Spontaneous chorioamniotic membrane separation discovered by preterm prelabor rupture of membranes

Key Clinical Message

Chorioamniotic membrane separation (CMS) is a rare finding in ultrasound examination during pregnancy. It is mostly seen as a complication after invasive prenatal procedures but also can present spontaneously. Extensive CMS is found to be associated with adverse perinatal fetal outcomes.

1. INTRODUCTION

During embryologic development, the chorionic and amniotic membranes arise from different germ layers. Sonographic identification of the two separate membranes is a normal physiological finding before 14 weeks of gestation as the fusion of these membranes usually occurs between 14 and 16 weeks of gestation.1, 2

In complete chorioamniotic membrane separation (CMS), the chorionic and amniotic membranes are completely separated from each other, except at the insertion of the umbilical cord into the placenta.2

Chorioamniotic membrane separation is mostly seen as a complication after invasive prenatal procedures. We present a case with spontaneous partial chorioamniotic membrane separation, which is far more rare. Another cause of CMS is chromosomal abnormalities which presents in lack or delayed fusion of the membranes. Extensive CMS is found to be associated with adverse perinatal fetal outcomes.1, 2, 3, 4, 5, 6

2. CASE PRESENTATION

A healthy 29‐year‐old woman, gravida 2 para 1, arrived at the emergency room with a story of fluid loss at 17 weeks and 1 day of gestation. She had a large amount of fluid loss during the night and when going to the toilet. The patient had already been hospitalized during this pregnancy at 13 weeks and 6 days of gestation for hyperemesis gravidarum. There was no history of amniocentesis or abdominal trauma during this pregnancy.

The previous pregnancy was uneventful resulting in an uncomplicated spontaneous delivery at 37 weeks of gestation, 3 years before this pregnancy. Apart from an allergy against metoclopramide with a history of angioedema, her personal, and family history was unremarkable.

2.1. Investigations

On vaginal examination, no manifest fluid loss was detected, not even while performing a Valsalva maneuver. A rapid test for detecting amniorrhexis (Actim PROM test™) was taken, which did not demonstrate signs of preterm prelabor rupture of the membranes (PPROM). Ultrasound showed a single living fetus with a normal biometry and anatomy. There was a normal amount of fluid around the fetus but there was also amniotic fluid between the membranes, which is abnormal at this gestational age. Because the imaging did not look like an amniotic band and the fetus did not show signs of malformation, the diagnosis of spontaneous CMS was made. The Actim PROM test™, taking the history into account, was protocolled as possibly false negative. We took culture swabs to detect infections as possible cause. Keeping the gestational age in consideration, we had a conservative policy, as dictated by our PPROM protocol.

The patient was admitted to the hospital for observation. During hospitalization, no further fluid loss was noticed. Regular ultrasound examinations were performed (Figure 1A‐D). The amniotic fluid in the amniotic sac was increased, the largest pocket was 58mm, and the fluid between the membranes stayed the same. No evidence of band formation was noticed. Our patient was discharged after 3 days of observation and left the hospital with an intact pregnancy.

Figure 1.

(A‐D), Ultrasound imaging, made at the first hospital admission, shows a normal amount of fluid around the fetus but there is also amniotic fluid between the membranes. The space between the membranes is marked with an asterisk. The diagnosis of spontaneous chorioamniotic membrane separation is made

A couple of days later our patient again had amniotic fluid loss at 18 weeks and 1 day of gestation. This time, the Actim PROM test™ was positive. There was no fever, abdominal pain, or blood loss. The results of the cultures were only positive for Streptococcus agalactia. There was no presence of infections that could explain the spontaneous CMS. During this hospitalization, the fluid loss persisted and ultrasound examination showed oligohydramnion.

2.2. Treatment

The couple was counseled about the high risk of complication due to the oligohydramnion and stillbirth because of the early gestational age. Taking this information into account, they decided to terminate the pregnancy. This was performed by administration of mifepristone and misoprostol resulting in the expulsion of a dead male fetus. Due to retained placenta and hemorrhage manual removal of the placenta was performed. Control ultrasound showed an empty cavity afterward, and good contraction of the uterus was obtained. The patient needed two units of packed cells for anemia (hemoglobin 4.6 mmol/L). She was dismissed 1 day after the expulsion.

Examination of the placenta showed a separation of the chorion and amniotic membranes (Figure 2A‐C). A microbiologic culture of the placenta was taken, and the placenta was sent to pathology for further examination. Pathology showed a premature placenta without anomalies and no bacteria were cultured.

Figure 2.

(A‐C), The placenta showed no abnormalities. Only a separation of the chorion and amniotic membranes could be detected, which is marked with an asterisk

The parents did not want any genetic testing or autopsy on the fetus, so these examinations were not performed.

2.3. Outcome and follow‐up

Six weeks after the expulsion a completely normal examination showed no complications of the termination of the pregnancy. The patient became pregnant again after 3 months. This pregnancy was uneventful. A healthy male with a birth weight of 3355 g was born after a spontaneous vaginal delivery. There were no postpartum complications.

3. DISCUSSION

During embryologic development, the chorionic and amniotic membranes arise from different germ layers. Sonographic identification of the two separate membranes is a normal physiological finding before 14 weeks of gestation as the fusion of these membrane usually occurs between 14 and 16 weeks of gestation.1, 2

Chorioamniotic membrane separation is classified by the degree of separation. In partial CMS the separation is only found at one site, in contrast with a complete CMS which is an complete detachment of the membranes with exception of the insertion site of the umbilical cord into the placenta.2, 5

Review of the literature shows that CMS can happen for three reasons. The first reason is a lack of or an incomplete chorion‐amnion fusion due to chromosomal disorders, mostly aneuploidy (eg, trisomy 21, 13 and 18, or fetal connective tissue disorders [eg, restrictive dermopathy]).1, 7, 8 The other two reasons are a detachment of the already fused membranes, either iatrogenic or spontaneous. Most of the cases of CMS are the result of invasive fetal procedures such as amniocentesis, cordocentesis or fetal surgery.2, 3, 4, 5, 6 Depending on the type of intervention, complete CMS can develop during the second and third trimester. Spontaneous complete CMS is extremely rare. In these cases, no cause can be identified yet. Further reporting and examination of these cases is needed. Joung et al. described in 2016 a uterine scar as a possible cause of a spontaneous CMS after a cesarean section in the history of their patient.8 In their case, the CMS was diagnosed at 21 weeks and 5 days of gestation. The baby was born at a gestational age of 27 weeks and 4 days with an emergency cesarean section after admission of bethamethasone for fetal lung maturation and magnesium sulfate as tocolytics 1 week before. The reason of the cesarean section was minimal variability of heart rate and recurrent variable deceleration.

Our case showed PPROM as possible cause of CMS. We suggest that rupture of the inner membrane with accumulation of amniotic fluid between the membranes can be an explanation of some cases of CMS.

Review of literature shows a lot of possible adverse effects following complete CMS such as miscarriage, in utero fetal death, neonatal death, amniotic band syndrome, umbilical cord complications, and preterm delivery. Fetal malformations can be caused by either amniotic band syndrome and/or oligohydramnion.1, 2, 3, 5 Although there also cases who describe good outcome with live births after complete CMS.8, 9

In our case, the partial CMS was diagnosed after a history of fluid loss at 17 weeks and 1 day of gestation. PPROM was diagnosed at 18 weeks and 1 day of gestation. We suspect that the first test was falsely negative. This can be explained by a sensitivity of 89% of the Actim PROM test™, which implies that 11% of amniorrhexis can be missed using this test.10

A recent published case report by Bibbo et al. showed that CMS is significantly associated with a higher rate of preterm delivery. Furthermore, they concluded that CMS before 24 weeks show a significantly higher rate of stillbirth.11 This information was used to counsel our patient and her husband. Taking this into account, they decided to terminate the pregnancy.

4. CONCLUSION

Spontaneous chorioamniotic membrane separation is extremely rare. It can happen for three reasons. The first reason is a lack of or an incomplete chorion‐amnion fusion due to chromosomal disorders or fetal connective tissue disorders. The other two reasons are a detachment of the already fused membranes, either iatrogenic or spontaneous. CMS has a lot of possible adverse effects.

Therefore, further reporting and examination of cases need to be published to discover the cause of this pregnancy complication. The following step will be to find possible interventions to keep the adverse outcome as minimal as possible.

CONFLICT OF INTEREST

None declared.

AUTHOR CONTRIBUTION

JG: Substantial contributed the conception and designed the work; the acquisition and analyzed the work, drafted the work critically for important intellectual content, finally approved the version to be published, and agreed to be accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. PC: Substantial contributed to acquisition, analysis, and interpretation for the work, revised the work critically for important intellectual content, finally approved the version to be published, and agreed to be accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. YJ: Substantial contributed to acquisition, analysis, and interpretation for the work, revised the work critically for important intellectual content, finally approved the version to be published, and agreed to be accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.

Govaerts J, Cryns P, Jacquemyn Y. Spontaneous chorioamniotic membrane separation discovered by preterm prelabor rupture of membranes. Clin Case Rep. 2019;7:762–765. 10.1002/ccr3.2083