Spontaneous partial chorioamniotic membrane separation followed by the formation of amniotic bands: a case report

Abstract

Background

Chorioamniotic membrane separation (CMS) is associated with various adverse pregnancy outcomes, including miscarriage, preterm labor, stillbirth, amniotic band syndrome, etc. Spontaneous CMS is extremely rare, especially followed by the formation of amniotic bands. At present, there is no standardized monitoring and treatment protocols for CMS.

Case presentation

We present an unusual case of spontaneous partial CMS with amniotic bands at 27⁺⁶weeks of gestation in a 34-year-old woman. About one month later, an emergency cesarean section was performed because of unavoidable preterm labor and fetal transverse presentation. The partial CMS with amniotic bands was confirmed by the examination for the placenta. There were no congenital anomalies for the infant. The infant received systemic treatment for 40 days for neonatal respiratory distress syndrome(NRDS). The infant underwent a 10 months of follow-up period and currently is in good health despite experiencing two respiratory infections.

Conclusions

Based on our experience and combined with previous research, we think that etiological screening is the primary priority for CMS cases. The management depends on the presence of fetal amniotic band syndrome (ABS), preterm labor, or PPROM, and it may be beneficial for neonatal prognosis that continuation of pregnancy under close ultrasonographic scans and prolonging gestational age as much as possible if none of these conditions exist.

Background

As we know, the fetal membranes consist of two distinct layers: the inner amniotic membrane and the outer chorionic membrane. These layers undergo separation before the 14th week of gestation, followed by fusion of the chorioamniotic membrane between the 14th and 16th weeks of gestation. Any separation occurring after the 16th week is considered abnormal and is known as chorioamniotic membrane separation (CMS) [1]. Prenatal ultrasonographic findings of CMS are classified as either partial or complete, with an incidence of 0.023 to 0.534% [2]. Intraamniotic surgery and fetal chromosomal aneuploidy are established etiologies of CMS [1, 2]. However, spontaneous CMS is extremely rare. Herein, we report a case of spontaneous partial CMS followed by the formation of amniotic bands, and no case has been reported before.

Case presentation

A 34-year-old multipara (gestation, 4; parity, 1; abortion, 2) who had one live birth through vaginal delivery seven years ago, conceived her current pregnancy naturally. Fetal nuchal translucency measurement was within normal ranges. Non-invasive prenatal testing indicated low risk, and amniocentesis was not performed during this pregnancy. At 23 weeks of gestation, an ultrasound examination at a local hospital revealed a partial CMS for the first time, with the fetus positioned above the separated amniotic membrane. Subsequent ultrasound at 27⁺⁶ weeks of gestation indicated the presence of banded echoes (the rupture of the separated amniotic membrane) in the central part of the uterine cavity, which divided the uterine cavity into upper and lower portions. The fetus was confined to the upper part of the cavity. Unfortunately, ultrasound images from local hospitals are not available.

At 31 weeks of gestation, the patient experienced irregular contractions and a slight vaginal fluid discharge. The patient was referred to West China Second Hospital, a maternal and child care center in west China. Immediate interventions included:

• Magnesium sulfate: 4 g was administered intravenously within 50 min to protect the fetal central nervous system.

• Dexamethasone: 6 mg every 12 h for a total of 4 doses was administered intramuscularly to promote fetal lung maturation.

• Ritodrine hydrochloride: Continuous intravenous infusion of 0.05 mg/min to inhibit uterine contractions.

The ultrasound examination (Fig. 1a, b,c) showed that the fetus was positioned transversely and that the chorioamniotic membrane had partially detached, the uterine cavity contained 2−3 banded echoes. Some of these echoes were in close proximity to the fetus, which was surrounded by reduced amniotic fluid. The fetus was predominantly situated above the banded echoes, while the amniotic fluid was primarily located below them. Furthermore, the umbilical cord was positioned in the pool of amniotic fluid beneath the banded echoes.

Fig. 1.

Longitudinal section images of ultrasound at 31 weeks’ gestation. These ultrasound images were made in West China Second Hospital. The amniotic bands (arrowhead in a, b,c) formed by ruptured amniotic membranes detached from the chorion (triangle in a, b,c), is close to the fetus (circle in a, b,c). The umbilical cord (star in b) enters the chorioamniotic cavity through the gap between the amniotic bands

At 31⁺⁵weeks of gestation, the patient experienced unavoidable preterm labor. An emergency cesarean section was performed because of a transverse presentation. We used a scalpel to cut the lower segment and decidua layer of the uterus, and used vascular forceps to puncture the fetal membrane (chorionic membrane), the assistant sucked up the amniotic fluid. We found that the umbilical cord passes through the space between the amniotic bands from the amniotic cavity into the chorioamniotic cavity. The fetus was in a transverse position, multiple bands (amniotic membrane) wrapped the back of the fetus, we cut part of the bands, inverted the fetus into the breech position, and delivered the fetus by gluteal traction. After the fetus was delivered, we performed neonatal initial resuscitation immediately. We assessed the neonatal to be in a wheezing breathing state with a Heart rate (HR) of 64 beats per minute, we used a T-piece resuscitator to deliver positive-pressure ventilation. After 30 s of effective positive-pressure ventilation, the neonatal HR was 80 beats per minute, then we performed endotracheal intubation for the neonate, and 240 mg of Poractant Alfa Injection was administered through the tube. The neonate, a male weighing 1,810 g, exhibited no congenital anomalies. Apgar scores at 1, 5, and 10 min were 6, 8, and 9, respectively. Subsequently, the neonate was transferred to the neonatal intensive care unit (NICU) due to NRDS. Placental examination (Fig. 2) showed 3 typical amniotic bands were separated from the chorionic membrane, the amniotic membrane was still fused with the chorionic membrane on the fetal side of the placenta, which indicated a partial CMS with the formation of amniotic bands. The placenta and membrane tissue were sent for pathological examination. Separated band-like connective tissue with epithelial degeneration was observed next to the placenta by pathologists, and evidence of intra-amniotic infection was not discovered (Fig. 3). The infant received systemic treatment for 40 days in the NICU for NRDS before being discharged. The mother was discharged without complications one week postoperatively. Over 10 months of follow-up period, the infant was hospitalized twice for severe pneumonia. No chromosomal abnormalities, genetic disorders, or inherited metabolic disorders were identified in the infant through relevant examinations. The infant’s growth and development progressed normally.

Fig. 2.

Clinical features of the patient. 3 typical amniotic bands (arrowhead) were shown in the photograph of the placenta, which were separated from the chorionic membrane (triangle). The chorionic membrane was still fused with the amniotic membrane on the fetal side of the placenta, so the patient was diagnosed with partial CMS

Fig. 3.

Histology of the placental and fetal membrane tissue. Separated band-like connective tissue with epithelial degeneration(arrowhead) was observed next to the placenta(triangle)

Discussion and conclusions

The occurrence of CMS, particularly in spontaneous cases, is relatively rare. Currently, no standardized approach for managing CMS is available. Although no established grading system exists for CMS, Corroenne et al. proposed a classification based on the extent of separation [3]. The classification was as follows: “mild” for amniotic membrane detachment of < 25%, “moderate” for 25%−50%, and “severe” for > 50%. However, the clinical utility of this criterion for determining pregnancy outcome and fetal prognosis remains unclear.

The primary cause of CMS is a medical complication resulting from invasive fetal procedures, including amniocentesis, pleurodesis, fetoscopy, or fetal surgery, which disrupt the fusion of the two membranes [4]. A study indicated that the occurrence of CMS following fetoscopy is approximately 40% [5]. The secondary cause is fetal chromosomal aneuploidy (trisomy 21, 13, and 18) or fetal connective tissue disorders (restrictive dermopathy), resulting in membrane insufficiency and incomplete chorioamniotic fusion [1]. Bromley et al. performed prenatal diagnosis through amniocentesis in ten patients with CMS and reported that three fetuses had Down syndrome [6]. Another study in 2017 identified distinct miRNA expression patterns in fetal membranes specific to tissues and regions. The miRNA expression, including miR-99a, miR-125b, and let-7c, was found to be downregulated in the fetal membranes of patients with trisomy 21. This downregulation potentially contributed to fetal membrane abnormalities associated with trisomy 21, including delayed separation of chorionic villi from the amniotic membrane or delayed fusion between chorionic villi and amniotic membrane [7]. Furthermore, a few cases have been associated with seromucinous collection resulting from chorionic hemangioma [8]. Joung et al. reported a case where post-cesarean section uterine scarring was proposed as a potential factor in spontaneous CMS [9]. Govaerts et al. suggested that endothelial rupture in preterm premature rupture of membranes (PPROM), resulting in amniotic fluid accumulation in the space between the chorionic and amniotic membranes, could be an etiology of CMS [1]. In a word, spontaneous CMS cases without a history of invasive procedures or fetal chromosomal abnormalities are significantly rare, and the precise mechanism remains unclear. In our case, we excluded a history of invasive fetal surgery, fetal chromosomal abnormalities, and other uncommon causes, the etiology of CMS was uncertain.

Previous studies indicated that CMS is associated with various adverse pregnancy outcomes, including miscarriage, preterm labor, fetal growth restriction, stillbirth, neonatal death, amniotic band syndrome, and umbilical cord complications [2, 6]. Fetal malformations can result from amniotic band syndrome and/or reduced amniotic fluid levels. Previously, a study revealed a significantly higher stillbirth rate in cases of CMS occurring before 24 weeks of gestation [10]. A study involving 118 instances of CMS reported that 53.1% (60/113) of deliveries resulted in preterm births, and 6.2% (7/113) in stillbirth. Furthermore, among 104 postpartum follow-up cases, neonatal deaths occurred in 5.8% (6/104) and infant deaths in 0.96% (1/104). The overall perinatal mortality rate (including intrauterine fetal deaths and neonatal deaths) was 11.0% (13/118) [11]. CMS has been associated with an increased risk of PPROM and preterm labor [10, 11]. This is due to the normal attachment of the chorionic membrane with the maternal decidua, which provides support to the amniotic membrane against physical pressures. This supportive function is lost when separation occurs, which can result in PPROM. Apart from physical factors, membrane separation can trigger preterm labor and premature rupture of membranes by releasing chemical mediators. In our case, the separated amniotic membrane ruptured, forming amniotic bands. The amniotic bands secured the fetus to the upper uterine region. Consequently, the amniotic fluid surrounding the fetus decreased. The fetus did not experience malformations of organs, fetal distress, or umbilical cord complications. However, the fetus was confined in a restricted environment with relatively insufficient amniotic fluid for nearly one month. This probably resulted in some impairment of fetal lung maturation, demonstrated by NRDS and pneumonia during infancy. PPROM and preterm labor inevitably occurred during hospitalization for observation.

There is a lack of standardized monitoring and treatment protocols for CMS. Vigilant monitoring throughout the pregnancy is essential, including regular ultrasound assessments to monitor fetal growth, amniotic fluid levels, ABS, and the potential for umbilical cord compression to evaluate fetal condition. Hospitalization for monitoring and treatment can reduce fetal mortality [2, 12]. As we know, ABS is a condition involving fetal entrapment in amniotic bands that causes a variety of deformations and deletions [13]. Invasive surgical intervention may be beneficial in improving neonatal outcomes by addressing the constriction caused by ABS. Schlehe et al. documented a case in which a patient with CMS underwent fetoscopic release of amniotic bands at 24 weeks of gestation, resulting in the extension of gestation to 34 weeks [14]. Although our case did not involve serious complications of amniotic band syndrome, it is important to investigate the feasibility of performing amniotic band release prior to PPROM to reduce the impact of amniotic band constriction and decreased amniotic fluid volume on fetal development.

In summary, our case demonstrates that CMS can occur without exact cause, but we recommend that chromosomal analysis should be performed to exclude fetal aneuploidy in cases of spontaneous CMS without a history of invasive fetal surgery. The management of CMS depends on the presence of fetal ABS, preterm labor, or PPROM, and it may be feasible that continuation of pregnancy under close ultrasonographic scans and prolonging gestational age as much as possible if none of these conditions exist, which is well illustrated by our case.

Abbreviations

CMS

Chorioamniotic Membrane Separation

NRDS

 Neonatal Respiratory Distress Syndrome

ABS

Amniotic band syndrome

HR

Heart Rate

NICU

 Neonatal Intensive Care Unit

PPROM

Preterm Premature Rupture Of Membranes

Authors’ contributions

SW and RZ contributed to the study conception and design. XT carried out the data collection. SW drafted the manuscript. RZ reviewed and edited the manuscript. All authors read and approved the final manuscript.

Funding

None.

Data availability

All data generated or analyzed during this study are included in this published article. The datasets used and/or analyzed during this study are available from the corresponding author on request.

Declarations

Ethics approval and consent to participate

The study was approved by the Ethics Committee of West China Second University Hospital. The informed consent of the patient involved in the article has been obtained. The study complied with the Declaration of Helsinki.

Consent for publication

The patient provided written informed consent for publication of this case report. Moreover, the manuscript does not involve any personal information.

Competing interests

The authors declare no competing interests.