American Pediatric Surgical Association :: Resources : Hirschsprung's Disease

CLINICAL PRESENTATION
Hirschsprung’s disease often presents in newborns as intestinal blockage or obstruction occurring most commonly in the colon or rectum. The child may or may not have an infection called enterocolitis, resulting from the obstruction. This is caused by to many bacteria (overgrowth) in the affected segment of intestine. Although the incidence of enterocolitis is variable, this complication makes the diagnosis and early treatment of Hirschsprung’s disease urgent. In the mildest case, delayed passage of meconium (the stool first passed by a baby) may be the only abnormality.

Most patients with Hirschsprung’s fail to pass meconium swithin the first 48 hours of life. At the other end of the spectrum a newborn infant may become seriously ill and appear to have an intestinal obstruction. In these patients, abdominal distention, green stained or foul smelling vomiting, and failure to pass meconium are the presenting signs. Plain abdominal x-rays commonly show many dilated segments of bowel consistent with intestinal obstruction (See Figure 5A).

The sickest infants may present with a picture of overwhelming sepsis (a serious type of infection). This picture may create confusion in making the diagnosis because may not work normally when sepsis is present. In other words, it may be difficult to tell if a problem in the intestine is caused by the sepsis or if the sepsis is causing a problem with the intestine.

The clinical presentation of enterocolitis resulting in sepsis demands the most urgent medical attention. Sepsis in newborns may include progressive respiratory failure (breathing problems), hypovolemia (loss of fluids within the body), shock (low blood pressure), coagulopathy (problems with clotting) with decreased platelet count (a type of blood cell that helps with clotting), decreased urine production, and temperature instability. Finally a few infants present with the intestines perforated or ruptured.

These variations in the clinical presentation are substantiated by several large series. Swenson, in his review of 501 patients, verified that 94% of patients had delayed passage of meconium beyond 24 hours. This well-quoted finding is not always seen, however, and even if the child does pass meconium within this time frame the diagnosis of Hirschsprung’s cannot be completely excluded. In a series of 35 newborns reported at the University of Michigan Medical Center, 54% showed abdominal distention, 46% failed to pass meconium after 48 hours, 34% presented with constipation, 26% presented with vomiting, and 6% had perforation (rupture) of the intestine. Enterocolitis occurred in 12% of patients. Each child has a unique presentation and the clinical picture may not always be clear. Hirschsprung’s disease must be kept in mind and a suction rectal biopsy performed if there are any suspicions.

The age at diagnosis varies widely, but approximately half of patients in the United States are diagnosed in the newborn period, and most of the remainder are diagnosed before the age of 2. In older children or occasionally adults, Hirschsprung’s disease is discovered during evaluation for chronic constipation. Symptoms range from minimal to severe, but chronic abdominal distention is characteristic. Malnutrition and failure to thrive (grow and maintain weight) may be seen in these patients, but this has become relatively uncommon in more recent years in the developed world.

What other cause of intestinal obstruction might my child have?
The consideration of diagnoses other than Hirschsprung’s disease must include all the entities responsible for intestinal obstruction (blockage) in the small bowel or colon as listed below. A qualified pediatric surgeon will know how to differentiate between these different diagnoses. Many of these problems can be excluded based on the history of the problem, physical examination or by some simple tests. Information on some of these diagnoses is available on this Web site.

MAKING THE DIAGNOSIS OF HIRSCHSPRUNG'S DISEASE
When the clinical suspicion of Hirschsprung’s disease has been raised, plain x-rays of the abdomen are obtained to look for evidence of intestinal obstruction, perforation or both. These studies can be followed by a barium enema or anorectal manometry and full-thickness or suction rectal biopsy (all explained below). Some surgeons have questioned the usefulness of the barium enema study in the newborn period because of the absence of a transition zone which helps to make the diagnosis of Hirschsprung’s disease in many cases, but many find it useful. The diagnostic accuracy of a barium enema in the first month of life as ranges from 21% to 96%.

This study is very suggestive if there is demonstration of a small distal (end toward the anus) intestinal portion with an enlarged proximal (end toward the mouth) bowel. (Figures 1-5) Another suggestive finding is failure of the patient to evacuate the barium from the colon within 24 hours of the performance of the study. A follow up abdominal x-ray needs to be taken to demonstrate this. A characteristic series of radiographs with the typical pattern of rectosigmoid Hirschsprung’s disease. Photo (A) shows a plain abdominal film with dilated loops of intestine. This indicates some type of intestinal obstruction, but cannot tell exactly which one. Photo (B) shows a barium enema in a child with Hirschsprung’s disease. The rectum is small and contracted while the colon just before the segment with Hirschsprung’s has become very enlarged and distended. The point at which the bowel changes from distended (enlarged), to non-distended (small) is called the transition zone.

Some investigators use anorectal manometry in establishing the diagnosis of Hirschsprung’s disease. This may not be available in all institutions and some surgeons and gastroenterologists may prefer to do this only in older children. This technique has the advantage of bedside performance and the immediate availability of results. The study is fairly noninvasive and can be performed in an outpatient setting. However not all children will tolerate the procedure. There have been no reported complications from this test. Some studies report that the test is less reliable in infants and is more difficult in this age group because of the sensitivity of the equipment and the difficulty of appropriately positioning the manometry probe. In general, anorectal manometry in children is used to help with the diagnosis when it remains unclear.

Swenson established the full-thickness rectal biopsy as the standard for diagnosis in 1955, reporting a 98% accuracy rate in follow-up studies. With this technique a very small piece of all layers of the rectum near the anus is removed while the child is under anesthesia. The site where the piece is removed is sutured close. This technique has some disadvantages, however, including the need for general anesthesia and the occasional report of post-biopsy rectal bleeding. Scarring at the site of the biopsy may moderately interfere with the subsequent pull through procedure (operation for correction of Hirschsprung’s).

Subsequently, the use of the suction rectal biopsy has been established as an acceptable and accurate means of diagnosis. A suction rectal biopsy device is shown in Figure 10. The device is used to remove small pieces of the inner layers of the rectum. This technique requires the availability of an experienced pathologist who sees this disease and reviews pathologic slides for Hirschsprung’s disease with some frequency. The findings at times may be subtle and the pathologist plays a vital role in the treatment of this problem.

The suction rectal biopsy has several advantages over the full thickness biopsy, including simplicity, absence of need for anesthesia, performance at the bedside or in the outpatient setting, and very few complications. Its widespread use has been supported by several studies that report an accuracy rate of 99.7% with no complications.

Full thickness biopsies are now usually used when a suction biopsy has not been successful or in older patients. An experienced pathologist can interpret the biopsy specimen easily and provide a report within 48 hours. Finally, in contrast to full-thickness rectal biopsy, the suction rectal biopsy is less likely to interfere with the subsequent pull-through procedure (operation for correction of Hirschsprung’s).

Other studies on the biopsy specimen are helpful in making the diagnosis. The presence of increased AchE (acetylcholinesterase) content in the nerve fibers of the affected bowel in patients with Hirschsprung’s disease is highly suggestive. There is a reported 95% accuracy rate with this technique. This technique works only for Hirschsprung’s disease affecting the rectum and left side of the colon because there is no AChE activity in the right or middle segments of the colon. Many pathologists do not need or use the AcLE test, however.

Occasionally the diagnosis of Hirschsprung’s disease is not made prior to surgically exploring the abdomen in patients with intestinal obstruction. This may be especially true in patients with total colonic aganglionosis (missing ganglion cells from the entire colon). (Figure 10)

Figure 10: Total colonic Hirschsprung’s disease. The transition zone (arrow) is in the small intestine.

If no clear-cut transition zone is seen, many surgeons perform an appendectomy with frozen section evaluation for ganglion cells, during a frozen section the biopsy is flash frozen and examined under the microscope. This flash-frozen technique is only used during an operation when information is needed immediately because it is not as accurate as the "permanent" pathology assessment which takes days for processing. Further biopsy specimens may be needed to establish the transition zone.

TREATMENT
The successful treatment of infants and children with Hirschsprung's disease depends on prompt diagnosis and early treatment. This is not a problem that a child will outgrow nor will it get better given time. Surgery is necessary, followed by close follow-up in the pediatric surgery clinic. If left untreated, Hirschsprung's disease can lead to many problems including in some cases, death.

Traditionally Hirschsprung's disease is treated in several operative stages. It has become more common to treat this in one operative stage with a primary pull-through though this is not always possible. The decision to perform a primary pull-through when the diagnosis is established depends on the condition of the child and the response to initial treatment. Once the diagnosis is made, decompression of the colon with a large-caliber soft tube placed in the rectum may be performed. This is followed by gentle irrigations of the rectum and colon, while leaving the catheter within the rectum. Antibiotics and extra intravenous fluids may be needed.

Further measures to care for the child will depend on the condition. The safest approach to a very ill child with evidence of enterocolitis and sepsis is the performance of a colostomy. While in the operating room the surgeon establishes the part of intestine where normal ganglion cells exist and brings out the colon as an ostomy (sews the bowel to the skin and the child has bowel movements into a bag (Figure 11). This is a temporary measure. A stable child with a mild case of enterocolitis can undergo a definitive, primary pull-through. Infants with longer lengths of aganglionosis may not respond to gentle irrigations and may require a colostomy on a more urgent basis.

Figure 11: A colostomy may be formed in some cases with Hirschsprung’s disease (arrow).

DEFINITIVE PULL-THROUGH OPERATIONS FOR THE CORRECTION OF HIRSCHSPRUNG’S DISEASE
There are three major operations for Hirschsprung's disease and several variations of these (Figure 12). The operation chosen usually depends on the training and experience of the surgeon though at times a specific operation may be indicated for a particular situation. The outcome of the three operations is fairly similar though some surgeons feel strongly about or feel most comfortable with one of these techniques or its variations.

Figure 12: The bold lines in each drawing indicate the retained aganglionic rectum.

The first definitive operation was described by Swenson and Bill in 1948. Commonly called the Swenson procedure, this procedure involves removal of the aganglionic bowel and sewing ganglionated colon to the rectum very near the anus. The important steps in this operation are to keep the dissection immediately next to the rectal wall to avoid injury to the pelvic nerves responsible for rectal and bladder innervation and sexual function. There is also risk of injury to the seminal vesicles near the bladder if the proper dissection is not maintained. The results presented by Swenson in a 25-year follow-up are excellent as are those reported subsequently by other surgeons. In Swenson's series, there were no cases of impotence or urinary incontinence, a 1.4% incidence of permanent colostomy or ileostomy, and a 3.2% incidence of permanent soiling. Of these patients, 90% experienced normal bowel habits.

Duhamel introduced his technique in 1956. In this procedure, the pelvic dissection is limited to the space behind the rectum. This avoids potential injury to the pelvic nerves. The normal bowel is brought down behind the rectum and the end of this bowel is sewn to the side of the rectum near the anus. A surgical stapler is used to then further connect the pulled-through bowel to the rectum. The patient ends up with a new rectum, the front half of which is composed of the old aganglionic rectum and the back half is composed of the new pulled-through ganglionic colon. To minimize the pelvic dissection, however, a relatively long rectal stump may be left, which may predispose to stool retention and subsequently a relatively high incontinence rate. Modifications to the technique have been developed to deal with this problem. The advantage of this procedure is that it is technically easy to perform and can be used in the case of a failed Swenson procedure.

The Soave or endorectal pull-through was introduced by Soave in 1960. Conceptually, this procedure consists of removing the mucosa (the lining) of the rectum and pulling ganglionic bowel through a short aganglionic muscular cuff (See Figure 13). By remaining within the muscular cuff of the aganglionic segment, important sensory fibers and the function of the internal sphincter are preserved. Although leaving behind aganglionic muscle surrounding normal bowel conceptually might lead to a high incidence of constipation, this has not been the experience clinically.

Figure 13: An endorectal pull-through is being performed. This is a picture taken inside the abdomen down in the pelvis. The cotton swab is pointing to the rectum. The muscular portion of the rectum (white arrow) is being separated from the mucosa (lining) of the rectum. The normal portion of the intestine with ganglion cells will be pulled down through the muscular portion and sewn to the anus after the lining has been removed down to the anus.

PRIMARY PULL-THROUGH FOR HIRSCHSPRUNG'S DISEASE
As originally described, all three of the operations listed above are performed after first creating a colostomy when the diagnosis of Hirschsprung's is made. The pull-through is usually performed sometime in the first year of life. In 1980, a study reported a 10-year experience with primary endorectal pull-through in neonates without the use of a preliminary colostomy. In two thirds of the patients, the definitive pull-through was performed by the fourth week of life with no deaths or major complications. A subsequent multi-institutional analysis of the primary pull-through showed it to be equally effective and safe compared with a two-stage approach in patients. A primary pull-through without colostomy is now offered to many patients if the child is appropriate for the operation. The operation has been done using all three of the major techniques listed above as well as several newer methods described below. Only children who are well, without evidence of severe enterocolitis are good candidates for the primary pull-through.

LAPAROSCOPIC AND TRANSANAL APPROACHES TO HIRSCHSPRUNG'S DISEASE
The use of advanced laparoscopic techniques for Hirschsprung's disease is now used by many pediatric surgeons. All three of the primary operations have now been performed using laparoscopic techniques. The transanal method allows the operation to be performed entirely or almost entirely through the anus (see Figure 14). This approach is best used in children with a transition zone in the sigmoid colon or rectum. Some surgeons may use a combination of the laparoscopic and transanal techniques. Both of these techniques have the potential advantage of smaller incisions, less post operative pain and the possibility of faster recovery. Both of these operations have gained wide use in the pediatric surgical community in recent years.

Figure 14: This picture shows a “transanal pull-through.”The mucosa (lining) of the rectum has been separated from the muscles by working up through the anus for a few inches. At that point the entire “full thickness”of the rectum and large intestine can be removed out through the anus until a transition zone is seen (black arrow) and the size of the colon becomes larger (white arrowhead) indicating that the portion of the large intestine no longer has Hirschsprung’s disease. The large intestine is divided above the transition zone and sewn to the anus. Biopsies are checked in the operating room to make sure that the large intestine at that point is normal.

INTESTINAL NEURONAL DYSPLASIA (IND)
Intestinal neuronal dysplasia (IND) initially was described by Meier-Ruge in 1971. This disorder was classified as a colonic problem, although the disease can involve any portion of the gastrointestinal tract. Two forms of the disease have been described, Type A and Type B. The difference between the two is in the microscopic appearance of the bowel. Type B IND is seen much more commonly than type A, and symptoms in type B are milder. The typical presentation of IND is variable. Children with type A present at a younger age than children with type B. Most children have complaints of abdominal distention. Some have constipation and develop enterocolitis (see next section).

The extent of IND may range from a short colonic segment to the entire length of the gastrointestinal tract. In contrast to Hirschsprung's disease, the internal sphincter relaxation reflex is absent or atypical in only 75% of patients with IND. The association of IND and Hirschsprung's disease also has been noted by some authors. The incidence ranges from 0 to 75% in reported series. Because the symptoms of Hirschsprung's disease may mask those of IND, the diagnosis often is not made until the patient develops stooling problems after a definitive pull-through.

It is important to note that the precise criteria for the diagnosis of IND are lacking. This lack of rigid criteria most likely explains the variability in the incidence of this disorder. There is also a broad range of clinical symptoms with this condition. Some patients will have few if any gastrointestinal complaints while others will have significant problems. Caution should be observed when making the diagnosis of IND, and a conservative approach to surgery for this disorder should be used.