mm, 27.0mmand 29.0mmrespectively. The multiple logistic regression analysis, including maternal age, previous PTB and cervical surgery showed a significant negative association between TUCL and PTB, with an odds ratio (OR) of 0.92 (95% confidence interval [95%CI]: 0.90-0.95; p<0.001). The use of a TUCL of 20mm is the best cut-off, when compared with the 25-mm cut-off, improving the prediction of risk.

Conclusion

The present study showed an inverse association between TUCL and PTB, and that the inclusion of other risk factors like maternal age, previous PTB and cervical surgery can improve the screening algorithm. Furthermore, it emphasizes that the TUCL cut-off that defines short cervix can differ according to the population.

Keywords:
preterm birth; preterm birth screening; transvaginal ultrasound cervical length; cervical length cut-off

Maternal features	Medical background	Risk factors for Preterm birth
Age (years) Mean ± standard deviation: 30.7 ± 5.5 Min: 14 Max: 50 Body mass index (kg/m²) Mean ± standard deviation: 24.6 ± 4.9 Obesity (> 30): 8.0% Years of schooling < 4th grade: 0.7% 4th to 12^th grades: 64.6% > 12^th grade: 34.7% Smokers: 12.9% Alcohol/drug users: 0.2%	None: 86.5% Uterine malformations: 0.3% Psychiatric disorders: 1.4% Sexually-transmitted diseases: 1.0% Cardiac or renal disorders: 1.0% Diabetes: 0.7% Hypertension: 2.6% Hypothyroidism: 5.2% Neoplasia: 0.8%	Spontaneous preterm birth: 1.6% Cervical surgery: 0.9% Short cervical length (≤25 mm) -» On 2^nd-trismester ultrasound: 3.0% Obstetric background None: 96.7% Preeclampsia: 0.9% Fetal death: 0.6% Fetal malformation: 0.4% 2^nd T abortion: 0.1%
Obstetric intercurrences	Actual obstetric data	Time of delivery
Fetal growth restriction: 3.9%	Primigravida: 45.4%	Mean: 39.2 weeks
Fetal malformation: 1.6%	Nullipara: 56.2%	Minimum: 24.2 weeks
Urinary infection: 3.2%	Assisted reproduction: 2.7%	Maximum: 42 weeks
Other infections: 4.4%	Labor induction: 35.7%	Term delivery (≥37 week): 96.0%
Hypertensive syndrome: 3.2%	Vaginal delivery: 76.4%	Preterm delivery (< 37 week): 4.0%
Gestational diabetes: 9.6%	Male newborn: 50.6%	Early preterm birth (< 34^th week): 0.7%
Surgery on 1^st/2^nd trimesters: 0.2%		Late preterm birth (≥ 34^th week): 3.3%

Cervical length	Early preterm birth (< 34 weeks): n (%)	Preterm birth (< 37 weeks): n (%)	Term birth (≥37weeks): n (%)	Total: n (%)
< 15 mm	4 (13.3)	5 (2.8)	11 (0.3)	16 (0.4)
15.1 to 20 mm	3 (10.0)	4 (2.2)	11 (0.3)	15 (0.3)
20.1 to 25 mm	0 (0)	6 (3.4)	74 (1.7)	80 (1.8)
25.1 to 30 mm	3 (10.0)	30 (16.8)	506 (11.8)	536 (12.0)
≥ 30 mm	20 (66.7)	134 (74.9)	3,700 (96.5)	3,834 (85.6)

Cut-off	Sensitivity	Specificity	Area under the curve	Positive predictive value	Negative predictive value
15 mm	2.8	99.7	0.51	10.9	0.97
20 mm	6.2	99.5	0.53	11.5	0.94
25 mm	10.6	97.3	0.54	3.9	0.91
30 mm	30.7	80.1	0.55	1.5	0.86

		Preterm birth – n: 179 (4.0%)	Term birth – n: 4302 (96.0%)	p-value
Maternal age	Mean ± standard deviation	31.4 ± 6.0	30.7 ± 5.5	0.098^a
	< 40 years old	161 (89.9%)	4122 (95.8%)	< 0.001^b
	≥40 years old	18 (10.1%)	180 (4.2%)	< 0.001^b
Body mass index	Mean (kg/m²)	2397 ± 5.3	24.6 ± 4.9	0.055^a
Schooling	≤ 12th grade	111 (62.4%)	2807 (65.4%)	0.404^b
Schooling	> 12th grade	67 (37.6%)	1485 (34.6%)	0.404^b
Addictions	Smoking	21 (11.7%)	556 (12.9%)	0.640^c
	Drugs	0 (0%)	4 (0.1%)	1.000^c
	Alcohol	1 (0.6%)	4 (0.1%)	0.184^c
Gestational age at cervical length measurement	Mean ± standard deviation (weeks)	21.5 ± 0.5	21.5 ± 0.6	0.592^a
Type of pregnancy	Spontaneous	165 (95.4%)	4,041 (97.2%)	0.150^b
Type of pregnancy	Medical assisted	8 (4.6%)	115 (2.8%)	0.150^b
Gravidity	Primigravida	83 (46.5%)	1,953 (45.4%)	0.789^b
Parity	Nulliparous	101 (56.4%)	2,417 (56.2%)	0.949^b
Obstetric history	Preterm birth	17 (9.5%)	55 (1.3%)	< 0.001^c
	Second trimester miscarriage	1 (0.6%)	4 (0.1%)	0.184^c
	Recurrent pregnancy loss	2 (1.1%)	16 (0.4%)	0.160^c
Maternal background	Conization	10 (5.6%)	31 (0.7%)	< 0.001^b
	Mullerian anomalies	3 (1.7%)	11 (0.3%)	0.016^c
	Chronic hypertension	9 (5.0%)	100 (2.3%)	0.021^b
	Diabetes	3 (1.7%)	28 (0.7%)	0.125^c
	Hypothyroidism	7 (3.9%)	227 (5.2%)	0.429^b
Obstetrical complications	Malformations and cromossomopathies	6 (3.4%)	64 (1.5%)	0.059^c
	Fetal growth restriction	9 (5.0%)	167 (3.9%)	0.439^b
	Hypertensive syndromes	0	143 (3.3%)	0.040^c
	Gestational diabetes	24 (1.4%)	405 (9.4%)	0.751^b
	Short interpregnancy intervals	1 (0.6%)	4 (0.1%)	0.184^c
	Surgical procedure during pregnancy	0 (0%)	7 (0.2%)	1.000^c
	Urinary infections or asymptomatic bacteriuria	8 (4.5%)	135 (3.1%)	0.321^b
	Others infections during pregnancy	10 (5.9%)	188 (4.4%)	0.438^b
Treatment with progesterone or Arabin pessary		25 (13.9%)	116 (2.7%)	0.000^b

			Cervical length (mean ± standard deviation)	p-value ^a
Maternal age	< 40 years old		33.8 ± 4.8	0.546
Maternal age	≥ 40 years old		34.0 ± 5.0	0.546
Schooling	≤ 12th grade		33.8 ± 4.8	0.568
Schooling	> 12th grade		33.9 ± 4.9	0.568
Addictions	Smoking	No	33.9 ± 4.8	0.089
	Smoking	Yes	33.5 ± 5.3	0.089
	Drugs	No	33.8 ± 4.8	0.443
	Drugs	Yes	35.5 ± 2.8	0.443
	Alcohol	No	33.8 ± 4.8	0.170
	Alcohol	Yes	30.5 ± 3.1	0.170
Type of pregnancy	Spontaneous		33.8 ± 4.8	0.664
Type of pregnancy	Medically-assisted		33.6 ± 6.4	0.664
Gravidity	Primigravida		33.5 ± 4.8	0.000
Gravidity	Multigravida		34.1 ± 4.9	0.000
Parity	Nulliparous		33.4 ± 4.8	0.000
Parity	Multiparous		34.3 ± 4.8	0.000
Obstetric history	Preterm birth	No	33.9 ± 4.8	0.000
	Preterm birth	Yes	31.8 ± 5.0	0.000
	Second-trimester miscarriage	No	33.8 ± 4.8	0.001
	Second-trimester miscarriage	Yes	26.8 ± 8.4	0.001
	Recurrent pregnancy loss	No	33.8 ± 4.8	0.412
	Recurrent pregnancy loss	Yes	32.3 ± 7.9	0.412
Maternal background	Conization	No	33.9 ± 4.8	0.000
	Conization	Yes	30.8 ± 5.6	0.000
	Mullerian anomalies	No	33.8 ± 4.8	0.993
	Mullerian anomalies	Yes	33.9 ± 3.2	0.993
	Chronic hypertension	No	33.8 ± 4.8	0.540
	Chronic hypertension	Yes	34.1 ± 6.2	0.540
	Diabetes	No	33.8 ± 4.8	0.120
	Diabetes	Yes	35.9 ± 4.6	0.120
	Hypothyroidism	No	33.8 ± 4.9	0.659
	Hypothyroidism	Yes	34.0 ± 4.5	0.659
Obstetrical complications	Malformations and cromossomopathies	No	33.8 ± 4.8	0.821
	Malformations and cromossomopathies	Yes	34.0 ± 4.9	0.821
	Fetal growth restriction	No	33.9 ± 4.8	0.000
	Fetal growth restriction	Yes	32.4 ± 4.9	0.000
	Hypertensive syndromes	No	33.8 ± 4.8	0.448
	Hypertensive syndromes	Yes	33.5 ± 4.8	0.448
	Gestational diabetes	No	33.8 ± 4.8	0.967
	Gestational diabetes	Yes	33.8 ± 45.0	0.967
	Short interpregnancy intervals	No	33.8 ± 4.8	0.871
	Short interpregnancy intervals	Yes	34.3 ± 2.4	0.871
	Surgical procedure during pregnancy	No	33.8 ± 4.8	0.934
	Surgical procedure during pregnancy	Yes	34.0 ± 3.3	0.934
	Urinary infections or asymptomatic bacteriuria	No	33.8 ± 4.8	0,112
	Urinary infections or asymptomatic bacteriuria	Yes	33.12 ± 4.8	0,112
	Other infections during pregnancy	No	33.9 ± 4.9	0.880
	Other infections during pregnancy	Yes	33.2 ± 4.6	0.880
Treatment with progesterone or Arabin pessary		No	34.2 ± 4.3	0.000
Treatment with progesterone or Arabin pessary		Yes	24.1 ± 7.2	0.000

Outcome	Odds ratio	95% confidence interval		p-value
Cervical length	0.925	0.90	0.95	0.000
Maternal age	2.265	1.32	3.90	0.003
Previous preterm birth	6.754	3.72	12.16	0.000
Cervical surgery	0.178	0.81	0.40	0.000
Constant	14.557	2.61	81.31	0.002

		Group probability – TUCL: 20 mm
		< 0.25	0.25-0.50	0.50-0.75	≥ 0.75	Total reclassified
Group probability – TUCL: 25 mm	< 0.25	4,456	1	0	0	0.02%
	PTB% (n)	3.8% (168)	0%	0%	0%	0.02%
	0.25-0.50	8	8	2	0	55.6%
	PTB% (n)	12.5% (1)	50.0% (4)	50.0% (1)	0%	55.6%
	0.50-0.75	0	0	1	4	80.0%
	PTB% (n)	0%	0%	100% (1)	75.0% (n3)	80.0%
	≥ 0.75	0	0	0	1	0%
	PTB% (n)	0%	0%	0%	0%	0%

Federação Brasileira das Sociedades de Ginecologia e Obstetrícia Av. Brigadeiro Luís Antônio, 3421, sala 903 - Jardim Paulista, 01401-001 São Paulo SP - Brasil, Tel. (55 11) 5573-4919 - Rio de Janeiro - RJ - Brazil
E-mail: editorial.office@febrasgo.org.br

Acompanhe os números deste periódico no seu leitor de RSS

[1] Address for correspondence Joana Patricia Rodrigues Félix Peixoto de Almeida, PhD, R. de Dr. Eduardo Torres, Sra. da Hora, Portugal (e-mail: joanapatriciafelix@gmail.com).