Very short cervix in low-risk asymptomatic singleton pregnancies: Outcome according to treatment and cervical length at diagnosis.

INTRODUCTION: The aim of this study was to explore the outcome of low-risk singleton pregnancies with very short cervical length (CL ≤15 mm) according to method of treatment and CL at diagnosis. MATERIAL AND METHODS: Retrospective study on singleton pregnancies devoid of risk factors for spontaneous preterm delivery identified in the course of universal screening programs by vaginal sonography at 20-24 weeks of gestation to have very short CL ≤ 15 mm. RESULTS: The study group consisted of 233 pregnancies with CL ≤ 15 mm of which 88 had cervical cerclage inserted and the remaining 145 were treated with vaginal progesterone. Mean CL at diagnosis was significantly shorter in the cerclage group (5 mm) compared with the progesterone group (12 mm). Regardless of treatment there was no difference in the rate of spontaneous preterm delivery at <32 weeks of gestation in women with CL ≥ 9 mm at screening (11% and 12% in the cerclage and progesterone groups, respectively). In contrast, in the subgroup with CL ≤ 8 mm cervical cerclage resulted in significantly lower rates of spontaneous preterm delivery at <32 weeks of gestation compared with progesterone treatment (20% and 45%, respectively, P = .009) and the median gestational age at birth was significantly greater (37 weeks vs 36 weeks, respectively, P = .013). CONCLUSIONS: The majority of asymptomatic singleton pregnancies with short CL will remain undelivered until 32 weeks of gestation whether treated with progesterone or cerclage. Women with extreme cervical shortening appear to benefit more from cervical cerclage.

Cervical length at 11-40 weeks: unconditional and conditional longitudinal reference ranges.

INTRODUCTION: Our aim was to establish unconditional and conditional longitudinal reference ranges for cervical length throughout pregnancy. MATERIAL AND METHODS: Prospective longitudinal study. In singleton pregnancies repeated cervical length measurements were carried out by transvaginal ultrasound throughout gestation. Multilevel modeling was applied to establish cervical length reference ranges from 11 to 40 weeks. RESULTS: In all, 4397 women contributed to 13 765 cervical length measurements. A linear mixed effects random intercept-random slope model was fitted to the data. Mean cervical length had a negative non-linear polynomial association with gestational age. Unconditional ranges were developed. Terms that allow the construction of personalized cervical length charts conditional to a previous measurement were calculated. CONCLUSIONS: We constructed longitudinal reference charts for cervical length in singleton pregnancies. Cervical length should be adjusted according to specific gestational-age-dependent ranges. Individualization of cervical assessment is feasible by the application of charts conditional to previous measurements.

Predicting fetal growth deviation in parous women: combining the birth weight of the previous pregnancy and third trimester ultrasound scan.

AIM: To investigate the value of the birth weight of the previous pregnancy (BW1) alone and combined with the third trimester ultrasonographically estimated fetal weight (EFW) and Doppler studies in the prediction of small (SGA) and large for gestational age (LGA) neonates in the index pregnancy (BW2). METHOD: Some 1298 parous women with uncomplicated singleton pregnancies who had a third trimester ultrasound scan were considered as samples in this retrospective cohort study. Maternal and pregnancy characteristics, BW1, EFW, umbilical artery, and middle cerebral artery pulsatility indices were investigated as predictors of SGA and LGA. RESULTS: BW1, maternal weight, mode of conception, and smoking status were associated with BW2 (R2=0.39) with BW1 being the strongest predictor (R2=0.37). The addition of EFW conferred significant improvement (R2=0.63), whereas the addition of the Doppler indices did not. The sensitivity of BW1 alone in the prediction of SGA was 75% for 25% screen positive rate and increased to 92% with the addition of EFW. The equivalent figures for LGA were 68% and 93%, respectively. CONCLUSIONS: BW1 used as a continuous variable is predictive of growth deviations in the index pregnancy. Incorporating EFW enhanced the sensitivity for the detection of both conditions.

Prediction of Preterm Delivery by Late Cervical Length Measurement after 24 Weeks.

OBJECTIVE: To examine the value of the cervical length (CL) measurement at 24-30 gestational weeks in the prediction of spontaneous preterm delivery (SPD) between 30 and 34 weeks (SPD34) and between 34 and 37 weeks (SPD37). METHODS: We performed a prospective cross-sectional study. CL was measured once by transvaginal ultrasound examination between 24 and 30 weeks. RESULTS: The study sample consisted of 1,180 low-risk singleton pregnancies. 10 women (0.85%) had a SPD34 and 60 (5.08%) had a SPD37. CL was shorter (p < 0.001) in the women who had a SPD34 (median 11 mm) compared to the women who delivered after 34 weeks (median 31 mm). CL was shorter (p < 0.001) in the women who had a SPD37 (median 22 mm) compared to the women who delivered after 37 weeks (median 31 mm). CL predicted SPD34 (OR = 0.837, R² = 0.2768, AUC = 0.9406, p < 0.001) and SPD37 (OR = 0.907, R² = 0.1085, AUC = 0.7584, p < 0.001). The model achieved a sensitivity of 70.0 and 38.3% for 10% false-positive rate for SPD34 and SPD37, respectively. CONCLUSIONS: CL after 24 weeks is significantly shorter in women destined to have a SPD. In low-risk singleton pregnancies CL performs very well in predicting SPD34 and adequately in predicting SPD37.

Towards detecting open spina bifida in the first trimester: the examination of the posterior brain.

INTRODUCTION: Our aim was to examine the value of indirect signs of open spina bifida in the mid-sagittal view of the posterior brain at the 11-13 weeks' ultrasound examination and to summarize the current evidence for the first-trimester diagnosis of spina bifida. METHODS: This was a prospective study in routine obstetric population. The presence of four almost parallel lines (four-line view) in the posterior brain was recorded. Biparietal diameter (BPD), intracranial translucency (IT) and cisterna magna (CM) were measured. The ratio of IT to CM (R ratio) was calculated. RESULTS: 2,491 pregnancies were examined prospectively. Updated reference ranges for IT and CM were constructed. There were 3 cases with open spina bifida, and the four-line view was abnormal in 2 of them. The abnormal fetuses had smaller BPD as well as pronounced reduction in the CM and increase in the R ratio. DISCUSSION: Examination of the posterior brain was feasible in all fetuses in the setting of the routine 11-13 weeks' ultrasound examination. Indirect signs of spina bifida are visible in the mid-sagittal view of the posterior brain, and the assessment of these structures can be a reliable tool in the early identification of this abnormality.

Screening for birth weight deviations by second and third trimester ultrasound scan.

OBJECTIVE: The aim of this article was to predict small for gestational age (SGA, at or less than the fifth birth weight percentile) and large for gestational age (LGA, at or greater than the 95th birth weight percentile) fetuses by using maternal and fetal parameters from the second and third trimester ultrasound examinations. METHOD: This article is a retrospective cohort study on 1979 singleton pregnancies that had a routine 20 to 24 weeks anomaly and a 30 to 34 weeks growth ultrasound scans. SGA delivered before 30 gestational weeks were excluded. RESULTS: Second trimester estimated fetal weight (EFW2 ), uterine arteries pulsatility index (PI), and maternal pregnancy characteristics were predictive for SGA (SGA second trimester model: R(2) = 0.225, area under the curve [AUC] = 0.815) and LGA (LGA second trimester model: R(2) = 0.203, AUC = 0.793). Third trimester EFW (EFW3 ), EFW2 , uterine arteries PI2 , umbilical PI, and maternal pregnancy characteristics improved the prediction of SGA (SGA combined model: R(2) = 0.423, AUC = 0.896) and LGA (LGA combined model: R(2) = 0.383, AUC = 0.882). Contingent screening with risk stratification by the second trimester model performed equally well for SGA (AUC = 0.882) and LGA (AUC = 0.861) as the combined models. CONCLUSION: Second trimester model performs well in the prediction of SGA and LGA. The addition of third trimester scan offers substantial improvement. Contingency screening is feasible with similar effectiveness.

Fetal volume at 11-14 gestational weeks: reference ranges and association with first trimester biochemical and biophysical markers.

AIMS: To establish reference ranges for fetal volume (FV) measured by three-dimensional ultrasound (3D-US) at 11-14 weeks of gestation and to examine the possible association of FV with maternal/pregnancy characteristics and biochemical parameters. METHODS: Prospective observational study on 240 fetuses at 11-14 weeks. FV was measured by 3D-US using Virtual Organ Computer-Aided Analysis. Pearson correlation coefficient (cc) and regression analysis were used. RESULTS: FV increased exponentially with crown rump length and was unrelated to maternal weight (cc=-0.137, P=0.071), age (cc=0.009, P=0.899), parity (0.76), smoking status (t-test, P=0.149) and mode of conception (t-test, P=0.8). Z-scores (z) of FV was not associated with z-mean uterine artery pulsatility index (cc=-0.026, P=0.733), log10 multiples of the median (MoM) free beta human chorionic gonadotrophin (cc=0.002, P=0.982), delta value (d) of nuchal translucency (cc=0.072, P=0.331) and d-fetal heart rate (cc=0.009, P=0.902), z-FV was significantly positively correlated with log10 MoM pregnancy associated plasma protein-A (PAPP-A; regression coefficient=1.420976, R2=0.0957, P<0.0001). CONCLUSIONS: FV is strongly related to PAPP-A even after adjustment for crown rump length with a mechanism unrelated to placental perfusion. FV is independent of the vast majority of first trimester parameters; hence, it is a promising marker of early fetal growth.

Performance of the ultrasound examination in the early and late third trimester for the prediction of birth weight deviations.

OBJECTIVES: This study aimed to define the optimal gestational age in the third trimester, early (30-33 weeks + 6 days) versus late (34-37 weeks), for performing an ultrasound examination for fetal biometry to predict birth weight deviations: small for gestational age (SGA ≤ 5th centile) and large for gestational age (LGA ≥ 95th centile) neonates. METHODS: We used an observational cross-sectional study in uncomplicated singleton pregnancies that had a third trimester ultrasound for fetal biometry and umbilical and middle cerebral fetal Doppler studies. Estimated fetal weight and fetal Doppler parameters were the examined variables for the prediction of SGA and LGA. RESULTS: Three thousand six hundred ninety women had an early examination, and 2288 women had a late one. For a screen-positive rate of 10%, estimated fetal weight achieved 58% and 53.4% sensitivity for the prediction of SGA [area under the curve (AUC) = 0.8578, p < 0.001] and LGA (AUC = 0.8547, p < 0.001), respectively, by the early examination. Accordingly, the sensitivities significantly increased to 75.2% and 63.2% for the prediction of SGA (AUC = 0.9074, p < 0.001) and LGA (AUC = 0.8782, p < 0.001), respectively, by the late examination. The inclusion of the Doppler indices did not improve the predictive models. CONCLUSIONS: A late third trimester ultrasound was superior in the prediction of SGA and LGA, and this improvement was more pronounced for the prediction of SGA.

Assessment of the posterior brain at 11-14 weeks for the prediction of open neural tube defects.

OBJECTIVE: To evaluate the routine midsagittal view of the posterior brain at the 11-13 weeks' ultrasound examination, for predicting open neural tube defects. METHODS: Posterior brain was examined midsagittally for normality of the four-line view (upper and lower border of the brain stem, the choroid plexus of the fourth ventricle and the occipital bone). Intracranial translucency and cisterna magna (CM) were measured. RESULTS: The posterior brain was assessed in 1330 cases. The four-line view was normal in all but one case. In the two cases of open spina bifida contained in the study population, intracranial translucency was within normal range. The CM and the four-line view were normal in the first case, whereas in the second case, the four-line view was abnormal, and CM was obliterated and impossible to measure. No other cases of abnormal four-line view were observed in the study population. CONCLUSION: Obliteration of the CM appears to be the most consistent early sign of open neural tube defects. Attention should focus on either measuring the cisterna magna or simply observing the presence of four lines in the midsagittal view of the posterior brain. However, these early signs of brain herniation are not present in all abnormal cases.

Reproducibility study of crown-rump length and biparietal diameter measurements in the first trimester.

OBJECTIVE: This study aims to investigate the intra-observer and inter-observer variability of crown-rump length (CRL) and biparietal diameter (BPD) measurements in the first trimester. METHODS: A prospective observational study on 592 fetuses between 8 and 14 gestational weeks was conducted. Intra-class correlation coefficients (ICCs) were computed, and Bland-Altman analysis was carried out. RESULTS: The ICCs (95% confidence interval) and the 95% limits of agreement, expressed as a percentage of the average, for CRL's intra-observer and inter-observer variability were 0.979 (0.974-0.982, p < 0.001), +8.53% to -8.376%, and 0.968 (0.952-0.978, p < 0.001), +9.06% to -7.69%, respectively. The corresponding figures for BPD were 0.981 (0.977-0.984, p < 0.001), +7.41% to -7.51%, and 0.968 (0.952-0.978, p < 0.001), +6.65% to -7.25%. After conversion in days, the ICCs and 95% limits of agreement for CRL's intra-observer and inter-observer variability were 0.983 (0.980-0.986, p < 0.001), +2.88% to -2.84%, and 0.971 (0.957-0.980, p < 0.001), 2.83% to -2.60%, respectively. The corresponding figures for BPD were 0.982 (0.979-0.986, p < 0.001), +3.36% to -3.40%, and 0.968 (0.953-0.978, p < 0.001), +3.06% to -3.38%. CRL's standard deviation of the differences increased with gestation for intra-observer (r = 0.289, p < 0.001) and inter-observer (r = 0.197, p = 0.023) variability. CONCLUSION: The BPD and CRL are highly reproducible measurements. CRL's measurement error increased with the magnitude of CRL, whereas BPD's reproducibility was not affected by gestational age.

Third trimester ultrasound for the prediction of the large for gestational age fetus in low-risk population and evaluation of contingency strategies.

OBJECTIVE: Evaluation of the effectiveness of third trimester fetal biometry and Doppler studies in predicting the birth of a large for gestational age neonate (LGA ≥ 95(th) centile). Assessment of the value of integrated models (combining maternal characteristics, first trimester parameters, third trimester fetal biometry) and the usefulness of contingency strategies. METHOD: Observational cross-sectional study on 2308 uncomplicated singleton pregnancies examined at 11 to 14 weeks and at 30 to 34 weeks. RESULTS: Ultrasound estimated fetal weight (EFW, area under the curve (AUC) = 0.83) was the best single predictor of LGA. Maternal weight, delta nuchal translucency and EFW were independent predictors for the integrated model, but the latter was not statistically better (AUC = 0.84) than using EFW alone. The detection rates for LGA were 72.5% and 73.7% for a 25% screen positive rate, by EFW and the third trimester integrated model respectively. A contingency strategy of rescanning 50% of the population in the third trimester according to the risk estimation by a first trimester prediction model results in detection rate of 64.7% for LGA for the same 25% screen positive rate (AUC = 0.78). CONCLUSIONS: Third trimester ultrasound is an effective screening modality for identifying fetal macrosomia. A contingency strategy utilizing first trimester parameters can reduce the need for unnecessary examinations.

First trimester prediction of small- and large-for-gestation neonates by an integrated model incorporating ultrasound parameters, biochemical indices and maternal characteristics.

OBJECTIVE: To identify maternal/pregnancy characteristics, first trimester ultrasound parameters and biochemical indices which are significant independent predictors of small-for-gestational age (SGA) and large-for-gestational age (LGA) neonates. DESIGN: Retrospective cross-sectional study. SETTING: Two fetal Medicine Units. POPULATION: 4 702 singleton pregnancies presenting for screening for chromosomal abnormalities by nuchal translucency and maternal serum biochemistry at 11-14 weeks. METHODS: Reference ranges for birthweight applied to our population were constructed by the Royston and Wright method. Multiple logistic regression was applied to develop first trimester prediction models for SGA and LGA. MAIN OUTCOME MEASURES: Birth of SGA or LGA neonate. RESULTS: Maternal height, parity, smoking, assisted conception, delta crown-rump length, delta nuchal translucency, free beta human chorionic gonadotrophin and pregnancy-associated plasma protein-A were significant independent predictors of SGA. Maternal weight and height, smoking, delta crown-rump length and delta nuchal translucency were significant independent predictors of LGA. Models for SGA (AUC=0.7296, CI: 0.69-0.76, p<0.0001) and LGA (AUC=0.6901, CI: 0.65-0.72, p<0.0001) were derived, applicable to routine obstetric population at low risk for these conditions. For 20% screen positive rate the modeling achieves sensitivities of about 55% for SGA and 48% for LGA neonates. CONCLUSION: Prediction for birthweight deviations is feasible using data available at the routine 11-14 weeks' examination. Delta CRL and delta nuchal translucency were significant independent predictors for both SGA and LGA.

Reproducibility of cervical length measurement throughout pregnancy.

OBJECTIVES: To assess the intra- and interobserver variability of cervical length (CL) measurement in the three trimesters of pregnancy. METHODS: Prospective observational study. Transvaginal CL measurement was performed by two operators ignorant of each other's results. Two methods of measurement were assessed: the straight line method (SL = from internal to external cervical os along the endocervical mucosa) and the two-line method (TL = the sum of two lines following the curvature of the endocervical canal). RESULTS: There were 236 sets of CL measurements of which 96 (40.7%), 73 (30.5%), and 67 (28.8%) were performed in the first, second, and third trimesters of pregnancy, respectively. Intra- and interobserver variability was excellent for both methods (ICC 0.90) and was not influenced by gestational age. Mean difference was 1 mm (LOA -4 to -3 mm) for the same examiner and 1 mm as well between examiners (LOA -5 to -7 mm). Mean CL was slightly longer for the 2-L method (33 mm, SD = 5.2) compared to the SL method (31.4 mm, SD = 4.9). There was significantly more bias in the difference between methods the longer the CL measurement was (p <.001). CONCLUSIONS: CL measurement shows excellent intra- and interobserver variability across gestation and the variability of the measurement is not influenced by gestational age or CL length for either method. The TL method produces slightly longer values.

Quality assessment of the detailed anomaly ultrasound scan.

OBJECTIVES: The objective of this study is to assess the quality of the views in the detailed anomaly ultrasound scan and examine the parameters that influence it. METHODS: Prospective study on singleton pregnancies examined at 20-24 weeks. Detailed views of all fetal organs were classified by the examiner as optimal/suboptimal. The duration of the examination was observed. Maternal characteristics, Fat Index (FI) (distance between the skin and the surface of the uterus), and fetal position were recorded. RESULTS: The study population consisted of 940 singleton pregnancies. Optimal visualization of all fetal structures was achieved in 66% of cases. Significant predictors were BMI, FI, and fetal position. None of the women with BMI ≥ 44 and none of the women with FI ≥ 60 mm had optimal visualization of all fetal structures. Median duration of the examination was 23 min. In 75% of cases, it was completed in the first attempt. Maternal weight, FI, and fetal position were the significant independent predictors of total examination time. CONCLUSIONS: Optimal visualization of the fetal anatomy is restricted by maternal parameters and fetal position. The main limitation is accumulation of abdominal fat, usually but not always related to maternal obesity. The FI may be recorded as a measure of technical difficulty. The anomaly scan should be allocated at least 30 min scanning time.

Screening for major structural abnormalities at the 11- to 14-week ultrasound scan.

OBJECTIVE: The purpose of this study was to examine the value of performing a detailed examination of the fetus as part of the routine 11 to 14 weeks' ultrasound scan in a 2-stage screening process for major structural defects in low-risk pregnancies. STUDY DESIGN: This was a prospective study in 1148 singleton pregnancies at 11 to 14 weeks of gestation using a combination of transabdominal and transvaginal sonography to estimate the sensitivity of the first and second trimester ultrasound scan in the detection of major anomalies. RESULTS: Seven of the 14 major anomalies were detected at the 11 to 14 weeks scan, and an additional 6 at the second trimester scan. The sensitivity of the early anatomic examination and the overall sensitivity of the 2-stage screening were 50% and 92.8%, respectively. Nuchal translucency was increased in 5 of the 14 (35.7%) abnormal fetuses and in 1 of the 4 cases (25%) with major heart defects. CONCLUSION: Detailed, structured examination of fetal anatomy during the routine 11 to 14 weeks' scan can detect half of major structural defects in low-risk pregnancies.

First trimester cervical length is associated with mid-trimester loss.

OBJECTIVE: To study the value of the cervical length (CL) measurement at 11-14 weeks in predicting second trimester miscarriage occurring at 16-24 weeks. METHODS: Prospective study in routine obstetric population using transvaginal ultrasound examination to measure the length of the endocervical canal at 11-14 weeks. RESULTS: The study group consisted of 2836 singleton pregnancies. Eleven (0.0038%) women miscarried between 16 and 24 weeks whereas 2825 delivered after 34 weeks. CL was significantly shorter (Mann-Whitney U test, p = 0.001), in women that had a second trimester miscarriage in comparison to those who delivered after 34 weeks (median CL 28 mm versus 32 mm, respectively). First trimester CL was predictive of a late miscarriage (OR = 0.7093304, R(2 )= 0.1211, AUC = 0.7838, p < 0.001). The detection rate was 63.64% for 20% screen positive rate. CONCLUSIONS: First trimester endocervix is significantly shorter in women destined to miscarry between 16 and 24 weeks. In low risk singleton pregnancies, first trimester CL can be useful in predicting second trimester miscarriage.

First-trimester NRBC count in maternal circulation: correlation with doppler ultrasound studies.

This study aimed to determine whether the number of nucleated red blood cells (NRBCs) in maternal circulation during the first trimester of pregnancy could identify pregnancies that will have an anomalous Doppler in the second trimester. A total of 85 blood samples were obtained at 11-14 weeks of gestation with mean uterine arterial perfusion index >1.6, as noted by Doppler ultrasonography. NRBCs were enriched by magnetic automated cell sorting using anti-CD71 and were stained with May/Grunwald/Giemsa. A total of 4.8 NRBCs (range 1-75) were identified in 68 cases. Follow-up scans at 22-24 weeks were available in 46 cases. In 39 women, blood flow in the uterine arteries normalized, whereas in seven, high resistance was noted. One woman in the high-resistance group developed preeclampsia (PET; four NRBCs) and another delivered an intrauterine growth restriction (IUGR) baby (75 NRBCs). The number of NRBCs in women whose Doppler indices later normalized and in those who continued to have increased impedance was similar. The study indicates that NRBC number in maternal circulation during the first trimester cannot be used to screen pregnancies at high risk for developing preeclampsia (PET)/IUGR. High-impedance blood flow in the uterine arteries in the first trimester may be due to an unfinished process of trophoblastic invasion, most likely to be completed successfully by 22-24 weeks.

Histologic implications of Pap smears classified as atypical glandular cells.

OBJECTIVE: To evaluate the histologic outcome of Pap smears reported as atypical glandular cells (AGC). STUDY DESIGN: Cervical cytology smears reported as AGC were reviewed and correlated with histologic follow-up. RESULTS: Of a total of 41,500 Pap smears performed at Alexandra Hospital during 2000-2002, 113 (0.2%) were reported as AGC. Of these, 64 were classified as AGC not otherwise specified (NOS) (56.6%), 48 AGC favor neoplasia (42.5%) and 1 (0.9%) adenocarcinoma in situ. All these women underwent histological evaluation. The mean age of the patients was 52 years. Significant abnormality was found in 30 women (26.5%). Eleven percent of women with smears reported as AGC NOS and 45.8% of those with AGC favor neoplasia had significant abnormality. Of these patients, 14 (12.4%) had endometrial involvement, whereas cervical abnormalities were identified in the remaining 16 (14.1%). Older women were more likely to have involvement of the endometrium and younger women, involvement of the cervix. CONCLUSION: Cytologic criteria and patient age might effectively direct the clinician toward the likely origin of AGC.

Rupture of noncommunicating rudimentary uterine horn pregnancy.

BACKGROUND: We present a rare case of pregnancy in a noncommunicating rudimentary horn that ruptured at 20 weeks. CASE: A 30-year-old woman presented with a history of two spontaneous abortions. An ultrasound scan showed a bicornuate uterus, with one normal and one hypoplastic horn. Hysterosalpingography revealed a single uterine cavity with only one tube, suggesting a unicornuate uterus. Hysteroscopy and laparoscopy were recommended but declined. She presented again 2 months later at 7 weeks' gestation. A single intrauterine pregnancy in the hypoplastic right horn was diagnosed. A transvaginal scan showed a single cervical canal in continuity with the left uterine horn, which led to the suspicion of a pregnancy in a rudimentary horn. The option of pregnancy termination was offered. A laparoscopy was repeatedly suggested but declined. Excision of a ruptured noncommunicating rudimentary horn and ipsilateral salpingectomy were performed after an emergency laparotomy at 20 weeks because of the sudden onset of abdominal pain and signs of shock. CONCLUSION: Although a rudimentary horn pregnancy had been suspected before the laparotomy, the patient presented as a clinical emergency. This report, like others, indicates that prompt diagnosis and immediate removal of the rudimentary horn is lifesaving.

First trimester diagnosis of dicephalus conjoined twins.

Dicephalus twinning is an extremely rare type of conjoined twins. Early prenatal diagnosis of this condition is important to provide an opportunity for pregnancy termination. We present such a case, which was diagnosed by ultrasound examination at 12 weeks of gestation. The ultrasonographic criteria are discussed together with implications for management.