How is cervix measured

Sonographic measurement of cervical length is useful in firstly, the prediction of pregnancies at high-risk of early preterm delivery, secondly, distinction between true and false labor in women presenting in threatened preterm labor, and thirdly, in the prediction of likelihood of cesarean section after induction of labor.

The requirements for obtaining the FMF certificate of competence in cervical assessment are:. To view the list of sonographers who have obtained the certificate of competence in cervical assessment please click here. Risk based on maternal characteristics and history: click here. Risk based on cervical length: click here. This content does not have an English version. This content does not have an Arabic version. See more conditions. Request Appointment.

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Sign up now. During pregnancy, what's the significance of cervical length? Show references Frequently asked questions. Labor, delivery, and postpartum care FAQ Preterm labor and birth. American College of Obstetricians and Gynecologists. Accessed April 6, The shorter the cervical length, the greater the risk. Therefore, measuring cervical length by ultrasound can help predict spontaneous preterm birth.

The cervical length is measured by an ultrasound scan through the vagina transvaginal or TVU , abdomen transabdominal , or the perineum transperineal.

The most common causes of spontaneous preterm birth are preterm labour or preterm premature rupture of the membranes. Many of the interventions used to prevent preterm birth are used once symptoms develop. Preterm birth before 37 weeks is the main cause of a newborn baby being sick and disabled, or dying. The cervix is the opening or passage through which the baby must pass before being born vaginally.

Ultrasound can detect early changes of the cervix, such as shortening of the cervical length, to predict preterm birth. On identifying a short cervical length, interventions can be applied to prevent preterm birth. These interventions include giving the expectant mother progesterone to relax the uterus, or applying a stitch, known as a cerclage, to tighten the opening of the cervix. This review assessed if knowing the cervical length can prevent preterm birth.

We included seven randomised controlled studies, which involved pregnant women at 14 to 32 weeks' gestation. One study included expectant mothers with twins, without any symptoms of preterm birth or labour, and looked at the number of babies born prematurely before 36 weeks. Four studies included expectant mothers of single babies with threatened preterm labour, and one study involving women with premature rupture of the membranes looked at the safety of transvaginal ultrasound.

One trial included expectant mothers with singleton pregnancies who did not have any symptoms of preterm birth or labour to look at the efficacy of transvaginal ultrasound cervical length screening. Exclusion criteria included: a planned cesarean section delivery, b women presenting in the active phase of labor, c history of cervical insufficiency, d history of previous cervical surgery cone biopsy, large loop excision of the transformation zone LLETZ , e previous preterm births, f women with severe obstetric and medical conditions, g fetal growth restriction, and h fetal abnormalities.

Women eligible for the study were asked to participate in this study after obtaining informed written consent. We illustrated the necessity of transvaginal ultrasound to them. Patients were evaluated for their demographic data, including age, parity, body mass index BMI , occupation, and education level.

A sagittal view of the cervix with no compression was obtained. The cervical length was measured from the internal to the external os with visualization of the entire cervical canal. The same investigator did the cervical length measurement for all cases.

Three measurements were obtained for the cervical length, and the shortest one was considered in the analysis. Women were asked to attend to the emergency ward with the start of painful uterine contractions. Upon admission to the labor ward, patients were evaluated for the following items;. Failed induction was managed after patient counseling with either a further attempt to induce labor or CS delivery [ 8 ]. Each situation was dealt with according to the NICE clinical guideline [ 7 ].

The eligible women were asked to attend to the emergency and delivery ward at the onset of regular uterine contractions. The duration of the first stage of labor latent phase and active phase and the second stage of labor were recorded. Data were statistically described in terms of mean and standard deviation, frequencies number of cases , and percentages when appropriate.

P values less than 0. Parametric tests were used in variables with a normal distribution. Non-normally distributed data were tested using non- parametric tests. Pearson correlation coefficient was calculated between pairs of parametric quantitative variables, and Spearman was calculated for others. Significance was calculated and considered when the p -value was found to be less than 0.

For survival analysis, Cox regression modeling was done. The hazard ratio was calculated for each significant factor in the final model reached.

A model was fitted with vaginal delivery is the outcome measure. A total of patients [66 The mean gestational age at which delivery ensued was matched in nulliparous and multiparous women. The majority of the patients labored spontaneously The remaining ones required induction of labor due to different causes obstetric cholestasis 3. Using logistic regression for the prediction of the mode of delivery, all factors cervical length, BMI, the onset of labor, and parity were significant in the univariate model as well as the multivariate one Table 5.

Multiple univariate survival Cox regression models were done to extract the significant factors affecting the duration of the active phase of labor for normal vaginal delivery.

The Cox regression model for women who were to have vaginal delivery showed that higher BMI and labor induction were lengthening factors HR 0. The study revealed that the mean gestational age at the onset of labor was Also, the cervical length was correlated with the gestational age at delivery positive correlation in nulliparous women.

This agreed with Donelan et al. Additionally, another study said that cervical length predicted the delay in the onset of labor in women with long cervix significantly; however, they recruited patients in labor pain [ 10 ]. They also reported a continued decrease in cervical length as gestation advances.

This is explained by the antenatal changes occurring in the cervix and during labor to accomplish complete dilatation, although independent of its length [ 11 ]. Induction of labor was required for about one- third of patients There was a significant association between the cervical length and the onset of labor. The vast majority of patients CS was required in about one- third of the patients, which was higher than the reported results by El Mekkawi and his colleagues.

Different studies claimed that the cervical length could predict successful labor induction [ 14 , 15 ]. The cervical length replaces the effacement in the Bishop score, which increases the importance of the cervical length alone or when combined with other factors in the prediction of successful vaginal birth. In the study performed by Lehner et al. They mentioned that there was no correlation between the cervical length and the duration of labor, which might be reassuring to women with elongated cervices [ 11 ].

This was following our findings. This contradicted what was reported by Giyahi et al. The cervical length cannot be used as a predictor factor for CS alone; it should be combined with other known predictors, as reported by de Vries et al.

In a study conducted previously evaluating the effect of maternal weight on the duration of labor in nulliparous women only, the researchers reported that the duration of the active phase of labor was prolonged in overweight women. However, after adjustment for other confounders, the duration of the active labor did not differ significantly [ 19 ]. Overall, conflicting results were reported regarding the effect of maternal BMI on the duration of the active phase of labor [ 20 , 21 ].