N. E. Russell

Not all large neural tube defects have a poor prognosis: a case of prenatally diagnosed limited dorsal myeloschisis

Limited dorsal myeloschisis is a distinctive form of spinal dysraphism characterized by a focal midline neural tube defect associated with tethering of the dorsal spinal cord to the overlying skin1–4. Since prenatal diagnosis is rare, we stress in this letter the importance of distinguishing limited dorsal myeloschisis from myelomeningocele, as the two conditions have very different prognoses. We report on the case of a 22-year-old primigravida referred to our tertiary center at 35 weeks’ gestation when second-trimester ultrasound examination revealed bilateral ventriculomegaly and a large neural tube defect, suggestive of a large thoracic myelomeningocele. The presence of a large thoracic meningocele measuring 13 × 8 × 6 cm (volume, 325 cm3) with spinal cord tethering to the overlying skin was confirmed (Figure 1). There was also evidence of moderate bilateral ventriculomegaly (13 mm) and bilateral polydactyly of the feet. The cerebellum was displaced inferiorly without evidence of an Arnold Chiari malformation. These initial findings were suggestive of spina bifida. However, a three-dimensional (3D) computed tomography scan at 34 weeks’ gestation suggested the absence of spinal defect and when this was confirmed by fetal magnetic resonance imaging (MRI) at 35 weeks’ gestation, a limited dorsal myeloschisis was suspected. Elective Cesarean section was performed at 38 weeks’ gestation and a healthy male infant weighing 4760 g was delivered, with Apgar scores of 8, 9 and 10 at 1, 5 and 10 min, respectively. Postnatal examination confirmed a large dorsal midline fluid-filled mass at the level of T7−T12 covered by a thin layer of normal skin (Figure 2). The structure was easily transilluminated, without evidence of neural tissue within. No neurological deficits were found on neonatal examination. Postnatal MRI confirmed the diagnosis of limited dorsal myeloschisis. The infant underwent surgery on day 2 to remove the 680-g exophytic lesion and to release the tethered neural tissue (Figure 2). The postoperative course was uneventful and the infant was discharged 10 days later. Despite the markedly abnormal prenatal appearance of limited dorsal myeloschisis, with a large meningocele and a tethered fibroneural stalk, it is usually associated with a good prognosis1,5. However, it is important to look for associated anomalies, in particular ventriculomegaly and other subtle anomalies of the central nervous system that may negatively affect the prognosis. Children born with such a lesion usually have no neurological deficits Figure 1 Prenatal images in a case of limited dorsal myeloschisis. (a) Magnetic resonance imaging at 35 weeks’ gestation: sagittal image of a large cystic area at midthoracic level. (b) Threedimensional (3D) computed tomography at 34 weeks’ gestation showing an intact spinal column. (c) 3D ultrasound image at 35 weeks’ gestation showing spinal cord tethering.

OP01.01: Second trimester growth restriction and underlying fetal anomalies

Objectives: To determine the incidence of chromosomal abnormalities, syndromic association and fetal defects in second trimester fetal growth restriction (FGR) in a tertiary referral center for prenatal diagnosis. Methods: Retrospective review of all cases referred between 14 and 27 weeks with an abdominal circumference (AC) < 5th centile between 2008 and 2012. The presence of aneuploidy and associated malformations was also assessed. Multiple pregnancies were excluded. Results: A total of 8626 fetuses had ultrasonographic examination between 14 and 27 weeks. Of these, there were 239 cases (2.8%) with evidence of FGR. Thirty-seven fetuses had an abnormal karyotype or an identified syndromic association (15%), 67 had at least one morphological abnormality without aneuploidy or syndromic association (28%), 135 cases were isolated fetal growth retardation (57%). The most common chromosomal defect was Trisomy 18. Most common morphological abnormalities were relative short femur (5%), omphalocele (5%) and gastroschisis (4%). The Maternal age was higher (33 yr ± 5 yr versus 31 yr ± 5, 6 yr, P = 0.007) and the z-score for the AC lower (2.5 ± 1 versus 2.15 ± 0.6) in the group with abnormal karyotype or syndromic association than in the group without malformation. Amniotic fluid was more often increased in the group with an abnormal karyotype or associated malformation (14% and 17%) than in the group without malformations (0%, P = 0.0003 and 0.0001). Conclusions: This study describes abnormalities and outcomes associated with second trimester fetal growth retardation in a large population of patients referred for that purpose. Our results suggest that the degree of growth restriction, maternal age and the amniotic fluid index may help in the prenatal management and counseling of this high risk population.

P33.04: Importance of antenatal MRI in the diagnosis of curarrino syndrome in a familial case

in several of the ‘‘cysts’’. MRI at 23 wks confirmed normal fetus and placenta with thick, high-signal myometrium and abnormal blood pooling on GRE sequences. The diagnoses of molar twin and triploidy were dismissed. In a case reported by Uotila et al. (massive multicystic dilatation of the uterine wall with myometrial venous thrombosis) maternal anemia, marked uterine enlargement, and abdominal discomfort occurred necessitating Cesarean delivery at 30 wks complicated by > 3L blood loss. Our patient was counseled re the risk of similar complications. She was managed conservatively and, although the uterus was abnormally large, she was not anemic or otherwise symptomatic. Spontaneous labor at 39 weeks resulted in vaginal delivery with manual extraction of the placenta for delayed third stage. There was no postpartum hemorrhage. Placental pathology was normal. Although the US and MR appearances are almost identical to Uotila’s case, our patient had a benign course and a NSVD. It is important to differentiate this appearance from GTN as an excellent pregnancy outcome is possible. Careful clinical and ultrasound surveillance is a reasonable management strategy.

P19.16: Not all large neural tube defects have a poor prognosis: a case report of prenatally diagnosed limited dorsal myeloschisis

Submission of an uncommon fetal condition, which is not usually diagnosed before birth, with good postnatal development. We report clinical data, most representative ultrasound images and a review of recent literature. 27 year old patient. Previous Cesarean delivery for non-progression of labor. In the current pregnancy 1/111 risk for trisomy 21, in the first trimester combined screening. The result of the amniocentesis was normal 46 XY karyotype. On 16 th week an urethral dilation and penile deformation was observed. On 20th week ultrasound we objective left curved penis with urethral dilation. Bladder wall thickening. Bilateral ureteral dilatation and mild pyelic ectasia. Ultrasound findings remain unchanged for the rest of gestation, mild pyelic ectasia and normal amniotic fluid. We observed corpus cavernosum development (scaphoid megalourethra). There was no hipospadias evidence. Testes in the scrotum. Good postnatal development with normal renal function. Currently awaiting surgical correction of penile deformity. Congenital megalourethra is a rare malformation characterized by dilation of the penile urethra. Its diagnosis is usually postnatal. It is characterized by hypoplasia of the corpus spongiosum and occasionally hypoplasia of the corpus cavernosum (megalourethra fusiform). It could be associated with upper urinary tract defects, VACTERL sequence, oligohydramnios with lung hypoplasia and abdominal wall defects. Prognosis is fairly good if normal renal function.

P07.01: Patient's perception of first trimester risk assessment for Down syndrome: what is a “high risk” for you?

Objectives: The purpose of this study was to evaluate first trimester biochemical screening benefit with and without adding NT in enlarged measurements on screening performances. Methods: Nine thousands five hundreds and twenty-three patients underwent first trimester screening performing NT measurement and first trimester serum screening. Clinical management was decided on the basis of NT/biochemistry risk calculation. Retrospectively enlarged NT were evaluated and risk calculation was evaluated with and without NT measurements when above 2.0 MoM. Results: One hundred and seven fetuses presented at 11–14 weeks’ gestation NT measurement above 2.0 MoM. 87 presented positive ultrasound-biochemical screening whilst only 21 had a positive risk calculation using only PAPP-A and free beta hCG. 24 patients were lost at follow-up. The whole population with adverse obstetric outcome (27 patients) where within the 87 with combined screen positive (Detection rate 100%; 87–100% CI 95%), while only nine were detected by biochemical screen (Detection rate 33%; 17–54% CI 95%). Seven cases of trisomy 21 were identified by combined screen (Detection rate 100%; 59–100% CI 95%) and only five by biochemistry alone (detection rate 71%; 29–96% CI 95%). Conclusions: NT measurements above 2.0 MoM increase significantly the risk from biochemistry having 4 times positive screen patients. Whilst an increase of OAPR, the detection rate is reduced significantly not considering NT measurements above 2.0 MoM. Larger population is needed in order to confirm our population result and screening policy.

OC22.05: Cervical length in early pregnancy and spontaneous preterm delivery in twin pregnancies

Objectives: Monochorionic (MC) twins are at increased risk of fetal loss in early pregnancy as a consequence vascular complications such as twin-twin transfusion syndrome (TTTS). Previous small studies estimated that the cumulative MC loss rate was > 12% by 24 weeks’ gestation in an era prior to routine fetoscopic laser treatment for TTTS. The aim of this study is to compare fetal loss rates between MC and dichorionic (DC) twins in an era of invasive treatment of TTTS. Methods: A retrospective study of all twin pregnancy births of known chorionicity from a large regional cohort of 9 hospitals over a ten year period. Ultrasound data was matched to hospital delivery records and a mandatory national register for perinatal losses (CMACE). Cumulative fetal and perinatal loss rates for MC and DC twins from 14 to 26 weeks gestation were analysed using Kaplan-Meier survival curves to assess the difference in mortality between MC and DC twins. Results: 3133 twin pregnancies (599 MC and 2534 DC) were included in the analysis. The total fetal loss rate in MC and DC twins were 6.3% (75/1198) and 0.9% (44/5068), respectively (OR 0.14, 95% CI 0.09 to 0.20). The cumulative rate of loss in MC twins rose significantly from 0.5% at 14 weeks’ gestation up to a plateau of 6.3% at 24–26 weeks’ gestation, whereas there was no significant change in DC pregnancy loss rate (0.5%) over this period. Kaplan Meier curves for MC and DC twins were statistically different (log-rank test < 0.05). Conclusions: Early perinatal loss rates before 26 weeks are significantly higher in MC compared to DC twins. Cumulative fetal loss rate before 26 weeks’ gestation in MC twins has almost halved compared to the rates available in the published literature a decade ago. Early detection and prompt treatment of complications in MC twins is likely to have contributed to this improvement in twin pregnancy outcomes.

OC22.08: Brain lesions diagnosed prenatally following laser coagulation for twin‐twin transfusion syndrome

Objectives: (i) To describe the types of fetal brain lesions developing following fetoscopic laser ablation of communicating vessels in twintwin transfusion syndrome (TTS) and (ii) to analyse the lesions based on gestational age at diagnosis of TTS and at surgery to understand further the underlying pathophysiology. Methods: Retrospective study of all cases of laser ablation for TTTS performed between January 1999 and March 2012. The cases were retrieved via interrogation of ASTRAIA database. The fetoscopy was performed within 48 hours of diagnosis of TTTS. Weekly surveillance was implemented up until delivery. In addition fetal MRI was routinely performed at 32 weeks in all cases unless lesions were suspected on ultrasound earlier. Results: 948 laser ablations were performed. Of these, 27 (3%) were followed by the development of brain lesions. Eight different types of lesions were observed, including: ischemic (1), hemorrhagic (8), ventriculomegaly (7), white matter calcifications (1), schizencephaly (5), atrophy (4), periventricular leukomalacia (1), massive dysgenesis (1). In 7 cases (25.9%) the cerebral lesions were visible within two weeks of the fetoscopy. 4 cases (14.8%), were only diagnosed by MRI. The recipient was more likely to be affected than the donor twin. Conclusions: Brain lesions developed in 3% compared to 10–20% reported in the literature. One quarter were visible within two weeks of the procedure. Underlying pathophysioogyl include prematurity, growth restriction, anaemia and hemodynamic imbalance. The multiple contributing factors may explain the diversity of these lesions.

OC22.06: Discordant anomalies in monochorionic twins

Methods: Retrospective cohort of 453 twin pregnancies in two tertiary centers over an 11-year period. All women had serial ultrasound assessment of CL from 11–13+6 weeks through to 14–15+6, 16–17+6, 18–19+6 and 20–21+6 weeks as part of routine antenatal care. A total of 720 serial CL measurements were recorded. Monochorionic twin pregnancies complicated with twin to twin transfusion syndrome and monoamniotic pregnancies were excluded. We estimated the association between cervical length at each of the five study periods and preterm delivery before 28, 32 and 34 weeks’ respectively. Results: The cumulative incidence of preterm delivery was 6.8%, 13.2% and 26.1% before 28, 32 and 34 weeks’ respectively. A CL below 50 mm at 11–13+6 weeks was associated with preterm delivery before 28 weeks (RR = 1.63, 95% CI = 1.21–2.18, P 45 mm for delivery before 28 (LR− 0.33) and 34 weeks (LR− 0.29) respectively. CL 50 mm at this gestation reflects a low likelihood of preterm delivery.

P23.05: Fetal cardiac function in normal monochorionic twin pregnancy

Methods: Data on 209 twin pregnancies and 418 neonates who were delivered in the tertiary center between 2003 and 2009 were retrospectively reviewed. Perinatal and neonatal outcomes were compared between twins from monochorionic and dichorionic pregnancies. Results: We were able to establish chorionicity in 148 out of 209 twin pregnancies, and only these have been recruited in this study. Monochorionic pregnancies (n = 56; 38%) in comparison with dichorionic (n = 92; 62%) were related to a higher risk of preterm birth (both between 33–36 hbd and below 33 hbd; P < 0.01), low and very low birth weight (P = 0.012), Apgar scores between 1–4 (P = 0.029). Monochorionic twins were more often admitted to neonatal intensive care unit (58% vs. 41%; P = 0.006) and had a higher incidence of intraventricular hemorrhage (39% vs. 20%; P < 0.001), anemia (31% vs. 14%; P < 0.001), sepsis (10% vs. 2%; P < 0.001) and metabolic complications (14% vs. 7.6%; P < 0.02). Both groups did not differ in the rate of neonatal death (7.1% vs. 4.3%, NS) and neonatal pneumonia (35% vs. 26%, NS). Exclusion of 10 (18%) pairs of twins with TTTS did not affect the results. Conclusions: Monochorionicity is a risk factor in twin pregnancy. It is associated with a higher risk of prematurity, worse neonatal condition at birth and during the first month of life and longer hospitalization but it is not related to a higher neonatal mortality.

OP16.08: Periventricular nodular heterotopia (PNH): an antenatal ultrasound and MRI analysis of associated abnormalities

B. Deloison1,2, P. Sonigo3, A. Millischer3, N. Bahi-Buisson4, G. E. Chalouhi1,2, N. E. Russell1, F. Brunelle3, N. Boddaert4, Y. Ville1,2, L. J. Salomon1,2 1Obstetrics and Gynecology, University Paris Descartes, Sorbonne Paris Cite, Assistance Publique-Hopitaux de Paris, Hopital Necker-Enfants Malades, Paris, France; 2SFAPE Societe Francaise pour l’Amelioration des Pratiques Echographiques, Paris, France; 3Pediatric Radiology, University Paris Descartes, Sorbonne Paris Cite, Assistance Publique-Hopitaux de Paris, Hopital Necker-Enfants Malades, Paris, France; 4Pediatric Neurology, University Paris Descartes, Sorbonne Paris Cite, Assistance Publique-Hopitaux de Paris, Hopital Necker-Enfants Malades, Paris, France