Y Abdallah

Publications (27)80.65 Total impact

• Article: Does the presence of a Caesarean section scar affect implantation site and early pregnancy outcome in women attending an early pregnancy assessment unit?

  O Naji, L Wynants, A Smith, Y Abdallah, S Saso, C Stalder, S Van Huffel, S Ghaem-Maghami, B Van Calster, D Timmerman, T Bourne
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  ABSTRACT: STUDY QUESTION: Are there any differences in the location and distance to the internal cervical ostium of the implantation site of the intrauterine gestation sacs, early pregnancy symptoms and pregnancy outcome at 12 weeks gestation between women with and without a previous Caesarean section (CS)? SUMMARY ANSWER: The presence of a CS scar affects the site of implantation, and the distance between implantation site and the scar is related to the risk of spontaneous abortion. WHAT IS KNOWN ALREADY?: Little is known about the impact of a CS scar on implantation other than the risk of Caesarean scar pregnancy (CSP). Furthermore, there is a paucity of information on how the proximity of implantation to the scar impacts on pregnancy outcome in the first trimester. STUDY DESIGN, SIZE, AND DURATION: A prospective cohort study conducted over 15 months in the early pregnancy unit of a London Teaching Hospital. Three hundred and eighty women underwent a transvaginal scan at 6-11 weeks of gestation. A total of 170 women had undergone ≥1 CS, and 210 women had no history of CS. PARTICIPANTS/MATERIALS, SETTING, METHODS: The 380 women were recruited as consecutive non-selected cases. The relationship between the implanted sac and the CS scar was assessed by quantifiable measures and by subjective impression. Logistic regression analysis was used to determine the influence of the presence of a CS scar on pregnancy outcome. The final outcome of the study was the viability of the pregnancy at 12 weeks. MAIN RESULTS AND THE ROLE OF CHANCE: Implantation was most frequently posterior (53%) in the CS group and fundal in the non-CS group (42%). Gestation sac implantation was 8.7 mm lower in the CS group (95% confidence interval (CI) 6.7-10.7, P < 0.0001). Presenting complaints differed in women with and without a previous CS (P = 0.0009). More frequent vaginal bleeding [73 versus 55%, difference -18, 95% CI (-27 to -8%] yet no clearly increased spontaneous abortion rates were noted in the CS group compared with the non-CS group (adjusted odds ratio = 1.1, 95% CI 0.6-1.9, P = 0.74). Subjective impression showed that in eight cases the implantation site crossed the scar, seven of which resulted in spontaneous abortion, while the remaining case survived to term complicated by placenta praevia and post-partum haemorrhage. The subjective impression of the examiner was supported by the measurements of distance between implantation site and CS scar. LIMITATIONS, REASONS FOR CAUTION: A weakness of the study is the lack of a reference technique to verify the location of implantation. WIDER IMPLICATIONS OF THE FINDINGS: This study adds further support to the hypothesis that the presence of a CS on the uterus impacts on the implantation site of a future pregnancy. The possibility that the CS scar has an impact on the risk of spontaneous abortion should be further studied. Caution must be exercised when implantation occurs near to, and crosses, a CS scar as this is not always associated with the diagnosis of CSP. A potential limitation of the study is that we did not examine scar dimensions and morphology. STUDY FUNDING/COMPETING INTEREST(S): The authors have no competing interests to declare. The study was not supported by an external grant.
  Human Reproduction 04/2013; · 4.47 Impact Factor
• Article: The influence of weight gain patterns in pregnancy on fetal growth using cluster analysis in an obese and non-obese population.

  S Galjaard, A Pexsters, R Devlieger, I Guelinckx, Y Abdallah, C Lewis, B Van Calster, T Bourne, D Timmerman, J Luts
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  ABSTRACT: OBJECTIVE: Excessive weight gain during pregnancy has an important influence on fetal growth and on weight development in future generations. DESIGN AND METHODS: We performed a prospective cohort study of 325 obese and non-obese Caucasian women with naturally conceived, singleton pregnancies. They were followed up until delivery for maternal weight gain and for fetal growth with ultrasound based weight estimations and final birth weight. Using cluster analysis distinct profiles of maternal weight gain during pregnancy were obtained. Longitudinal regression analysis was performed to investigate the relationship of the maternal weight gain profile and body mass index (BMI) on fetal growth and final birth weight. RESULTS: Cluster analysis revealed four discernable maternal weight gain profiles: twelve cases (3.7%) ended up at their starting weight or decreased in weight (cluster 1), 16 cases (4.9%) that slightly increased in weight (maximum 4 kg) as compared to their initial weight (cluster 2), 114 cases (35.1%) that gained between 4 and 12 kg in weight (cluster 3) and 183 cases (56.3%) that showed the largest weight gain: more than 12 kg (cluster 4). There were statistically significant differences in fetal growth associated with weight gain cluster which became apparent late in the second trimester and increased towards the end of pregnancy. Maternal BMI and maternal weight gain profile were independent predictors of fetal growth and birth weight. CONCLUSIONS: Therefore we conclude that cluster analysis permits to discern four gestational weight gain patterns in obese and non-obese subjects and that both maternal BMI and maternal weight gain pattern during pregnancy positively influence fetal growth and birth weight.
  Obesity 02/2013; · 4.28 Impact Factor
• Article: Predicting successful vaginal birth after cesarean section using a model based on cesarean scar features examined using transvaginal sonography.

  O Naji, L Wynants, A Smith, Y Abdallah, C Stalder, A Sayasneh, A McIndoe, S Ghaem-Maghami, S Van Huffel, B Van Calster, D Timmerman, T Bourne
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  ABSTRACT: OBJECTIVES: To develop a model to predict the likelihood of vaginal birth after cesarean section (VBAC) based on measurements of cesarean section scar features using ultrasound, demographic variables and previous obstetric history. METHODS: We used transvaginal sonography (TVS) to examine the cesarean scar of 320 consecutive pregnant women. TVS was carried out at 11-13, 19-21 and 34-36 weeks gestation, and prospective measurements of the scar were recorded at each visit according to a defined protocol. A logistic regression model to predict successful VBAC was developed for patients with a visible scar and only one previous CS. The model was evaluated with bootstrap validation. RESULTS: One hundred and thirty-one women with one previous CS were included in the study. Ten women had a CS carried out prior to labor and were excluded. Successful VBAC was achieved in 74/121 of remaining cases (61%). The prediction model was based on patients' age, previous history of VBAC, residual myometrial thickness (RMT) and the change in RMT between the first and second trimester. The internally validated area under the receiver-operating characteristic curve (AUC) was 0.62 when measurement of RMT and Δ RMT were excluded, but 0.94 when scar information was incorporated into the model. CONCLUSION: Ultrasound measurements of the CS scar expressed as RMT and the change in RMT between the first and the second trimester of pregnancy, when incorporated into a mathematical model, can accurately predict a successful trial of labor in patients with one previous CS.
  Ultrasound in Obstetrics and Gynecology 02/2013; · 3.01 Impact Factor
• Article: Rationalizing the management of pregnancies of unknown location: temporal and external validation of a risk prediction model on 1962 pregnancies.

  B Van Calster, Y Abdallah, S Guha, E Kirk, K Van Hoorde, G Condous, J Preisler, W Hoo, C Stalder, C Bottomley, D Timmerman, T Bourne
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  ABSTRACT: STUDY QUESTION: Can we accurately define a group of pregnancies of unknown location (PULs) as low risk in order to safely reduce follow-up for these pregnancies and allocate resources to pregnancies at an increased risk of being ectopic? SUMMARY ANSWER: Prediction model M4 classified around 70% of PULs as low risk, of which around 97% were later characterized as failed PULs or intrauterine pregnancies (IUPs), while still classifying 88% of ectopic pregnancies as high risk. WHAT IS KNOWN ALREADY: Depending on the level of suspicion of ectopic pregnancy (EP), women with a PUL receive a lengthy follow-up in order to confirm the location and viability of the pregnancy. STUDY DESIGN, SIZE, DURATION: A multi-centre diagnostic accuracy study of 1962 patients was carried out between 2003 and 2007 for retrospective temporal validation and between 2009 and 2011 for prospective external validation. The reference standard is the final characterization of PUL as failed pregnancies or IUPs (low risk), or as ectopic pregnancies (high risk). M4 is a multinomial logistic regression model based on the serum human chorionic gonadotrophin (hCG) levels at presentation and 48 h later. PARTICIPANTS/MATERIALS, SETTING, METHODS: Temporal validation data from 1341 PULs collected at St George's Hospital in London were available, of which 53% were failed, 39% were intrauterine and 8% were ectopic pregnancies. External validation data from 621 PULs collected at four other London-based teaching hospitals were available, of which 63% were failed, 22% were intrauterine and 15% were ectopic pregnancies. MAIN RESULTS AND THE ROLE OF CHANCE: The EP rate varied between 8 and 16% across the five hospitals. At St George's, 980 [73.1%, 95% confidence interval (CI): 70.5-75.4] PULs were considered low risk. Of these, 963 were failed PULs or IUPs (98.3%, 95% CI: 97.2-98.9) and 17 were ectopic pregnancies. At the other four hospitals, 62-75% were considered low risk, with 96-98% of these turning out to be failed PUL or IUP. Eighty-five percent (95% CI: 76.8-90.2) of the ectopic pregnancies were considered high risk at St George's, compared with 80-92% in the other hospitals. LIMITATIONS, REASONS FOR CAUTION: Of total, 120 patients had been excluded due to loss to follow-up, and a further 102 patients because of missing hCG levels due to differences in local clinical practice. There are variations in the definition of a PUL used in different countries. WIDER IMPLICATIONS OF THE FINDINGS: The suggested protocol could safely reduce the follow-up in the majority of PUL such that units could increase the focus on women at a risk of complications. This would lead to a change in the management of the majority of women with a PUL and a more efficient use of resources. At the end of the manuscript, we provide a link to enable clinicians to use the protocol. STUDY FUNDING/COMPETING INTEREST(S): B.V.C. is supported by a postdoctoral fellowship from the Research Foundation Flanders (FWO). K.V.H. is supported by a fellowship from the Flanders' Agency for Innovation by Science and Technology (IWT-Vlaanderen), by the Research Council KU Leuven (GOA MaNet), by the Flemish Government (iMinds) and by the Belgian Federal Science Policy Office (IUAP P7/DYSCO). T.B. is supported by the Imperial Healthcare NHS Trust NIHR Biomedical Research Centre. No competing interests are declared.
  Human Reproduction 01/2013; · 4.47 Impact Factor
• Article: Changes seen in the ultrasound features of a presumed decidualised ovarian endometrioma mimicking malignancy.

  A Sayasneh, O Naji, Y Abdallah, C Stalder, T Bourne
  Journal of obstetrics and gynaecology: the journal of the Institute of Obstetrics and Gynaecology 11/2012; 32(8):807-11. · 0.43 Impact Factor
• Article: Changes in Cesarean section scar dimensions during pregnancy: a prospective longitudinal study.

  O Naji, A Daemen, A Smith, Y Abdallah, S Saso, C Stalder, A Sayasneh, A McIndoe, S Ghaem-Maghami, D Timmerman, T Bourne
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  ABSTRACT: Objectives: To describe the changes in cesarean section (CS) scars longitudinally throughout pregnancy, and relate initial scar measurements, demographic and obstetric variables to subsequent changes in scar features and the final pregnancy outcome. Methods: In this prospective observational study we used transvaginal sonography (TVS) to examine the CS scar of 320 consecutive pregnant women at 11-13, 19-21 and 32-34 weeks gestation. Visible scars consisted of hypoechoic shadow and residual myometrial thickness (RMT) segments. The hypoechoic segment was measured in three dimensions. Analyses were carried out using one-way repeated measures ANOVA and mixed modeling tests. The incidence of subsequent scar rupture was recorded. Results: The scar was visible in 284/320 cases (89%). For both scar segments, the larger the initial scar size, the more the scar decreased in size during pregnancy. For the hypoechoic segment, scar width on average increased by 1.8mm per trimester in 98% of cases, while scar depth and scar length decreased by 1.8 and 1.9mm in 97 and 99% of cases respectively (FDR p-value <0.0001>. The mean RMT segment was 3.6mm and on average decreased by 1.1mm in 98% of the cases. Two cases <0.62%> of uterine scar rupture were confirmed, these had a mean RMT of 0.5mm and average decrease in RMT of 2.6mm over the course of pregnancy. Conclusion: Our study establishes reference data and confirms that CS scars change in dimension throughout pregnancy. Scar rupture was associated with a smaller RMT and greater decrease in RMT during pregnancy. The absolute value and changes seen in CS scars have the potential to be tested as predictors of uterine scar rupture and performance in trials of VBAC. Copyright © 2012 ISUOG. Published by John Wiley & Sons, Ltd.
  Ultrasound in Obstetrics and Gynecology 10/2012; · 3.01 Impact Factor
• Article: A case of pregnancy following a modified Strassman procedure applied to treat a placental site trophoblastic tumour.

  S Saso, J Chatterjee, J Yazbek, Y Thum, Kw Keefe, Y Abdallah, O Naji, I Lindsay, Pm Savage, Mj Seckl, Jr Smith
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  ABSTRACT: Please cite this paper as: Saso S, Chatterjee J, Yazbek J, Thum Y, Keefe K, Abdallah Y, Naji O, Lindsay I, Savage P, Seckl M, Smith J. A case of pregnancy following a modified Strassman procedure applied to treat a placental site trophoblastic tumour. BJOG 2012; DOI: 10.1111/j.1471-0528.2012.03501.x.
  BJOG An International Journal of Obstetrics & Gynaecology 10/2012; · 3.41 Impact Factor
• Article: Impact of ovulation and implantation timing on first trimester crown-rump length and gestational age.

  Aa Mahendru, A Daemen, Tr Everett, Ib Wilkinson, Cm McEniery, Y Abdallah, D Timmerman, T Bourne, Cc Lees
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  ABSTRACT: Objective: Our aim was to determine the impact of ovulation and implantation timing on first trimester crown rump length (CRL) and the derived gestational age (GA). Method: 143 women trying to conceive were prospectively recruited. The timing of ovulation, implantation and ovulation to implantation (O-I) interval were established in 101 pregnancies using home urinary tests for luteinizing hormone (LH) and chorionic gonadotrophin (hCG). In 71 ongoing pregnancies, GA determined by fetal CRL at 10-14 weeks was compared to GA based on ovulation and implantation day. First trimester growth was determined by serial ultrasound scans. Main results: The median ovulation and implantation days were 16 and 27 respectively with O-I interval range of 11 days. GA estimated from CRL at 10-14 weeks was 1.3 days greater than that derived from ovulation timing. CRL z-score was inversely related to O-I interval (ρ = -0.431, P = 0.0009). There was no significant relationship between CRL growth rate and the difference between observed or expected GA (ρ = 0.224, P = 0.08). Conclusions: Early implantation led to a larger CRL and late implantation to a smaller CRL at 10-14 weeks independent of CRL growth rate. Implantation timing is a major determinant of fetal size at 10-14 weeks and largely explains the variation in GA in first trimester derived from embryonic or fetal CRL. Copyright © 2012 ISUOG. Published by John Wiley & Sons, Ltd.
  Ultrasound in Obstetrics and Gynecology 08/2012; · 3.01 Impact Factor
• Article: Do pocket-sized ultrasound machines have the potential to be used as a tool to triage patients in obstetrics and gynecology?

  A Sayasneh, J Preisler, A Smith, S Saso, O Naji, Y Abdallah, C Stalder, A Daemen, D Timmerman, T Bourne
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  ABSTRACT: To evaluate the performance and potential impact on patient management of a pocket-sized ultrasound machine (PUM) in comparison to high-specification ultrasound machines (HSUM). This was an observational cohort study with 204 unselected patients in three categories: 1) women with pain and bleeding in early pregnancy (101 patients); 2) women presenting for routine obstetric ultrasound assessment (53 patients); 3) women with possible gynecological pathology (50 patients). Scans were carried out transabdominally using a PUM. A second operator repeated the examination transvaginally and/or transabdominally, depending on the clinical indication, using an HSUM. The operators were blind to each other's findings. In the early pregnancy group, there was good to very good agreement between the PUM and HSUM for identifying the presence or absence of an embryo, gestational sac, fetal heart motion, pregnancy location and final diagnostic outcome (kappa coefficients, 0.844, 0.843, 0.729, 0.785 and 0.812, respectively; P < 0.0001). In the obstetric ultrasound group there was good to very good agreement for fetal presentation, placental location and placental position (kappa coefficients, 0.924, 0.924 and 0.647, respectively; P < 0.0001). In the gynecological pathology group, there was very good agreement for final diagnosis and type of ovarian mass (low risk or complex) (kappa coefficients, 0.846 and 0.930, respectively; P < 0.0001). For the measured continuous variables, there was close agreement for crown-rump length, mean sac diameter, femur length and mean diameter of an ovarian mass, but not for endometrial thickness. Neither patient demographics (age, body mass index, ethnicity) nor operator experience and familiarity with a PUM had an impact on agreement between the two machines. If a PUM had been the only equipment available for an initial assessment, only two cases would have led to a suboptimal patient management plan. The findings and final diagnosis in the three study groups were similar for both a PUM used transabdominally and an HSUM used transvaginally and/or transabdominally.
  Ultrasound in Obstetrics and Gynecology 05/2012; 40(2):145-50. · 3.01 Impact Factor
• Article: Reply.

  Y Abdallah, A Daemen, E Kirk, A Pexsters, O Naji, C Stalder, D Gould, S Ahmed, S Guha, S Syed, C Bottomley, D Timmerman, T Bourne
  Ultrasound in Obstetrics and Gynecology 03/2012; 39(3):364-5. · 3.01 Impact Factor
• Article: Reply.

  Y Abdallah, A Daemen, E Kirk, A Pexsters, O Naji, C Stalder, D Gould, S Ahmed, S Guha, S Syed, C Bottomley, D Timmerman, T Bourne
  Ultrasound in Obstetrics and Gynecology 03/2012; 39(3):362. · 3.01 Impact Factor
• Article: Does the presence of a Caesarean section scar influence the site of placental implantation and subsequent migration in future pregnancies: A prospective case-control study.

  O Naji, A Daemen, A Smith, Y Abdallah, E Bradburn, R Giggens, Dcy Chan, C Stalder, S Ghaem-Maghami, D Timmerman, T Bourne
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  ABSTRACT: OBJECTIVES: To describe placental location in the first trimester and subsequent placental migration in women with and without a history of previous Caesarean delivery. METHODS: In this prospective case-control study, placental location was defined according to 5 anatomical sites in relation to the endometrial cavity. Placental localisation was carried out by transabdominal ultrasound between 11 and 14 weeks gestation. We recruited 738 women who had undergone one or more previous Caesarean sections (CS) and 1856 patients without previous Caesarean delivery. Chi-square test was used to perform comparative analysis of placental location between the two groups, and to assess placental migration of those classified as being low-lying at 20 and 32 weeks gestation. RESULTS: There were significant differences in placental location between the two groups. In the Caesarean group there were significantly more posterior and fewer fundal placentas than in the control group, (47.2 vs. 31.5% and 4.7 vs. 15.5%, respectively). The number of previous Caesarean deliveries did not have a significant effect on placental location. The incidence of anterior low-lying placenta was greater in the Caesarean group than the control group (1.5% vs. 0.9%). Placental migration of the low-lying subtypes was similar in both groups (61% vs. 64%). CONCLUSION: The presence of a CS scar in the uterus is associated with an increase in the number of posterior placentas and a reduced number that implant in the fundus of the cavity. There is also an increase in the number of low-lying anterior placentas in the CS group. Migration of a low-lying placenta is independent of the presence of a Caesarean scar in the uterus. Copyright © 2012 ISUOG. Published by John Wiley & Sons, Ltd.
  Ultrasound in Obstetrics and Gynecology 02/2012; · 3.01 Impact Factor
• Article: The visibility and measurement of Caesarean section scars in pregnancy: an interobserver variability study.

  O Naji, A Daemen, A Smith, Y Abdallah, S Saso, C Stalder, A Sayasneh, A McIndoe, S Ghaem-Maghami, D Timmerman, T Bourne
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  ABSTRACT: OBJECTIVES: To evaluate the visibility of Caesarean section (CS) scars by Transvaginal Sonography (TVS) in the pregnant state, to apply agreed methods and nomenclature for measuring Caesarean scars and to test their reproducibility throughout the course of pregnancy. METHODS: In this observational cohort study, 320 consecutive pregnant women with a previous Caesarean delivery were examined to assess scar visibility by two independent examiners. TVS was carried out at 11-13, 19-21 and 34-36 weeks gestation. A scar was defined visible when a hypoechoic shadow representing myometrial discontinuity at the anterior wall of the lower uterine segment was identified. In a subset of patients (n = 111), visible scars were measured by two independent examiners in three dimensions: scar width, depth and length as well as the residual myometrial thickness (RMT). Descriptive analysis was used to assess scar visibility, and Intraclass Correlation Coefficient (ICC) was calculated to show the strength of absolute agreement between two examiners on scar measurements, using RMT cut-off of 2.4 mm by the Kappa Coefficient. RESULTS: The scar was visible in 284/320 cases (89%). Visible scars were significantly associated with anteverted uteri (p-value <0.0001). Both examiners had 100% agreement on scar visibility at 12 and 20 weeks gestation, while the agreement was 96% at 34 weeks. The intra and inter-observer agreement for scar measurements were generally good (ICC 0.86 and 0.89) respectively. The Kappa coefficient for the RMT was 0.26 in the first trimester, compared with 0.51 and 0.71 in the second and third trimester, respectively. CONCLUSION: CS scars remain visible in the majority of women throughout pregnancy. CS scars can be reproducibly measured in three dimensions when assessed by TVS in all phases of pregnancy. The agreement between two observers for CS scar measurements can be considered good in the second trimester, compared with moderate agreement in the first and third trimesters. Copyright © 2012 ISUOG. Published by John Wiley & Sons, Ltd.
  Ultrasound in Obstetrics and Gynecology 02/2012; · 3.01 Impact Factor
• Source

  Available from: Anneleen Daemen

  Article: Limitations of current definitions of miscarriage using mean gestational sac diameter and crown-rump length measurements: a multicenter observational study.

  Y Abdallah, A Daemen, E Kirk, A Pexsters, O Naji, C Stalder, D Gould, S Ahmed, S Guha, S Syed, C Bottomley, D Timmerman, T Bourne
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  ABSTRACT: There is significant variation in cut-off values for mean gestational sac diameter (MSD) and embryo crown-rump length (CRL) used to define miscarriage, values suggested in the literature ranging from 13 to 25 mm for MSD and from 3 to 8 mm for CRL. We aimed to define the false-positive rate (FPR) for the diagnosis of miscarriage associated with different CRL and MSD measurements with or without a yolk sac in a large study population of patients attending early pregnancy clinics. We also aimed to define cut-off values for CRL and MSD that, on the basis of a single measurement, can definitively diagnose a miscarriage and so exclude possible inadvertent termination of pregnancy. This was an observational cross-sectional study. Data were collected prospectively according to a predefined protocol. Intrauterine pregnancy of uncertain viability (IPUV) was defined as an empty gestational sac or sac with a yolk sac but no embryo seen with MSD < 20 or < 30 mm or an embryo with an absent heartbeat and CRL < 6 mm or < 8 mm. We recruited to the study 1060 consecutive women with IPUV. The endpoint was presence or absence of a viable pregnancy at the time of first-trimester screening ultrasonography between 11 and 14 weeks. The sensitivity, specificity, positive and negative predictive values were calculated for potential cut-off values to define miscarriage from MSD 8 to 30 mm with or without a yolk sac and from CRL 3 to 8 mm. Of the 1060 women with a diagnosis of IPUV, 473 remained viable and 587 were non-viable by the time of the 11-14-week scan. In the absence of both embryo and yolk sac, the FPR for miscarriage was 4.4% when an MSD cut-off of 16 mm was used and 0.5% for a cut-off of 20 mm. There were no false-positive test results for miscarriage when a cut-off of MSD ≥ 21 mm was used. If a yolk sac was present but an embryo was not, the FPR for miscarriage was 2.6% for an MSD cut-off of 16 mm and 0.4% for a cut-off of 20 mm, with no false-positive results when a cut-off of MSD ≥ 21 mm was used. When an embryo was visible with an absent heartbeat, using a CRL cut-off of 4 mm the FPR for miscarriage was 8.3%, and for a CRL cut-off of 5 mm it was also 8.3%. There were no false-positive results using a CRL cut-off of ≥ 5.3 mm. These data show that some current definitions used to diagnose miscarriage are potentially unsafe. Current national guidelines should be reviewed to avoid inadvertent termination of wanted pregnancies. An MSD cut-off of > 25 mm and a CRL cut-off of > 7 mm could be introduced to minimize the risk of a false-positive diagnosis of miscarriage.
  Ultrasound in Obstetrics and Gynecology 11/2011; 38(5):497-502. · 3.01 Impact Factor
• Article: Three-dimensional image of a tubal heterotopic pregnancy following assisted reproduction treatment.

  Y Abdallah, C Stalder, T Bourne
  Ultrasound in Obstetrics and Gynecology 10/2011; 38(4):484-5. · 3.01 Impact Factor
• Article: Ultrasound assessment of the peri-implantation uterus: a review.

  Y Abdallah, O Naji, S Saso, A Pexsters, C Stalder, S Sur, N Raine-Fenning, D Timmerman, J J Brosens, T Bourne
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  ABSTRACT: Emerging evidence suggests that early embryo implantation is a more active maternal process than hitherto appreciated, involving active encapsulation of the implanting blastocyst by maternal decidual cells and coordinated changes in the underlying inner myometrium, known as the junctional zone. These concepts raise the possibility that early ultrasound markers predictive of adverse pregnancy outcome could be identified. In this review we assess the role of ultrasound in predicting the likelihood of different pregnancy outcomes and highlight potential novel markers that could be tested.
  Ultrasound in Obstetrics and Gynecology 09/2011; 39(6):612-9. · 3.01 Impact Factor
• Article: Gestational sac and embryonic growth are not useful as criteria to define miscarriage: a multicenter observational study.

  Y Abdallah, A Daemen, S Guha, S Syed, O Naji, A Pexsters, E Kirk, C Stalder, D Gould, S Ahmed, C Bottomley, D Timmerman, T Bourne
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  ABSTRACT: We studied changes in mean gestational sac diameter (MSD) and embryonic crown-rump length (CRL) in intrauterine pregnancies of uncertain viability (IPUVs). We aimed to establish cut-off values for MSD and CRL growth that could be definitively associated with either viability or miscarriage, and to establish the relationship between growth in MSD and appearance of embryonic structures in the gestational sac. One thousand and sixty consecutive IPUVs were recruited prospectively from four London University hospitals: 462 with no yolk sac or embryo, 419 with a yolk sac but no embryo, and 179 with an embryo but no heartbeat visible. IPUV was defined as an empty gestational sac with or without a yolk sac but no embryo seen with MSD < 20 or < 30 mm (depending on center) or an embryo with no heartbeat and CRL < 6 mm or < 8 mm (depending on center). Scans were repeated 7-14 days later. The endpoint was viability at first-trimester screening ultrasonography between 11 and 14 weeks. Change in MSD and CRL between the first and second scans of each pregnancy was compared with respect to viability and appearance of embryonic structures using the two-sample t-test. The study included 359 pregnancies in which a gestational sac with or without embryo was identified at the follow-up scan 7-14 days later. Of these, 192 were viable and 167 non-viable at the 11-14-week scan. MSD growth was significantly higher in viable than non-viable pregnancies (mean 1.003 vs. 0.503 mm/day; P < 0.001, 95% CI of difference 0.403-0.596). A difference in CRL growth was found between the two groups (mean 0.673 vs. 0.148 mm/day; P < 0.001, 95% CI of difference 0.345-0.703). MSD growth of 0.6 mm/day was associated with a specificity for diagnosing miscarriage of 90.1%, a sensitivity of 61.7% and 19 false-positive test results. A cut-off of CRL growth rate of 0.2 mm/day gave a sensitivity of 76.3% and there were no false-positive test results for miscarriage. On repeat scan the failure of either a yolk sac or embryo to be visualized was always associated with miscarriage. There is an overlap in MSD growth rates between viable and non-viable IPUV. No cut-off exists for MSD growth below which a viable pregnancy could be safely excluded. A cut-off value for CRL growth of 0.2 mm/day was always associated with miscarriage. These data suggest that criteria to diagnose miscarriage based on growth in MSD and CRL are potentially unsafe. However, finding an empty gestational sac on two scans more than 7 days apart is highly likely to indicate miscarriage, irrespective of growth.
  Ultrasound in Obstetrics and Gynecology 08/2011; 38(5):503-9. · 3.01 Impact Factor
• Article: Standardized approach for imaging and measuring Cesarean section scars using ultrasonography.

  O Naji, Y Abdallah, A J Bij De Vaate, A Smith, A Pexsters, C Stalder, A McIndoe, S Ghaem-Maghami, C Lees, H A M Brölmann, J A F Huirne, D Timmerman, T Bourne
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  ABSTRACT: Incomplete healing of the scar is a recognized sequel of Cesarean section (CS) and may be associated with complications in later pregnancies. These complications can include scar pregnancy, a morbidly adherent placenta, scar dehiscence or rupture. To date there is uncertainty relating to the factors that lead to poor scar healing and how to recognize it. In recent years, there has been an increase in studies using ultrasound that describe scars as deficient, or poorly, incompletely or inadequately healed with few data to associate the morphology of the scar with the functional integrity of the lower segment of the uterus. There have been multiple attempts to describe CS scars using ultrasonography. Different terminology, methods and results have been reported, yet there is still no consensus regarding the prevalence, clinical significance or most appropriate method to describe the appearances of these scars. Developing a test that can predict the likelihood of women having problems associated with a CS scar is becoming increasingly important. On the other hand, understanding whether the ultrasound appearances of the scar can tell us anything about its integrity is not well supported by the research evidence. In this article we present an overview of ultrasound-based definitions and methods used to describe CS scars. We also present information relating to the performance of alternative techniques used to evaluate CS scars. Having examined the current evidence we suggest a standardized approach to describe CS scars using ultrasound so that future studies can be meaningfully compared.
  Ultrasound in Obstetrics and Gynecology 08/2011; 39(3):252-9. · 3.01 Impact Factor
• Article: P02.03: Longitudinal growth of MSD and CRL in intrauterine pregnancies of uncertain viability (IPUV) and its relationship to gestation sac shape.

  Y Abdallah, O Naji, A Daemen, A Pexsters, C Stalder, C Bottomley, E Kirk, C Lees, N Raine-Fenning, D Timmerman, T Bourne
  Ultrasound in Obstetrics and Gynecology 10/2010; 36(S1):170-171. · 3.01 Impact Factor
• Article: OC05.07: Gestation sac shape, sub-chorionic haematoma and vaginal bleeding as predictors of viability in intrauterine pregnancies of uncertain viability (IPUV).

  O Naji, Y Abdallah, A Daemen, A Pexsters, C Stalder, C Bottomley, E Kirk, N Raine-Fenning, C Lees, D Timmerman, T Bourne
  Ultrasound in Obstetrics and Gynecology 10/2010; 36(S1):10. · 3.01 Impact Factor