Prenatal examination of the fetal profile [1Avni FE, Cos T, Cassart M, et al. Evolution of fetal ultrasonography. Eur Radiol 2007; 17(2): 419-31.
[http://dx.doi.org/10.1007/s00330-006-0307-1] [PMID: 16733679] ] has become more common and detail-oriented alongside technical advances in ultrasonography. Observation of fetal facial structure [2Benacerraf BR, Frigoletto FD Jr, Bieber FR. The fetal face: Ultrasound examination. Radiology 1984; 153(2): 495-7.
[http://dx.doi.org/10.1148/radiology.153.2.6385109] [PMID: 6385109] ] has become an important part of the peri-natal examination [3Zhou Y, Zhu Z, Gao Y, et al. Effects of maternal and fetal characteristics on cell-free fetal DNA fraction in maternal plasma. Reprod Sci 2015; 22(11): 1429-35.
[http://dx.doi.org/10.1177/1933719115584445] [PMID: 25963912] ]. Especially through the 4Dimensional color Doppler ultrasound examination [4Kanenishi K, Hanaoka U, Noguchi J, Marumo G, Hata T. 4D ultrasound evaluation of fetal facial expressions during the latter stages of the second trimester. Int J Gynaecol Obstet 2013; 121(3): 257-60.
[http://dx.doi.org/10.1016/j.ijgo.2013.01.018] [PMID: 23497746] ], visual display of fetal facial structure [2Benacerraf BR, Frigoletto FD Jr, Bieber FR. The fetal face: Ultrasound examination. Radiology 1984; 153(2): 495-7.
[http://dx.doi.org/10.1148/radiology.153.2.6385109] [PMID: 6385109] ] and real-time display of fetal facial three-dimensional images, the expectant father and mother look forward to receiving the first picture of their fetus. This examination is not only needed for diagnosing deformities but also causes an emotional attachment [5de Jong-Pleij EA, Ribbert LS, Pistorius LR, Tromp E, Mulder EJ, Bilardo CM. Three-dimensional ultrasound and maternal bonding, a third trimester study and a review. Prenat Diagn 2013; 33(1): 81-8.
[http://dx.doi.org/10.1002/pd.4013] [PMID: 23169046] ]. Therefore, four-dimensional ultrasound fetal facial imaging technology as compared to the two-dimensional ultrasound in the prenatal diagnosis is now being selected by most pregnant women and their families, due to its clinical significance and social value.

However, there is a small potential disadvantage which has been encountered during four-dimensional ultrasound examination of the fetus. Sometimes, the fetal facial structure is unclear due to the positioning of the fetus [6De Jong-Pleij EA, Ribbert LS, Tromp E, Bilardo CM. Three-dimensional multiplanar ultrasound is a valuable tool in the study of the fetal profile in the second trimester of pregnancy. Ultrasound Obstet Gynecol 2010; 35(2): 195-200.
[http://dx.doi.org/10.1002/uog.7471] [PMID: 20014328] ] (occiput posterior position; limb covering face; umbilical cord obstruction; fetal face being close to the uterine wall or placenta) during examination, and diagnosis. In our hospital, during the fetal 4D ultrasound, the fetus’s center of gravity is changed by means of knee-chest position method, which can rapidly change the facial position of the fetus and facilitate clear imaging of the four-dimensional facial feature. It not only saves time for the ultrasound doctors and patients but is also simple and practical. It is worth promoting this maneuver.

Knee-chest Decubitus position group (Group A): 5-minute post Knee-chest position, Four-dimensional Color Doppler ultrasound showed a clear fetal facial structure in 185 people; 15-minute post was observed in 86 people; 30 minutes post was observed in 77 people. For 12 people, a clear facial feature could not be obtained even after 30 minutes and they were asked to come back the consecutive day for re-examination.

Free activity group (Group B): 5-minute post free activity, Four-dimensional Color Doppler ultrasound showed a clear fetal facial structure in 72 people; 15 minute post was observed in 90 people; 30 minutes post was observed in 140 people. For 58 people, a clear facial feature could not be obtained even after 30 minutes and they were asked to come back the consecutive day for re-examination.

Re-examination for both the groups returning on the second day was successful.

Graph. (1) compares the success rates in both Groups utilizing the two different maneuvers using the following data.

Graph. 1 Comparison of Success rates in two different maneuver groups.

3.1. Data

Two groups of pregnant women after the intervention showed the success rate of facial comparison [n(%)] as follows:

Group A: Post 5,15,30,>30 minutes/1Day: 185 (51.4%), 86 (23.9%), 77 (21.4%), 12 (3.3%)

Group B: Post 5,15,30,>30minutes/1Day: 72 (20%), 90 (25%), 140 (38.9%), 58 (16.1%).

Figs. (2 to 4) shows the obscured and unobscured fetal facial features in both groups A and B.

Fig. (2I) 4D Ultrasound Imaging of Fetal Face at the beginning of the test for a Group A Patient. Facial feature is unclear because its blocked by the hand and arms of the fetus.

Fig. (2II) Successful 4D Ultrasound Imaging of Fetal Face with clear features Post 5 minutes of Knee-Chest Decubitus Positions in the same Group A patient as in Picture 1. [I].

Fig. (3I) 4D Ultrasound Imaging of Fetal Face at the beginning of the test for a Group B Patient. Picture is unclear because face being blocked by artifacts and limbs.

Fig. (3II) Successful 4D Ultrasound Imaging of Fetal Face with clear facial features Post 30 minutes of walking in that same Group B patient as in picture 2. [I].

Fig. (4I) 4D Ultrasound Imaging of Fetal Face at the beginning of the test for a Group A Patient.

Fig. (4II) Successful 4D Ultrasound Imaging of Fetal Face with clear facial features post 5 minutes of Knee-Chest Decubitus Position for that same Group A Patient.

Four-dimensional ultrasound imaging [2Benacerraf BR, Frigoletto FD Jr, Bieber FR. The fetal face: Ultrasound examination. Radiology 1984; 153(2): 495-7.
[http://dx.doi.org/10.1148/radiology.153.2.6385109] [PMID: 6385109] ] of the fetus in pregnant women is highly acceptable these days because it enables pregnant women to see their baby in their own body. This is one of the most touching moments as it marks the successful establishment of the bond [5de Jong-Pleij EA, Ribbert LS, Pistorius LR, Tromp E, Mulder EJ, Bilardo CM. Three-dimensional ultrasound and maternal bonding, a third trimester study and a review. Prenat Diagn 2013; 33(1): 81-8.
[http://dx.doi.org/10.1002/pd.4013] [PMID: 23169046] ] between mother and child. So, many pregnant women are likely to choose this procedure. However, the four-dimensional imaging surface model needs a good sound window set off and an ideal fetal position in order to obtain three dimensional, intuitive and clear images. In a number of cases, some fetuses in the abdomen were prone or their faces were obstructed by the limbs, umbilical cord [8Jian W, Du QT, Lai ZF, et al. Prenatal diagnose of a fetus with harlequin ichthyosis in a chinese family. Taiwan J Obstet Gynecol 2018; 57(3): 452-5.
[http://dx.doi.org/10.1016/j.tjog.2018.04.023] [PMID: 29880184] ] or other obstructions. As a result, it is difficult to see the clear face of the fetus during ultrasound imaging. The traditional and widely used method [4Kanenishi K, Hanaoka U, Noguchi J, Marumo G, Hata T. 4D ultrasound evaluation of fetal facial expressions during the latter stages of the second trimester. Int J Gynaecol Obstet 2013; 121(3): 257-60.
[http://dx.doi.org/10.1016/j.ijgo.2013.01.018] [PMID: 23497746] ], which is used to achieve an unobstructed view of the fetal face is to let the pregnant women move freely or climb stairs. The success rate, in that case, is found to be 20% in 5 minutes and 25% in 15 minutes. Nearly half of the pregnant women needed to walk for half an hour or more, which consumed a lot of time. So, physically and mentally exhausted pregnant women were often likely to give up the quest automatically. In contrast, the knee-chest decubitus position results in fully acceptable fetal facial clarity in a very short span of time. A 51.4% success rate is achieved in 5 minutes. This method besides being simple, safe and effective, is substantially more convenient for patients, clinics and hospitals and also is therefore worth promoting.

This is such an amazing discovery in the field of Fetal ultrasound [9Kurjak A, Stanojevic M, Azumendi G, Carrera JM. The potential of four-dimensional (4D) ultrasonography in the assessment of fetal awareness. J Perinat Med 2005; 33(1): 46-53.
[http://dx.doi.org/10.1515/JPM.2005.008] [PMID: 15841614] ], because it enables the mother to see her child’s face even before delivery and establishes a more human touch and connection developed with her. There are instances when the clear visualization of the fetal face would not be possible because of the face being obstructed with fetus’s other body parts. So it is very important to manipulate different positions in order to be able to obtain a clear face of the fetus.

Sometimes, even after a long duration of walking by the mother, it is still impossible to obtain a clear image of the fetal face. In that case, we ask them to lie down on their belly for some time, that enables us to get a clear picture.

This is not harmful to the pregnant mother as neither does this compromise any blood flow to the fetus, nor does this affect the pregnant mothers health condition [10Reid VM, Dunn K, Young RJ, et al. The human fetus preferentially engages with face-like visual stimuli. Curr Biol 27(12): 1825-1828 e3.].

The only kind of problem which might be encountered while examining few patients would be their unwillingness to lie down in the same position for more than 5 minutes or just an uneasy feeling while lying down in that position. This is not medically relevant but the patient’s wishes should be acknowledged. On the other hand, rather than waiting for almost 30 minutes or sometimes even till next day to get a clear view of the fetus, the knee-chest maneuver enables a mother to quickly get a clear and unobstructed view of her unborn child.

Although Knee-chest decubitus position considerably decreases the total time required for a patient to achieve a 4D ultrasound image, there are minor limitations [11Zhen Y, Dong N, Siping C, Shengli L, Tianfu W, Baiying L. Fetal facial standard plane recognition via very deep convolutional networks. Conf Proc IEEE Eng Med Biol Soc 2016; 2016: 627-30.
[PMID: 28268406] ]. Some advanced stage pregnant patients would not be willing to lie down in this position given their inner discomfort and anxiety. Some patients might not agree to lie down for such a long time in the same position. Furthermore, allowing one patient to lie for 30 minutes in a Knee-chest decubitus position would be quite inefficient resulting in a prolonged waiting period for a large number of patients in the queue to get checked. Nevertheless, the present study indicates that the knee-chest procedure will be unsuccessful in a substantially smaller proportion of patients than the free activity strategy [12Pooh RK, Kurjak A. Novel application of three-dimensional HD live imaging in prenatal diagnosis from the first trimester. J Perinat Med 2015; 43(2): 147-58.
[http://dx.doi.org/10.1515/jpm-2014-0157] [PMID: 25014518] ]. As benefit outweighs the risk, this maneuver can still be considered to cut down on valuable examination time and be used successfully worldwide.

As seen from the study, the knee-chest decubitus position compared to the free activity proved to be successful in the delineation of the fetal facial structure. In a larger proportion of patients for whom the first-time imaging was not able to provide a clear picture, knee-chest decubitus position for 5 minutes proved to be quite successful. If this maneuver is carried out, it will successfully reduce real time ultrasound imaging time and also reduce the disappointment and stress of the mother when not being able to view the fetuses face at the first instance.