Baby Hand 20 Week Ultrasound What Is N/l Abbriviation on Ultrasound

Australas J Ultrasound Med. 2013 Aug; 16(three): 98–113.

A pictorial guide for the second trimester ultrasound

Michael Bethune, FRANZCOG, DDU, COGU, ^{i , 2} Ekaterina Alibrahim, FRANZCR, ¹ Braidy Davies, Grad Dip US, AMS, ¹ and Eric Yong, MBBS, BMed Sci ¹

Michael Bethune

^oneMedical Imaging Department, The Mercy Infirmary for Women, Melbourne, Victoria, Australia

²Specialist Women'due south Ultrasound Box Hill, Melbourne, Victoria, Australia

Ekaterina Alibrahim

¹Medical Imaging Department, The Mercy Infirmary for Women, Melbourne, Victoria, Australia

Braidy Davies

¹Medical Imaging Department, The Mercy Infirmary for Women, Melbourne, Victoria, Australia

Eric Yong

ⁱMedical Imaging Department, The Mercy Hospital for Women, Melbourne, Victoria, Australia

Abstract

Introduction: The second trimester ultrasound remains an important screening tool for detecting fetal abnormalities. This pictorial guide for the 2nd trimester ultrasound is designed to assist practitioners to produce a high quality diagnostic survey of the fetus past demonstrating and describing recommended images.

Methods: Each image is discussed in detail and has an associated drawn line diagram to assist in the identification of the important features of that image. There is a description of the salient landmarks and relevant measurements.

Result: The authors hope this article may human action as a useful guide to all practitioners performing 2d trimester ultrasounds.

Keywords: imaging, prenatal ultrasound, second trimester routine ultrasound

Introduction

The 2d trimester ultrasound is commonly performed between 18 and 22 weeks gestation. Historically the second trimester ultrasound was often the only routine browse offered in a pregnancy and so was expected to provide information well-nigh gestational age (correcting menstrual dates if necessary), fetal number and blazon of multiple pregnancy, placental position and pathology, besides as detecting fetal abnormalities. ¹ Many patients now take several ultrasounds in their pregnancy with the first trimester nuchal translucency assessment condign particularly common. ^two The 2nd trimester ultrasound is now less often required for dating or detection of multiple pregnancies simply remains very important to notice placental pathology and, despite advances in first trimester anomaly detection, remains an important ultrasound for the detection of fetal abnormalities. In order to maximise detection rates there is evidence that the ultrasound should be performed by operators with specific preparation in the detection of fetal abnormalities. ⁱⁱⁱ

Second trimester ultrasound landmarks

This pictorial guide is provided every bit, despite a big volume of literature on the subject field, it is difficult to find a single publication that describes the landmarks and range of images which are most useful to look for when performing the 2nd trimester ultrasound. These images were all obtained on GE Healthcare Voluson E8 or 730 machines (GE Healthcare, Sydney, Australia). The images provided are representative. Some examinations may yield significantly ameliorate images while other examinations, especially in big patients, may yield much less clear images. The authors are not suggesting that an examination is simply complete if all of these images are presented. Rather, nosotros are suggesting that each labelled landmark is worth examining advisedly during a second trimester ultrasound. Although the important features are described it is beyond the scope of this article to discuss the associated pathologies of each characteristic.

This guide is presented roughly in cephalic to caudal lodge, but where possible grouped by organ organization. Operators would benefit from a systematic approach to ensure that all structures are seen even in difficult circumstances, as information technology can be possible to miss a structure, specially when there are active fetal movements.

Recording the ultrasound

It is useful to accept some record of the examination for future reference. Video clips or DVD recording of the scan has the advantage of providing moving images, which is peculiarly helpful when assessing the fetal heart. A series of withal images is however easier to shop and refer to in the future. Images should clearly display identifying information such as the patient's full name; birth date; medical record or identification number; date of the ultrasound test; and site where the exam was performed (hospital or private exercise), ⁴ ensuring compliance with local legal requirements.

Biometry

At that place are a number of measurements to take during the examination. Some measurements of fetal size should be included in the formal study of each examination. The minimum measurements to study are: biparietal diameter (BPD), head circumference (HC), abdominal circumference (AC), and femur length (FL). ^{5 – 7} Other biometry which could be reported include: humerus length (HL), nasal bone length (NB), nuchal fold (NF), cerebellar diameter (TCD), cisterna magna and cervical length. A combination of BPD and HC measurements can be used to summate an estimated date of delivery (EDD). ^viii

General scanning principles

Many automobile pre‐sets are a compromise of resolution and persistence and it is important to have a high resolution pre‐set available. A separate pre‐set with higher frame rates and higher contrast is useful for cardiac images. When taking images the structure of involvement should occupy about 75% of the screen to maximise resolution. Write zoom (pre‐acquisition) is the zoom style of choice as it has college resolution than read zoom (postal service acquisition).

Because of the run a risk of artefacts it is often useful to visualise the major structures in at least two planes. The measurement techniques recommended here are widely accepted techniques, notwithstanding some charts may utilise unlike techniques and each operator should measure in accord with the charts agreed inside their own work place and population.

Amniotic fluid assessment is normally subjective ^nine but maximum vertical pocket or amniotic fluid Index (AFI) tin can be used if there is concern about excess or insufficient amniotic fluid.

Fetal movements should be observed and commented upon. It is essential to see flexion or extension of a limb at least one time during the scanning procedure to reduce the take chances of missing a case of arthrogryposis. ^ten Similarly the opening of the hands to exclude clenched fingers is important to rule out several syndromes. ^eleven

The fetal head

The standard centric fetal brain planes include the biparietal diameter, the transventricular plane and the cerebellar airplane (Figures 1–3). Many of the fetal measurements are taken from these planes including the BPD and HC. Measurements of the Cerebellum, Cisterna Magna and Nuchal fold can exist useful. Further images of the head which may add value include the mid sagittal plane to view mid line brain structures, coronal cerebellum and coronal face up (Figures 4–vi).

Biparietal bore plane.

• 1

  Biparietal diameter

• 2

  Cavum Septum pellucidum

• three

  Thalami

• 4

  Hypoechoic skull sutures

• 5

  Third Ventricle

• 6

  Choroid

• 7

  Posterior Lateral ventricle

• eight

  Corpus callosum

Cavum septum pellucidum.

The corpus callosum is visible as a hypoechoic region just anterior to the CSP.

Cerebellar plane.

• i

  Cavum Septum Pellucidum

• 2

  Cerebellar lobes

• 3

  Cerebellar vermis

• iv

  Cisterna Magna

• v

  Nuchal Fold

• six

  Cerebral peduncles

• 7

  Falx

• eight

  Thalami

Coronal cerebellum.

• 1

  Cerebellar lobe

• two

  Cerebellar vermis

• 3

  Falx

• 4

  Posterior horn of lateral ventricle

• v

  Cisterna magna

Figure 1: Biparietal diameter airplane

This is a cross section of the fetal caput obtained at the level of the thalami. The cerebellum, orbits and ears should non exist visualised in this scanning plane. The falx should be positioned horizontal and equidistant from both parietal bones to avoid acynclitism (head tilted to one side). The operator should expect for a symmetrical advent to both hemispheres. The continuous midline echo representing the falx is cleaved in the anterior third by the cavum septum pellucidum (CSP). Behind this in the centre of the falx a thin slit representing the third ventricle is often visible.

The BPD measurement is obtained from outer skull bone to inner skull bone (leading edge to leading edge), perpendicular to the falx at the maximum diameter. ¹² The HC is measured every bit an ellipse around the outside of the skull bones. Both of these measurements can exist used to confirm gestational age. A caput circumference measuring less than 3 standard deviations from the hateful may bespeak microcephaly. ¹³

Slight gaps in the echogenic skull bone outline are evident and correspond the skull sutures. There should be a normal oval skull shape with no depression of the petrous temporal bones and no angulation nearly the sutures. The normal bone density of the skull should exist more echogenic than the falx.

Figure 2: Transventricular plane

Transventricular airplane.

The lower right images demonstrate that angling the fetal head can improve visualisation of the near field lateral ventricle.

• ane

  Near field posterior horn of lateral ventricle

• two

  Choroid

• iii

  Far field posterior horn of lateral ventricle

• 4

  Cavum Septum Pellucidum (CSP)

• five

  Corpus callosum (CC)

This image is a cross‐section of the head merely above the BPD‐ airplane, at the level of the atrium of the lateral ventricles but still with the CSP in view. The epitome ordinarily demonstrates a substantial length of choroid plexus superior to the level of the thalami.

The lateral ventricular measurement can exist taken from inner wall to inner wall at the level of the glomus of the choroid plexus. The lateral ventricle should exist measured at right angles to the falx. ¹² Over the gestational range xv to xl weeks ten mm or larger is considered aberrant. ^xiv

It may exist advantageous to measure the near field ventricle too as the far field lateral ventricle. Angling the probe to place the falx at ~15° to horizontal may facilitate visualisation of the about field ventricle.

Figure three: Cavum septum pellucidum

It is beneficial to await carefully at the CSP to ensure information technology is distinguished from the third ventricle and to identify the corpus callosum. Just anterior to the CSP in that location is often a fine hypoechoic 'U' shaped structure representing the inductive leaflets of the corpus callosum. The CSP is an important landmark for development of the corpus callosum, if it is not visualised then there is a chance of a range of brain abnormalities. ^xv

Effigy 4: Cerebellar plane

This plane is inferior to the BPD airplane with the probe tilted backward into the posterior fossa. The aeroplane is correct when one can visualise the thalami and cavum septum pellucidum in the same aeroplane equally the cerebellum. ¹²

The cerebellum is a dumbbell shaped structure, with symmetrical lobes. The central vermis is slightly more than echogenic than the lateral lobes.

The trans‐cerebellar diameter is the widest measurement across the cerebellum, perpendicular to the falx. Cerebellar size in millimetres correlates with gestational age upwards to 20 weeks and is larger than gestational historic period after this fourth dimension. A cerebellum measuring 2 mm less than gestational historic period is a apropos finding. ¹⁶

The cisterna magna can be measured from the posterior margin of the cerebellar vermis to the inside of occipital bone in the midline (following an imaginary continuation of the falx). A measurement of 2–10 mm is normal in the second and third trimesters. ¹⁷

The nuchal fold is a measurement taken from outer skin line to outer bone in the midline (following an imaginary continuation of the falx). Less than half dozen mm is considered normal upwardly to 22 weeks.

When measuring the nuchal fold line-fishing the probe to identify the falx at ~15° to horizontal may provide a sharper image of skin line and bone. This may minimise the run a risk of beam width artefact causing a thickened nuchal fold measurement.

Figure 5: Corpus callosum

Corpus callosum.

• i

  Corpus callosum

• two

  Cavum Septum Pellucidum

• three

  Nasal bone

This is a mid‐sagittal image through the fetal head. A mid sagittal plane can frequently visualise most of the length of the corpus callosum. Visualisation of the corpus callosum tin can be facilitated by trying to angle the probe so as to scan through the area of the anterior fontanelle. The corpus callosum connects the left and right lobes of the brain. It sits superior to the cavum septum pellucidum and extends backwards as a hypoechoic line. The presence of the corpus callosum can exist confirmed with color Doppler of the pericallosal artery. ^eighteen

Figure 6: Coronal cerebellum

This is a coronal image through the dorsum of the fetal head. This image may exist useful to demonstrate normal depth of the cerebellar vermis. The cerebellar lobes should be equal size. The vermis of the cerebellum should exist more than i/2 the summit of the lobes. ^xix

The fetal face up

The facial structures can exist examined both coronally and axially. The orbits, nose and rima oris need to exist separately visualised (Figures seven–eleven). Areas which warrant particular attention are the size and spacing of the eyes likewise as the upper lip (which is best imaged in two planes). There are a number of ultrasound techniques which have been suggested to amend detection of facial abnormalities including measurement of facial angles and 3D ultrasound techniques, ^{20 , 21} these techniques are usually employed when at that place is a suspicion of an abnormality rather than in the routine setting and are beyond the telescopic of this paper. Shortening (hypoplasia) of the nasal bone has been associated with Down syndrome ²² (Effigy 12).

Coronal Orbits.

• 1

  Orbit

• ii

  Lens of the eye

• 3

  Nasal bridge

Lower lip and mandible.

• one

  Lower lip

• ii

  Mandible

Contour and nasal bone

• one

  Nasal bone

• 2

  Olfactory organ

• 3

  Mandible

• 4

  Difficult palate.

Figure 7: Coronal orbits

This is a coronal image of the dorsum of the face, through the orbits. The orbits should be equal size with the gap between each orbit approximately the same as the width of each orbit (dividing the face into thirds). The lenses can exist seen as fundamental circles that should non accept internal echogenicity. Lens opacity may indicate congenital cataracts.

Figure viii: Coronal lips and nose

Coronal lips and nose

• 1

  Ii nostrils

• 2

  Upper lip

• 3

  Lower lip

• 4

  Mentum

This image is obtained by moving the scanner forward from the coronal orbital view to the very forepart of the face. This image demonstrates 2 nostrils and a separate intact upper lip. Being able to visualise the tip of all four structures (the olfactory organ, upper lip, lower lip, and chin) in the same coronal image makes micrognathia an unlikely finding.

Figure 9: Axial orbit and lenses

Centric orbit and lenses.

• one

  Orbit

• 2

  Lens

• 3

  Nasal bridge

This is a transverse section of the fetal confront though the orbits. The face needs to be looking up for all-time views. The orbits should be approximately equal size and should exist evenly spaced. The width of the nasal bridge between each orbit is approximately the aforementioned as the size of each orbit – dividing the face into thirds.

Figure x: Upper lip and palate

Upper lip and palate.

• 1

  Upper lip

• 2

  Hard palate.

This is a transverse epitome used to obtain a cantankerous section through the upper lip and hard palate. It demonstrates an intact skin line of the upper lip (no cleft). Backside this is an echogenic intact hard palate; this confirms the correct aeroplane, and is useful to distinguish palate involvement if a cleft lip is present. The hard palate has internal areas of reduced echogenicity representing tooth sockets. This image does non exclude fissure of the soft palate or secondary hard palate.

Figure 11: Lower lip and mandible

This is a transverse image obtaining a cross section through the lower lip and jaw. The image demonstrates an intact lower jaw line. The width of the mandible should exist similar to the width of the maxilla and may be reduced in micrognathia. Once again tooth sockets are credible.

Figure 12: Profile and nasal bone

This is a mid‐sagittal paradigm best taken with the angle of the face up at most 45°. ²² The skin line over the olfactory organ should be close to horizontal. This is a slightly more laid back angle than the corpus callosum view. A slight gap between the nasal bone and the frontal bone should be visualised to help identify the extent of the nasal bone.

The full length of the echogenic calcified nasal os can be measured. The 2.5th centile for the nasal os measurement has been reported as 4.4 mm at xviii weeks and five mm at xx weeks. ²³ Other authors take used the 0.75th multiples of the median (MoM) being three.6 mm at 18 weeks and 4 mm at 20 weeks. ²⁴ A hypoplastic nasal os has been associated with an increased risk of Down's syndrome. ²⁵

There should be no frontal bossing – no forwards sloping of the forehead. The tip of the olfactory organ, upper lip, lower lip, and chin should line up forth the same imaginary line. If the chin is significantly backside this imaginary line and so micrognathia is suspected. ²⁶

The fetal chest and eye

It is important to establish situs. Both the heart and tum should be seen to be on the left side of the fetus. Establishing situs can be confusing, especially for learning practitioners due to variable fetal positions.

1 method to ostend visceral situs (sometimes referred to as the Cordes technique) has been demonstrated to be useful in normal and abnormal situations. ²⁷ The technique is to orientate the fetal head to the correct side of the ultrasound screen with the fetus lying horizontally across the screen. From this starting position, rotate the transducer xc° clockwise to obtain a transverse image of the fetus through the fetal middle. If the left hand of the operator is placed in front of the ultrasound screen positioned every bit an 'L' shape with the tips of fingers pointing towards the fetal sternum and the palm placed on the fetal spine, the pollex will now be pointing towards the left side of the fetus.28

Both hemidiaphragms tin exist visualised sagittally (Figures 14 and ​ 15). The lung fields should be advisedly inspected for cystic or echogenic areas.

Diaphragm and lungs.

• one

  Breadbasket

• 2

  Diaphragm

• 3

  Heart

• 4

  Lungs

Coronal situs.

• i

  Tum

• 2

  Centre

• 3

  Scapula

• 4

  Diaphragm

• 5

  Iliac crest

Cordes Technique. The operator places his left manus in front of the screen with the palm on the spine and the fingers pointing at the sternum – the pollex of his left hand now points to the left side of the fetus.

The heart is a hard organ to appraise due to the size, rapid movements and large number of small parts. It is unfortunately besides a common site for abnormalities. This is an area of the examination which is best washed in real time or saved every bit a video clip. Likewise as the internal cardiac structures the examiner must exist certain that the middle is correctly positioned on the left side of the breast, with the interventricular septum at about a 45° bending and is of normal size.

The centric images presented here are based on the five curt axis views ²⁹ (Figures 17–24). These views can also be assessed with color and/or power Doppler. Sagittal views of the chest can be also used to evidence the fetal arterial vessels (Figures 25–28). The heart rate should exist noted throughout the scanning time to look for arrhythmias and can be recorded (Figure 29). Actress views of the systemic venous return to the correct atrium can be readily obtained (Effigy 30).

Four chamber view of heart.

• 1

  Correct ventricle (RV)

• 2

  Moderator ring

• iii

  Left ventricle (LV)

• 4

  Left atrium (LA)

• 5

  Foramen ovale

• half-dozen

  Descending aorta

• 7

  Ribs

• 8

  Pulmonary veins

• nine

  Right atrium (RA)

3 vessels and trachea view (3VT), Doppler assessment. The correct direction of flow (away from the heart) is demonstrated in both the aorta and ductus Arteriosus.

Aortic arch.

• i

  Aortic curvation

• 2

  Three head and neck vessels ascend from the aorta

• 3

  Descending aorta

• 4

  Spine

• 5

  Heart

Ductal curvation, Doppler assessment.

Demonstrates flow away from the heart with no obvious turbulence or opposite period and no tributaries directed towards the neck.

SVC & IVC.

• 1

  Superior vena cava

• ii

  Right atrium

• 3

  Inferior vena cava

• 4

  Diaphragm

• 5

  Spine

4‐bedchamber with blood menstruum – intraventricular septum. Color period is seen into both ventricles, all of the way to the noon. Flow is demonstrated across the foramen ovale.

LVOT Doppler assessment. Forward flow is seen beyond the aortic valve with no obvious turbulence.

RVOT Doppler assessment. No turbulence is seen across the pulmonary valve, the direction of catamenia down the ductus arteriosus is correct.

Aortic curvation, Doppler assessment.

Figure 14: Diaphragm and lungs

This sagittal image demonstrates intact diaphragms on each side especially posteriorly near the spine, a mutual site for diaphragmatic defects. The stomach is visible beneath and centre higher up the diaphragm. It is also beneficial to identify homogeneous actualization lung fields to attempt to exclude echogenic or cystic lung lesions.

Figure 15: Coronal situs

This is a coronal section through the thorax and abdomen. The eye and stomach are observed to be both left sided with the diaphragm as an intact line between.

Figure 16: Abdominal situs

Intestinal situs.

• 1

  Stomach

• 2

  Aorta

• iii

  IVC

• 4

  Spine

This epitome is a transverse department through the upper belly just below the four‐chamber view of the heart. It is the same section or just above the level of the abdominal circumference. The stomach is a left sided cystic construction that should non cross the mid line to the right side.

The aorta sits just in front of the spine, slightly to the left of the spine. The junior vena cava (IVC) is anterior to the aorta and correct sided.

Figure 17 and 18: Iv chamber view

This is an centric view through the lower office of the fetal chest. The best B‐way images are obtained with the noon orientated superiorly. Obtaining a full length of a rib on each side is a proficient technique to avoid an oblique section.

There are a big number of features to demonstrate in this image, each should be separately considered.

• 1

  Size of the heart should exist ~i/iii the size of the thorax.

• two

  Axis of the interventricular septum is ~45° pointing to the left.

• 3

  Left and correct sides of the center should be approximately equal size. Both left and right ventricles should extend to the apex of the heart and should exist approximately equal in width at the level of the atrio‐ventricular (AV) valves.

• four

  The crux of the middle demonstrates an offset cantankerous arrangement of the AV valves. The right valve (tricuspid) is closer to noon than the left (mitral).

• v

  Normal valve opening and closing with no focal valve echogenicities or thickening.

• 6

  The correct ventricle has the moderator band at the noon, closest to the sternum.

• 7

  The left atrium has pulmonary veins inbound it.

• 8

  The foramen ovale leaflet is visible moving in the left atrium, no more than one-half mode into the atrial cavity.

• 9

  In that location is a single vessel (descending aorta) behind eye simply to the left of the midline (every bit divers by the ossification centre of the spinal torso).

• 10

  There is occasionally some fluid in the pericardial sac where a sparse rim is likely to be physiological (up to 2 mm). ^xxx Color Doppler is best performed with the septum between 45° and horizontal. This allows for improved Doppler detection of flow.

Doppler settings need to be sufficient to demonstrate the physiological atrial septal defect of the foramen ovale and complete filling of the ventricles. ³¹

Figures 19 and 20: Left ventricular outflow tract (LVOT)

Left ventricular outflow tract.

• 1

  Correct ventricle

• 2

  Left ventricle

• 3

  Rib

• 4

  Spine

• 5

  Descending aorta

• half-dozen

  Left atrium (tip of appendage)

• 7

  Correct atrium

• eight

  Ascending aorta (tin can simply see tip of the aortic valve between this and the left atrium)

From the iv chamber view rotate the probe slightly towards the right shoulder and move the probe slightly in a cephalic management. ³² This plane will demonstrate the aorta arising from the left ventricle; its medial wall must be seen to exist continuous with the interventricular septum to exclude aortic override. Often the aortic valve can be seen opening and closing in the centre of the vessel. The ascending aorta is directed towards the right shoulder and turns back to the left at a higher level to course the aortic arch.

Doppler can exist used to demonstrate no turbulence across aortic valve and to ensure that there is the correct direction of menstruum across this valve.

Figures 21 and 22: Correct ventricular outflow tract (RVOT)

Right ventricular outflow tract.

• 1

  Correct ventricle

• 2

  Pulmonary valve

• three

  Pulmonary torso

• 4

  Ductus arteriosus

• 5

  Descending aorta

• 6

  Right pulmonary artery

• 7

  Superior vena cava

• 8

  Ascending aorta

• ix

  Correct atrium

Still in an axial section motion further in a cephalic direction from the four‐sleeping accommodation view. The pulmonary trunk arises from the right ventricle close to the sternum, it is directed backwards towards spine. ³² The pulmonary trunk divides into the ductus arteriosus which continues directly towards the spine in the midline; and the right pulmonary artery which curves backside ascending aorta and SVC. The left pulmonary artery is not usually visible in this plane; it is directed in a more inferior direction. Bifurcation of the pulmonary torso into ductus arteriosus and right pulmonary artery is of import to establish that the vessel arising from the right ventricle is going to the lungs.

Figures 23 and 24: Three vessels and trachea view (3VT)

3 vessels and trachea view (3VI).

• ane

  Pulmonary Curvation

• 2

  Aortic Arch

• 3

  SVC

• 4

  Trachea

• v

  Spine

• 6

  Rib

This is the highest transverse plane for evaluating the fetal centre. Move the transducer further in a cephalic direction from the right ventricular outflow tract view, maintaining an axial department. The iii vessels are, from left to right: the top of the pulmonary curvation, the aortic arch and the SVC. ³³ The trachea lies to right of the aorta and behind the SVC and has echogenic walls compared to the other vessels.

A 'Five' shaped 'arrowhead' of aorta and ductus is made at their meeting indicate; the aorta is now directed towards the left shoulder. The width of the ductus is slightly larger than that of the aorta. In approximately 1% of fetuses an aberrant right subclavian artery tin can exist seen passing backside the trachea towards the right shoulder, this has been associated with an increased risk of trisomy 21. ³⁴

Figures 25 and 26: Aortic curvation

This is an oblique sagittal view. The aortic curvation arises from the center of the heart and has a curved 'walking stick' shape to its arch. Three head and neck vessels arise from the aorta. The arch can be seen to be continuous with the descending aorta with no arch interruption or narrowing to suggest coarctation.

Doppler Assessment should aim to demonstrate consummate filling of the aorta with color, and forrard menstruum away from the heart with no obvious turbulence. Filling of the three caput and neck vessels is platonic but not always obtainable.

No turbulence is seen in the arch, the head and neck are identified.

Figures 27 and 28: Ductal arch

Ductal arch.

• 1

  Ductal arch arises anteriorly from the heart.

• 2

  Pulmonary valve

• 3

  Descending aorta

• 4

  Heart

This is a mid‐sagittal view of the fetal chest, best obtained with the fetus lying supine. Shadowing from the spine tin can make this a difficult view to obtain when the fetus is decumbent. The ductal arch is directed directly back towards the spine with no head and neck vessels arising from it. The ductus arteriosus is continuous with the descending aorta. In contrast to the curved appearance of the aortic arch there is a straight 'hockey stick' appearance to the ductal arch. The pulmonary valve can often exist visualised opening and closing. No head or neck vessels can be seen arising from this arch.

Effigy 29: Fetal heart rate

The center rate tin exist observed throughout the fetal heart evaluation. Formal measurement of the heart rate is only a snapshot and at that place is considerable middle rate variation, particularly with fetal movements. Heart rate can be measured with M‐mode or pulse wave Doppler. Pulse wave has an added do good of allowing the mother to heart the heartbeat but involves higher energy levels. Actress data can exist gained by placing the M fashion through both a ventricle and atrium to demonstrate the heart rate in both structures.

The normal baseline fetal middle rate in the second trimester is 120–160 beats per infinitesimal. A regular rhythm should be demonstrated.

Figure 30: SVC & IVC into the right atrium

This is an optional epitome not often included in the routine examination but information technology is easy to obtain and is useful when evaluating potential abnormalities. The image is obtained by a para‐sagittal department just to the right of the mid line and but to the right of the ductal arch view.

The superior vena cava and IVC can both exist seen entering the correct atrium; this can exist confirmed with colour Doppler assessment.

The fetal belly

The abdominal circumference is a standard biometry measurement ^{vi , 7} (Figure 31). The umbilical cord insertion should be imaged to look for abdominal wall defects (Effigy 32). The renal tract is reviewed past imaging urine in the bladder with surrounding umbilical arteries (Effigy 33) and assessing the kidneys. The fetal kidneys should be imaged in 2 planes, both coronal and axial (Figures 34 and ​ 35). Although non essential, visualising the renal arteries can help with kidney identification especially if unilateral renal anomalies are suggested (Figure 36).

Abdominal circumference.

• one

  Umbilical vein

• 2

  Middle portal vein

• iii

  Stomach

• iv

  Spine

• v

  Rib

Umbilical string insertion.

• 1

  Umbilical arteries

• 2

  Skin line

• three

  Spine

Bladder and umbilical arteries.

• 1

  Bladder

• 2

  Umbilical arteries

• 3

  Thighs

Centric kidneys.

• 1

  Spine

• 2

  Kidney

• 3

  Renal pelvis

Coronal kidneys.

• 1

  Kidney

• 2

  Renal pelvis

• three

  Aorta

• 4

  Iliac arteries

• five

  Iliac crest

Renal arteries. Coronal section with the aorta horizontal facilitates demonstrates of menstruation from the aorta to each renal artery.

Figure 31: Abdominal circumference

This image is a transverse section of the upper function of the fetal abdomen. This view is straight inferior to the iv–bedroom view. In difficult cases it can exist obtained past placing the fetal spine horizontally across the screen with the tum visible in the centre of the screen and and then rotating the probe 90°.

The stomach should be visualised in the left side of the belly. A 'J' shaped hypoechoic construction is seen in the midline; it should be 1/3 of the way across the abdomen and represents the internal portion of the umbilical vein branching to the right portal vein.

The Intestinal Circumference is measured around the outside of the skin line. It is important that this section is correctly obtained to minimise measurement error. A number of features tin be used to assess if the section is correct: The department should be circular non oval; the kidneys should not exist visible in the section; the string insertion should non be visible; and the 'J' should not extend all of the mode to the skin line anteriorly (umbilical vein should not be visible to out to the skin line). If these features are incorrect then the department may exist oblique and the Air conditioning may exist overestimated.

Occasionally the gall float is visible as a tear shaped hypoechoic structure situated to the right inductive of the umbilical vein. The Adrenal glands can sometimes also exist seen in this department. There should be no cystic dilatation of the bowel or abdominal cysts visible.

Figure 32: Umbilical string insertion

This is a transverse section of the abdomen junior to the abdominal circumference. The best views are obtained with the cord insertion near the 3 or 9 o'clock position. The pare line should be clearly visualised on both sides of the insertion. The base of operations of the cord should insert cleanly into abdominal wall with no evidence of associated mass to propose gastroschisis or omphalocele.

Figure 33: Float and umbilical arteries

This is a transverse section of the abdomen at the level of the bladder. Fluid should be seen within the float at some stage during the examination. A large bladder may be 'keyhole' shaped and may indicate urethral obstruction (partial or complete).

Colour or power Doppler is used to identify the two umbilical arteries that surround the bladder and so are directed towards the string insertion.

These arteries need to be traced around the bladder towards the cord insertion to differentiate them from the iliac vessels that are seen more laterally in the pelvis directed towards the thighs. It is important to ensure that the Doppler settings are suitable for low menses to maximise the ability to detect both arteries.

Figure 34: Axial kidneys

This is a transverse section of the abdomen. Placing the spine uppermost obtains the best image. The kidneys tin be seen on either side of the spine.

Each hypoechoic renal pelvis tin be measured in the anterior posterior management. The normal renal pelvis measures ≤ four mm in the 2d Trimester. ³⁵

Figure 35: Coronal kidneys

This is a coronal section through the dorsum just anterior to the fetal spine. A kidney should be seen on each side of the aorta. Each kidney is 'C' shaped around a single renal pelvis.

The centrality of each kidney is roughly parallel to the aorta; if they angle towards each other at the caudal ends then this may indicate a horseshoe kidney. Each kidney should exist similar sized (xx–22 mm length in the 2d trimester) with no renal cysts visible.

Effigy 36: Renal arteries

This is a coronal section through the back simply anterior to the fetal spine, the aforementioned section as Coronal Kidneys. Low flow settings are needed to observe both arteries. The arteries should extend all of the way into the renal pelvis.

The fetal musculoskeletal system

It is beneficial to paradigm the fetal spine throughout its length and the spine is all-time imaged in three planes: coronal, sagittal and axial (Figures 37–forty).

Spine and pare line – longitudinal.

• 1

  Skin line

• 2

  Bladder

• 3

  Abdominal Aorta

• 4

  Vertebrae

Axial spine images.

Four images of dissimilar levels of the spine clockwise from upper left to lower left: cervical spine, thoracic spine, abdominal spine, lumbar spine.

• 1

  Vertebral torso

• 2

  Ossification middle in vertebral lamina.

• iii

  Intact pare line

• iv

  Clavicle

• five

  Rib

• 6

  Heart

• 7

  Kidney

• eight

  Iliac crest

• 9

  Bladder

Each of the twelve long bones should be separately visualised (Figures 42–47). Although both femurs could be measured it is probably sufficient to only measure one provided both have been seen to be of similar lengths. When imaging the long basic the operator should ensure they are non angulated or bowed, that they are echogenic and are of an advisable length. If there is doubt nearly long os length then they tin each exist individually measured and checked against standardised charts. ³⁶ Easily and anxiety should be separately imaged taking particular care to ensure that both left and right sides are separately seen (Figures 45 and ​ 48).

Leg basic.

The tibia and fibula are noted to be the same length.

• 1

  Tibia

• 2

  Fibula

Humerus.

The humerus is identified on each arm; the posterior acoustic shadow is noted.

Hands.

The hand is best imaged open palmed, the full length of the fingers is seen, and the thumb is non adducted

Male person gender sagittal and axial.

The top image and diagram are mid sagittal and demonstrate the genitalia separate to the string insertion. The bottom axial image and diagram confirms the presence of penis and scrotum between the legs.

• 1

  Penis

• ii

  Scrotum

• 3

  Leg

Effigy 37: Spine and pare line – longitudinal

This is a sagittal midline department; all-time views are obtained if the fetus is prone. There should be an intact skin line i.e. a continuous pare line overlying the back, peculiarly over the sacral region. There should be no spinal angulation or deformity. At the inferior end in that location should be sacrococcygeal tapering of the spine.

Figure 38: Coronal spine

Coronal spine.

• one

  Iliac crest

• ii

  Sacrum

• 3

  Vertebrae

• four

  Ribs

This is a coronal prototype through the back. Often more than than one prototype is required to see the whole spine. The sacrum extends just beyond the iliac wing. Tapering of the spine in the sacrococcygeal region is normal. The examiner should carefully assess for angulation or deformity of the spine and ensure that no hemivertebrae are seen. A slight expansion of the width of the lumbar spine is common.

Effigy 39: Coronal spine – sacrum

Coronal spine – sacrum.

• 1

  Iliac crest

• ii

  Sacrum

• 3

  Vertebrae

This is a coronal prototype through the back designed to more than carefully assess the base of operations of the spine. Sacrococcygeal tapering of the spine is normal; the sacrum extends just below the iliac wing. Separation of the lateral ossification centres or lack of visualisation of the central ossification centres may signal a spinal defect. Occasionally the central ossification centres are not seen due to shadowing artefact from the adjacent iliac wing, angling abroad from a true coronal prototype to an oblique coronal image should assist avert this shadow artefact.

Figure xl: Axial spine images

The whole spine should be assessed in transverse department, this is all-time done past running upward and downwardly the spine in real time merely representative images of each role of the spine can be taken. The 3 ossification centres form an approximately equilateral triangle throughout the length of the spine. Spreading of the laminae to grade a more obtuse angled triangle may signal open up spina bifida. The operator should look for an intact skin line over the spine throughout, taking particular attention to ensure that there are no cysts or masses visible on the back.

Figure 41: Femur

Femur.

• 1

  Femur

• two

  Posterior acoustic shadow

The calcified bone is actually the femoral diaphysis, the epiphyseal ends practice not lapidify until afterward in pregnancy. The image should exist taken with the femur horizontal (perpendicular to the ultrasound beam). ³⁷ This makes information technology easier to see the full extent of the bone and avoid foreshortening. When the total length of the femur is on the screen at that place is often a posterior acoustic shadow noted.

Measure the femur horizontally across the ossified diaphysis down the eye of the shaft of the bone avoiding whatever triangular echogenic extensions (seldom seen before the third trimester). A measurement less than the 2.5th centile may increment the take a chance of aneuploidy and raise concerns about skeletal dysplasia. ³⁸

Figure 42: Leg bones and Figure 43: Heel

Heel.

In that location is a right angle between the sloe of the foot and the leg bones.

• 1

  Tibia

• 2

  Fibula

• 3

  Heel

Two long bones should be seen in each leg. The tibia and fibula are of equal length. A sagittal side on image of each leg will demonstrate the ankle to exist correctly orientated. In order to exclude talipes the heel should be 'square' with the sole of the foot orientated at right angles to the leg basic. The sole of the foot and the length of tibia and fibula should non be able to be seen in the aforementioned prototype.

Figure 44: Feet

Anxiety.

5 toes are identified on each foot.

This epitome is used to ensure that at that place are a correct number of toes on each foot. The leg should not exist visible in aforementioned airplane equally the sole of the foot. The 2nd toe can be longer than the keen toe. There should be no cleft in the human foot. The toes are best counted when they are pointing up towards the transducer.

Effigy 45: Humerus

The humerus is best measured with it lying horizontal across the screen (perpendicular to the sound beam). ³⁷ This makes it easier to see the total extent of the bone and avoid foreshortening. Less than the ii.5th centile may increase the risk of aneuploidy and raise concerns about skeletal dysplasia. ³⁸

Figure 46: Forearm

Forearm.

The ulna is longer than the radius at the elbow.

Normally both bones terminate at the same level at the wrist merely the ulna is longer than the radius past 2–3 mm at the elbow. Both ulnas are lower in the images with wrists on the right of each image. Information technology is of import to identify the total length of the radius as radial ray defects can occur. ³⁹

Figure 47: Easily

Each hand needs to be separately imaged. Hands need to be seen to open fully at least in one case during the scanning time, and should be seen to open at least one time. If the hands remain clenched throughout the scan then at that place is a risk of trisomy eighteen. ⁴⁰ The thumb should not be persistently adducted. ⁴¹

The fetal gender

Rarely genital abnormalities are seen prenatally and therefore it is useful for the sonographer to examine this area. Some departments will allow parents to know the gender of the fetus. If the external genitalia are to be visualised for sex determination then imaging in both mid‐sagittal and axial planes is recommended to minimise error ⁴² (Figures 48–49).

Female person gender sagittal and axial.

The top image and diagram are mid sagittal and demonstrate the flat mons pubis below the string insertion. The bottom axial image and diagram show the iii lines of the labia.

• 1

  Bladder

• 2

  Mons pubis

• three

  Umbilical cord

• iv

  Labia

• 5

  Thigh

Figure 48: Male person gender sagittal and axial

The male genitalia are best assessed past taking 2 images. Firstly a mid‐sagittal image of the lower belly below the cord insertion demonstrates penis and scrotum caudally to the cord insertion. Secondly a transverse paradigm, just below the level of the bladder, best taken with the knees separated. Penis and scrotum are seen between the thighs in this image. Testes are undescended at this gestation, and ordinarily descend after in the third trimester.

Effigy 49: Female Gender sagittal and axial

Equally with the male genitalia the female external ballocks are best assessed past looking from two directions. The first image is a mid‐sagittal image of the lower abdomen demonstrating the apartment mons pubis caudal to the string insertion. Secondly a transverse image, just beneath the level of the bladder, all-time taken with the knees separated. No penis is seen between the thighs, rather there are 3 lines representing the labia visible.

Other structures

The placenta should be visualised throughout to await for abnormalities, placenta previa, or hemorrhages (Figure l). The operator should bank check the entire internal surface of the myometrium to ensure that there is no succenturiate lobe. The position of the placenta needs to exist established to see if information technology is shut to the internal os (Figure 51). The maternal cervical culvert can also be measured, preferably with an empty or nigh empty maternal bladder (Figure 51).

Placenta and cord insertion.

The cord inserts centrally into an anterior placenta. Identification of the insertion point is facilitated by the apply of color or ability Doppler.

Placental site and cervical length.

• 1

  Placenta

• two

  Lower placental edge

• 3

  Cervical canal

• 4

  Fetal limbs

Colour or ability Doppler over the internal os may assistance exclude vasa previa (Figure 52). If there is whatever suspicion of shortening of the cervix or low lying placenta then a transvaginal scan often provides more accurate measurements43 (Effigy 53). Many centres will perform a transvaginal scan to assess the placental site and neck more accurately if at that place is any doubt about placental position.

Doppler over the internal os.

No vasa praevia is seen overlying the internal os

Transvaginal cervical length.

The hypoechoic cervical canal is demonstrated; the vaginal probe is not sitting hard upwardly confronting the cervix and therefore is not artificially elongating the cervical canal measurement.

• ane

  Cervical canal

• two

  Fetal head

• 3

  Maternal bladderz

A review of the uterine wall looking for fibroids or bicornuate uterus and a review of the adnexae for ovarian cysts is suggested (these images are non presented in this publication).

Effigy 50: Placenta and cord insertion

The placenta is quite uniform in appearance at this gestation. Pocket-sized hypoechoic vascular lakes can appear and do not announced significant. ⁴⁴ These normally volition not prove menstruation with power Doppler. Large lakes, greater than 2 cm by 2 cm, may increment the risk of small for gestational age in the third trimester. ⁴⁵ The placenta should be less than four cm thick. ⁴⁶

It is advisable to scan through the placenta to attempt to find where the cord inserts into the placental mass. ⁴⁷ This is easy with an anterior placenta but can be difficult to locate if the fetus is lying on a posterior string insertion. If the cord inserts to the margin of the placenta then it should be reported as a marginal insertion and it is helpful to specify the side of insertion (e.g. upper left, lower right). If the cord inserts into the uterine wall and vessels then course around the wall to insert into the side of the placenta and so this is described as a velamentous insertion. Either marginal or velamentous insertions can increase the risk of succenturiate lobes and vasa previa. These abnormalities should be scanned for advisedly. ⁴⁸

Figures 51 and 52: Placental site and cervical length

This image is obtained by taking a mid‐sagittal view through the cervix. Ensure that the cervical canal can be seen equally a hypoechoic line. The closest edge of the placenta should be located; sometimes this is not in the mid line but situated more laterally. The distance from the lowest edge of the placenta to the internal os should then be measured. A low lying placenta is suggested if the placenta lies less than ii cm from internal os. ⁴⁹ Accurate measurements cannot be obtained with a contraction of the myometrium occurring and time must be given for this to relax. Many centres will perform a transvaginal scan to assess the placental site more accurately if there is any dubiety near placental position. ⁵⁰ Color or ability Doppler over the internal bone is a quick technique to exclude a vasa previa. Occasionally the string is draped over the neck and this can atomic number 82 to erroneous diagnosis of vasa previa, information technology is worthwhile checking once more after asking the female parent to roll from side to side to come across if the cord moves to a different position.

Placing a Doppler box over the internal os is useful to exclude vasa previa (Figure 52). Ane must be sure that whatsoever vessel seen is not only a mobile loop of umbilical cord. If a vasa previa is found an endeavour at locating a succenturiate lobe should also be made.

Figure 53: Transvaginal cervical length

If a measurement of cervical length is requested (usually because of a risk factor for cervical incompetence), or the cervix appears short on abdominal views, the cervix should be assessed transvaginally with an empty bladder. ⁵¹ The operator should aim to obtain a mid‐sagittal view of the cervix demonstrating the hypoechoic cervical canal. Withdrawing the vaginal probe a brusque manner is useful to ensure the probe is not pressing on the cervix as force per unit area on the cervix may artificially elongate the cervical measurement and may prevent opening of the culvert with fundal pressure. The cervix should be measured with and without fundal pressure. ⁵² The shortest length measured with fundal pressure is the virtually of import measurement. ⁵¹

Conclusion

The authors have provided a selection of images which we feel are suitable for a comprehensive screening examination. Other images will be required if an abnormality is suspected or detected. Prenatal ultrasound is a rapidly developing field and other structures may become important in future years and these may require different or extra images.

Not all departments will require each of the images presented in this manuscript to exist obtained at each ultrasound. The authors are not suggesting that a second trimester test is only complete if all these images are presented. Rather the authors hope that presenting these labelled images will assist with education and agreement of the important structures, which tin be visualised at a 2nd trimester anatomy survey. It may not be possible to see every construction in some patients due to fetal position or maternal size. This manuscript may find value equally a pictorial reference in imaging departments.

References

1. Chitty LS, Hunt GH, Moore J, Lobb MO. Effectiveness of routine ultrasonography in detecting fetal structural abnormalities in a low chance population. BMJ 1991; 303 (6811): 1165–69. [PMC gratis article] [PubMed] [Google Scholar]

ii. Nisbet DL, Robertson Air conditioning, Schluter PJ, McLennan AC, Hyett JA. Auditing ultrasound assessment of fetal nuchal translucency thickness: a review of Australian National Data 2002–2008. Aust N Z J Obstet Gynaecol 2010; 50 (5): 450–55. [PubMed] [Google Scholar]

3. Vintzileos AM, Ananth CV, Smulian JC, Beazoglou T, Knuppel RA. Routine second‐trimester ultrasonography in the United States: a cost‐benefit analysis. Am J Obstet Gynecol 2000; 182 (3): 655–60. [PubMed] [Google Scholar]

4. American Institute of Ultrasound in Medicine . AIUM standard for documentation of an ultrasound test. American Plant of Ultrasound in Medicine. J Ultrasound Med 2002; 21 (x): 1188–89. [PubMed] [Google Scholar]

half-dozen. Salomon LJ, Alfirevic Z, Berghella V, Bilardo C, Hernandez‐Andrade E, Johnsen SL, et al, and the ISUOG Clinical Standards Committee . Practise guidelines for performance of the routine mid‐trimester fetal ultrasound browse. Ultrasound Obstet Gynecol 2011; 37 (1): 116–26. [PubMed] [Google Scholar]

7. American Institute of Ultrasound in Medicine . AIUM practice guideline for the operation of an antepartum obstetric ultrasound test. J Ultrasound Med 2003; 22: 1116–25. [PubMed] [Google Scholar]

8. Johnsen SL, Rasmussen Due south. Sollien Accurateness of second trimester fetal caput circumference and biparietal bore for predicting the fourth dimension of spontaneous birth. J Perinat Med 2006; 34 (5): 367–lxx. [PubMed] [Google Scholar]

9. Magann EF, Chauhan SP, Whitworth NS, Isler C, Wiggs C, Morrison JC. Subjective versus objective evaluation of amniotic fluid book of pregnancies of less than 24 weeks' gestation: how can nosotros exist accurate? J Ultrasound Med 2001; 20: 191–95. [PubMed] [Google Scholar]

10. Rink BD. Arthrogryposis: a review and approach to prenatal diagnosis. Obstet Gynecol Surv 2011; 66 (6): 369–77. [PubMed] [Google Scholar]

11. Rypens F, Dubois J, Garel 50, Fournet JC, Michaud JL, Grignon A. Obstetric Us: scout the fetal hands. Radiographics 2006; 26 (3): 811–29. [PubMed] [Google Scholar]

12. International Order of Ultrasound in Obstetrics and Gynecology . Sonographic examination of the fetal primal nervous organisation: guidelines for performing the 'basic examination' and the 'fetal neurosonogram'. Ultrasound Obstet Gynecol 2007; 29: 109–16. [PubMed] [Google Scholar]

13. Bromley B, Benacerraf BR. Difficulties in the prenatal diagnosis of microcephaly. J Ultrasound Med 1995; 14: 303–05. [PubMed] [Google Scholar]

fourteen. Cardoza JD, Goldstein RB, Filly RA. Exclusion of fetal ventriculomegaly with a single measurement: the width of the lateral ventricular atrium. Radiology 1988; 169: 711–14. [PubMed] [Google Scholar]

xv. Winter TC, Kennedy AM, Byrne J, Woodward PJ. The cavum septi pellucidi: why is it important? J Ultrasound Med 2010; 29: 427–44. [PubMed] [Google Scholar]

xvi. Snijders RJ, Nicolaides KH. Fetal Biometry at 14–40 weeks' gestation. Ultrasound Obstet Gynecol 1994; 4: 34–48. [PubMed] [Google Scholar]

17. Colt RA, Cardoza JD, Goldstein RB, Barkovich AJ. Detection of fetal fundamental nervous system anomalies: a practical level of effort for a routine sonogram. Radiology 1989; 172: 403–08. [PubMed] [Google Scholar]

xviii. Achiron R, Achiron A. Development of the human fetal corpus callosum: a high‐resolution, cross‐sectional sonographic study. Ultrasound Obstet Gynecol 2001; xviii: 343–47. [PubMed] [Google Scholar]

19. Malinger Chiliad, Ginath South, Lerman‐Sagie T, Watemberg Northward, Lev D, Glezerman Yard. The fetal cerebellar vermis: normal development as shown by transvaginal ultrasound. Prenat Diagn 2001; 21 (eight): 687–92. [PubMed] [Google Scholar]

twenty. Kurjak A, Azumendi One thousand, Andonotopo W, Salihagic‐Kadic A. Three‐ and four‐dimensional ultrasonography for the structural and functional evaluation of the fetal face. Am J Obstet Gynecol 2007; 196 (1): sixteen–28. [PubMed] [Google Scholar]

21. Rotten D, Levaillant JM, Martinez H, Ducou le Pointe, H , Vicaut Eastward. The fetal mandible: a second and 3D sonographic approach to the diagnosis of retrognathia and micrognathia. Ultrasound Obstet Gynecol 2002; 19 (2): 122–30. [PubMed] [Google Scholar]

22. Sonek JD, Nicolaides KH. Prenatal ultrasonographic diagnosis of nasal bone abnormalities in 3 fetuses with Down syndrome. Am J Obstet Gynecol 2002; 186: 139–41. [PubMed] [Google Scholar]

23. Mogra R, Schluter P, Ogle R, Walter M, Borg M, Hyett J. Normal ranges for fetal nasal bone length determined by ultrasound at eighteen–20 weeks of gestation in a multiethnic Australian population. Aust N Z J Obstet Gynaecol 2011; 51: 347–52. [PubMed] [Google Scholar]

24. Odibo AO, Sehdev HM, Stamilio DM, Cahill A, Dunn Fifty, Macones GA. Defining nasal bone hypoplasia in second‐trimester Downwards syndrome screening: does the use of multiples of the median better screening efficacy? Am J Obstet Gynecol 2007; 197: 361. e1–361.e4. [PubMed] [Google Scholar]

25. Cicero S, Sonek JD, McKenna DS, Croom CS, Johnson L, Nicolaides KH. Nasal bone hypoplasia in trisomy 21 at xv–22 weeks' gestation. Ultrasound Obstet Gynecol 2003; 21 (ane): 15–18. [PubMed] [Google Scholar]

26. Luedders DW, Bohlmann MK, Germer U, Axt‐Fliedner R, Gembruch U, Weichert J. Fetal micrognathia: objective assessment and associated anomalies on prenatal sonogram. Prenat Diagn 2011; 31 (2): 146–51. [PubMed] [Google Scholar]

27. Ozkutlu S, Bostan OM, Deren O, Onderoğlu Fifty, Kale 1000, Güçer S, et al. Prenatal echocardiographic diagnosis of cardiac right/left axis and malpositions according to standardized Cordes technique. Anadolu Kardiyol Derg 2011; eleven (2): 131–36. [PubMed] [Google Scholar]

28. Cordes TM, O'Leary PW, Seward JB, Hagler DJ. Distinguishing right from left: a standardized technique for fetal echocardiography. J Am Soc Echocardiogr 1994; 7: 47–53. [PubMed] [Google Scholar]

29. Yagel South, Cohen SM, Achiron R. Exam of the fetal heart past five short‐axis views: a proposed screening method for comprehensive cardiac evaluation. Ultrasound Obstet Gynecol 2001; 17: 367–69. [PubMed] [Google Scholar]

thirty. Di Salvo DN, Brown DL, Doubilet P Thou, Benson CB, and Frates MC. Clinical significance of isolated fetal pericardial effusion. JUM 1994; 13: 291–3. [PubMed] [Google Scholar]

31. Eggebø TM, Heien C, Berget M, Ellingsen CL. Routine employ of color Doppler in fetal heart scanning in a low‐risk population. ISRN Obstet Gynecol 2012: 496935. Epub 2012 May xx.

32. International Society of Ultrasound in Obstetrics and Gynecology . Cardiac screening examination of the fetus: guidelines for performing the 'basic' and 'extended basic' cardiac scan. Ultrasound Obstet Gynecol 2006; 27: 107–13. [PubMed] [Google Scholar]

33. Yagel Due south, Arbel R, Anteby EY, Raveh D, Achiron R. The three vessels and trachea view (3VT) in fetal cardiac scanning. Ultrasound Obstet Gynecol 2002; 20 (4): 340–45. [PubMed] [Google Scholar]

34. Borenstein Grand, Minekawa R, Zidere V, Nicolaides KH, Allan LD. Aberrant right subclavian artery at 16 to 23 + six weeks of gestation: a mark for chromosomal aberration. Ultrasound Obstet Gynecol 2010; 36: 548–52. [PubMed] [Google Scholar]

35. Benacerraf BR, Mandell J, Estroff JA, Harlow BL, Frigoletto FD Jr. Fetal pyelectasis: a possible association with Down syndrome. Obstet Gynecol 1990; 76: 58–sixty. [PubMed] [Google Scholar]

36. Chitty LS, Altman DG. Charts of fetal size: limb bones. BJOG 2002; 109 (8): 919–29. [PubMed] [Google Scholar]

37. Lessoway VA, Schulzer M, Wittmann BK. Sonographic measurement of the fetal femur: factors affecting accuracy. J Clin Ultrasound 1990; 18: 471–76. [PubMed] [Google Scholar]

38. Bethune Grand. Literature review and suggested protocol for managing ultrasound soft markers for Down syndrome: Thickened nuchal fold, echogenic bowel, shortened femur, shortened humerus, pyelectasis and absent or hypoplastic nasal bone. Australas Radiol 2007; 51: 218–25. [PubMed] [Google Scholar]

39. Kennelly MM, Moran P. A clinical algorithm of prenatal diagnosis of Radial Ray Defects with two and three dimensional ultrasound. Prenat Diagn 2007; 27 (8): 730–37. [PubMed] [Google Scholar]

twoscore. Bronsteen R, Lee Due west, Vettraino IM, Huang R, Comstock CH. 2nd‐trimester sonography and trisomy xviii: the significance of isolated choroid plexus cysts after an examination that includes the fetal hands. J Ultrasound Med 2004; 23: 241–45. [PubMed] [Google Scholar]

41. Ghani Hisham Abdel. El‐Naggar A, Hegazy M, Hanna A, Tarraf Y, Temtamy S. Characteristics of patients with built clasped pollex: a prospective written report of 40 patients with the results of treatment. J Child Orthop 2007; one (5): 313–22. [PMC free article] [PubMed] [Google Scholar]

42. Meagher S, Davison Chiliad. Early second‐trimester determination of fetal gender by ultrasound. Ultrasound Obstet Gynecol 1996; 8: 322–24. [PubMed] [Google Scholar]

43. Iams JD. Cervical ultrasonography. Ultrasound Obstet Gynecol 1997; x: 156–60. [PubMed] [Google Scholar]

44. Thompson MO, Vines SK, Aquilina J, Wathen NC, Harrington K. Are placental lakes of whatever clinical significance? Placenta 2002; 23 (8–9): 685–ninety. [PubMed] [Google Scholar]

45. Hwang HS, Sohn IS, Kwon HS. The clinical significance of large placental lakes. Eur J Obstet Gynecol Reprod Biol 2012; 162 (2): 139–43. [PubMed] [Google Scholar]

46. Lee AJ, Bethune M, Hiscock RJ. Placental thickness in the second trimester: a pilot written report to determine the normal range. J Ultrasound Med 2012; 31 (2): 213–18. [PubMed] [Google Scholar]

47. Sepulveda Due west, Rojas I, Robert JA, Schnapp C, Alcalde JL. Prenatal detection of velamentous insertion of the umbilical string: a prospective color Doppler ultrasound report. Ultrasound Obstet Gynecol 2003; 21: 564–69. [PubMed] [Google Scholar]

48. Rao KP, Belogolovkin Five, Yankowitz J, Spinnato JA 2d. Abnormal placentation: testify‐based diagnosis and management of placenta previa, placenta accreta, and vasa previa. Obstet Gynecol Surv 2012; 67 (8): 503–19. [PubMed] [Google Scholar]

49. Bhide A, Thilaganathan B. Recent advances in the management of placenta previa. Curr Opin Obstet Gynecol 2004; 16 (6): 447–51. [PubMed] [Google Scholar]

50. Royal College of Obstetricians and Gynaecologists . Guideline No. 27. Placenta Praevia and Placenta Praevia Accreta: Diagnosis and Management. RCOG: London, October, 2005. [Google Scholar]

51. Owen J, Yost Due north, Berghella V, Thom East, Swain GA, Dildy GA tertiary, et al. Mid‐trimester endovaginal sonography in women at loftier risk for spontaneous preterm nativity. JAMA 2001; 286: 1340–48. [PubMed] [Google Scholar]

52. Guzman ER, Rosenberg JC, Houlihan C, Ivan J, Waldron R, Knuppel R. A new method using vaginal ultrasound and transfundal pressure to evaluate the asymptomatic incompetent cervix. Obstet Gynecol 1994; 83: 248–52. [PubMed] [Google Scholar]

smithworence.blogspot.com

Source: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5029995/

Share this post