Usage of cervical cerclage in pregnancy with Mullerian anomalies and cervical insufficiency: A case report

Abstract

Usage of cervical cerclage in Mullerian anomalies remains unclear due to the few studies and reports conducted on such cases. This case report wishes to highlight the usage of cervical cerclage in Mullerian abnormalities and repeated preterm labour. A 26-year-old G3P2A0 with 13 weeks of pregnancy came with a history of repeated preterm birth, which ended at 23–24 and 28–29 weeks consecutively. Ultrasound examination revealed that she had 14–15 weeks of pregnancy and cervical length 2.2 cm. The patient was diagnosed with cervical insufficiency, and cervical cerclage was performed. The patient then presented at 36th–37th weeks of pregnancy with labour pain and fetal distress, emergency cesarean section was performed. During the operation bicorporeal uterus was found. The fetus was delivered weighing 2.690 g with 1-min APGAR score of 7 and 5 min at 9. We performed ultrasonography and pelvic MRI 2 months after delivery, which identified a U3bC0V0 as in the European Society of Human Reproduction and Embryology classification and a bicornuate uterus (serosal indentation >1 cm) as in the 2021 American Society of Reproductive Medicine classification. Patient presented with two preterm births and fulfilled classic historic features of cervical insufficiency which history-indicated cerclage is mandatory. Uterine anomalies themselves increase the risk of recurrent pregnancy loss, preterm birth, and cervical insufficiency. Only half of a pregnancy with a bicorporeal uterus lasts till term, and half of it ends up as early preterm pregnancy loss. It is important to diagnose or exclude Mullerian abnormalities in cases of repeated preterm labour or second-trimester pregnancy loss. Usage of cerclage has been useful in some cases, including this case; further research should be conducted for stabilizing the guidelines of cerclage in pregnancy with Mullerian abnormalities.

Introduction

Cervical cerclage was first performed in 1902 in women with a history of second-trimester loss or spontaneous preterm birth, suggesting a condition called cervical insufficiency. ¹ Based on the American College of Obstetricians and Gynecologists (ACOG) practice bulletin in 2014, cervical cerclage is indicated based on a history of cervical insufficiency, physical examination findings, or a history of preterm birth and certain ultrasonographic findings. ² Green top guideline by Royal College of Obstetricians and Gynaecologists (RCOG) states the same statement with slightly different threshold, history-based cerclage requires three or more prior preterm births. The usage of cervical cerclage has proven to be useful, as seen in the RCOG multicentre randomized trial in 1993 concluded cervical cerclage had a beneficial effect in 1 of 25 cases in the trial. ³

However, the usage of cervical cerclage in Mullerian anomalies remains unclear, due to no clear regulation, few studies and reports conducted on such cases. ⁴ Berghella et al. meta-analysis could not analyze the effectiveness of cervical cerclage in the Mullerian anomalies group due to its few case. ⁵ In research conducted by Yassaee and Mostafaee, the result of cerclage in patients with a bicornuate uterus is satisfying, with a reduction of preterm birth of more than 50% compared to the uncerclage group. ⁶ This case report wishes to highlight the usage of cervical cerclage in Mullerian abnormalities, which is a bicornuate communicant horn and repeated preterm labour.

Case report

A 26-year-old G3P2A0 with 13 weeks of pregnancy according to the last menstrual period came to the Fetomaternal Policlinic with a history of repeated preterm birth. Her previous pregnancies each ended at 23–24 and 28–29 weeks. She did not control her pregnancy to Obstetrician at her two previous pregnancies. Ultrasound examination revealed that she had 14–15 weeks of pregnancy with an estimated fetal weight of 92 g.

On transvaginal ultrasound, it was found that her cervical length was 2.2 cm. Patient was then diagnosed as G3P2A0 14–15 weeks of pregnancy with cervical insufficiency and planned for cervical cerclage the day after. McDonald cervical cerclage was performed, and the patient was followed up monthly by our consultant and was planned for cerclage removal and vaginal delivery at term pregnancy. She had a total of six times of antenatal care visits during her pregnancy. However, at 36–37 weeks of pregnancy patient presents to the emergency department with increasing labour pain. We performed an admission test and found the cardiotocography (CTG) with baseline 120–130, with variability <5 bpm, accompanied by late deceleration at every contraction. At internal examination, we found the cerclage was still intact and there was not yet softening nor opening in the cervix. The patient then planned for an emergency cesarean section. During the operation uterus was bicorporeal (Figure 1). The fetus was delivered with an incision on the lower segment of the uterus and weighed 2.690 g with a 1-min APGAR score of 7 and 5 min at 9. ⁷

Figure 1.

Patient uterus after fetal delivery. (a) Left uterine cavity where pregnancy occurred. (b) Right uterine cavity with no pregnancy.

We educated her about the findings during the operation and told her this was the reason for her repeated premature labour. In future pregnancy, cervical cerclage should be performed with the possibility of cesarean section. Patient was scheduled at Urogynecology Policlinic for further examination after the puerperium period for diagnosis confirmation and further workup (Table 1). We performed gynaecology ultrasound 2 months later and found two uterine corpus, each measuring 6.44 × 2.89 × 3.44, and 6.28 × 2.54 × 3.45 cm (Figure 2). Furthermore, after 3D rendering, we found a uterine septum or indentation dividing the right and left cavity measuring 1.23 cm. However, it is still unclear if the patient has a bicorporeal uterus (U3) or a septate uterus (U2).

Table 1.

Patient’s Timeline.

Date	Event
2020	First child lost at 23–24 weeks of pregnancy, 600 g
2022	Second child lost at 28–29 weeks of pregnancy, 1.200 g
August 2023	Last menstrual period, she had (+) pregnancy test
5 December 2023	Patient controlled herself to Sumedang District Hospital Diagnosed with G3P2A0 14–15 weeks of pregnancy with cervical insufficiency, cervical cerclage was performed on 6 December 2023
January–April 2024	Controlled herself routinely each month at Sumedang District Hospital. No fetal growth restriction was present during pregnancy
5 May 2024	Sumedang District Hospital 36th–37th weeks of pregnancy with increasing labour pain CTG category III Cerclage was removed, one cervix and vagina were found (C0V0) C-section was performed due to fetal distress Bicorporeal uterus (U3) was founded during the operation; we did not perform uterus sound on the small corpus
29 July 2024	Patient control herself to Urogynecology Clinic at Hasan Sadikin General Hospital Gynaecology ultrasound was performed, MRI was planned to differentiate U2 and U3
2 September 2024	Pelvic MRI with 1.5 T was performed with double contrast Patient was concluded with U3bC0V0/bicornuate uterus
3 September 2024	Patient controlled herself the next day and educated about her condition and future pregnancy management

Figure 2.

(a) Left uterine corpus measuring 6.44 × 2.89 × 3.44 cm. (b) Right uterine corpus measuring 2.8 × 2.54 × 3.45 cm. (c) Uterine septum or indentation dividing right and left cavity measuring 1.23 cm.

Pelvic MRI with double contrast was performed 3 months postpartum on the patient. On the sagittal plane, we found consistent findings of two uterine corpus, each measuring 4.36 × 3.04 cm on the right side and 2.99 × 1.78 cm on the left side. We also found the patient has clear fundal indentation on the outline, which exceeds 50% of the uterine wall thickness, as shown in Figure 3. We concluded the patient was classified in class U3 or bicorporeal uterus with normal cervix (C0) and vagina (V0) per European Society of Human Reproduction and Embryology (ESHRE) consensus on the classification of female genital tract congenital anomalies in 2013. With the American Society of Reproductive Medicine (ASRM) classification in 2021, due to serosal indentation more than 1 cm, we concluded the patient a bicornuate uterus.

Figure 3.

(a, b) Sagittal view of both corpus. (a) Right corpus and (b) left corpus. (c) Uterine indentation dividing two corpus at 1,24 cm (>50% of uterine wall thickness).

We explained the MRI findings, Magnetic Resonance Imaging (MRI) which are consistent with intraoperative findings. The patient and her family understood and were not planning pregnancy in the near future; however, she will consult with herself if she wants to conceive again. History-based cerclage would be performed on her next pregnancy to ensure a safe pregnancy.

Discussion

Prophylactic cervical cerclage has been known for a long time to be a solution for women with an unequivocal history of second-trimester painless delivery. ⁸ This patient undergoes history-based cerclage with two prior preterm labour episodes accompanied by painless cervical dilation. As we look at ACOG and RCOG guidelines, the threshold of history-based cerclage is different, with ACOG stating prior one-time preterm labour and RCOG stating prior three times preterm labour.^1,2 RCOG statement based on multicentre research conducted in 1993, which showed a significant result (p < 0.05) in the singleton group with ⩾3 times second-trimester miscarriage or preterm delivery.^1,3 Despite that, in this case, with the prior two times of preterm delivery, we performed history-indicated cerclage. This approach is also true due to the fact that ACOG recommends that if there are classic historic features of cervical insufficiency, history-indicated cerclage is mandatory. ² Other than history-indicated cerclage, cerclage could also be performed based on physical and ultrasound examination.^1,2,4 Women with a history of one or more spontaneous second-trimester loss or preterm births who are undergoing ultrasound surveillance of cervical length should be offered cerclage if the cervix is 25 mm with gestations <24 weeks. ¹ However woman with no history of previous second-trimester pregnancy loss, if presented with a short cervix, does not benefit from cervical cerclage.^1,4,9

According to Heinonen et al., in their evaluation of 182 cases of pregnancy with uterine anomalies increased the risk of recurrent pregnancy loss (25%), preterm birth (15%–25%), and cervical insufficiency (38%). ¹⁰ When the uterine anomalies were grouped based on the degree of uterine development failure, the complete septate uteri had the best fetal survival rate (86%), followed by complete bicornuate uteri (50%) and unicornuate (40%), which is the poorest. ¹⁰ This outcome is similar to our case, which presents as a bicornuate uterus where half of the pregnancy ends up as pregnancy loss. Her previous pregnancy ended as a secondary trimester pregnancy loss at 23–24 and 28–29 weeks.

Mullerian abnormalities could be caused due to disruption in the fusion, invagination, resorption, or recanalization process. ¹¹ ESHRE classified Mullerian anomalies based on female reproductive organ parts. ¹² According to ESHRE classification, our case is categorized as class U3b or complete bicorporeal uterus, characterized by an external fundal indentation completely dividing the uterine corpus up to the level of the cervix. It’s shown on MRI by the presence of external indentation at the fundal midline exceeding 50% of the uterine wall thickness. ¹² According to the newer classification by ASRM, the case was categorized as a bicornuate uterus in the bicornuate uterus group. ¹³ Bicornuate uterus group was divided into four categories, which are: bicornuate uterus (serosal indentation >1 cm), bicornuate septate uterus (serosal indentation <1 cm), bicornuate uterus with bicollis, and bicornuate uterus with communicating tract. ¹³

The reduction of uterine volume and size also affects the capability of the uterus to expand when pregnant. In a normal uterus without abnormalities, the uterus weighs ~70 g and has a cavity with a volume of 10 mL. ¹⁴ A study in 2016 proved the average of uterus normal volume in 20–35 years old is 51.3–79.1 mL. ¹⁵ This size could be cut in half in the case of Mullerian abnormalities, such as unicornuate and bicorporeal uterus, due to incomplete fusion, giving rise to a smaller functional capacity. When pregnancy occurs, stretching and hypertrophy of muscle cells in the uterus mainly happen, whereas the production of new myocytes is limited. ¹⁴ The uterus then transforms into a thin-walled muscular organ of sufficient capacity to contain the contents at term, with an average of 5 l. ¹⁴ However, in this case, it could be hypothesized that the decreased volume and capability in stretching of the uterus will push the pregnancy to the cervical area, which stimulates mechanical dilatation of the cervix and initiation of labour (Figure 4).

Figure 4.

Illustration between (a) normal and (b) Mullerian abnormality uterus in pregnancy correlates with preterm birth.

This statement is proven with the research that was performed in 2005 by Airoldi et al. who found that a short cervical length on transvaginal ultrasonography in women with uterine anomalies has a 13-fold risk for preterm birth. ¹⁶ In 2011, Yassaee and Mostafaee showed the use of cerclage in women with uterine abnormalities. A woman with a uterine bicornuate uterus who underwent cerclage had 76.2% term delivery compared uncerclaged woman, who only achieved 27.3% term delivery. ⁶ Newer case reports show the usage of abdominal cerclage before conception in bicornuate uterus patient with cervical insufficiency resulting in a term pregnancy.^17,18 However, abdominal cerclage has its own limitations; diagnosis of Mullerian abnormalities should be made before conception, and its removal needs to be performed transabdominally. Further research should be conducted for stabilizing the guidelines of cerclage in pregnancy with Mullerian abnormalities.

Conclusion

It is important to diagnose or exclude Mullerian abnormalities in cases of repeated preterm labour or second-trimester pregnancy loss. Mullerian abnormality, such as a bicornuate uterus, could significantly increase the risk of pregnancy loss with its decreased capability of stretching and functional space.

History-indicated cervical cerclage should be performed if there are two or more histories of preterm labour or second-trimester pregnancy loss. Short cervical length combined with uterine anomalies has an exceptional high risk for preterm birth.

Take-home message

1. Mullerian abnormalities increase the risk of preterm labour due to impairment of normal uterine function, which could lead to funnelling and cervical dilation as pregnancy progresses relatively.

2. Screening for Mullerian abnormalities is important in cases of repeated preterm labour or second-trimester pregnancy loss; hence, the risk of preterm birth increases 13-fold in cases of uterine abnormality and short cervical length.

3. Cervical cerclage could be performed during pregnancy with Mullerian abnormalities such as unicornuates despite cervical length to prevent preterm labour and increase fetal survival rate.