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Case 75 - Fetal lymphatic malformation
- from Section 8 - Fetal imaging
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- By Erika Rubesova, Stanford University
- Edited by Heike E. Daldrup-Link, Beverley Newman
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- Book:
- Pearls and Pitfalls in Pediatric Imaging
- Published online:
- 05 June 2014
- Print publication:
- 24 April 2014, pp 313-315
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Summary
Imaging description
A 32-year-old patient at 22 weeks of gestation was referred carrying a female fetus that had previously been diagnosed with a left thigh mass on ultrasound (US). Repeat US demonstrated a hypoechoic cystic soft tissue mass of the left thigh, most consistent with a lymphatic malformation (Fig. 75.1a). The mass was well circumscribed in the subcutaneous soft tissues and anterior muscle, but follow-up US demonstrated extension of the mass into the retroperitoneum. Displacement of the fetal bladder to the right and mild hydronephrosis in the left kidney was noted. Follow-up US studies were performed on a weekly basis to follow the size of the mass and check for development of hydrops fetalis. These showed progression of the lymphatic malformation with further extension into the retroperitoneum. A fetal MRI at 32 weeks showed a high T2-and low T1-signal cystic mass of the left thigh with an extensive retroperitoneal component (Fig. 75.1b, c), infiltrating the pelvic structures. Postnatally, the mass appeared as a multiseptated hypoechoic mass infiltrating most of the soft tissues of the left thigh, labia, and perineum, and extending into the retroperitoneum, surrounding the ureters (Fig. 75.1d). Slow Doppler flow was detected in the septations; the diagnosis of lymphatic malformation was confirmed, and sclerotherapy was begun.
Case 78 - Gastroschisis
- from Section 8 - Fetal imaging
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- By Binh Huynh, Stanford University, Erika Rubesova, Stanford University
- Edited by Heike E. Daldrup-Link, Beverley Newman
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- Book:
- Pearls and Pitfalls in Pediatric Imaging
- Published online:
- 05 June 2014
- Print publication:
- 24 April 2014, pp 322-325
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Summary
Imaging description
Gastroschisis is a para-umbilical, anterior abdominal wall defect, resulting in the herniation of bowel, and occasionally other organs, such as stomach and liver, into the amniotic cavity. The defect is usually to the right of midline and the umbilicus insertion (Figs. 78.1a–f and see 78.3a, b). There is no membrane covering the herniated structures and, as a result the extracorporeal loops of bowel are directly exposed to amniotic fluid. This causes an inflammatory, fibrous coating on the bowel, called peel; additionally, there is thickening of the muscularis propria and atrophy of the mucosa (Fig. 78.1b).
During fetal gastrointestinal development, the midgut elongates rapidly, such that at the sixth week of gestation, developing loops of bowel project into the extra-embryonic coelom, causing physiologic herniation of bowel into the umbilicus (Fig. 78.2a and b). The intestines return into the fetal abdominal cavity after 11 weeks of gestation. As a result, the diagnosis of an anterior abdominal wall defect should not be made until after this event is expected to have occurred.
Case 79 - Fetal osteogenesis imperfecta
- from Section 8 - Fetal imaging
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- By Jordan Caplan, Stanford University, Erika Rubesova, Stanford University
- Edited by Heike E. Daldrup-Link, Beverley Newman
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- Book:
- Pearls and Pitfalls in Pediatric Imaging
- Published online:
- 05 June 2014
- Print publication:
- 24 April 2014, pp 326-328
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Summary
Imaging description
A 37-year-old G2P1 white female presented for a fetal anatomic survey at 19 weeks 3 days gestational age. She had been previously seen by the Genetic Counseling Service to discuss prenatal diagnosis options due to maternal age. She chose to proceed with sequential screening by nuchal translucency and first and second trimester biochemical analysis. Results of the sequential screening were negative.
Fetal ultrasound images showed an abnormal triangular-shaped calvarium (Fig. 79.1a) which demonstrated deformity on compression by the ultrasound probe (Fig. 79.1b). The fetal chest was abnormally shaped, with irregular contour of the ribs (Fig. 79.1c). The fetal humeri and femora were extremely short, with the length corresponding to a 13- to 14-week fetus (Fig. 79.1d, e). The head circumference, by comparison, reflected the true gestational age of 19 weeks 3 days (images not shown). The findings were strongly suggestive of osteogenesis imperfecta (OI).
After genetic counseling the couple decided to undergo termination of the pregnancy. Tissue was sent for mutation analysis of the COL1A1 and COL1A2 genes.
Case 77 - Cystic dysplasia of the kidneys
- from Section 8 - Fetal imaging
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- By Erika Rubesova, Stanford University
- Edited by Heike E. Daldrup-Link, Beverley Newman
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- Book:
- Pearls and Pitfalls in Pediatric Imaging
- Published online:
- 05 June 2014
- Print publication:
- 24 April 2014, pp 319-321
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Summary
Imaging description
A 16-year-old patient was diagnosed at 22 weeks of gestational age (GA) with a fetus with multicystic dysplastic kidney (MCDK). The contralateral kidney appeared slightly echogenic but otherwise normal on ultrasound (Fig. 77.1a,b). Fetal MRI confirmed large disorganized cortical cysts of different size in the right kidney but also demonstrated the presence of small subcortical cysts in the left kidney (Fig. 77.1c). However, the amount of amniotic fluid remained normal throughout the pregnancy and the patient carried the baby to term. At birth, ultrasound of the kidneys confirmed a right MCDK that got progressively smaller over time (Fig. 77.1d, f), but failed to demonstrate the small subcortical cysts in the left kidney (Fig. 77.1e). A dysplastic appearance of the left kidney with subcortical cysts was only noticed on follow-up ultrasound at the age of 1 year (Fig. 77.1g). The renal function was mildly decreased postnatally.
Importance
Renal cystic dysplasia is usually unilateral and may affect an entire kidney, a segment of a kidney, or a pole of a duplex kidney. Recent studies demonstrate that MCDK and obstructive dysplasia may have a similar pathogenesis, with glomerular cysts being the initial dysplastic event in the kidneys. Early prenatal studies show that MCDK appear as normal kidneys on ultrasound up to 14 weeks of gestational age despite complete obstruction. They are often diagnosed at the routine anatomic scan around 20 weeks of gestational age. Small subcortical cysts in the setting of obstructive dysplasia may appear later in pregnancy or after birth and are often more difficult to diagnose prenatally than MCDK.
Case 80 - Congenital diaphragmatic hernia
- from Section 8 - Fetal imaging
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- By Vy Thao Tran, Stanford University, Erika Rubesova, Stanford University
- Edited by Heike E. Daldrup-Link, Beverley Newman
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- Book:
- Pearls and Pitfalls in Pediatric Imaging
- Published online:
- 05 June 2014
- Print publication:
- 24 April 2014, pp 329-333
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Summary
Imaging description
Antenatal screening ultrasound (US) demonstrated multiple echogenic rounded foci within the left chest causing mass effect on the heart. The stomach was not noted to be in its expected location within the left upper abdomen. Longitudinal US images demonstrated the stomach above the diaphragm and the heart shifted towards the right side of the chest (Fig. 80.1a, b). T2-weighted MR sequences demonstrated multiple rounded hyperintense (fluid-filled) bowel loops in the left chest and the heart shifted towards the right aspect of the chest (Fig. 80.1c–e). The diagnosis of left congenital diaphragmatic hernia (CDH) was suggested. Immediate postnatal chest radiograph in a different patient with CDH demonstrated both opacification of the left hemithorax and multiple rounded lucencies in the left thorax, representing a combination of herniated tissues and gaseous distended bowel loops (Fig. 80.2).
Importance
CDH affects 1/3000 live births. The diaphragm is completely formed at eight weeks of gestation by the septum transversum and the pleuroperitoneal membranes. A defect in formation of the diaphragm leads to CDH. Approximately 85–90% of diaphragmatic hernias occur on the posterolateral left side, referred to as a Bochladek hernia, 5% occur in the anteromedial region, referred to as a Morgagni hernia. Morgagni hernias are frequently small and asymptomatic and discovered incidentally postnatally. The following discussion refers to the Bochdalek hernia as CDH. Despite advances in antenatal and perinatal care, when CDH is associated with morphologic or genetic anomalies, there is a high overall mortality rate of up to 50%. Severe pulmonary hypoplasia and pulmonary hypertension are the main etiologies for one-third of neonatal deaths from CDH. The administration of antenatal steroids, use of extracorporeal membrane oxygenation (ECMO), new modes of ventilation, timing of the hernia repair, as well as ex utero intrapartum treatment (EXIT) to ECMO along with intermittent in utero fetal tracheal occlusion have provided neonatologists and surgeons with various modes of management.
Case 76 - Anal atresia with urorectal fistula
- from Section 8 - Fetal imaging
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- By Erika Rubesova, Stanford University
- Edited by Heike E. Daldrup-Link, Beverley Newman
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- Book:
- Pearls and Pitfalls in Pediatric Imaging
- Published online:
- 05 June 2014
- Print publication:
- 24 April 2014, pp 316-318
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Summary
Imaging description
A 21-year-old patient with twin pregnancy at 19 weeks of gestational age (GA) was referred for echogenic bowel on ultrasound (US) in one of the two male fetuses. On repeat US some mildly distended loops of bowel were noted and the presence of echogenic bowel was confirmed. A fetal MRI was performed at 22 weeks of GA. T1-weighted images failed to demonstrate normal high signal meconium in the rectum (Fig. 76.1a). The fluid-sensitive sequences demonstrated distended fluid-filled colon, including the rectum, and within the fluid multiple low signal intensity pellets were noted. The diagnosis of imperforate anus with urorectal fistula was made based on these findings. The follow-up US and MRI at 32 weeks of gestational age confirmed the findings (Fig. 76.1b, c). A newborn abdominal radiograph demonstrated discrete oval to rounded calcifications along the course of the colon, consistent with intraluminal calcified meconium. The infant was treated surgically for imperforate anus with urorectal fistula.
Importance
In the fetus, meconium is formed primarily by the accumulation of dehydrated amniotic fluid swallowed by the fetus, bile salts, and desquamation of enteric cells. On US, meconium has intermediate echogenicity while on MRI images meconium has high T1 and low T2 signal. Since fetuses apparently do not pass large amounts of meconium during pregnancy, meconium accumulates in the rectum, which is the largest meconium-filled area of the fetal bowel. Anal atresia is therefore difficult to diagnose prenatally by US or MRI if there is not an associated urorectal fistula. Anal atresia is typically differentiated into two types: low atresia (below the levator ani muscle) and high atresia (above the levator ani muscle). An urorectal fistula is typically associated with high anal atresia, mainly in boys (ratio boys:girls = 6:1). In girls, imperforate anus is most frequently associated with urogenital sinus or a cloaca. Cloaca usually presents with a fluid-filled bladder and vagina and with a rudimentary sigmoid colon.