Single or double needle insertion in twin's amniocentesis: Does the technique influence the risk of complications?

OBJECTIVE: To compare complication rates following amniocentesis in twin gestations, according to sampling technique and number of needle insertions. STUDY DESIGN: A retrospective cohort study of all women with twin gestations who underwent amniocentesis and delivered in a single university affiliated medical center during 2002-2016. Amniocentesis was performed either through one uterine entry with passage through the inter-twin membrane or through two different entries to the two amniotic sacs. Pregnancy outcome of women that underwent single needle insertion amniocentesis, was compared to this of double needle insertion. Primary outcome was neonatal complications within 4 weeks after amniocentesis (late abortion, chorioamnionitis, preterm premature rupture of membranes, or hospitalization due to related symptoms). Secondary outcomes were gestational week at delivery and labor characteristics. RESULTS: The study group comprised 212 women. Of them, 73 (34.4%) underwent a single uterine insertion and 139 (65.6%) two separate needle insertions. Baseline characteristics did not differ between the groups. The amniocentesis complication rate was 13.7% in the single insertion group and 16.5% in the double insertion group (p = 0.587). Multivariate analysis found that a single insertion method had no statistically significant influence on complication rate, after making adjustments for potential confounders (OR = 1.085, 95% CI 0.4-2.9; p = 0.871). Other labor characteristics were similar between the groups. CONCLUSION: Needle insertion technique in twin gestation amniocentesis was not associated with procedure related complications.

Association of fetal biparietal diameter with mode of delivery and perinatal outcome.

OBJECTIVE: To determine the association between sonographic assessment of fetal biparietal diameter (BPD) and pregnancy outcome. METHODS: This was a retrospective cohort study of pregnancies at 37-42 weeks of gestation which had antepartum sonographic measurement of BPD within 7 days before delivery. Eligibility was limited to singleton pregnancies with neither known structural or chromosomal abnormalities nor prelabor Cesarean delivery (CD). The association of BPD with outcome was analyzed using multivariate logistic regression, receiver-operating characteristics curves and stratification according to BPD quartiles. RESULTS: In total, 3229 women were eligible for analysis, of whom 2483 (76.9%) had a spontaneous vaginal delivery (SVD), 418 (12.9%) underwent operative vaginal delivery (OVD) and 328 (10.2%) underwent CD. The mean BPD in the obstetric intervention groups (OVD and CD) was significantly higher than that in the SVD group (P < 0.001). After adjusting for confounders, increased BPD was an independent risk factor such that higher values of BPD were associated with progressively higher risk of obstetric intervention (adjusted odds ratio, 1.05 for each 1-mm increase in BPD (95% CI, 1.02-1.09)), but no clear cut-off value for obstetric intervention was found. The fourth quartile group (BPD ≥ 97 mm) was associated with a significantly lower SVD rate (P < 0.001) and higher OVD rate (P = 0.04), relative to the first (BPD 88-90 mm) and second (BPD 91-93 mm) quartile groups, with no apparent adverse impact on immediate neonatal outcome. CONCLUSIONS: Increased BPD within the week prior to delivery is an independent risk factor such that higher values of BPD are associated with progressively higher risk of obstetric intervention; however, in our experience, no adverse neonatal outcome resulted from such intervention. Thus, increased BPD should not discourage a trial of vaginal delivery.

Predictive value of cervical length in women with twin pregnancy presenting with threatened preterm labor.

OBJECTIVE: To assess the accuracy and determine the optimal threshold of sonographic cervical length (CL) for the prediction of preterm delivery (PTD) in women with twin pregnancies presenting with threatened preterm labor (PTL). METHODS: This was a retrospective study of women with twin pregnancies who presented with threatened PTL and underwent sonographic measurement of CL in a tertiary center. The accuracy of CL in predicting PTD in women with twin pregnancies was compared with that in a control group of women with singleton pregnancies. RESULTS: Overall, 218 women with a twin pregnancy and 1077 women with a singleton pregnancy, who presented with PTL, were included in the study. The performance of CL as a predictive test for PTD was similar in twins and singletons, as reflected by the similar correlation between CL and the examination-to-delivery interval (r, 0.30 vs 0.29; P = 0.9), the similar association of CL with risk of PTD, and the similar areas under the receiver-operating characteristics curves for differing delivery outcomes (range, 0.653-0.724 vs 0.620-0.682, respectively; P = 0.3). The optimal threshold of CL for any given target sensitivity or specificity was lower in twin than in singleton pregnancies. However, in order to achieve a negative predictive value of 95%, a higher threshold (28-30 mm) should be used in twin pregnancies. Using this twin-specific CL threshold, women with twins who present with PTL are more likely to have a positive CL test, and therefore to require subsequent interventions, than are women with singleton pregnancies with PTL (55% vs 4.2%, respectively). CONCLUSION: In women with PTL, the performance of CL as a test for the prediction of PTD is similar in twin and singleton pregnancies. However, the optimal threshold of CL for the prediction of PTD appears to be higher in twin pregnancies, mainly owing to the higher baseline risk for PTD in these pregnancies.

Is measurement of cervical length an accurate predictive tool in women with a history of preterm delivery who present with threatened preterm labor?

OBJECTIVE: To determine whether sonographically measured cervical length is an effective predictive tool in women with threatened preterm labor and a history of past spontaneous preterm delivery. METHODS: This was a retrospective cohort study of all women with singleton pregnancies who presented with preterm labor at less than 34 + 0 weeks' gestation and underwent sonographic measurement of cervical length in a tertiary medical center between 2007 and 2012. The accuracy of cervical length in predicting preterm delivery was compared between women with and those without a history of spontaneous preterm delivery. Women with risk factors for preterm delivery other than a history of preterm delivery were excluded from both groups. RESULTS: Overall, 1023 women who presented with preterm labor met the study criteria, of whom 136 (13.3%) had a history of preterm delivery (past-PTD group) and 887 (86.7%) had no risk factors for preterm delivery (low-risk group). The rate of preterm delivery was significantly higher for women with a history of preterm delivery (36.8% vs 22.5%; P < 0.001). Cervical length was significantly correlated with the examination-to-delivery interval in low-risk women (r = 0.32, P < 0.001) but not in women who had had a previous preterm delivery (r = 0.07, P = 0.4). On multivariable analysis, cervical length was independently associated with the risk of preterm delivery for women in the low-risk group but not for women with a history of previous preterm delivery. For women with previous preterm delivery who presented with threatened preterm labor, cervical length failed to distinguish between those who did and those who did not deliver prematurely (area under the receiver-operating characteristics curve range, 0.475-0.506). When using standardized thresholds, the sensitivity and specificity of cervical length for the prediction of preterm delivery were significantly lower in women with previous preterm delivery than in women with no risk factors for preterm delivery. CONCLUSION: Cervical length appears to be of limited value in the prediction of preterm delivery among women with threatened preterm labor who are at high risk for preterm delivery owing to a history of spontaneous preterm delivery in a previous pregnancy.

Does use of a sex-specific model improve the accuracy of sonographic weight estimation?

OBJECTIVE: To determine whether the use of a sex-specific sonographic model improves the accuracy of fetal weight estimation. METHODS: New regression models (sex-independent and sex-specific) were developed, based on 1708 sonographic weight estimations performed within 3 days prior to delivery. The accuracy of these models was compared to that of several published models including two of the original Hadlock models (which incorporate the biometric indices abdominal circumference (AC), biparietal diameter (BPD), femur diaphysis length (FL) and head circumference (HC) as follows: AC-FL-BPD and AC-FL-HC, designated here as Hadlock I and Hadlock II, respectively), modified versions of the Hadlock I and II models for which coefficients were adjusted to our local cohort, sex-specific versions of the Hadlock I and II models and Schild's model (a previously published sex-specific model). RESULTS: The unadjusted models of Hadlock and Schild were associated with the highest systematic error (1.6-4.9%; P < 0.001) which was significantly higher for females (2.3-4.9%) compared to males (1.6-2.0%; P < 0.001). Adjustment of model coefficients to the local population decreased the systematic error (-1.4% to 1.5%) and resulted in a systematic error that was of similar magnitude (P = 0.3) but opposite in direction for male and female fetuses. The sex-specific models (adjusted or newly developed) were associated with the lowest systematic error (-0.4 to 0.5%) and were the only models for which the systematic error was similar for male and female fetuses. There were no differences in the systematic error between adjusted sex-specific versions of the Hadlock I and II models and the newly developed sex-specific models (0.0% to 0.4% vs. - 0.4% to 0.5%; P = 0.4). The random error was similar for all models and, for most of the models, was unrelated to fetal sex. CONCLUSIONS: The use of sex-specific models appears to improve the accuracy of fetal weight estimation, principally because the optimal set of model coefficients differs for male and female fetuses. The improved accuracy is mainly the result of a decrease in systematic error, as the random error was not affected by the use of such sex-specific models.

Accuracy of sonographic fetal weight estimation: a matter of presentation.

OBJECTIVES: To assess the accuracy of sonographic weight estimation for fetuses in breech presentation, and to determine whether certain sonographic models perform better than others in cases of breech presentation. METHODS: This was a retrospective cohort study of all sonographic weight estimations of fetuses in breech presentation performed within 3 days prior to delivery (n = 165). The accuracy of weight estimation was evaluated using eight sonographic models and was compared with a control group of fetuses in vertex presentation matched to the study group by birth weight and fetal gender (n = 165). RESULTS: After exclusion of a model based on femur diaphysis length alone, which was found to be highly inaccurate, the systematic error for fetuses in breech presentation was smaller than that observed for fetuses in vertex presentation (mean of all models - 0.14% vs. 2.0%, P = 0.01). The random error was higher in cases of breech presentation (9.4-13.2% vs. 7.5-8.9%, P < 0.05), and was lower for models that are based on three to four biometric indices (9.4-9.5%) compared with models that incorporate one to two biometric indices (10.8-13.6%, P < 0.05). Overall, the higher random error outweighed the decrease in the systematic error, as reflected by the lower fraction of weight estimations within 10% of birth weight among fetuses in breech presentation. Models based on three to four biometric indices were more accurate in detecting the weight thresholds beyond which a trial of vaginal delivery is usually not recommended. CONCLUSION: Sonographic weight estimation appears to be less accurate for fetuses in breech presentation, principally because of a larger random error. The use of sonographic models that are based on three to four biometric indices, training aimed at improving measurement in breech fetuses and the development of sonographic models derived from fetuses in breech presentation, may improve the accuracy of weight estimation in these cases.

Prediction of fetal macrosomia: effect of sonographic fetal weight-estimation model and threshold used.

OBJECTIVE: To compare the accuracy of 21 sonographic fetal weight-estimation models and abdominal circumference (AC) as a single measure for the prediction of fetal macrosomia (> 4000 g) using either fixed or optimal model-specific thresholds. METHODS: A total of 4765 sonographic weight estimations performed within 3 days prior to delivery were analyzed. The predictive accuracy of 21 published sonographic fetal weight-estimation models was calculated using three different thresholds: a fixed threshold of 4000 g; a model-specific threshold obtained from the inflexion point of the receiver-operating characteristics (ROC) curve; and a model-specific threshold associated with the highest overall accuracy. Cluster analysis was used to determine whether a certain combination of fetal biometric indices is associated with a higher predictive accuracy than others. RESULTS: For a fixed threshold of > 4000 g, there was considerable variation among the models in sensitivity (range, 13.6-98.5%) and specificity (range, 63.6-99.8%) for fetal macrosomia. Use of the threshold derived from the inflexion point of the ROC curve decreased the intermodel variation to a minimum (sensitivity, 84.4-91.4%; and specificity, 79.5-86.3%). Even when this optimal model-specific threshold was applied, models based on three to four biometric indices were more accurate than were models based on only two biometric indices or on AC as a single measure (P=0.03). CONCLUSIONS: Sonographic fetal weight-estimation models based on three to four biometric indices appear to be more accurate than are models based on two indices or on AC as a single measure, for the diagnosis of macrosomia. In these cases, the use of an optimal, model-specific threshold is associated with a higher degree of accuracy than is the uniform use of a fixed threshold of an estimated weight of > 4000 g.

Accuracy of sonographic weight estimation as a function of fetal sex.

OBJECTIVES: To determine whether the accuracy of sonographic fetal weight estimation is related to fetal sex. METHODS: The accuracy of sonographic fetal weight estimation was compared between male and female fetuses using 3672 sonographic weight estimations performed within 3 days prior to delivery. Fetal weight was estimated using eight regression models that are based on different combinations of the following biometric parameters: abdominal circumference (AC), femur diaphysis length (FL), biparietal diameter (BPD) and head circumference (HC). RESULTS: In seven out of the eight models tested, the presence of a male fetus was associated with a significantly lower systematic error compared with a female fetus (-0.2 to 2.1% vs. 1.3 to 6%, P<0.001). On multivariate analysis, fetal sex was independently associated with sonographic accuracy so that the likelihood of a weight estimation within 10% of birth weight was 30% higher for male fetuses compared with female fetuses. The biometric parameters that contributed most to these sex-related differences were FL and AC, while models that included HC were associated with the lowest differences in the systematic error between male fetuses and female fetuses. For most models, the random error and correlation between estimated weight and birth weight were not affected by fetal sex (8.1-12.8% vs. 8.2-13.6%, and 0.856-0.944 vs. 0.842-0.944, respectively). CONCLUSION: Sonographic estimation of fetal weight is more accurate for male fetuses than for female fetuses. The use of sex-specific models may improve the accuracy of fetal weight estimation for female fetuses.

Sonographic estimation of fetal head circumference: how accurate are we?

OBJECTIVES: To assess the accuracy of sonographic estimation of fetal head circumference (HC). METHODS: We compared sonographic estimations of fetal HC with actual measurements performed immediately after delivery using 3008 sonographic examinations performed within 3 days prior to delivery. The following measures of accuracy were calculated: correlation with actual HC, systematic error, random error, simple error, mean absolute percentage error and fraction of estimates within 5% of actual HC. Multivariate logistic regression analysis was used to identify factors affecting the accuracy of sonographic HC estimation. RESULTS: There was a high correlation between sonographic and postnatal measurements of HC (r = 0.845, P < 0.001). Overall, sonographic HC measurements consistently underestimated actual HC measured postnatally (mean simple error, - 13.6 mm; 95% CI, - 13.2 to - 13.9), and the difference increased with gestational age. A high cephalic index (> 0.81) (odds ratio (OR), 0.3; 95% CI, 0.2-0.4), HC > 90(th) centile (OR, 0.5; 95% CI, 0.3-0.6), delivery by vacuum extraction (OR, 0.6; 95% CI, 0.4-0.8), gestational week (OR, 0.7; 95% CI, 0.6-0.9) and male fetal gender (OR, 0.8; 95% CI, 0.6-0.9) were associated with decreased sonographic accuracy. At term, breech presentation at the time of sonographic examination was associated with a higher sonographic accuracy compared with vertex presentation (-12.0; 95% CI, - 10.5 to - 13.5 vs. - 13.9 mm; 95% CI, - 13.6 to - 14.3; P = 0.02). The random error was relatively constant, and was unaffected by any of the obstetric factors studied. CONCLUSION: Sonographic estimation of HC is associated with significant underestimation compared with the actual postnatal HC. This measurement error may have important clinical implications and should be taken into account in the interpretation of sonographically measured HC.

The hazards to practitioners of obstetric and gynecological ultrasound.

OBJECTIVES: To investigate the specific complaints of physicians and technicians performing obstetric and gynecological ultrasound. METHODS: This was a cross-sectional retrospective survey. Questionnaires were distributed to members of the Israeli Society of Gynecological Ultrasound, including questions on gender and profession, number and type of scans performed, pain related to profession and any therapy undergone. Statistical analysis included chi-square or Fisher's exact test, Student's t-test, Pearson's correlation coefficient and logistic regression. RESULTS: Joint pain was reported by 51.7% (30/58) of the technicians compared with 25.3% (19/75) of the physicians (P = 0.002). It was more common in females than in males (P = 0.05) and it was more common among those who performed transabdominal sonography more frequently than they did transvaginal sonography (P = 0.004). There was a significant association between performing transabdominal ultrasound and back pain (P = 0.05). Although females reported pain more frequently, the rate of surgical procedures was higher among males (P < 0.05). CONCLUSIONS: A technician is 3.5 times more likely to report joint pain than is a physician. Transabdominal sonography is a risk for both joint and back pain. There may be gender differences in pain perception.

Fetal gender assignment by first-trimester ultrasound.

OBJECTIVE: Ultrasound determination of fetal sex can benefit decision-making regarding invasive prenatal testing in pregnancies at risk of sex-linked genetic abnormalities. The aim of this study was to assess the accuracy of fetal sex determination by ultrasound at 12-14 weeks of gestation in a large cohort. METHODS: Fetal gender assessment by transabdominal ultrasound was performed in 656 singleton pregnancies at 12-14 weeks of gestation. The genital region was examined in the mid-sagittal plane. The angle of the genital tubercle to a horizontal line through the lumbosacral skin surface was measured. The fetus was assigned male gender if the angle was > 30 degrees , and female gender if the genital tubercle was parallel or convergent (<10 degrees ) to the horizontal line. At an intermediate angle of 10-30 degrees the gender was not determined. Crown-rump length (CRL) was measured in all cases. RESULTS: Gender assignment was possible in 613 of the 656 (93%) fetuses. Gender identification according to CRL was feasible in 85%, 96% and 97% of the fetuses at gestational ages of 12 to 12 + 3, 12 + 4 to 12 + 6 and 13 to 13 + 6 weeks, respectively. Phenotypic sex was confirmed in 555 newborns. The accuracy of male gender assignment in this group was 99-100% at all ages, and that of female gender assignment was 91.5% at 12 to 12 + 3 weeks, 99% at 12 + 4 to 12 + 6 weeks and 100% at 13 to 13 + 6 weeks. CONCLUSION: Prenatal gender assignment by ultrasound has a high accuracy rate at 12-14 weeks. These results indicate that invasive testing can probably be carried out in fetuses identified as males at this gestational age. However, in fetuses identified as female at a CRL of <62.6 mm, despite the relatively high 91.5% accuracy rate, the decision regarding invasive testing should be postponed until a higher CRL is achieved.

Ultrasound diagnosis of fourth branchial arch sinus at 22 weeks' gestation.

Fourth branchial arch sinus is the rarest of the branchial cleft anomalies and its prenatal detection has not previously been reported in the English literature. We describe a case of fourth branchial arch sinus identified in a fetus during a routine ultrasound evaluation at 22 weeks' gestation. Survey of the fetal anatomy revealed a small 'nipple-like' structure on the neck, arising anteriorly to the sternocleidomastoid muscle, midway between the chin and the left shoulder. The structure persisted unchanged throughout the pregnancy. The prenatal diagnosis of fourth branchial arch sinus was confirmed at delivery at term.

Fetal hyperechogenic kidney with normal amniotic fluid volume: a diagnostic dilemma.

OBJECTIVE: To determine the prognostic value of sonographically detected fetal hyperechogenic kidneys with normal amniotic fluid volume. METHODS: Seven cases of hyperechogenic fetal kidneys were identified by sonography over a 7-year period (1996--2002). Increased renal echogenicity was diagnosed when the renal parenchyma was of greater echogenicity than adjacent liver tissue. Amniotic fluid volume was measured by the semiquantitative sonographic technique known as the amniotic fluid index (AFI). RESULTS: Three of the live-born infants had autosomal dominant polycystic kidney disease and one had autosomal recessive polycystic kidney. In the remainder, autopsy study revealed multifocal renal dysplasia in two cases and normal kidneys in one. CONCLUSIONS: Increased renal echogenicity with normal amniotic fluid volume in a fetus without other anomalies is a difficult diagnostic dilemma. Although it is usually indicative of renal parenchymal disease with possible renal failure after birth or in early childhood, in some cases, it represents a normal variant. .

Prenatal ultrasound diagnosis of club foot: outcome and recommendations for counselling and follow-up.

Club foot was diagnosed by ultrasonography in 91 feet (52 fetuses) at a mean gestational age of 22.1 weeks (14 to 35.6). Outcome was obtained by chart review in 26 women or telephone interview in 26. Feet were classified as normal, positional deformity, isolated club foot or complex club foot. At initial diagnosis, 69 feet (40 fetuses) were classified as isolated club foot and 22 feet (12 fetuses) as complex club foot. The diagnosis was changed after follow-up ultrasound scan in 13 fetuses (25%), and the final ultrasound diagnosis was normal in one fetus, isolated club foot in 31 fetuses, and complex club foot in 20 fetuses. At birth, club foot was found in 79 feet in 43 infants for a positive predictive value of 83%. Accuracy of the specific diagnosis of isolated club foot or complex club foot was lower; 63% at the initial ultrasound scan and 73% at the final scan. The difference in diagnostic accuracy between isolated and complex club foot was not statistically significant. In no case was postnatal complex club foot undiagnosed on fetal ultrasound and all inaccuracies were overdiagnoses. Karyotyping was performed in 25 cases. Abnormalities were noted in three fetuses, all with complex club foot and with additional findings on ultrasound.

Early sonographic detection of recurrent fetal eye anomalies.

OBJECTIVE: To determine the possible association between congenital eye anomaly of a previous child in the family and current congenital eye anomaly. METHODS: An early transvaginal anomaly scan at 14-16 gestational weeks was used to diagnose fetal eye anomalies in five cases in which at least one previous child in the family had the same congenital eye anomaly. RESULTS: At least one cataract was detected in four of the five fetuses and bilateral anophthalmia in one. The congenital cataract in one case was part of multiple pterygium syndrome. Both of these extremely rare malformations are commonly associated with other fetal anomalies. CONCLUSION: Our data suggest that a detailed targeted ultrasound survey with a special focus on the orbital region should be offered at the time of genetic counseling to couples with children with congenital eye anomalies.

Accuracy of sonographically estimated fetal weight in 840 women with different pregnancy complications prior to induction of labor.

OBJECTIVES: To evaluate the accuracy of sonographically estimated fetal weight (EFW) shortly before induction of labor in the presence of different pregnancy complications, and to define possible variables affecting it. METHODS: The study sample consisted of 840 women with singleton pregnancies and cephalic presentation who were admitted to our unit for induction of labor between January 1999 and December 2000. All underwent detailed ultrasound assessment for EFW, amniotic fluid index, biophysical profile and placental location. Indications included previous Cesarean section, postdate pregnancy, pregnancy-induced hypertension, diabetic pregnancy, suspected large-for-gestational age (LGA) infants, suspected fetal growth restriction (FGR), oligohydramnios, decreased fetal movements, premature rupture of membranes at or before term. EFW was calculated after measuring fetal abdominal circumference and femur length. The EFW was compared with the weight at delivery, 1-3 days later. RESULTS: There was a high correlation between EFW and birth weight (R(2) = 0.775, P < 0.001). The mean birth weight was 3207 +/- 561 g, and mean absolute weight difference was 227 +/- 197 g; (absolute range, 0-1700 g; actual range, - 986 to + 1700 g). The mean weight difference was significantly different between the patients with LGA infants, FGR infants and preterm premature rupture of membranes (PPROM) (- 110 +/- 281 g, + 113 +/- 195 g and + 115 +/- 307 g, respectively, P < 0.01). Stepwise linear regression analysis of the effects of maternal and pregnancy characteristics on the weight difference yielded lower gestational age, higher birth weight, anterior placenta, higher gravidity, and younger maternal age as independent and significant variables associated with greater actual weight difference inaccuracy (R(2) = 0.099, P < 0.001), and higher birth weight as the only independent and significant variable associated with greater absolute weight difference (R(2) = 0.09, P = 0.018). CONCLUSIONS: The sonographic EFW is highly correlated with birth weight. However, clinicians should be aware of the risk of overestimation in pregnancies with suspected LGA and underestimation in pregnancies with PPROM and suspected FGR.

The 'virtual' cervical internal os: diagnosis during the first trimester of pregnancy.

OBJECTIVE: To determine the appropriate time during gestation for assessing the cervix for possible incompetence by ascertaining the gestational week at which the sac reaches the level of the internal os. METHODS: Three hundred and eighteen women with an intact singleton pregnancy at 5 to 15 weeks' gestation underwent endovaginal sonographic examination to measure the distance between the gestational sac and the cervical internal os. The change in location of the gestational sac in the endometrial cavity over time, and the earliest gestational week at which the gestational sac reached the level of the internal os, were calculated and analyzed with one-way analysis of variance. RESULTS: The distance between the gestational sac and the 'virtual' cervical internal os decreased from a mean of 4.72 cm at 5 weeks to 1.71 cm at 13 weeks. This distance decreased significantly during the early first trimester (weeks 5 to 7) (P = 0.004), but remained almost unchanged from 12 to 15 weeks. Only at 12 weeks' gestation could the entire cervical length be determined and the configuration of the cervical internal os assessed for incompetence. CONCLUSIONS: Transvaginal sonography is a good method for evaluating the cervix during pregnancy. The location of the 'virtual' internal os can be determined in the first trimester using the urinary bladder as a reference point.

The 'tulip sign': a sonographic clue for in-utero diagnosis of severe hypospadias.

OBJECTIVE: To describe a unique sonographic sign for prenatal detection of severe penoscrotal hypospadias. METHODS: Ultrasound findings of hypospadias diagnosed in the second trimester of pregnancy in seven patients were compared with postnatal clinical features. All patients were recruited from routine sonographic examinations performed for various obstetric indications. RESULTS: In six of the seven cases with hypospadias, a severe form of peno-scrotal hypospadias was found. In all six cases, a unique ultrasound feature was observed represented by extreme ventral angulation of the penis, with or without chordee, in a form resembling a tulip flower. This 'tulip' is formed by the ventrally bent penis located between the two scrotal folds. In all six patients, the postnatal pictures of the newborns' genitalia corresponded perfectly to the prenatal sonograms. Associated anomalies occurred in two cases, with Nager syndrome in one case and mild renal hydronephrosis in the other case. CONCLUSIONS: The 'tulip sign' is a specific ultrasonic finding of severe hypospadias. The recognition of this may help to distinguish between severe hypospadias and other genital abnormalities (e.g. ambiguous genitalia).