Assessing Congenital Anomalies

chapter 5 Assessing Congenital Anomalies



Mark D. Ludman


image




Blessed are you, O Lord our God, King of the Universe, who varies the forms of his creatures.


JEWISH PRAYER, TRADITIONALLY RECITED UPON SEEING A PERSON OF UNUSUAL APPEARANCE, SUCH AS A GIANT OR A DWARF


Parents who seek help because their child has a congenital anomaly deserve a high level of competence and sensitive understanding from their physician. They want reliable, well-informed answers and an appropriate management plan. First and foremost, an accurate diagnosis is needed. Parents ask many questions, such as the following:


• “Why did this happen?”

• “What is going to become of my child?”

• “What problems will she have in the future?”

• “Will she go to school?”

• “Will he be ‘normal’?”

• “What are the chances that something like this will happen again?”

The importance of recognizing parents’ needs throughout the interview cannot be overemphasized. This issue is especially vital when you are dealing with the parents of a child who has a birth defect, as noted in Chapter 1. Remember the spectrum of emotions that parents may feel at the child’s birth and long afterward: shock, guilt, shame, anger, and denial.


Such parents have just given birth to a child who is less than perfect, who has a “defect.” Yet during the past 9 months, they had developed all sorts of fantasies about this child: “Will it be a boy or girl?” “Who will it look like?” “Will he have my nose?” Never did it occur to them that something like this could happen to them. When parents look over their new baby for the first time in the delivery room, they often begin by counting the baby’s fingers and toes, never imagining they would find anything other than ten of each.


When asking questions about topics such as drug and chemical exposures during the pregnancy, maternal employment conditions, or family history, remember that these particular parents are likely to feel guilt. Try not to add to their guilt feelings inadvertently, and do not allow yourself to be misled by such feelings either.



Key Point


It is imperative that you be sensitive to the parents’ concerns and feelings as you interview them and examine their child.


Comfort and counsel the parents throughout the interview; try to set them at ease, reassure them, and give them feedback and encouragement while eliciting information. Point out that we all vary in our appearance, otherwise we could not recognize one another. Emphasize that many features of a baby that an experienced clinician detects as unusual would never be noticed by the average person on casual observation.


One important point deserves emphasis: Never use demeaning, insensitive, or inappropriate terms, such as “funny-looking kid” or “FLK”, to describe the child either to the parents or to colleagues. If you use such terms when talking to a colleague, you can be sure some child’s parents will overhear and resent it.



The Logic Behind the Diagnostic Approach


Thousands of congenital anomalies have been identified, ranging from mild conditions with only minor cosmetic concerns to more serious, possibly lethal conditions. Congenital anomalies are the leading cause of death in infancy.


Major anomalies that adversely affect the child’s function or social acceptability are found in 2% to 3% of newborns. Many anomalies, although present at birth, are not detectable until later. Thus, 8% to 9% of 7-year-olds have a major anomaly. Examples include certain congenital heart defects, some types of craniosynostosis, and dental abnormalities. Minor abnormalities of no medical or cosmetic consequences may be seen in as many as 15% of births.


These statistics highlight the importance of an organized approach to detecting these problems. Only a careful methodical approach to diagnosing structural defects enables you to provide optimal care to the family. Furthermore, you will need great sensitivity in conducting the procedure; diagnostic labels may produce untoward results, such as stigmatization, as well as beneficial ones, for the child and family.



The “four Cs”


I use a sequential “four C” approach to the diagnosis of a child with congenital anomalies:


1. Collect the data.

2. Catalog and organize the data.

3. Categorize the defect or defects.

4. Compare with references and make the diagnosis.

The bulk of this chapter deals with Step 1, collecting the data, which is primarily the process of history-taking and physical examination, often aided by laboratory investigations. Step 2 involves listing the pertinent positive features that have been found. If the diagnosis is not instantly obvious, move to the subsequent steps.



Definition of Terms




Key Point


Before you can collect data, you must become familiar with the precise meaning of the following terms used to describe anomalies: major or minor anomaly, malformation and deformation, and sequence and syndrome.


The words malformation and deformation have specific meanings to dysmorphologists. This chapter deals with the child who has congenital anomalies rather than the child who has congenital malformations. Congenital anomaly is a more inclusive term covering all problems commonly referred to as “birth defects,” whereas congenital malformation is a defect specifically caused by an intrinsic developmental abnormality. A major external anomaly, such as a cleft lip and palate, may be apparent on superficial examination, but the specific nature of that defect and its association with more subtle features may be meaningful because anomalies such as cleft lips and palates occur not only as isolated defects but also as individual features of more than 250 different syndromes. Your approach to problems such as cleft lip, then, requires that the range of the genetic/dysmorphologic history and physical examination be comprehensive, as it will be if you use the information from each chapter of this book.



Congenital anomalies


Congenital anomalies have been noted throughout recorded history. Sculptures showing anomalies have been found dating back to 6500 bc, and records dating back to ancient Babylon indicate a keen awareness of congenital anomalies. However, it was only after 1966 that classification of an organized approach to these problems received serious attention. In that year, Dr. David W. Smith coined the term dysmorphology to refer to the clinical identification and assessment of structural anomalies, or “birth defects.” In the decades since then, much dysmorphology work was devoted to developing anomaly classification schemes. Such schemes help us understand at what point in development, and often how, the anomaly or constellation of anomalies occurred.



Key Point


After cataloging the child’s anomalies, the next task is to decide (1) whether they represent a single isolated defect or multiple defects and (2) which are major anomalies and which are minor anomalies.



Isolated versus multiple defects


Begin to classify and categorize structural abnormalities by deciding whether the observed defect is isolated or is one of multiple defects. If the anomaly is an isolated one, few additional investigations will be necessary and, generally, the prognosis will be clear and management less complex. However, a child with multiple congenital anomalies represents a diagnostic challenge that may entail considerable investigation. The prognosis may be more grave, especially if the central nervous system (CNS) is involved. If a chromosomal or mendelian disorder is present, the family may face a significant risk of recurrence in a subsequent pregnancy. Further, management of the child is likely to be much more complicated, requiring coordination of care by multiple specialists. Thus the approach to the child with a cleft palate, a ventricular septal defect, or polydactyly is quite different from that for the child with all three anomalies.



Major anomalies


Next, differentiate between major and minor anomalies. Major malformations have serious cosmetic, surgical, or functional consequences. Examples are cleft lip, congenital heart defects, spina bifida, anencephaly, and gastrointestinal obstructions such as duodenal atresia and imperforate anus. Major anomalies involve structures, such as the CNS, heart, lungs, kidneys, gastrointestinal tract, and genitalia, and are detected readily when organ dysfunction develops. Assessment for internal anomalies may be triggered by signs found on physical examination, such as a heart murmur or a scaphoid abdomen accompanied by bowel sounds in the chest. The diagnosis, however, generally requires further investigations, such as imaging studies. Cardiac evaluation may require a chest radiograph, electrocardiogram, and echocardiogram; computed tomography or magnetic resonance imaging may be indicated to assess the CNS. Assessment of the limbs and spine often involves reviewing skeletal radiographs.



Minor anomalies


Although individual minor anomalies may not be surgically or medically significant, their existence is clinically important to dysmorphologists. The presence of several minor anomalies alerts the astute clinician to the possibility that more serious major defects also may be present. Although single minor anomalies are common in the general population, the occurrence of two in a single infant is less common, and the occurrence of three or more is cause for concern. Although minor anomalies occur more frequently than major ones, they often are overlooked.



(This case history was modified from Woodhead JC: Pediatric clerkship guide, ed 2, Philadelphia, 2008, Mosby.)



Case history


A 5-lb, 3-oz male infant was just born in a small community hospital to a 24-year-old woman after an uncomplicated, full-term pregnancy. You are concerned because the infant has bilateral cleft lip and palate, small eyes, a loud heart murmur, undescended testicles, and clubfeet. The infant is also small for gestational age. The infant’s problems were a surprise, because this is the mother’s first pregnancy, and she had no history of abortions or miscarriages.


What information do you need to evaluate this patient? Based on the family history and the infant’s findings, what is the most likely cause of the anomalies? How would you evaluate this infant? What do you need to discuss with the family?


The baby’s mother has two healthy brothers, ages 21 and 28 years. Her mother is 56 years old and her father is 58 years old; both are healthy. The baby’s father is 25 years old and healthy. His father died at age 55 years of a heart attack, but his mother is healthy at age 57 years.


First, do a careful review of this pregnancy, including maternal fever, other illnesses, bleeding, diabetes, hypertension, and rashes. Ask about alcohol, tobacco, and prescription or over-the-counter drug use, including herbs. Ask whether prenatal studies were done, including ultrasound, amniocentesis, and triple screen. Obtain a detailed family history.


An infant with multiple congenital anomalies and in utero growth retardation whose family history does not demonstrate familial transmission of the problem may well have a chromosomal abnormality. Examples of such anomalies include trisomies, deletions, and duplications.



Key Point


Ninety percent of newborns who have three or more minor anomalies also have a major malformation. Often, it is the minor anomalies that allow a specific diagnosis to be established.



Constellations of minor anomalies


Most minor anomalies are detected simply by careful observation—the key element of the dysmorphologic examination. When examining individual characteristics, each of which is a minor abnormality, remember that it is not so important that a particular feature is “abnormal.”



Key Point


Few, if any, minor anomalies are pathognomonic for a specific syndrome. Although such features are individually nonspecific, it is the constellation of variations that constitutes an identifiable pattern of maldevelopment or syndrome, just as a particular constellation of features lets you instantly recognize your uncle in a crowd.


The constellation of minor anomalies gives the facies typical of certain so-called syndromes their characteristic appearance. In Down syndrome, for example, 79% of the malformations detectable by clinical examination are minor anomalies. When the diagnosis of Down syndrome is made, the “whole” (i.e., the constellation of minor anomalies) is more important than the sum of the individual parts. Many of these individual minor anomalies also can be found as isolated anomalies in perfectly “normal” people in the general population. This is where clinical experience plays an important role, because it often is easier to recognize individual anomalies than to spot the composite pattern that signals a particular syndrome.



Key Point


Generally, wide variation exists in the expression of any syndrome, and the severity and frequency of the individual minor anomalies may vary.


Minor anomalies include upward- or downward-slanting palpebral fissures, small or low-set ears, ear tags or pits, clinodactyly (incurving of the finger, generally the fifth, often associated with a dysplastic middle phalanx), or widely spaced nipples. Variations in features found frequently in the population (in more than 4% of individuals) are considered normal variants, not minor anomalies. They include mild webbing (syndactyly) between the second and third toes (see Fig. 4-22) and hydroceles (i.e., fluid accumulation surrounding the testes). Because of the large numbers of minor anomalies and potential variations, it would be impractical to list them all here.



Key Point


More than 70% of minor anomalies involve the hand or the face, including the eyes, ears, and mouth. Minor anomalies therefore are valuable clues in diagnosing a syndrome.


Nearly 50% of minor anomalies affect the head and face, reflecting both the complexity and variability of the structures involved. Remember the saying, “The face reflects the brain.” Craniofacial anomalies may be significant predictors of CNS abnormalities.


Anomalies are subdivided according to the mechanism of their abnormal morphogenesis, being classified as malformations, deformations, or disruptions. This classification poses the question of what happened in utero.



Malformations


A malformation is a structural defect caused by an intrinsic abnormality in the developmental process; that part of the body never developed normally. Malformations generally occur during the embryonic period and rarely correct spontaneously. Examples are anencephaly, spina bifida, cleft lip and palate, polydactyly, duodenal atresia, and congenital heart defects.



Deformations


A deformation, by contrast, is an abnormal shape, form, or position of a previously normally formed body part because of a mechanical force. Such forces generally result from uterine constraint because of insufficient amniotic fluid, malpresentation or uterine abnormalities, or lack of fetal movement. Sometimes the fetus is restrained; other times, severe neurologic problems cause the fetus to move less. Deformations generally arise later in the fetal period than malformations and often are corrected either spontaneously or through splinting. Examples are clubfoot, congenital hip dislocation, and some congenital contractures.



Disruptions


A disruption is a structural defect resulting from destruction of, or interference with, an originally normally formed body part. Typical examples are the anomalies produced by aberrant amniotic tissue bands that may cause amputation of digits, limb constrictions, or bizarre facial clefts. Vascular compromise also can lead to deprivation of blood supply to specific regions of the developing fetus, interfering with continued development. This process is thought to be the underlying cause of some unilateral limb reduction defects and of gastroschisis, an abdominal wall defect.



Sequences and syndromes


After categorizing a child’s defects as malformations, deformations, or disruptions, determining the developmental point at which they probably occurred, and arriving at a specific diagnosis, you turn to the next key question: Do the multiple anomalies seem to have occurred as a sequence, or do they likely represent a syndrome?


Dysmorphologists distinguish among different patterns of multiple anomalies as sequences and syndromes.



Sequence


A sequence is a pattern of multiple anomalies, a cascade of malformations or deformations, all developing as the result of a single initiating abnormality. An excellent example is the so-called Potter sequence. The initiating event is oligohydramnios, which leads to pulmonary hypoplasia and respiratory insufficiency. Oligohydramnios may have arisen for different reasons, such as an amniotic fluid leak or a lack of kidney development with no fetal urine production. The fetal compression in utero caused by the lack of fluid leads to:


1. A characteristic facial deformation that has been described as looking as if a silk (or nylon) stocking had been pulled down over it

2. Abnormal positioning of the hands and feet

3. Joint contractures

4. Growth deficiency

5. Often, a breech presentation

Whatever the cause, the obvious detectable features—the multiple minor facial anomalies, the joint contractures, and the pulmonary abnormalities—are all secondary to a lack of amniotic fluid.



Syndrome


A syndrome is a pattern of multiple anomalies all thought to be pathogenetically related but not known to represent a single sequence. Thus, all the congenital anomalies seen in the child with Down syndrome result from the presence of extra chromosome 21 material, but they do not all result as a cascade of events from a single initiating defect. In other syndromes, a single mutant gene, rather than a chromosomal defect, causes an intrinsic disturbance in multiple groups of embryonic tissues, resulting in a recognizable pattern of abnormality.


If the pattern of anomalies detected in a particular child is a syndrome, you must determine whether the constellation of defects is unique to this child or constitutes a recognizable pattern that has been identified previously in many other patients.


This consideration brings up the last stage of the “four C” diagnostic dysmorphologic approach: comparison with references.



Comparing patterns


The number of recognizable patterns of structural abnormalities and syndromes is enormous, and more are being recognized all the time. The pattern, such as Down syndrome, may be familiar, but if it is not, take heart.



Key Point


More than 4000 syndromes have been identified; most of them are rare. The average general practitioner may have seen 12 syndromes throughout his or her career, and a typical pediatrician may have seen 50. Even the dedicated geneticist may have a working knowledge of only about 200 syndromes.


Even experienced dysmorphologists generally cannot remember all the anomalies that constitute any specific syndrome. The amount of information concerning the individual features of specific syndromes is simply too vast to memorize. Luckily, there are many useful reference books for comparing the patient’s characteristics with descriptions and photographs of identified syndromes. Perhaps the most widely used is Smith’s Recognizable Patterns of Human Malformation, which has invaluable tables listing the differential diagnosis of specific individual anomalies. These tables allow you to create a short list of syndromes that manifest as the particular anomalies you have identified in a given patient.


When using these tables to generate a list of diagnostic possibilities, start with the rarest and most distinctive feature you have noticed. Starting with features such as low-set ears or epicanthic folds would result in an unwieldy list, whereas starting with a white forelock or a dislocated lens would result in a more manageable list. Likewise, if all you identify are several very common features, such as short stature, a broad nasal bridge, and clinodactyly, you are not very likely to attain a specific diagnosis.


Several computer programs are now available that can generate such lists after a constellation of identified anomalies has been entered (see http://www.possum.net.au/ or http://www.lmdatabases.com/). These programs provide descriptions and often photographs of patients with different syndromes. The major advantage of using such programs is having access to their encyclopedic quality, but their usefulness is always limited by the accuracy of the history and physical findings that the physician “feeds” them. Computer programs cannot take the history or perform the physical examination; only a clinician can do this. Further, your clinical judgment is required to determine if any of the suggested diagnoses is, in fact, likely to be the correct one.


As a result of the many advances in our understanding of the molecular basis of development and the progress of the Human Genome Project, we are learning the genetic basis for many syndromes. Nevertheless, although we may know the molecular basis for a syndrome, we still may not have any diagnostic laboratory test for it. For some syndromes, a test may be available to confirm a diagnosis made on clinical grounds. (A useful resource for determining whether a genetic test is available for any particular syndrome is the GeneTests Web site: http://www.ncbi.nlm.nih.gov/sites/GeneTests/?db=GeneTests).


Despite your best efforts and the use of all diagnostic modalities, you may never reach a diagnosis. In fact, in more than half of children with multiple anomalies, no diagnosis can be established. Do not be afraid to admit that you cannot reach a diagnosis when that situation arises. Remember that assigning an incorrect diagnosis can be worse than not coming up with one. Sometimes, even though you may not be able to reach a diagnosis the first time you assess the child, over time and with repeated assessments—often as new features develop or reveal themselves—you will be able to do so. As you watch the natural history of the condition unfold, the diagnosis often becomes obvious.



Obtaining The History


To make the proper diagnosis required to manage the patient and counsel the family, the clinician must elicit accurate and complete information.



History of pregnancy, labor, and delivery


Elements of a complete history that require special attention are the pregnancy, labor, delivery, and especially the family history.



Pregnancy History


The pregnancy history is outlined in Chapters 1 and 4. Be sure to relate calendar dates to gestation time. For example, note that the mother had a viral illness at 7 gestational weeks, not “on January 16.” Specifically inquire about the course of the pregnancy.


Ask about fetal growth. Were any size-date discrepancies noted? Did fetal growth rate seem to diminish? Uterine size may provide clues to both fetal growth and fetal physiology. Polyhydramnios (i.e., increased amniotic fluid volume) indicates either increased fetal urine excretion or, more typically, difficulties with fetal swallowing that may be seen with fetal neuromuscular disease, gastrointestinal tract obstruction, or heart failure. Lack of fundal growth may indicate intrauterine growth retardation or oligohydramnios. As mentioned earlier, one cause of the latter is poor fetal renal function. The deformations associated with the oligohydramnios sequence could be expected. Information from prenatal ultrasound examinations may help assess these situations, because other fetal anomalies, fetal position and activity, or uterine abnormalities may have been recognized at the time of the ultrasonography.



Significant Questions



1. Were any prenatal studies performed, such as amniocentesis, chorionic villus sampling, nuchal translucency, detailed ultrasonography, maternal serum screening, or cordocentesis?

2. Did the mother or father experience any chronic medical problems, such as diabetes, seizures, phenylketonuria or other metabolic diseases, or idiopathic thrombocytopenic purpura?
< div class='tao-gold-member'>

Related posts:

  1. Assessing the Skin
  2. Assessing Physical Growth and Nutrition
  3. Evaluating the Newborn: Diagnostic Approach
  4. Examining the Visual System

Stay updated, free articles. Join our Telegram channel
Tags:
Jul 3, 2016 | Posted by in PEDIATRICS | Comments Off on Assessing Congenital Anomalies

Full access? Get Clinical Tree
Get Clinical Tree app for offline access