32.1 Introduction
The colon absorbs water from the stool and serves a reservoir function. These processes depend on colonic motility, which is an area of physiology that is not well understood, and for which treatments of problems are limited. In normal individuals the rectosigmoid stores the stool, and every 24–48 h develops active peristal- tic waves indicating that it is time to empty. A normal individual feels this sensation and decides when to re- lax the voluntary sphincter mechanism. Patients with anorectal malformations, as discussed in Chaps. 29, 30 and 33, lack a normal anal canal, have deficient sphincters, and have an accompanying motility dis- order, usually hypomotility [1]. Their ability to have a voluntary bowel movement depends on these three factors. Solid stool allows for distension of the distal rectum, and proprioception allows the child to detect this. It is for this reason that loose stools make their ability to be fecally continent much less likely.
If a child is fecally continent (i.e., those with a good-prognosis anorectal defect, a normal sacrum, good sphincters, and an intact rectosigmoid), then management involves the treatment of constipation using laxatives, which help provoke peristalsis and overcome the dysmotility disorder. Patients in whom the rectosigmoid was resected, a common part of older operations for anorectal malformations, have hypermotility and require treatments that slow down the colon. Unfortunately, most of these patients are
fecally incontinent because their lack of anal canal, and deficient sphincters cannot hold back the loose stool. They do not detect rectal fullness and thus can- not rely on proprioception for help with a voluntary bowel movement. For patients with fecal inconti- nence, a bowel management program is a way to arti- ficially keep patients clean (Chaps. 29, 30 and 33). For the majority of patients (75%), management consists of avoidance and treatment of constipation, and toi- let-training strategies.
Constipation in anorectal malformations is ex- tremely common, particularly in the more benign types [2]. When left untreated, constipation can be ex- tremely incapacitating, and in its most serious forms can produce a form of fecal incontinence known as overflow pseudoincontinence. Diet impacts colonic motility, but its therapeutic value is negligible in the most serious forms of constipation. It is true that many patients with severe constipation suffer from psychologic disorders, but a psychologic origin cannot explain the severe forms as it is not easy to voluntarily retain the stool when an otherwise autonomous rec- tosigmoid peristalses. Passage of large, hard pieces of stool may provoke pain and make the patient behave like stool retainers. This may complicate the problem of constipation; but it is not the original cause.
The clinician must decide which type of patient he or she is dealing with. Patients with a good prognosis are those more likely to have constipation, and while they are in disapers, aggressive, proactive treatment of their constipation is the best approach. Once they reach the age of toilet training, the child must have the capacity for voluntary bowel movements before employing treatment for constipation. Otherwise, theys require bowel management and enemas.
Most of these patients suffer from different degrees of dilatation of the rectum and sigmoid, a condition defined as megarectosigmoid, due to a hypomotility disorder that interferes with complete emptying of the rectosigmoid [1]. These children are born with a good-prognosis type of anorectal defect and un- derwent a technically correct operation, but did not receive appropriate treatment for constipation. They
Contents
32.1 Introduction . . . 415 32.2 Treatment . . . 417 32.2.1 Disimpaction . . . 418
32.2.2 Determination of the Laxative Requirement in a Disimpacted Patient . . . 418
32.2.3 Surgical Treatment . . . 418 32.2.3.1 Sigmoid Resection . . . 418
References . . . 419
32 Treatment of Chronic Constipation and Resection of the Inert Rectosigmoid
Marc A. Levitt and Alberto Peña
therefore developed fecal impaction and overflow pseudoincontinence. The impaction needs to be re- moved with enemas and colonic irrigations to clean the megarectosigmoid. The constipation is subse- quently treated with the administration of large doses of laxatives. The dosage of the laxative is increased daily until the right amount of laxative is reached in order to completely empty the colon every day. If medical treatment proves to be extremely difficult because the child has a severe megasigmoid and re- quires an enormous amount of laxatives to empty, the surgeon can offer a resection of the sigmoid colon.
After the sigmoid resection, the amount of laxatives required to treat these children can be significantly reduced or even eliminated. Before performing this operation it is mandatory to confirm that they are definitely suffering from overflow pseudoinconti- nence rather than true fecal incontinence with consti- pation. Failure to make this distinction may lead to an operation in which a fecally incontinent constipated child is changed to one with a tendency to have loose stool, which will make them much more difficult to manage (see Chaps. 29, 30 and 33).
When managed from the beginning, with aggres- sive treatment of constipation, children with a good prognosis should toilet train without difficulty. When constipation is not managed properly and a patient presents after many years, they behave much like children with idiopathic constipation, and may have overflow pseudoincontinence.
On occasion, the constipation in anorectal malfor- mations is attributed to Hirschsprung’s disease, and it is not uncommon that clinicians perform a rectal biopsy. In our experience, Hirschsprung’s disease is no more common in patients with anorectal malfor- mations than in the general population and we do not routinely biopsy these patients.
Constipation in anorectal malformations is a self- perpetuating disease. A patient who suffers from a certain degree of constipation and who is not treated adequately only partially empties the colon, leaving larger and larger amounts of stool inside the recto- sigmoid, which results in greater degrees of megasig- moid. It is clear that dilatation of a hollow viscus pro- duces poor peristalsis, which explains the fact that constipation leads to fecal retention, thereafter mega- colon, which exacerbates the constipation. In addi- tion, the passage of large, hard pieces of stool may produce anal fissures, which result in a reluctance by the patient to have bowel movements.
The clinician must accept the fact that the dys- motility associated with anorectal malformations is essentially incurable. It is manageable, however, but
requires careful follow-up for life. Most importantly, it must be anticipated and treated early, even within weeks following the colostomy closure. Treatments cannot be given on a temporary basis; once they are tapered or interrupted, constipation recurs.
Some clinicians treat such patients with colosto- mies or colonic washouts via a catheterizable stoma or button device, and monitor the degree of colonic dilatation with contrast studies. Once the distal co- lon regains a normal caliber, the physician assumes that the patient is cured and the colostomy is closed or the washouts are discontinued with the predict- able return of symptoms. Washouts are really only for patients with fecal incontinence who are incapable of having voluntary bowel movements and thus require a daily irrigation to empty. The patients described in this chapter are capable of emptying their colon with the help of adequate doses of laxatives.
Determining if the patient is continent or inconti- nent is the challenge. If incontinent, washouts with a bowel management regimen are appropriate. If conti- nent, then aggressive management of the constipation after ensuring disimpaction is the appropriate treat- ment. These latter patients have a good-prognosis anorectal defect, good sacrum, and good sphincters.
Fecal impaction is a stressful event defined as a condition of retained stool for several days or weeks, crampy abdominal pain, and sometimes tenesmus.
When laxatives are prescribed to such a patient the result is exacerbation of the crampy abdominal pain and sometimes vomiting. This is a consequence of an increased colonic peristalsis (produced by the laxa- tive) acting against a fecally impacted colon. There- fore, disimpaction, proven by x-ray, must precede the initiation of laxative therapy.
Soiling of the underwear is an ominous sign of bad constipation. A patient who at an age of bowel con- trol soils the underwear day and night and basically does not have spontaneous bowel movements may have “overflow pseudoincontinence.” These patients behave as fecally incontinent individuals. When the constipation is treated adequately, the great major- ity of these pseudoincontinent children regain bowel control. Of course, this clinical presentation may also occur in a patient with anorectal malformation and true fecal incontinence. In such a patient with a poor- prognosis defect, poor sacrum, and poor sphincters, bowel management with a daily enema is needed (see Chaps. 29, 30 and 33).
When uncertain, we usually start the 3.5 to 4 year- old child having trouble with toilet training on a daily enema, and once clean with this regimen, and if they have the potential for bowel control, then try a laxa-
tive program. A contrast enema with a hydrosoluble material (never barium) is the most valuable tool that, in the constipated patient, usually shows a megarecto- sigmoid with dilatation of the colon all the way down to the level of the levator mechanism (Fig. 32.1).
There is usually a dramatic size discrepancy between a normal transverse and descending colon and the very dilated megarectosigmoid. The size of the colon guides the dosing of the laxatives, and it seems that the more localized the dilatation of the rectosigmoid, the better the results of a sigmoid resection. The con- trast study may show an absence of the rectosigmoid (Fig. 32.2), which may have been resected during the original operation, and correlates with hypermotility and usually fecal incontinence.
Some clinicans use rectal and colonic manometry in the evaluation of these patients; however, more objective techniques are needed. Manometry is per- formed by placing balloons at different levels of the colon and recording the waves of contraction [3] or the electrical activity [4]. Scintigraphy, a nuclear med- icine tool, is also being used to assess colonic motility [5]. These are sophisticated tools but at present, their help as guides for therapeutic decisions is lacking.
The key information the surgeon needs is to know if and where a colonic resection would provide benefit to the patient. Histologic studies of the colon in these patients mainly show hypertrophic smooth muscle in the area of the dilated colon and normal ganglion cells, but more sophisticated histopathologic investi- gations will hopefully soon yield results. Further in- vestigations in this area will enhance our knowledge about colonic dysmotility in this patients, and thereby guide therapy.
32.2 Treatment
Patients with anorectal malformations and severe constipation in whom dietary measures or gentle lax- atives do not work require a more aggressive regimen.
It cannot be overemphasized that the treatment must start early. Drugs designed to increase the motility of the colon are best, as opposed to medications that are only stool softeners. As discussed, softening of the stool without improving the colonic motility will likely make the patient worse, because with soft stool they no longer have control, whereas they do reason- ably well with solid stool that allow them to feel dis- tension of the rectum.
Our protocol of treatment of these patients in- cludes a trial of medical management [6]. If the pa- tients respond to this treatment but require an enor-
mous amount of laxatives to empty, then an operation is considered. The regimen uses the same medications as have been tried previously in many cases, but the protocol is different in that the dosage is adapted to the patient’s response, the response is monitored daily with an abdominal radiograph, and the laxative dose adjusted if necessary. The patient has almost always been receiving less laxative than they required.
When a patient with anorectal malformations presents with constipation, the steps of treatment are as follows.
Fig. 32.1 Megarectosigmoid (Reprinted from Current Prob- lems in Surgery, 39, Peña A., Levitt M. Colonic Inertia Disor- ders in Pediatrics, p 681, Mosby (2002), with permission from Elsevier.)
Fig. 32.2 Absence of rectosigmoid
32.2.1 Disimpaction
The disimpaction process is a vital and often neglected step. The routine first includes the administration of enemas until the patient is disimpacted (confirmed radiologically). If the patient remains impacted they are given a balanced electrolyte solution via a naso- gastric tube in the hospital, and the enema regimen is continued. If this is unsuccessful, a manual disim- paction under anesthesia may be necessary. It is im- portant to remember not to prescribe laxatives to a patient that is fecally impacted. To do so may provoke vomiting and severe abdominal pain. In addition, the patient will become reluctant to take laxatives because he or she is afraid of those symptoms.
32.2.2 Determination of the Laxative Requirement in a Disimpacted Patient Once the patient has been disimpacted, an arbitrary amount of laxative is started, usually a senna deriva- tive. The initial amount is based on the information that the parents give about the previous response to laxatives, and the subjective evaluation of the megasig- moid on the contrast enema. The empiric dose is given and the patient is observed for the next 24 h. If the patient does not have a bowel movement in the 24 hours after giving the laxative, it means the laxative dose was not enough, and it must be increased. An enema is also required in order to remove the stool produced during the previous 24 h. Stool in these ex- tremely constipated patients should never remain in the rectosigmoid for more than 24 h.
The routine of increasing the amount of laxatives and giving an enema, if needed, is continued every night until the child has a voluntary bowel move- ment and empties the colon completely. The day that the patient has a bowel movement (which is usually with diarrhea), a radiograph should confirm that the bowel movement was effective, meaning that the pa- tient has completely emptied the rectosigmoid. If the patient passed stool but did not empty completely, the dose of laxative must be increased.
Since this condition covers a wide spectrum, pa- tients may have laxative requirements much larger than the manufacturer’s recommendation. Occasion- ally, in the process of increasing the amount of laxa- tives, patients throw up before reaching any positive effect. In these patients, a different medication can be tried. Some patients vomit all kind of laxatives and and are unable to reach the amount of laxative that produces a bowel movement that empties the colon.
Such a patient is considered intractable, and there- fore a candidate for surgical intervention. Most of the time, however, the dosage that the patient needs in order to empty the colon completely, as demonstrated radiologically, can be achieved. At that dose, the pa- tient should stop soiling because they are successfully emptying their colon each day, and because the colon is empty, they remain clean until the next voluntary bowel movement.
At this point, the patient and the parents have the opportunity to evaluate the quality of life that they have with that kind of treatment, understanding that this treatment will most likely be for life. There is an operation, a sigmoid resection, which provides symp- tomatic improvement, sometimes to the point that they do not need laxatives at all. Since this is a quality of life issue, it must be determined by the parents and the patient.
32.2.3 Surgical Treatment 32.2.3.1 Sigmoid Resection
For the last 14 years, we have been performing a sig- moid resection for the treatment of these conditions [7,8]. The very dilated megarectosigmoid is resected and the descending colon is anastomosed to the rec- tum. In a recent review of patients with anorectal malformations, 315 suffered from severe constipation and were fecally continent, but required significant laxative doses to empty their colon. Of these, 53 un- derwent a sigmoid resection. The degree of improve- ment varied. Following sigmoid resection, 10% of pa- tients did not require any more laxatives, have bowel movements every day, and do not soil. Thirty percent of patients decreased their laxative requirement by 80%. The remaining 60% of patients decreased their laxative requirement by 40%. These patients must be followed closely because the condition is not cured by the operation. The remaining rectum is most likely abnormal, and without careful observation and treat- ment of constipation, the colon can redilate. It is vital however in its role as a reservoir, and to allow the pa- tient to feel rectal distension.
It is vital however in its role as a reservoir, and to allow the patient to feel rectal distension.
The most dilated part of the colon is resected be- cause it is most seriously affected. The nondilated part of the colon is assumed to have a more normal mo- tility. Clearly, there must be a more scientific way to assess the dysmotile anatomy. Perhaps with emerging colonic motility techniques, these studies will help
with surgical planning. It does seem that the patients who improve the most are those who have a more lo- calized form of megarectosigmoid. Patients with more generalized dilatation of the colon do not respond as well. Perhaps in the future, these observations can be corroborated, and the results of resection better pre- dicted by noninvasive modalities.
The administration of antegrade enemas through a continent appendicostomy or a button cecostomy is becoming popular [9]. Some clinicians use this approach, observe radiologically that the colon de- creases in size over time, and then start laxatives. In our patients, we have only utilized antegrade enemas in incontinent patients who require a daily enema and seek more independence for their bowel management program [10]. An appendicostomy represents a useful alternative for patients who are treated with enemas only, since those antegrade enemas are only a differ- ent route of administration of enemas. It must be em- phasized that the majority of patients with anorectal malformations and constipation can be treated with laxatives alone, provided it is in adequate doses, and on occasion benefit from a sigmoid resection. There- fore, most do not need washouts at all.
Distinguishing which patients require washouts because they cannot empty on their own from those who could empty if their constipation was adequately managed with laxatives is the key challenge for the clinician.
References
1. Peña A, Levitt MA (2002) Colonic inertia disorders in pe- diatrics. Curr Probl Surg 39:666–730
2. Peña A, Levitt MA (2005) Imperforate anus and cloacal malformations. In: Ashcraft KW, Holder TM, Holcomb W (eds) Pediatric Surgery, 4th edn. WB Saunders, Philadel- phia, pp. 496–517
3. DeLorenzo C, Flores AF, Reddy SN, Hyman PE (1992) Use of colonic manometry to differentiate causes of intractable constipation in children. J Pediatr 120:690–695
4. Sarna SK, Bardakjian BL, Waterfall WE, Lind JF (1980) Human colonic electric control activity (ECA). Gastroen- terology 78:1526–1536
5. Cook BJ, Lim E, Cook D, et al (2005) Radionuclear tran- sit to assess sites of delay in large bowel transit in chil- dren with chronic idiopathic constipation. J Pediatr Surg 40:478–483
6. Peña A, Guardino K, Tovilla JM, Levitt MA, Rodriguez G, Torres R (1998) Bowel management for fecal incontinence in patients with anorectal malformations. J Pediatr Surg 33:133–137
7. Peña A, El-Behery M (1993) Megasigmoid – a source of pseudo-incontinence in children with repaired anorectal malformations. J Pediatr Surg 328:1–5
8. Levitt MA, Carney DE, Powers CJ, Tantoco JG, Caty MG (2003) Laparoscopically assisted colon resection for severe idiopathic constipation with megarectosigmoid. J Pediatr Endosurg Innov Tech 7:285–289
9. Marshall J, Hutson JM, Anticich N, Stanton MP (2001) Antegrade continence enemas in the treatment of slow- transit constipation. J Pediatr Surg 36:1227–1230 10. Levitt MA, Soffer SZ, Peña A (1997) The continent appen-
dicostomy in the bowel management of fecally inconti- nent children. J Pediatr Surg 32:1630–1633
11. Peña A, Levitt MA (2002) Colonic inertia disorders in pe- diatrics. Current problems in surgery 39:681
