Yearly Archives: 2021

Normal Examination

Normal Spine

Fig 1, Fig 2, Fig 3, Fig 4, Fig 5, Fig 6

–     Mineralization of the spine begins at 8 weeks of gestation. The three ossification centers of individual vertebrae include a single ventral center for the vertebral body (centrum) and two paired dorsal centers that will become the lateral masses and the posterior arch. They are well visualized from 15 to 16 weeks onwards. However, spina bifida can be detected much earlier. The posterior ossification centers begin at the base of the transverse processes. As ossification progresses, the laminae become visible, usually after 19 weeks. The inward angulation of the normal laminae is the opposite of the outward splaying of the laminae seen in spina bifida, an optimal situation for detecting this anomaly. The arch of the upper sacral region is not consistently recognizable until after 25 weeks.

• Technique of examination: The spine can be systematically examined during the second and third trimesters as follows:
  • Adjust the transducer on the maternal abdomen to achieve a cross-section image of the fetal abdomen or thorax.
  • Identify the location of the fetal spine, noting the acoustic shadow behind the spine, and carefully adjust the transducer to demonstrate all three ossification centers.
  • To obtain the sagittal view, from the previous image, make an attempt to bring both posterior centers to the middle of the image, lying horizontally or perpendicular to the ultrasound beam, and then rotate the transducer 90 degrees and meticulously adjust it to obtain the best image of the coronal view.
  • To obtain the coronal view, from the cross-section image, make an attempt to bring both posterior centers to the middle of the image, lying vertically or parallel to the ultrasound beam, and then rotate the transducer 90 degrees and meticulously adjust it to obtain the best image of the coronal view.
• Evaluation of the three views of the spine:
  • On the transverse (axial) view, the anterior ossification center (vertebral body) and posterior ossification centers (pedicles, transverse processes, laminae, and spinous processes) may all be identified as echogenic structures. This view may be superior to longitudinal views in demonstrating small spinal defects, since all three ossification centers can be imaged simultaneously.
  • On the sagittal view, many vertebrae can be visualized on a single image. The curvature can be best evaluated<?is this sentence complete enough?>. The normal spine appears as two parallel lines formed by the vertebral bodies anteriorly and the ossification centers of the lateral processes converging in the sacrum. The lines correspond to the posterior elements of the vertebrae and the vertebral body. This view can optimally demonstrate interruption of the overlying integument when myelomeningocele is present.
  • On the coronal view, many vertebrae can be visualized on a single image. Hence, scoliosis, hemivertebrae, and disorganized vertebrae are optimally visualized on this view. <?can you check the following sentence>The images oriented through the dorsal ossification centers can demonstrate the two parallel rows of echogenicity in these centers and also the extent of a dysraphic defect compared to adjacent vertebrae in the case of spina bifida.

Fig 1:  Normal spine   Cross-sectional scan of the abdomen: posterior ossification centers of spine align vertically

Fig 2:  Normal thoracic spine  Coronal scan of the thoracic spine: normal echodensity and alignment

Fig 3:  Normal spine :   Cross-sectional scan of the abdomen posterior ossification centers of spine align horizontally (arrow = anterior ossification center)

Fig 4:  Normal spinal curvature  Sagittal view of the spine: normal curvature (arrow) with complete overlying skin

Fig 5:  Normal lumbar spine  Coronal scan of the lumbar spine (arrowhead) (arrow = iliac bone)

Potential pitfalls:

• • Incomplete ossification: Scanning in early pregnancy reveals incomplete ossification of the lateral centers. Hence, on the transverse view, the posterior centers may appear to be parallel to one another rather than converging to the midline. This may be misinterpreted as spinal dysraphism.
  • Pseudodyspharism: On the coronal plane of the cervical and lumbar spine, the two parallel lines of posterior centers normally diverge. This divergence should not be mistaken for a spinal dysraphism.
  • Pseudodyspharism: <?please check the following sentence>On the transverse scan of the lumbosacral spine, if the ultrasound beam angled obliquely across the vertebral body of one vertebra but missed the posterior element or the posterior centers of another, this could simulate dyspharism. A normal appearance is restored when the ultrasound beam is reoriented perpendicular to the spinal axis.
• High-quality sonograms can also show the spinal cord within the spinal canal. The central canal is readily detectable within the cord. The more echogenic cauda equina (nerve roots) can be seen distal to the conus medullaris (distal spinal cord). With growth of the spine, the position of the conus medullaris ascends with gestational age.
• The spinal cord neural tissue, like that of most brain tissue, is echopenic. The conus medullaris and the craniocervical junction can be seen, albeit inconsistently, in nearly all fetuses by 18-20 weeks. The tissues surrounding the cord (leptomeninges) are brightly echogenic, as are those that surround the brain, and the dura is usually also seen discretely as a linear bright reflector. In fetuses with myelomeningoceles, determination of the most cephalic spinal level lesion is an important factor in prognosis. This level can be determined by counting up from the last ossified vertebral segment.

Normal Examination

Normal limbs

      Fig 1, Fig 2, Fig 3, Fig 4, Fig 5, Fig 6, Fig 7, Fig 8

1. Development: During the 8th week from the last menstrual period (LMP), a hyaline cartilage outline of the future appendicular skeleton begins to appear. The primary ossification centers of a long bone are located in the center of the shaft (diaphysis) and appear between weeks 7 and 12. Transabdominal and transvaginal sonography can clearly define the fetal skeleton even in the first trimester. The secondary ossification centers located in the epiphyses are at the distal ends of the long bone. During bone growth, the epiphyseal plate intervenes between the epiphysis and the end of the diaphysis (i.e. metaphysis). When the epiphyseal plate is replaced by bone, growth of the bone ceases. By 15-16 gestational weeks both the appendicular and axial skeleton can be consistently well imaged by sonography, although phalanges may be difficult to perceive in some instances. In the second trimester, the scapula, clavicle, humerus, radius, ulna metacarpals, femur, tibia, fibula, metatarsals and phalanges can be appreciated well sonographically in most cases.
2. Systematic approach: All long bones should be visualized with a systematic and routine sonographic approach to minimize errors in detecting limb defects. For example, in a survey of the upper limbs, the scapula should first be located and then the probe is laterally moved to identify the humerus, which at first may be in the cross-section or longitudinal view of the long bones. After completion of the upper arm assessment, the transducer is moved to visualize the distal end of the humerus or the elbow joint and then the probe is meticulously adjusted to locate the proximal end of the radius and ulna. Similarly, after thorough examination of the forearm the wrist joints and hands will be demonstrated respectively. The lower survey must be approached in the same way from the iliac wing through the foot.
3. Identification of long bones: The simple technique to identify the types of long bones is to obtain planes of sections that traverse the short axis of the limb. Such a plane through the forearm and calf will demonstrate two bones. In the lower leg, the more lateral bone is the fibula, and the medial bone is the tibia. The tibia and fibula and radius and ulna end at the same level distally, however, proximally the ulna is longer than the radius. This allows ready differentiation of these two bony sets and of the radius from the ulna in the upper extremity set.
4. Femur length measurement: Femur length measurement is usually used as a means of predicting gestational age. The measurement is technically the easiest of the most common biometric measurements. The transducer need only be aligned to the long axis of the bone to obtain a proper plane of the section. Only the ossified portions of the diaphysis and metaphysis are measured. The cartilaginous ends of the femur are excluded.
5. Identification of hands: With patience one can usually visualize all four fingers and the thumb. The hand is frequently clenched in a fist-like fashion, which can complicate the counting of fingers. The toes, although smaller than the fingers, can be seen relatively well. If difficulty arises, it is usually the functionally less important fourth and fifth toes that are not seen.
6. If a skeletal dysplasia is suspected early in the second trimester, a follow-up study to assess the interval long bone growth should be performed. The growth rate of the long bones decreases before the absolute length falls below the cut-off point.
7. Fetal parts ratios: The proportions between specific fetal body parts may be helpful in the diagnosis of a skeletal dysplasia. For example, foot length is not affected by most skeletal dysplasias whereas most other long bones are affected. In a normal fetus, the femur length/foot ratio (age-independent) is approximately equal to 1, and can effectively distinguish skeletal dysplasias from fetal growth restriction. Furthermore, the femur/head circumference and abdominal circumference/thoracic circumference ratios are also reliable for the detection of severe skeletal dysplasia.
8. Degree of skeletal ossification: This should be routinely assessed, although it is usually evaluated by subjective impression. Examination of the acoustic shadow and the echogenicity of the bone itself are often helpful. However, the degree of skeletal ossification cannot be well judged. Only in the most extremely osteopenic bone can one appreciate diminished ossification on sonograms.

Fig 1:  Normal scapula  Coronal plane of the scapula: triangular shape

Fig 2:  Normal upper limb

Fig 3:  Normal radius and ulna   Note: proximal end not in the same level (arrow)

Fig 4:  Normal hand

Fig 5:  Normal hand in late first trimester

Fig 6:  Normal femur   Longitudinal scan of femur: standard plane for femur measurement

Fig 7:  Normal tibia and fibula  Note: proximal and distal end of the both bones are in the same level

Fig 8:  Normal toes

Pitfalls

1. Fetal position: The fetal position is very important for a complete examination. All limbs are best visualized when floating freely in the amniotic fluid and imaging is difficult when they are tucked under the fetal body. Usually the limbs are readily imaged when the fetus is in the supine position whereas the posterior elements of the spine may be easily imaged in prone or decubitus positions.
2. FL measurement error: A non-osseous tissue at the end of the femur can give equal brightness. Reflection is returned from tissues distal to the epiphyseal plate but in immediate contiguity with the distal femoral metaphysis.
3. Short long bones: A fetal long bone length greater than 2 standard deviations below the mean for the gestational age does not necessarily indicate the presence of a skeletal dysplasia. Other possibilities for short fetal long bone include a normal physiologic variation in bone length, intrauterine growth restriction and chromosome abnormalities and other syndromes that may have a skeletal abnormality as part of their presentation.

Bladder and Cloacal Exstrophy

This is a rare congenital anomaly characterized by the exteriorization of the viscera on the abdominal surface, low insertion of the umbilical cord, divergent pubic rami and abnormal exterior genitalia. Bladder and cloacal exstrophy share a common embryologic origin in abnormal cloacal development, but are different in terms of severity and extent of involvement. Bladder exstrophy is a lower abdominal wall defect with herniation of the bladder whereas cloacal exstrophy is much more complex, including omphalocele, bladder exstrophy, imperforate anus, spine malformation (also known as OEIS complex), spina bifida and intersex.

Incidence: Sporadic occurrence with a prevalence of 1 in 30,000 births with a male to female ratio of 2:1 for bladder exstrophy, 1 in 50,000 births with a higher frequency in twins for cloacal exstrophy, and 1 in 200,000-300,000 for OEIS complex.

Sonographic findings:

• Soft tissue mass at the lower abdominal wall
  Fig 1, Fig 2, Fig 3, Fig 4
• Persistently absent fetal bladder with a large midline infraumbilical cystic or solid mass.
• A large cystic mass in the pelvis representing a persistent cloaca can be seen in some cases.
• Omphalocele is usually seen.
• Lumbosacral abnormalities.
• Associated anomalies such as renal agenesis, myelomeningocele, horseshoe kidney, and clubfeet.
• Umbilical arteries running alongside the mass suggestive of bladder exstrophy.

Fig 1:  Bladder extrosphy  Sagittal view of the fetal abdomen: complex extra-abdominal mass (*) below the umbilicus, finally proven to be bladder extrosphy

Fig 2:  Cloacal extrosphy  Free floating complex mass (*) connecting with fetal perineum

Fig 3:  Cloacal extrosphy  Free floating complex mass (*) connecting with fetal perineum

Fig 4:  Cloacal extrosphy  Free floating complex mass (solid circle) connecting with fetal perineum, abnormal fetal limb (arrow) (* = femur)

Associations: Genital defects in both conditions; renal, skeletal, neural tube, intestinal, cardiovascular and omphaloceles defects in cloacal exstrophy.

Management: Termination of pregnancy can be offered when diagnosed before viability. Isolated bladder exstrophy requires postnatal surgery, either with initial repair using the staged approach or a complete primary repair technique with continent diversion. Neonatal assignment of genetic males to the female sex is often necessary in cloacal exstrophy because of severe phallic inadequacy resulting in unpredictable sexual identification.

Prognosis: Recently good in isolated bladder exstrophy, but poor in cloacal exstrophy, with a high rate of urinary tract infection in adult women with sexual problems in several cases.

Recurrence risk: Sporadic (rare recurrence) but there is a significant genetic predisposition in some familial cases.

Limb-Body Wall Complex (LBWC)

LBWC or body-stalk anomaly or cyllosomas is a complex set of disruptive abnormalities consisting of failure of the anterior abdominal wall to close, short umbilical cord, disruption of the lateral body wall, distinctive scoliosis of the spine, limb defects, non-fusion of the amnion and chorion. Therefore, the amnion does not cover the cord but extends as a sheet from the margin of the cord to be continuous with the body wall and placenta.

Incidence: Sporadic, 1 in 15,000 (1:3000-42,000) births; a higher incidence was observed among mothers with a history of cigarette, alcohol and marijuana use.

Sonographic findings:

• Large body wall defect allowing abdominal contents to herniate. Fig1, Fig2
• The umbilical cord is absent or is a very short segment with a single umbilical artery. Fig3, Fig4
• The fetal abdomen is connected directly to the placenta.
• Scoliosis is evident in most cases. Fig5, Fig6
• Limb anomalies in most cases, including clubfeet, oligodactyly, arthrogryposis, absence of limbs, single forearms, split hand and feet.
• Craniofacial defects frequently seen.
• An extremely elevated level of maternal serum-alpha-fetoprotein (MSAFP) is also indicative of LBWC.
• Other associated anomalies.
• Three-dimensional ultrasound may be helpful.
• For first trimester diagnosis, the upper part of the fetal body is in the amniotic cavity, whereas the lower part is in the coelomic cavity.
• Differential diagnoses include other types of abdominal wall defects and amniotic band syndrome which may have very similar features.
• Pitfalls: Some cases have been initially misdiagnosed as omphalocele or gastroschisis, for which the prognosis is much better.

Fig 1:  Limb-body wall complex  Free floating complex mass containing abnormal shaped liver (solid circle) and bowel (*)

Fig 2:  Limb-body wall complex  Free floating complex bowel (arrow) and liver (solid circle) in the amniotic fluid

Fig 3:  Limb-body wall complex  Free floating complex mass containing liver (*) with covering membrane (arrowhead), short umbilical cord (arrow) originating from the placenta to the mass

Fig 4:  Limb-body wall complex  Free floating complex mass containing liver (*) with short umbilical cord (arrow) originating from the placenta to the mass

Fig 5:  Kyphoscoliosis   Sagittal scan of the fetal trunk: disorganized spine in association with limb-body wall complex

Fig 6:  Disorganized spine  Coronal scan of the fetal spine: disorganized spine (arrow) in association with limb-body wall complex

Associations: Other than typical defects, other anomalies are also often seen, especially craniofacial or neural tube defects.

Management: Termination of pregnancy can be offered.

Prognosis: Uniformly fatal.

Recurrence risk: Sporadic (rare recurrence).

Gastroschisis

Gastroschisis is a paraumbilical defect involving all the layers of the abdominal wall. It is usually right-sided with the small bowel herniated through the defect. The stomach or other organs may occasionally be involved in herniation.

Fig 1

Incidence: 1 in 2000-5000 live births with a high prevalence among the maternal age of 11-19 years. It has been associated with various medications including recreational drugs, NSAIDs (aspirin, salicylate, ibuprofen), and decongestants (pseudoephedrine and phenylpropanolamine) . There has been a sustained increase in the incidence over the past decade, particularly in teenage women.

Sonographic findings:

• Abdominal organs herniate through an anterior abdominal wall defect; typically, there are multiple loops of bowel outside the abdomen. Fig2, Fig3, Fig4
• No covering membrane.
• Umbilical cord inserting on the abdominal wall (normal insertion site). Fig5, Fig6
• Varying degrees of bowel dilatation and wall thickening or increasing intraluminal meconium. Fig7, Fig8, Fig9
• The liver is very rarely involved. Fig10
• The amniotic fluid volume is usually normal, however, oligohydramnios may be observed in 36% of cases. Polyhydramnios may be seen in the case of bowel obstruction.
• An increase in serum alpha-fetoprotein levels, higher than those associated with omphalocele.
• Doppler velocity of the superior mesenteric artery found to be predictive of outcome in fetuses with gastroschisis.
• Usually first diagnosable in the early second trimester; the diagnosis prior to 13 weeks may be confused with physiologic herniation.
• Pitfalls: The cases with oligohydramnios, particularly in late pregnancy, can easily be missed. Additionally, extra-abdominal bowel can be overlooked and thought to be a coiled umbilical cord.
• Differential diagnoses include other types of abdominal wall defects (see omphalocele), especially ruptured omphalocele, though rare, limb-body wall complex, and tangled cord adjacent to the fetal abdomen, in which color flow will show vascular flow.
• Most standard ultrasound parameters are not significantly associated with an adverse neonatal outcome, except for polyhydramnios, which was strongly predictive of severe bowel complications in the neonatal period.

Fig 1:  Schematic drawing of gastroschisis; note normal location of the cord insertion

Fig 2:  Gastroschisis   Scan of the free-floating bowel loops in the amniotic fluid

Fig 3:  Gastroschisis  Cross-sectional scan of the abdomen: Free floating dilated bowel loops (arrow) in the amniotic fluid (arrowhead = spine, * = intra-abdominal stomach)

Fig 4:  Gastroschisis  Cross-sectional scan of the abdomen: bowel (arrowhead) protruding through the abdominal wall defect on the right-side of the umbilicus (arrow = umbilical vein)

Fig 5:  Gastroschisis  Cross-sectional scan of the abdomen: free floating bowel in the amniotic fluid on the right side of the umbilical vessels (*) protruding through the abdominal wall defect

Fig 6:  Gastroschisis   Cross-sectional scan of the abdomen: Free floating bowel loops (arrow) in the amniotic fluid, protruding through the abdominal wall defect on the right-side of the umbilical vein (*)  (solid circle = intra-abdominal stomach)

Fig 7:  Gastroschisis  Free floating dilated bowel loops in the amniotic fluid

Fig 8:  Gastroschisis   Free floating dilated bowel loops (*) in the amniotic fluid

Fig 9:  Gastroschisis  Free floating bowel loops (*), thickened wall caramelized by the turbid amniotic fluid

Fig 10:  Gastroschisis   Cross-sectional scan of the abdomen: liver mass (arrow) and bowel (arrowhead) without covering membrane protruding through large defect, note normal cord insertion (*) (solid circle = spine)

Associations: Related to other anomalies in 7-10% of cases, mostly GI anomalies, not associated with chromosomal abnormalities.

Management: Serial sonographic monitoring is necessary to evaluate the degree of dilation and wall thickness. Early delivery may be beneficial in cases of marked dilatation or thickened bowel wall, however, term delivery gives the best outcomes in most cases. Delivery should be performed in a tertiary center with appropriate facilities for surgical management of the newborn. The fetuses may carry a higher rate of fetal distress and intrauterine death and fetal surveillance is recommended, however, labor and ruptured membranes do not appear to be associated with increased neonatal morbidity or mortality rates in neonates with gastroschisis. Cesarean section probably does not improve the outcomes.

Prognosis: Good but complications are very common, especially those related to the gastrointestinal tract problems and prematurity, increased morbidity in cases of bowel obstruction, bowel wall thickening, or increased amniotic concentration of digestive compounds.

Recurrence risk: Sporadic except for rare familial cases.

Omphalocele

Omphalocele is a defect in the anterior abdominal wall with extrusion of abdominal contents in the base of the umbilical cord. The herniated mass is covered by parietal peritoneum and amnion, with Wharton’s jelly intervening between the two membrane layers.

Fig 1, Fig 2

Incidence: 1 in 3000-4000 births with a male to female ratio of about 1:5. An increased incidence has been observed with advancing maternal age.

Sonographic findings:

• Typically, a midline mass with a covering membrane adjacent to the abdominal wall containing abdominal contents (bowel or liver). Eighty percent of cases contain liver, sometimes with small bowel. The stomach and bladder may occasionally lie in the omphalocele. Fig 3, Fig 4, Fig 5, Fig 6, Fig 7
• Variable depending on the amount of ascites, degree of herniation and associated anomalies.
• Twenty percent contain gut and fluid only and most abnormal chromosomes are seen in this subgroup.
• Omphaloceles containing bowel alone tend to be small and can be missed or mistaken for gastroschisis. Fig 8
• Umbilical cord inserting on the sac.
• Ascites commonly seen.
• The covering membrane may not always be seen, particularly in the absence of ascites or when ruptured.
• Associated malformation commonly seen.
• Usually first diagnosable in the second trimester but can be detected in the first trimester if the liver is present within the mass, especially using three-dimensional ultrasound. In physiologic omphalocele, only the gut will be seen in the herniated sac.
• An anterior abdominal wall mass >7 mm at any crown-rump length (CRL), or of any size in a fetus of CRL >44 mm, is suggestive of a fetal anomaly. Alternatively, a cord base mass within the 4-7 mm range for a CRL of 19-44 mm can be considered normal and not to require any follow-up.
• Three-dimensional ultrasound can be useful for additional information and more efficient counseling and postnatal therapeutic planning.
• A false-positive diagnosis of omphalocele, or pseudo-omphalocele, can be produced by scanning in an oblique plane or by compressing the fetal abdomen.
• Main differential diagnoses include:
  • Gastroschisis: no surrounding membrane, normal cord insertion
  • Umbilical hernia: covered by skin rather than a membrane, indistinguishable from a small omphalocele
  • Bladder/cloacal exstrophy: a mass below the cord insertion site with no visible bladder
  • Limb-body wall complex: the placenta attached to the fetus, absent or very shortened cord, limbs and spine defects
  • Pentalogy of Cantrell: ectopia cordis with omphalocele
  • Urachal and omphalomesenteric cyst: cysts at the cord insertion site, no visceral contents

Fig 1:  Schematic drawing of physiologic omphalocele at 8 weeks of gestation with the disappearance at 12 weeks

Fig 2:  Schematic drawing of omphalocele containing liver and bowel; note the cord insertion on the covering membranes

Fig 3:  Omphalocele  Free floating sac (arrow) containing liver and bowel (*) with covering membrane (arrowhead) (arrow = omentum)

Fig 4:  Omphalocele  Free floating liver mass with covering membrane (*) in amniotic fluid

Fig 5:  Omphalocele  Cross-sectional scan of the abdomen: liver mass (*) protruding through large defect, invisible covering membrane blending with the liver (solid circle = spine)

Fig 6:  Small omphalocele  Cross-sectional scan of the abdomen: small part of the liver (solid circle) protruding through the umbilicus, (* = liver, arrow = umbilical vein)

Fig 7:  Omphalocele  Liver mass (solid circle) with covering membrane (arrows) located outside of the body

Fig 8:  Small omphalocele  Cross-sectional scan of the abdomen: bowel (arrow) protruding through the umbilicus (* = liver, arrowhead = spine)

Associations: Mostly sporadic but associated with other anomalies in 50-85% of cases (cardiac defect in 45-50%, and other anomalies such as neural tube defects, diaphragmatic hernia, etc.), and chromosomal abnormalities in 30% of cases, especially trisomy 18 and 13, particularly when the sac contains no liver and is associated with another anomaly.

Management: A careful search for associated anomalies and karyotyping are indicated. For isolated omphalocele, delivery should occur in a tertiary center with appropriate facilities for surgical management of the newborn. A multidisciplinary approach to the fetus can improve the neonatal outcome. There is still a relatively high rate of elective termination of pregnancies for both defects, even in isolated cases which generally have a good prognosis after surgical repair. Cesarean section probably does not improve the outcomes.

Prognosis: Good for isolated lesions with proper management but poor when associated with other anomalies or chromosome abnormalities.

Recurrence risk: Sporadic for isolated cases, but there is probably a high recurrent rate in cases with rare autosomal dominant or X-linked recessive inheritance.

Abnormal Genitalia

Ambiguous genitalia is the term used when on examination there is doubt as to whether the patient is phenotypically male or female. Ambiguous genitalia are made up of a heterogeneous group of disorders of various etiologies that are usually related to either an abnormal hormonal influence such as congenital adrenal hyperplasia or chromosomal defects such as trisomy 13 or trisomy 22.

Sonographic findings:

The types of abnormalities that lead to a suspicion of abnormal genitalia are short phallus, bent phallus, bifid scrotum, and apparently normal female genitalia in a fetus confirmed to be a karyotypic male, either by chorionic villous samplings or amniocentesis. If an XY karyotype is confirmed but a careful sonographic evaluation demonstrates normal-appearing female external genitalia, then the diagnosis of testicular feminization (XY chromosomes with female external genitalia) is assumed.

The short or bent penis seen in association with a normal-appearing scrotum is usually an indication of hypospadias with chordae.

When pseudohermaphroditism was detected in a male fetus by an experienced ultrasonographer at a tertiary center the prenatal diagnosis was accurate in 100% of cases. The prenatal diagnosis was less accurate (46% correct) in a female fetus.

Rarely, an examiner may perceive the genitalia as labia with a large clitoris or a bifid scrotum with a short penis. In such situations, a diagnosis of ambiguous genitalia may be made. However, the accurate diagnosis of ambiguous genitalia can be extremely difficult and should not place a diagnostic label on a fetus prenatally.

Autosomal Recessive Polycystic Kidney

Autosomal recessive polycystic kidney (PCK; Potter type I) is an autosomal recessive disorder, previously termed infantile PCK, characterized by bilateral microcystic change of renal tubules leading to enlarged non-functional kidneys with maintenance of their reniform shape. Most cases manifest in utero but some may be evident after birth or childhood. PCK may be associated with abnormality of fibrocystin, a receptor protein that acts in collecting-duct and biliary differentiation.

          Fig 1

Incidence: 1 in 40,000-50,000 births, male/female, 1:1.

Sonographic findings:

• Bilateral enlarged (above the 90th percentile for length and width), echogenic kidneys with reniform shape. Fig 2, Fig 3, Fig 4, Fig 5
• Oligohydramnios with non-visualization of the bladder, usually not before 15 weeks.
• Pulmonary hypoplasia.
• Usually diagnosed after 18 weeks.

Fig 1:  Schematic drawing of polycystic kidney (enlarged reniform shape)

Fig 2:  Polycystic kidneys   Coronal scan of the abdomen: symmetrical markedly enlarged echogenic kidneys (* = renal pelvis)

Fig 3:  Polycystic kidneys   Cross-sectional scan of the abdomen: symmetrical markedly enlarged echogenic kidneys (* = renal pelvis, arrowhead = spine)

Fig 4:  Polycystic kidneys  Coronal scan of the abdomen: symmetrical markedly enlarged echogenic kidneys

Fig 5:  Polycystic kidneys   Oblique coronal scan of the abdomen: symmetrical enlarged echogenic kidneys containing numerous microcystic lesions (* = renal pelvis)

Associations: Hepatic fibrosis, Meckel Gruber syndrome, trisomy 13.

Management: Termination of pregnancy can be offered. Vaginal delivery without electronic fetal monitoring in labor is appropriate.

Prognosis: Very poor, particularly the cases with severe oligohydramnios and fetal kidneys >4 SD.

Recurrence risk: About 25%.

Multicystic Dysplastic Kidney (MCDK)

MCDK is a congenital renal dysplasia characterized by multiple, smooth-walled, non-functioning, non-communicating cysts of variable size and number, replacing all or nearly all normal parenchyma. Normal nephrogenesis may occur before the secondary changes leading to MCDK.

Fig 1

Incidence: 1 in 3000 live births, more common in boys.

Sonographic findings:

• Enlarged kidney with multiple non-communicating cysts of varying size. Fig2, Fig3, Fig4, Fig5, Fig6
• The lesion is unilateral in 70-80% of cases but 20-30% have a renal anomaly of the contralateral kidney such as hydronephrosis or renal agenesis.
• Normal amniotic fluid volume if unilateral and oligohydramnios if bilateral.
• Differentiation from severe hydronephrosis (with several dilated calyces) may be difficult in some cases.
  • Severe hydronephrosis: the oval cysts communicate with each other and the renal pelvis; renal parenchyma is usually visualized, and ureteral dilatation is often seen.
  • MCDK: multiple round cysts of varying size are non-communicating with each other or the renal pelvis, renal parenchyma is often not seen, and ureteral dilatation is not visualized.

Fig 1:  Schematic drawing of multicystic kidney

Fig 2:  Small multicystic kidney  Oblique cross-sectional scan of the abdomen: multiple cysts varying in size in the kidney (arrow)

Fig 3:  Multicystic kidney  Sagittal scan of the abdomen: multiple cysts varying in size in the kidney (*)

Fig 4:  Multicystic kidney  Sagittal scan of the abdomen: multiple cysts varying in size in the kidney (*)

Fig 5:  Multicystic kidney  Cross-sectional scan of the abdomen: multiple cysts varying in size in the kidney

Fig 6:  Multicystic kidney  Cross-sectional scan of the abdomen: multiple cysts varying in size in the kidney (arrow = spine)

Associations: Renal anomalies of the contralateral kidneys (about 40%) and abnormalities of the lower urinary tract are common.

Management: Unilateral MCDK should not alter the standard obstetric care. For bilateral non-functioning MCDK with oligohydramnios, termination of pregnancy should be considered.

Prognosis: Good, depending on the contralateral kidney and associated anomalies; recurrent risk in subsequent pregnancy is low (<5%).

Recurrence risk: Sporadic.

Bladder Outlet Obstruction

Bladder outlet obstruction occurs almost exclusively in males, and is most often related to the posterior urethral valve, resulting in failure of complete disintegration of the urogenital membrane leaving membranous tissue within the posterior urethra; it is rarely secondary to a nearby lesion such as cloacal dysgenesis or ureterocele. It is the most common cause of severe obstructive uropathy in childhood.

Incidence: 1 in 5000-8000 boys.

Sonographic findings:

• Only males are affected.
• The urinary bladder is dilated (megacystis) regardless of the cause. Fig 1, Fig 2
• The bladder wall is commonly thickened.
• The posterior urethra may be dilated and appears as a projection from the bladder base, giving a keyhole appearance. Fig 3, Fig 4
• The ureters are usually dilated (megaureter). Fig 5, Fig 6, Fig 7
• Asymmetric hydronephrosis, with massive hydronephrosis on one side and minimal hydronephrosis on the other with relative sparing.
• The kidneys have a variable appearance depending on the presence and extent of dysplasia including hydronephrosis, cystic renal parenchyma, or small shrunken kidneys with echogenic parenchyma.
• Oligohydramnios with pulmonary hypoplasia.
• Prolonged distention of the bladder with deficiency of the abdominal musculature development, called Prune belly syndrome, is commonly seen.
• Usually presenting at 18-22 weeks but possibly as early as 11 weeks.

Fig 1:  Megacystis   Sagittal scan of the trunk: marked dilatation of the bladder (solid circle) with protrusion of the lower abdomen (arrow = diaphragm)

Fig 2:  Megacystis   Sagittal scan of the trunk: marked dilatation of the bladder (*), occupying nearly total abdomen

Fig 3:  Megacystis   Coronal scan of the lower abdomen: dilatation of the bladder (solid circle) with marked dilatation of the proximal urethra giving the key-hole appearance (*)

Fig 4:  Megacystis   Coronal scan of the lower abdomen: dilatation of the bladder (solid circle) with thickened wall; dilatation of the proximal urethra giving the key-hole appearance (*)

Fig 5:  Megacystis   Cross-sectional scan of the abdomen: marked dilatation of the bladder (solid circle) and ureter (+) and renal pelvis (*) with echogenic thin parenchyma (arrow = spine)

Fig 6:  Megaureter and megacystis  Oblique scan of the abdomen: marked dilatation of the ureter (arrow), simulating bowel loop, and bladder (*) (arrowhead = spine)

Fig 7:  Megacystis and megaureter  Coronal scan of the abdomen: marked dilatation of the ureter (arrow) with dilated renal pelvis and dilated bladder

Associations: Most are isolated and are rarely related to urethral atresia or caudal regression, and aneuploidy (trisomy 21, 18 and 13) in some cases.

Management: Termination of pregnancy can be offered when diagnosed before viability when oligohydramnios or renal insufficiency is present. In utero decompression can be considered in some selected cases. Cytogenetic analysis or FISH can be done using fetal urine specimens. The cause of obstruction may be corrected in some cases, such as ureterocele.

Prognosis: Variable, but most are poor, especially when combined with severe oligohydramnios, lung hypoplasia and renal dysplasia.

Recurrence risk: Sporadic (rare recurrence) with rare familial inheritance.