Chorioamniotic membrane separation (CMS) comprises cases of spontaneous and iatrogenic detachment between the amniotic and chorionic membranes, with various fetal outcomes due to possible complications, particularly the formation of constrictive amniotic bands and preterm rupture of membranes. In the absence of mandatory management standards conservative monitoring is the most reported approach. In the case we present here, close sonographic surveillance afforded us the opportunity to observe the process from CMS to amnion rupture with the formation of constrictive amniotic bands and threatened cord impairment via constrictive margins of the amniotic sac. Despite the complicated background of reduced membranous layers in ruptured CMS, we performed a successful fetoscopic intervention with band release at 24 weeks’ gestation and the pregnancy was prolonged to 34 weeks under close monitoring.
Chorioamniotic membrane separation (CMS) may occur as a rare spontaneous event (1:3400)1,2 with possible association to fetal malformations or aneuploidy,3 but more often it appears as an iatrogenic complication from invasive intrauterine procedures such as amniocentesis, fetoscopy and open fetal surgery.2,4,5 In both spontaneous and postinterventional cases CMS may jeopardize pregnancy as it is a risk factor for premature rupture of membranes and preterm delivery, presumably due to the chorion’s reduced mechanical resistance.6 Mesodermic fibrous strings developed from a denuded chorion may lead to amniotic band syndrome (ABS) with significant morbidity and mortality.7 Clinical management guidelines for ABS have been suggested,8,9 while in isolated CMS close monitoring is the most reported strategy.10
We present a case of extensive CMS where membrane separation evolves into ABS with ruptured and collapsed amniotic sac and subsequent constriction of the fetal parts and cord. We successfully performed fetoscopic band release, which, to our knowledge, may be the first described in the setting of preoperative collapsed amniotic membranes.
A 35-year-old woman, gravida 2, para 0, was referred to our clinic at 17 weeks’ gestation for suspected CMS. Sonographically we found an appropriately growing fetus with a right-sided clubfoot, posterior placentation, normal amniotic fluid volume and complete CMS with the amniotic sac anchored at the placental cord insertion (Figure 1). The patient refused karyotyping for personal reasons. At 22 weeks, the amnion membrane appeared to be ruptured with the lower fetal limbs protruding into the extra-amniotic cavity (Figure 2). At 23 weeks, gross edema of the left arm distal to two circumferential constrictions (Figures 3a and b) was detected, followed by the right arm a few days later. Fetal movements were not restricted and Doppler ultrasound showed present blood flow in both arms distal to the constriction. Because of threatened amputation and cord complication we referred the patient to the German Center for Fetal Surgery & Minimally Invasive Therapy (DZFT), Giessen University Hospital, Germany, to consider fetoscopic intervention. After counseling the risk of premature rupture of membranes and preterm birth we obtained informed consent for fetoscopy. After a course of betamethasone (2 × 12 mg), at 24 weeks, we performed percutaneous fetoscopy via two trocars (external diameter 5 mm). All parts of the amniotic sac encircling the insertion of umbilical cord and constricting the fetal occiput, neck and right upper arm were released (Figure 3c) using endoscopic micro-scissors. We noted several indentations on the left upper arm but no amniotic bands or residuals. Operative time was 70 min. The patient stayed hospitalized for routine prophylactic tocolysis (Atosiban for 48 h) and intravenous antibiotics (Gentamicin and Clindamycin), sonographic monitoring, fetal non-stress test and close surveillance of chorioamnionitis or amniotic leakage. At 34 weeks, cesarian section was performed due to spontaneous labor. On the neonate’s right arm, there was no indentation after fetoscopic band release. The left arm showed five circumferential imprints without band residuals (Figure 3d) but subsequent slight elbow flexion and finger extension deficit with intermittent clawhand. The right foot was clubbed with no other abnormalities. The premature neonate was hospitalized for 3 weeks with an uneventful course. Following physiotherapeutic exercises at 9 months the baby showed normal neurologic development, apart from a minor and decreasing neurologic deficit of the left hand.
The severity of CMS we report here contrasts with previously described cases as membranous detachment affected the whole cavity and was complicated by amnion rupture with extraamniotic fetal parts and ABS. Despite detached and ruptured amniotic membranes and the additional iatrogenic injury, the chorion offered sufficient support and adherence to maintain pregnancy into the 34th week without amniotic leakage.
In CMS, clinical experience is limited to case reports and pathogenesis is not completely understood, but early leakage of amniotic fluid into the chorionic cavity is the most accepted view.7 The detached membranes may float,11 entrap the fetus, or rupture with fetal parts protruding into the extra-amniotic cavity. Fetal outcome varies from intrauterine fetal demise due to cord complications5,10 to otherwise uneventful pregnancies with mostly preterm delivery.2,4,5,9,11 Although there is a potentially lethal risk of cord strangulation that might be hard to predict by ultrasound,5 previous reports of complete CMS suggest expectant management.10 Amniocentesis is a feasible option for karyotyping and amnioninfusion;11 a detailed search for malformations is obligatory.
If amniotic band formation is detected, in well-defined cases9 fetoscopic release is the current preferred option.12 Despite a low rate of intraoperative bleeding complications, no maternal postoperative complications have been reported in the literature.9,13 Limb function preservation was reported in 50% of cases (7/14),13 with the majority of interventions performed by laser dissection (71%), and less frequently by endoscopic scissors (14%).13 Successful blunt dissection is reported in only one case of non-adhesive amniotic bands.14 Preterm premature rupture of membranes was reported in 57% of cases.13 In one case of fetoscopic band release, intraoperative partial amnion separation was described with post-interventional fetal loss, presumably due to postoperative collapsed and dissected amnion around the fetus and cord.9 In the case we report here neither intra- or postoperative complications nor premature rupture of membranes occurred in the 10 weeks following. Fetoscopic findings were concordant with our ultrasound findings, while others report intraoperative detection of further constrictions, particularly at the umbilical cord.15 At our fetal surgery center it became policy to intervene by fetoscopy in any case of cord involvement. Limb constrictions are only treated if blood flow signals and muscle activity distal to the constriction are present. Supporting this policy, limb function was preserved after fetoscopic band release. Concordant to others15 and considering the potentially lethal complication of cord compromise, we believe that dissecting the membranous ring around the head and umbilical cord was the crucial preventive action.
The case we present here illustrates that fetoscopic intervention might be considered in selected cases despite complete detachment of the amniotic membrane and extra-amniotic pregnancy. This may aid in further definition of the benefits and limitations of fetoscopic intervention in similar cases and improve counseling. Further research in a large cohort is needed to concentrate clinical experience and to appreciate the clinical significance of CMS and ABS.
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The authors declare no conflict of interest.
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Schlehe, B., Elsässer, M., Bosselmann, S. et al. Complete chorioamniotic membrane separation with constrictive amniotic band sequence and partial extra-amniotic pregnancy: serial ultrasound documentation and successful fetoscopic intervention. J Perinatol 34, 941–944 (2014). https://doi.org/10.1038/jp.2014.159