Absent mandibular gap in the retronasal triangle view: a clue to the diagnosis of micrognathia in the first trimester

Ultrasound measurements of fetal facial profile markers and their associations with congenital malformations during early pregnancy

BACKGROUND

Fetal facial profile could be measured during the early pregnancy. Its abnormalities might be associated with certain congenital malformations. We aimed to study the associations between fetal facial profile measurements with crown-rump length and congenital malformations (cleft lip and palate, micrognathia, and open spina bifida) during early pregnancy.

METHODS

We performed a prospective cross-sectional study between June 2019 and April 2022. Pregnant women at a gestational age between 11-13+ 6 weeks were enrolled. Two sonographers performed fetal facial profile measurements independently. The associations between these measurements with crown-rump length and congenital malformations were evaluated.

RESULTS

There were 406 and 25 fetuses without or with congenital malformations, respectively. Two sonographers showed satisfactory inter- and intra-observer agreements and reproducibility. The maxillary gap was only observed in 7.6% of normal fetuses, whereas all cleft lip and palate fetuses had a maxillary gap ≥ 0.8 mm. The crown-rump length was negatively correlated with frontomaxillary facial angle, inferior facial angle, and profile line distance but positively correlated with maxilla-nasion-mandible angle, facial maxillary angle, frontal space distance, and palatine maxillary diameter. These measurements showed various significant changes with different congenital malformations.

CONCLUSIONS

Measurements of fetal facial profile in early pregnancy were feasible with satisfactory reproducibility. These measurements correlated with crown-rump length and showed significant differences with certain fetal congenital malformations.

Understanding the distinction between cleft lip and cleft palate: a critical step for successful prenatal detection

PURPOSE OF REVIEW

Orofacial clefts (OCs) are among the most common congenital anomalies, however, prenatal detection of cleft palate without cleft lip (CP) remains low. CP is associated with a higher risk of associated structural anomalies, recurrence risk and genetic aberrations. There is opportunity to optimize prenatal diagnosis, counseling and diagnostic genetic testing for OCs.

RECENT FINDINGS

Improving prenatal diagnosis of CP requires understanding that embryologically, the secondary palate develops from the 6th to the 10th week and fuses with the primary palate by the 12th week. Multiple first, second and third trimester 2D ultrasonographic markers for OCs have been described including the maxillary gap, frontal space, maxilla-nasion-mandible angle, retronasal triangle, palatino-maxillary diameter, equal sign, nonvisualization or gap in the soft to hard palate interface and loss of the superimposed line. We discuss the technique, evidence and limitations of each.

SUMMARY

Prenatal detection of OC can be optimized by employing 2D sonographic markers. Prenatal detection of CP may be improved by recognizing its high association with retrognathia/micrognathia.

Ultrasound and fetal magnetic resonance imaging: Clinical performance in the prenatal diagnosis of orofacial clefts and mandibular abnormalities

Cleft lip, with or without cleft palate, is the most common congenital craniofacial anomaly and the second most common birth defect worldwide. Micrognathia is a rare facial malformation characterized by small, underdeveloped mandible and frequently associated with retrognathia. Second- and third-trimester prenatal ultrasound is the standard modality for screening and identification of fetal orofacial abnormalities, with a detection rate in the low-risk population ranging from 0% to 73% for all types of cleft. The prenatal ultrasonography detection can also be performed during the first trimester of pregnancy. Given the potential limitations of obstetric ultrasound for examining the fetal face, such as suboptimal fetal position, shadowing from the surrounding bones, reduce amniotic fluid around the face, interposition of fetal limbs, umbilical cord and placenta, and maternal habitus/abdominal scars, the use of adjunct imaging modalities can enhance prenatal diagnosis of craniofacial anomalies in at-risk pregnancies. Fetal magnetic resonance imaging (MRI) is a potentially useful second-line investigation for the prenatal diagnosis of orofacial malformations with a pooled sensitivity of 97%. In this review, we discuss the role of ultrasound and fetal MRI in the prenatal assessment of abnormalities of the upper lip, palate, and mandible.

Prenatal diagnosis of micrognathia: a systematic review

Purpose

This systematic review aimed to analyze the characteristics of different diagnostic techniques for micrognathia, summarize the consistent diagnostic criteria of each technique, and provide a simple and convenient prenatal diagnosis strategy for micrognathia.

Methods

In accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, the search was undertaken in three international databases (PubMed, Scopus, and Web of Science). The three reviewers assessed all papers and extracted the following variables: author's name and year of publication, country, study design, number of participants, gestational age, equipment for prenatal examination, biometric parameters related to micrognathia, main results.

Results

A total of 25 articles included in the analysis. Nineteen articles described cross-sectional studies (76 percent), 4 (16 percent) were case-control studies, and 2 (8 percent) were cohort studies. Fifteen studies (60 percent) had a prospective design, 9 (36 percent) had a retrospective design, and one (4 percent) had both prospective and retrospective design. Thirty-two percent of the studies (n = 8) were performed in USA, and the remaining studies were performed in China (n = 4), Israel (n = 3), Netherlands (n = 3), UK (n = 1), France (n = 1), Italy (n = 1), Belgium(n = 1), Germany (n = 1), Spain (n = 1), and Austria (n = 1). The prenatal diagnosis of micrognathia can be performed as early as possible in the first trimester, while the second and third trimester of pregnancy were the main prenatal diagnosis period. The articles that were included in the qualitative synthesis describe 30 biometric parameters related to the mandible.

Conclusion

Of the 30 biometric parameters related to the mandible, 15 can obtain the simple and convenient diagnostic criteria or warning value for micrognathia. Based on these diagnostic criteria or warning value, clinicians can quickly make a preliminary judgment on facial deformities, to carry out cytologic examination to further clarify the diagnosis of micrognathia.

Study on normal reference value of fetal facial profile markers during the first trimester of pregnancy

BACKGROUND

To establish a normal reference value for fetal facial profile markers during the first trimester of pregnancy.

METHODS

We collected the data of 800 pregnant women who were examined during early pregnancy. The range of values of inferior facial angle (IFA), frontal nasal-mental (FNM) angle, frontomaxillary facial (FMF) angle, mandibulomaxillary facial (MMF) angle, fetal profile line (FPL), and maxilla-nasion-mandible (MNM) angle in normal fetuses of 11-13⁺⁶ weeks was measured and correlated. For the 1,000 fetuses that were screened in the early pregnancy period (11-13⁺⁶ weeks), follow-up the normal fetus, observe and measure the above parameters to obtain the normal measurement range. These markers were measured through GE Voluson E8 ultrasound machines by two experienced sonographers.

RESULTS

A total of Images of 800 fetuses were included in the study. The results showed that the average value of fetal nasal bone was 11.9 mm at 11-13⁺⁶ weeks, which increased with the increase of crown-rump length (CRL); the average value of IFA angle was 64.91°, which has no obvious correlation with CRL; the average value of FNM angle was 143.79°, and the FNM angle decreased slightly with the increase of CRL. Both the FMF angle and the MMF angle decreased with the increase of CRL, and the ratio of FMF/MMF was fixed at 0.75; the average value of MNM angle was 9.55°, which had no obvious correlation with CRL; FP line value was "0" in 177 cases, The positive value of 623 cases did not change significantly with the growth of the fetus, and the gap of the mandible of the normal fetus was almost visible.

CONCLUSIONS

This study established a range of normal reference values for facial and facial angles during early pregnancy, providing a reference for prenatal early detection, early diagnosis of fetal micrognathia, and other facial abnormalities.

Ultrasonographic study of fetal mandibular markers during the first trimester in a Chinese population

AIM

To establish reference ranges for fetal mandibular markers in low-risk singleton pregnancies between 11 and 13 + 6 weeks of gestation in a Chinese population.

METHODS

The inferior facial angle (IFA), transverse, and anteroposterior diameters of the mandible, and mandibular length were measured at 11-13 + 6 weeks of gestation. The utility of these sonographic markers for detecting micrognathia was explored in seven fetuses.

RESULTS

In healthy fetuses at 11-13 + 6 weeks, there were linear correlations between gestational age and the transverse (Y = -15.615 + 1.987X, r = 0.718, p < 0.001) and anteroposterior (Y = -8.557 + 1.101X, r = 0.581, p < 0.001) diameters of the mandible; mean ratio of the anteroposterior: transverse diameters of the mandible decreased with gestational age (Y = 0.603-0.003X, r = 0.018, p = 0.755); there was a positive correlation between crown rump length and mandibular length (mandible length = 0.861 + 0.137*crown rump length; r = 0.723, p < 0.001); and there was a positive correlation between crown rump length and IFA (r = 0.234, p < 0.05). Reference ranges were: mean ratio of anteroposterior diameter: transverse diameter of the mandible 0.56; mean mandibular length 9.05 mm; and median IFA 66.5°. The values for these mandibular markers in seven cases of fetal micrognathia were outside the normal range.

CONCLUSIONS

Evaluations of fetal mandibular markers during first trimester ultrasound screening may contribute to the early detection and diagnosis of micrognathia. We recommend obtaining a subjective impression of the mandible on the mid-sagittal view routinely used to measured nuchal translucency, followed by targeted objective measurements on the mid-sagittal and axial views in suspected cases.

Fetal micrognathia in the first trimester: An ominous finding even after a normal array

OBJECTIVE

To evaluate the prognosis of fetuses with a prenatal diagnosis of micrognathia in the first trimester.

STUDY DESIGN

Over a 3-year period, patients with fetal micrognathia were detected at the time of nuchal translucency screening. The medical records of these pregnancies were reviewed, including maternal demographics, sonographic findings, genetic testing results and pregnancy outcomes.

RESULTS

Forty-three cases of first-trimester micrognathia were included in this study. Chromosomal abnormalities were detected in seven cases. Of the fetuses with a normal array, further investigation of monogenic disorders with whole-exome sequencing was undertaken in 13 cases. Monogenic syndromes were identified in eight cases, including six with de-novo dominant alleles and two with recessive conditions. Whole-exome sequencing was refused in 23 cases; among these, other additional anomalies were found on anatomic ultrasound in 10 cases.

CONCLUSION

This study demonstrated that caution should be adopted when finding an apparently isolated micrognathia in early gestation, even with a normal array. A diagnosis of genetic syndrome or multiple anomalies on subsequent scans is most likely, and will affect the final prognosis.

First-Trimester Diagnosis of Agnathia-Otocephaly Complex: A Series of 4 Cases and Review of the Literature

First-trimester ultrasound findings in 4 fetuses with agnathia-otocephaly complex are described. In addition, information from 3 cases reported in the literature was also reviewed, for a total of 7 cases analyzed. All 7 fetuses presented with agnathia and 6 with ventrocaudal displacement of the ears (melotia/synotia). Four fetuses had holoprosencephaly. In 6 cases, the parents opted for termination of pregnancy. The remaining case resulted in premature delivery at 26 weeks due to severe polyhydramnios and early neonatal death. This report highlights the important role of ultrasound in the identification of agnathia-otocephaly complex in the first trimester of pregnancy.

First trimester sonographic diagnosis of orofacial defects. Review of literature

Ultrasound has been used since the 1950s as a useful tool for the screening of several pregnancy abnormalities. The National Institute for Excellence in Health and Care (NICE) guidelines for prenatal control recommend its routine use between 12 and 20 weeks of gestational age, given that during the first trimester, a series of very frequent markers that determine a high risk of fetal anomalies can be evaluated. Among these markers, the most frequently studied are: increased nuchal translucency, the absence of nasal bones, increased tricuspid regurgitation, and altered flow in the venous duct. There is also a new ultrasound technique consisting of the evaluation of the retronasal triangle view, which captures the coronal plane of the face in which the primary palate and the frontal process of the maxillary are simultaneously visualized, presenting high sensitivity and specificity for malformations such as oropalatine clefts, malformations of the nasal bones, and micrognathia. The purpose of this article is to make a comprehensive review of first trimester sonographic diagnosis of orofacial defects.

Frontal space distance in facial clefts and retrognathia at 11-13 weeks' gestation

OBJECTIVE

To examine the frontal space (FS) distance in first-trimester fetuses with bilateral, unilateral or median cleft lip and palate and in those with retrognathia.

METHODS

This was a retrospective study using stored two-dimensional ultrasound images of fetal profiles that were recorded at the time of the nuchal translucency (NT) scan at three prenatal medical centers. Images of 300 normal fetuses and 53 fetuses with facial defects were obtained. To measure the FS distance, a line was drawn between the anterior edge of the mental protuberance of the mandible and anterior edge of the maxilla (MM line) and extended upwards in front of the forehead. The perpendicular distance (FS distance) between the MM line and the skin at the point of largest excursion of the fetal forehead was measured. In cases in which the MM line was located anteriorly to the forehead, the distance was measured in the same fashion but was multiplied by -1. Two operators measured the FS distance twice, independently of each other. FS distances were transformed into Z-scores based on the linear relationship with crown-rump length (CRL) in normal fetuses. The distribution of FS distances in fetuses with bilateral, unilateral or median cleft lip and palate and those with retrognathia were compared with that in the normal group using Student's t-test.

RESULTS

A search of the centers' databases identified 53 abnormal cases including 20, nine and eight with a bilateral, unilateral and median cleft lip and palate, respectively, and 16 cases of retrognathia. In fetuses with bilateral, unilateral and median clefts and those with retrognathia, median delta NT was 1.00 mm, 0.37 mm, 4.00 mm and 0.26 mm, respectively. Among these affected groups, 12 (60.0%), six (66.7%), two (25.0%) and eight (50.0%) fetuses had an abnormal karyotype. In the normal population, FS distance was dependent on CRL measurement (FS = 6.62 - (0.08 × CRL); r = -0.539; P < 0.0001). In fetuses with a bilateral and median cleft and in those with retrognathia, FS distance was significantly different from that in the normal population (all P < 0.0001), however, the difference was not significant in fetuses with unilateral clefts (P = 0.103). The respective Z-scores of FS distance for fetuses with bilateral, unilateral and median clefts and retrognathia were -9.7 ± 2.0, -3.1 ± 5.1, 8.2 ± 3.4 and -7.3 ± 2.3. Measurements were ≥ 99(th) and ≤ 1(st) centiles in all but one (98.1%) case.

CONCLUSION

The FS distance appears to be a helpful tool in the detection of facial clefts at 11-13 weeks' gestation. Copyright © 2015 ISUOG. Published by John Wiley & Sons Ltd.

Maxillary gap at 11-13 weeks' gestation: marker of cleft lip and palate

OBJECTIVE

To describe a new sign of cleft lip and palate (CLP), the maxillary gap, which is visible in the mid-sagittal plane of the fetal face used routinely for measurement of nuchal translucency thickness.

METHODS

This was a retrospective study of stored images of the mid-sagittal view of the fetal face at 11-13 weeks' gestation in 86 cases of CLP and 86 normal controls. The images were examined to determine if a maxillary gap was present, in which case its size was measured.

RESULTS

In 37 (43.0%) cases of CLP the defect was isolated and in 49 (57.0%) there were additional fetal defects. In the isolated CLP group, the diagnosis of facial cleft was made in the first trimester in nine (24.3%) cases and in the second trimester in 28 (75.7%). In the group with additional defects, the diagnosis of facial cleft was made in the first trimester in 46 (93.9%) cases and in the second trimester in three (6.1%). A maxillary gap was observed in 96% of cases of CLP with additional defects, in 65% of those with isolated CLP and in 7% of normal fetuses. There was a large gap (>1.5 mm) or complete absence of signals from the maxilla in the midline in 69% of cases of CLP with additional defects, in 35% of those with isolated CLP and in none of the normal controls.

CONCLUSIONS

The maxillary gap is a new simple marker of possible CLP, which could increase the detection rate of CLP, especially in isolated cases.

Prenatal Identification of Pierre Robin Sequence: A Review of the Literature and Look towards the Future

Fetal ultrasonography is an important tool used to prenatally diagnose many craniofacial conditions. Pierre Robin sequence (PRS) is a rare congenital deformation characterized by micrognathia, glossoptosis, and airway obstruction. PRS can present as a perinatal emergency when the retropositioned tongue obstructs the airway leading to respiratory compromise. More predictable and reliable diagnostic studies could help the treating medical team as well as families prepare for these early airway emergencies. The medical literature was reviewed for different techniques used to prenatally diagnose PRS radiologically. We have reviewed these techniques and suggested a possible diagnostic pathway to consistently identify patients with PRS prenatally.

Clinical Significance of First-Trimester Screening of the Retronasal Triangle for Identification of Primary Cleft Palate

OBJECTIVE

To investigate the use of the retronasal triangle (RNT) for identification of orofacial cleft (OC) in the first trimester and the clinical application of three-dimensional (3D) ultrasound techniques for confirming the diagnosis of OC.

METHODS

A total of 5,054 women with singleton pregnancies underwent first-trimester screening for Down syndrome at 11-13(+6) weeks. The RNT was scanned in each fetus, and 3D volumetric images of cases with abnormal or indeterminate RNT were obtained.

RESULTS

Satisfactory images were obtained from all cases. Seven cases (1.4‰) of abnormal RNT were diagnosed as OC in the first trimester, which were confirmed at a 16 weeks scan or at a postmortem examination. One case that was considered a normal RNT was diagnosed with OC at 22(+2) weeks and after term delivery. Six cases of indeterminate RNT were diagnosed as normal by 3D ultrasound. Identification of OC by visualization of the RNT in the first trimester had a sensitivity of 87.5% and a specificity of 99.9%.

CONCLUSION

The RNT is an important sonographic landmark that has a high sensitivity and specificity for the detection of OC in the first trimester. 3D ultrasound is an important tool that aids in confirming diagnosis of OC in the first and second trimesters.

Prenatal diagnosis of isolated agnathia with two and three-dimensional ultrasound

We report a case of isolated agnathia, detected at 21+4 weeks’ gestation by two and three-dimensional (3D) ultrasound when routine morphological scan was performed. The scan showed an alteration of the fetal profile suggesting mandible agenesis, as well as cleft lip and palate, and low implantation ears. No midline alterations were found. Midsagittal sections of the fetal profile and 3D imaging supported the diagnosis of agnathia, and also improved the genetic counseling. The parents decided to terminate the pregnancy. The fetal necropsy confirmed the findings, which correlated with the 3D ultrasound.

Prenatal Detection of Fetal Anomalies at the 11- to 13-Week Scan—Part I: Brain, Face and Neck

In the last 20 years, the role of first-trimester ultrasound screening has expanded from individual calculation of the risk of aneuploidy through measurement of the nuchal translucency to a powerful technique to evaluate important aspects of the fetal anatomy. Traditionally, the full anatomy scan for detection of structural anomalies has been performed in the second trimester of pregnancy. However, with the implementation of the first-trimester scan at 11 to 13 weeks of gestation many of the structural anomalies traditionally detected in the second trimester can now be identified earlier in pregnancy. In the first part of this review we discuss the main ultrasound findings that may facilitate the prenatal detection of fetal brain, face and neck abnormalities in the first trimester of pregnancy.

How to cite this article

Sepulveda W, Illescas T, Adiego B, Martinez-Ten P. Prenatal Detection of Fetal Anomalies at the 11- to 13-Week Scan—Part I: Brain, Face and Neck. Donald School J Ultrasound Obstet Gynecol 2013;7(4):359-368.