Summary

Near universal ultrasound screening in the second trimester and ever better ultrasound resolution have increased the number of anomalies diagnosed prenatally. Among these are anomalies without physical evidence at birth, which nonetheless can have serious implications for the infant's health. We shall review 3 anomalies of the chest, brain, and urinary systems that are commonly diagnosed prenatally and may have no outward newborn findings. These conditions require timely surveillance in the first months of life to identify problems of potentially major importance, so prompt treatment can be initiated.

Educational objectives

At the conclusion of this activity, participants will be able to:

• Perform recommended follow-up of children with prenatally diagnosed chest masses, borderline ventriculomegaly, and simple pyelectasis
• Describe the serious outcomes that are prevented by timely follow-up of these anomalies in primary care

CME credit

This is an article from The Child's Doctor, Spring 2006 issue. You may take the quiz for learning purposes, but credits are no longer valid.

Author disclosures

Dr. Talbot has no industry relationship to disclose and does not refer to products that are still investigational or not labeled for the use in discussion.

Dr. Maizels has no industry relationship to disclose and does not refer to products that are still investigational or not labeled for the use in discussion.

Dr. Reynolds has no industry relationship to disclose and does not refer to products that are still investigational or not labeled for the use in discussion.

Dr. Tolden has no industry relationship to disclose and does not refer to products that are still investigational or not labeled for the use in discussion.

Dr. Chaviano has no industry relationship to disclose and does not refer to products that are still investigational or not labeled for the use in discussion.

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Introduction

CHRISTOPHER TALBOT, MD

Ultrasound screening in the first and second trimesters has long been the standard of care in developed European countries, but difficulty in proving its value through evidence-based medicine evaluation has delayed its acceptance in U.S. Nonetheless, in the 21st century in the Chicago area, detailed ultrasound examination of nearly all pregnancies in the first and second trimesters has become the norm. These examinations with highly sophisticated machines are finding anomalies at an ever increasing rate. Indeed, while it was once thought that birth defects were found in 3% of all births, and that in 1.5% of infants these anomalies signaled major problems, today the accepted figures are closer to twice those rates.

The authors below will discuss suggested follow-up of prenatally diagnosed chest masses, borderline cerebral ventriculomegaly, and renal pyelectasis. Each of these conditions may be overlooked at birth. Appropriate surveillance and management, therefore, first requires that the pediatrician be aware that these conditions are present, making communication between clinicians critical.

Communication gaps that may exist between fellow caregivers in a large practice, and those that may occur between the obstetrical caregivers and the pediatric team, add to the challenge of providing timely follow-up of prenatally detected conditions that are not physically apparent at birth. We have found that fetal consultation between parents-to-be and surgical specialists enhances parental understanding of these conditions and improves compliance with subsequent care.

Chest Masses

MARLETA REYNOLDS, MD

Prior to the current age of nearly universal prenatal ultrasound in metropolitan areas, chest masses were typically diagnosed only when they became symptomatic due to respiratory compromise or recurrent pulmonary infections in the child. Now, chest masses are typically identified in fetal life by the routine prenatal ultrasound examination performed at around 20 weeks of gestation. As such, chest masses are appreciated as being more common than they were once thought to be.

Most commonly, the masses found in the fetal lung represent congenital cystic adenomatous malformations (CCAMs) and bronchopulmonary sequestrations. Occasionally, diaphragmatic hernias may be confused with these masses. If necessary, further information on the nature of a mass may be obtained by magnetic resonance imaging (MRI) and Doppler color flow studies in the second trimester or later in the pregnancy. Children with diaphragmatic hernias are often critically ill at birth and require emergent special care.

The larger masses will be followed closely during pregnancy watching for hydrops, the major indicator of poor outcome and occasionally an indication for prenatal intervention. Smaller masses, especially those thought to be sequestrations, however, receive less attention. If they are small enough to be clinically unapparent, lung masses may be easily forgotten until they cause a problem. With these cases, the primary care physician's role is crucial, since even small chest masses require follow-up after birth.

Both sequestrations and CCAMs are known to become infected, and CCAMs may undergo malignant transformation. For these reasons, both are typically electively removed.

Recommended evaluation of the newborn with a history of prenatal lung mass, but a normal birth examination, includes a chest x-ray before hospital discharge and a computerized tomography of the chest in the first month of life. Any evidence of persistence of the fetal lung mass at this time is an indication for surgical consultation.

When the child is asymptomatic, surgery is usually planned for around the first birthday to remove any mass that has persisted. In later childhood and beyond, the chest x-ray usually can give no suggestion of the lung mass that was previously removed. When treated in this fashion, these children enjoy a normal life expectancy without any activity restriction.

SUGGESTED READING

[1.] Reynolds M. Congenital lesions of the lung. In: Shields T, et al, eds. General Thoracic Surgery. Vol 1. 6th ed. Philadelphia: Lippincott, Williams, and Wilkins; 2005:1101-1117(chap 80).

Borderline Ventriculomegaly

TORD ALDEN, MD

With increasing use of the improving prenatal ultrasound technology, the prevalence of fetal cerebral ventriculomegaly has increased over time. With the advent of the fetal brain MRI, we are making this diagnosis even more frequently. Ventriculomegaly occurs in approximately 0.5 to 2 of 1000 births, and is an isolated finding in roughly half of the cases. Once found on prenatal ultrasound, it is the indication for up to 40% of all fetal brain MRI studies performed and is the cause for much concern for parents to be.

Intracranial contents consist primarily of the brain tissue, blood, and cerebrospinal fluid (CSF). CSF is made, for the most part, in the ventricles by choroid plexus. Making too much CSF, inadequate brain development, or destruction of brain tissue can result in enlargement of the ventricular system. For this reason, the ventricular system of the brain serves as a prenatal marker for neuro-developmental abnormalities.

The ventricular system is convoluted and has many different areas to measure. By convention, to determine the degree of ventriculomegaly, the transverse diameter of the atria is used as a standard. Starting at around 13 to 15 weeks of gestation, the transverse diameter of the atria is stable in size and is usually less than 10 mm, with an average of about 7.6 mm. Borderline ventricular enlargement is present when the measures are 10 mm to 12 mm. Ventriculomegaly is considered mild if the atrial diameter is greater than 10 mm, but less than 15 mm. The enlargement is severe if the measurement is greater than 15 mm.

If the difference between the right and left sides is greater than 2 mm, ventriculomegaly is considered to be asymmetric.

The prognosis varies greatly and is influenced by several factors, such as degree of ventriculomegaly (borderline, mild, or severe), etiology (genetic, infectious, or anatomic blockage), nature over time (regressive, stabilized, or progressive), and association with other anomalies. Most of the severe and mild cases will need both prenatal and postnatal evaluation by neurosurgeons and neurologists. However, there is a large subset of cases with stable, borderline ventriculomegaly as an isolated finding in an otherwise normal pregnancy. The prognosis for this group is very good, with 90% to 100% having normal outcome.

Children with borderline ventriculomegaly, however, need continued monitoring by pediatricians, to ensure that the process of ventricular enlargement does not become progressive. Without intervention, a small percentage of these patients may go on to develop hydrocephalus. Postnatal follow-up aims to prevent this possibility through early identification of patients with progressive ventricular enlargement. Recommended follow-up involves monitoring the child's developmental mileposts, careful and frequent recording of serial head circumference measures, and serial brain imaging, usually with ultrasound.

SUGGESTED READING

[1.] Glonek M, Kedzia A, Derkowski W. Prenatal assessment of ventriculomegaly: An anatomical study. Med Sci Monit 2003;9(7):MT69-77

[2.] Valsky DV, Ben Sira L, Porat S, et al. The role of magnetic resonance imaging in the evaluation of isolated mild ventriculomegaly. J Ultrasound Med 2004;23:519-523.

[3.] Girard N, Ozanne A, Chaumoitre K, et al. MRI and in utero ventriculomegaly. J Radiol 2003;84:1933-1943.

Fetal Pyelectasis

MAX MAIZELS, MD

ANTONIO CHAVIANO, MD

Renal pyelectasis (or pelviectasis) is a frequent prenatal ultrasound observation made by obstetrical sonographers. The clinical correlation of this finding is not clearly understood, however. Pyelectasis represents an enlargement of the normally imperceptible renal pelvis. The diagnosis is made when the anteroposterior (AP) measurement of the pelvis of a developing kidney exceeds 4 mm at 20 weeks gestation in the absence of other urinary findings.

It is unfortunate that this relatively innocent condition has also been referred to as hydronephrosis, a condition with serious implications. Confusion exists because while the majority of children with pyelectasis/pelviectasis will not require further care, a minority of children may be susceptible to urinary tract infections, which if left untreated can harm kidney function.

Until recently it was incorrectly believed that the degree of renal pelvis dilation alone predicted whether the child was at risk for developing a significant urological condition that required ongoing care. But exceptions have disproved this rule. An ongoing cooperative study in Chicago, co-led by our team at Children's Memorial, has evaluated a sufficient number of affected mothers to predict outcomes of prenatally diagnosed pelviectasis. Study analyses indicate that the best predictor of developmental outcome of pyelectasis includes a combination of measurements of the urinary system followed serially through the pregnancy. These measurements include the AP of the renal pelvis, the diameter of the renal pelvis at the mid plane, the length of the kidney, and the sagittal diameter of the bladder.[1]

While cases with urinary obstructions will be cared for by urologists immediately following birth, primary care providers can take basic precautions to ensure that babies with simple pyelectasis (also called "SERP" for sonographically evident renal pelvis) do not get into trouble. The main thrust is to identify infants who are prone to develop urinary tract infections. This may be done by performing renal ultrasound and a voiding cystourethrogram (VCUG) along with urinalysis shortly after birth. Antibiotic prophylaxis may be administered until the radiological findings normalize.

These recommendations can be conveniently carried out locally by the primary care physician with consultation of a pediatric urologist. If infection or enlargement of the pelviectasis occurs, these cases should be referred to a pediatric urologist for specialty care. This simplified protocol minimizes the expense and inconvenience to the family, maximizes the efficiency of the doctors, and ensures appropriate care of the child with this increasingly common finding.

SUGGESTED READING

[1.] Maizels M, Wang E, Sabbagha RE, et al. Late second trimester assessment of pyelectasis (SERP) to predict pediatric urological outcome is improved by checking additional features. Journal of Maternal-Fetal and Neonatal Medicine 2006 March.

[2.] Maizels M. The fetal urinary tract. In: Maizels M, Cuneo BF, Sabbagha RE, eds. Fetal Anomalies: Ultrasound Diagnosis and Postnatal Management. New York: Wiley-Liss, John Wiley & Sons, Inc; 2002:93-162.

[3.] Maizels M, Alpert SA, Houston JT, et al. Fetal bladder sagittal length: A simple monitor to assess normal and enlarged fetal bladder size, and forecast clinical outcome. J Urol 2004 Nov;172(5 Pt1):1995-1999.