16.1 Introduction
Given the emerging knowledge of embryogenesis involving the sonic hedgehog (Shh) gene and the relationship to both upper and lower intestinal mal- formations [1–6], it is surprising that more patients with anorectal malformations (ARM) and esophageal atresia/tracheoesophageal fistula (EA/TEF) do not manifest both anomalies. The collections of data over the years have indicated that the coincidence of the major associated anomalies has remained remarkably constant (Table 16.1) [7–10].
In the earlier series reported, the mortality from many of the associated anomalies was higher than
Contents
16.1 Introduction . . . 263
16.2 Esophageal Atresia/Tracheoesophageal Fistula Malformations . . . 264 16.3 Other Intestinal Malformations . . . 266 16.4 Hirschsprung’s Disease . . . 266 16.5 Cardiac Malformations . . . 266 16.6 Spinal Deformities . . . 267
References . . . 267
it is at present. Unless the ARM is exceedingly com- plex, the mortality is almost always related to one of the concomitant lesions and not to the ARM itself. At the time of the Survey of the Surgical Section of the American Academy of Pediatrics in 1964 [11] the sur- vival of babies born with EA/TEF was reported at 78%
without associated anomalies, whereas at present the survival of these babies born without other anomalies would be expected to approach 100%. In that survey data only 43% of babies born with ARM and EA/TEF survived, whereas at present this combination of le- sions would not be expected to be fatal in the absence of major cardiac or chromosomal defects.
Associated anomalies of all types are much more frequent with the more complex ARM. The definitive treatise on this subject, albeit almost 2 decades old, continues to accurately reflect the spectrum of associ- ated malformations correlated with the level of ARM that are seen to this day [8].
The genitourinary malformations are that are commonly seen in babies born with ARM are cov- ered in Chap. 17. In this chapter we will consider only the nongenitourinary malformations, which include EA/TEF, duodenal and other intestinal atre- sias, Hirschsprung’s disease (HD), neuronal intestinal dysplasia (NID), cardiac malformations, and spinal malformations. It is important to remember that al-
16 Nonurologic Anomalies Associated with Anorectal Malformations
Keith W. Ashcraft
Table 16.1 Anomalies associated with anorectal malformations. Vert Vertebrae, EA esophageal atresia, TEF tracheoesophageal fis- tula, GI gastrointestinal, GU genitourinary
Author Gross 1953 [7] Kiesewetter
1981 [8] Smith 1988 [9] Ratam 2005 [10] Totals
No. of patients 507 317 246 416 1,479
% anomalies 40 % 54% 61% 58% 51%
Vert/Skeletal 5% 6% 26% 41% 19%
Cardiovascular 8% 7% 9% 10% 9%
EA/TEF 4% 9% 4% 6% 7%
GI other 5% 4% 8% 9% 6%
GU system 16% 40% 25% 39% 29%
most any condition seen in a newborn child may oc- cur with an ARM, but the most commonly occurring ones are covered in this chapter. It may be that the same embryogenic events that produce EA/TEF are responsible for the development of an ARM. It is not known that duodenal atresia (DA) is related embryo- genically to ARM, but the incidence of DA is signifi- cant enough to warrant consideration herein. Other intestinal atresias seem to be a result of vascular ac- cidents far beyond the embryologic stage and are only rarely found in association with ARM. The septation defects that comprise the majority of cardiac mal- formations seen in patients with ARM are probably only randomly associated with the ARM. The surgical treatment of cardiac anomalies will not be covered in detail. Since cardiac malformations are the most com- mon associated malformations that can threaten the survival of the child, they must be investigated before the ARM is definitively treated.
Many of the vertebral anomalies associated with pelvic malformation, while not life-threatening, have a profound impact upon the functional outcome of the surgical treatment of ARM. The surgical treat- ment of spinal anomalies, specifically tethered cord, will be addressed in Chap. 18.
16.2 Esophageal Atresia/
Tracheoesophageal Fistula Malformations
Timing is everything! Nowhere is this old axiom truer than in the triage of babies born with ARM and an associated anomaly. Recognition of an associated anomaly thus becomes the first order in the planning of any approach to treating an ARM. The most im- mediately troublesome associated lesion is that of EA/
TEF. Because the child with EA is at risk of potentially fatal respiratory complications as a result of either spillover aspiration of saliva or milk or as a result of refluxed gastric content in the instance of a distal TEF, this lesion must be excluded very early. The presence of a distal fistula also complicates anesthetic manage- ment.
The diagnosis of EA/TEF is easily made (or ex- cluded) by the passage of a nasogastric tube. It is imperative that a relatively stiff tube be passed gen- tly to the stomach by the oral route before the child receives any oral intake. It is possible for a flimsy tube to curl in a blind-ending upper esophageal pouch giv- ing the impression of having passed into the stomach (Fig. 16.1). There are times when some well-inten-
tioned person will use a 5-Fr feeding tube for this diagnostic test to reduce the perceived discomfort to the newborn but a tube of less than 10 Fr is not satis- factory. Using a rigid tube obviates the need to inject air into the stomach to confirm passage of the tube.
This maneuver will not exclude the possibility of an isolated TEF, but the clinical recognition of this uncommon anomaly is often delayed in most chil- dren who have no other anomalies and is unlikely to adversely affect the early treatment of the ARM from either a nutritional or an anesthetic point of view.
The components that make the constellation known as the VACTERL association (Vertebral, Anal, Car- diac, TracheoEsophageal, Renal, and Limb malforma- tions) are so common that it is necessary to perform other initial diagnostic studies. Chief among these are the radiograph of the baby to include the torso and the limbs, a so-called babygram. It may be helpful to
Fig. 16.1 Magnified view of the mediastinum and upper abdo- men from a chest and abdominal radiograph in a newborn in- fant, demonstrating an orogastric tube curled within the upper esophageal pouch and gas in the stomach. This appearance is pathognomonic for esophageal atresia with a distal tracheo- esophageal fistula. Image courtesy of Dr. E. Bekhit, Department of Medical Imaging, Royal Children’s Hospital, Melbourne, Australia
leave the orogastric tube in the stomach during this radiographic study for documentation purposes. This radiographic study provides important information including the presence (or absence) of air in the stom- ach, the presence of and distribution of air beyond the duodenum, the distribution of air in the small bowel, the cardiac silhouette, the vertebrae (especially the pelvic structures), and limb abnormalities.
More sophisticated investigations are warranted if the babygram indicates absence of air in the stomach.
This indicates the presence of isolated EA without communication of the distal esophageal segment to the airway. Very rarely a distal TEF may be obstructed by mucus, giving the radiographic impression of iso- lated EA. Because isolated EA is a lesion that requires elongation of the blind ends of the esophagus or any of a number of substitution procedures to establish esophageal continuity, a gastrostomy is indicated for nutrition. The definitive esophageal procedure will occur in most cases long after the ARM has been treated surgically.
The upper esophageal pouch may be safely managed by sump suction drainage and intermittent bouginage for an indefinite period. Either gastroesophageal re- flux or the intermittent bouginage via gastrostomy will serve to elongate the lower esophageal segment while a decision is reached on the method of defini- tive esophageal treatment. Most commonly the estab- lishment of a colostomy in the presence of an obvi- ously high ARM or an indeterminate low ARM will accompany the gastrostomy procedure. The potential use of colon for esophageal interposition must be kept in mind at all stages of the ARM repair. Similarly, the placement of a gastrostomy near the greater curvature of the stomach may compromise the ability to develop a reversed gastric tube for later esophageal substitu- tion. If the initial whole body radiograph indicates air in the stomach but none beyond the duodenum, atresia of the duodenum may be present. Because of the absence of intraabdominal air in the case of iso- lated EA, the patency of the gut between the stomach and colon must be confirmed intraoperatively during the creation of these ostomies to insure that duodenal atresia or small bowel atresia is not also present. Once a route for nutrition has been established the plans for the definitive treatment of both EA and ARM can be formulated and undertaken.
In the presence of duodenal atresia (Fig. 16.2) the treatment of the upper GI tract becomes much more complex and the establishment of a colostomy to pal- liate the ARM becomes much more probable. Often prematurity will complicate the therapeutic plans.
Parenteral nutrition is certainly indicated for patients with this constellation of associated anomalies, but the volume of intravenous fluid required is not with- out its potential to complicate an associated cardiac malformation. Because low birth weight was more of a risk factor for mortality in the past, staging the surgical treatment was popular. The upper esopha- geal pouch can be safely managed with sump suction drainage, but the presence of the distal TEF is a risk factor for aspiration that is not always eliminated by the establishment of a decompression gastrostomy.
The upper gastrointestinal tract has been managed by transthoracic ligation of the distal TEF. Definitive repair of EA/TEF can be safely accomplished in pre- mature babies weighing as little as 1200–1300 g and is probably the preferred approach at present. A small transesophageal tube passed at operation will suffice for initial postoperative decompression of the stom- ach. A decompression gastrostomy and a colostomy can be established a day or two later at the time of the procedure to treat DA. In our experience, sufficient gut function to allow enteral nutrition is usually de- layed for a period of weeks following duoduodenos- tomy. During this time the treatment program for the ARM may be undertaken if appropriate.
Fig. 16.2 Abdominal radiograph, demonstrating marked gaseous distension of the stomach and duodenal cap (arrow), in keeping with a high-grade duodenal obstruction. Duode- nal atresia was identified at surgery. Image courtesy of Dr. E.
Bekhit, Department of Medical Imaging, Royal Children’s Hos- pital, Melbourne, Australia
16.3 Other Intestinal Malformations
Other intestinal malformations that may accompany ARM include jejunal-ileal atresia and colonic malfor- mations. Given the association between notochordal malformations and intestinal malformations, some of the same processes that produce EA/TEF and ARM may be applicable to other malformations. Many years ago we reported a congenital malformation of the colon associated with a teratoma arising from L2 that was associated with a low ARM and in whom the aorta was noted to be bifid below the level of T12 [12].
Other cases, although rare, of dilated, dysfunctional colon found in patients with ARM may be of similar etiology (see Chap. 11 on congenital pouch colon).
16.4 Hirschsprung’s Disease
The coincidence of HD and ARM is not easily de- termined. In the aforementioned extensive series of lesions associated with ARM, the incidence of classi- cally proven HD was thought to be very low [9]. Hy- poganglionosis of the terminal gut has been observed in cases of ARM where it was felt to be a result of the etiologic factors producing the ARM rather than due to a de novo failure of ganglion cell migration [13,14].
It has been suggested that the terminal bowel in cases of high ARM be biopsied and that the aganglionic or hypoganglionic segments be resected during the pull- through [15], but most surgeons now feel that the as- sociation between HD and ARM is sufficiently rare that biopsy sampling is unnecessary. Constipation following repair of an ARM is unlikely to be due to HD and can be managed by ensuring patency of the anus and attention to dietary factors.
More recently, the subject of NID and the occur- rence of classical HD in the presence of low ARM have entered the complex picture of innervation disorders of the anorectum and terminal colon. Using the more modern techniques of histochemical analysis of the fistula or terminal rectum in patients with ARM, the criteria for both HD and NID have been seen with somewhat alarming frequency [16]. All fistulas were
“abnormally” innervated. The four patients with low ARM and recognizable innervation disorders of the distal centimeter of the rectal pouch portion of the resection ultimately had severe constipation. Only 5 of 19 patients with intermediate or high ARM and innervation disorders suffered from constipation or soiling. The authors’ recommendation was that since the clinical course could not be correlated with the
type or severity of the distal innervation disorder, the fistula and the distal segment of rectal pouch should not be used in the repair of the ARM. Perhaps the saf- est course in the absence of the histochemical analysis is to follow the authors’ recommendation and discard the distal 1 cm of the rectal pouch.
16.5 Cardiac Malformations
Because the association between ARM and cardiac malformations exceeds that of any other “correct- able” associated malformation, it is necessary to ob- tain a cardiology consultation and an echocardio- gram as part of the initial evaluation (Fig. 16.3). The most common associated cardiac malformation is a ventricular septal defect (VSD). Some are associated with tetralogy of Fallot (TOF) and others are isolated defects. It is unusual for a VSD of any type to be as- sociated with cyanosis or cardiac failure in the new- born except for those with complex cardiac malfor- mations such as pulmonary atresia or transposition of the great vessels. In the very rare instance of these latter lesions being associated with ARM patency of the ductus arteriosus may be maintained by the use of prostaglandin while the colostomy is established.
Additionally, the patent foramen ovale may need to be enlarged by the balloon technique in the case of in-
Fig. 16.3 Transthoracic echocardiogram demonstrating a gap between the left ventricle (LV) and right ventricle (RV) that does not involve the left ventricular outflow tract and aorta (curved arrow), in keeping with a perimembranous ventricular septal defect (arrow). Image courtesy of Dr. G. Lane, Department of Cardiology, Royal Children’s Hospital, Melbourne, Australia
adequate atrial mixing. This is probably the only time the cardiac lesion will take precedence over the repair of the ARM. The usual associated cardiac malforma- tions of VSD and TOF will be addressed following the repair of the ARM.
When EA/TEF is present to further complicate the clinical and therapeutic course, many factors enter into the treatment algorithm. Among these is the pos- sibility of ligation or division of the distal TEF along with a colostomy to temporize. If the baby has TOF the descending aorta may be on the right side, mak- ing the definitive repair of the EA/TEF easier from the left thoracic approach.
Only in the presence of a cyanotic cardiac lesion without ductal patency will a systemic-to-pulmonary shunt be required. Although most of these are cur- rently done by the interposition of a Gore-Tex graft from the subclavian artery to the ipsilateral pulmo- nary vessel, the classic Blalock-Taussig shunt is cre- ated on the side of the innominate artery and may cause the later repair of the EA/TEF to be performed through a previously violated pleural cavity.
The mortality rate of the commonly associated cardiac malformations has dropped significantly over the last decade or two, but the constellation of a more severe, cyanotic cardiac defect with EA or ARM will obviously increase the complexity of the surgical ap- proach as well as the mortality and morbidity.
16.6 Spinal Deformities
These are the most commonly associated malforma- tions with ARM. The most common of the spinal deformities are aberrations in the numbers and sym- metrical development of the pelvic vertebrae. There are usually hemivertebrae present that will tilt the pel- vis to a varying degree and, if extensive, may result in severe deformity of the lower body. The absence of several pelvic vertebrae is more often associated with urinary incontinence than with bowel incontinence.
At times the spinal malformation may be very severe with lack of development of the sacrum and sacral nerve plexus, a condition know as caudal re- gression or caudal dysgenesis sequence. In these in- stances the baby’s buttocks are flat and the gluteal crease is barely discernable. The clinical import of this condition is that the pelvic musculature and innerva- tion are impossible to utilize. The establishment of an anal opening on the perineum will result in a perineal colostomy with little or no bowel control and no pos- sibility of maintaining a colostomy bag seal. In these
cases, establishment of a permanent colostomy is re- quired following separation of the distal bowel from the urogenital tract.
Some of the associated spinal malformations are accompanied by a tethered spinal cord. The filum ter- minale is fixed to the abnormal sacral vertebrae and the spinal cord is stretched, resulting in dysfunction of the most distal spinal nerves first – those innervat- ing the levator/sphincter mechanism, which results in a flaccid anus. There is usually is some skin abnormal- ity such as a hairy nevus located over the sacrum or distal lumbar vertebrae. Ultrasonography will usually detect the tethered cord or will indicate the presence of an intraspinal lipoma or meningeal cyst that might also eventually prevent the patient from being satis- factorily continent following repair of an ARM. There continues to be no hard evidence that the presence of a tethered cord affects continence or that release of the tethered cord alone will improve continence when it is suboptimal. The reader is directed to Chap. 18 for a more complete discussion of this topic.
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