A. Early decision-making
The early management of a newborn infant born with an anorectal anomaly is crucial and two important questions must be answered during the first 24 to 48 hours of life. First; are there associated anomalies that threaten the baby's life and should be dealt with right away? And second, should the infant undergo a primary procedure and no protective colostomy or a protective colostomy and a definitive repair at a later date? For babies born with persistent cloaca, the surgeon must also determine whether a dilated vagina is present and if it should be drained, as well as determining whether urinary diversion will be required. These maneuvers are intended to prevent sepsis or metabolic acidosis [14].
The decision to perform an anoplasty in the newborn period or to delay the repair and to perform a colostomy is based on the infant's physical examination, the appearance of the perineum, and any changes that occur over the first 24 hours of life [15–17].
After the baby is born, an intravenous line is placed for fluids and antibiotics, and a nasogastric tube is inserted to keep the stomach decompressed to avoid the risk of vomiting and aspiration. Meconium is usually not seen at the perineum in a baby with a recto-perineal fistula until at least 16–24 hours. Abdominal distension does not develop during the first few hours of life and is required to force meconium through a recto-perineal fistula as well as through a urinary fistula. This is because the most distal part of the rectum in these children is surrounded by a funnel-like voluntary muscle structure that keeps that part of the rectum collapsed and empty. The intraabdominal pressure must be high enough to overcome the tone of the muscles that surround the rectum if one expects to see meconium at the perineum or in the urine. Therefore, the decision of whether to perform a colostomy or an anoplasty must wait for these 16–24 hours while the surgeon observes for clinical evidence of the baby's anorectal anomaly.
Clinical inspection of the buttocks is important. A flat "bottom" or flat perineum, as evidenced by the lack of a midline gluteal fold and the absence of an anal dimple indicates that the patient has very poor muscles in the perineum. These findings are associated with a high malformation and therefore a colostomy should be performed.
Perineal signs found in patients with low malformations include the presence of meconium at the perineum, a "bucket-handle" malformation (a prominent skin tag located at the anal dimple below which an instrument can be passed), and an anal membrane (through which one can see meconium).
Decision-making for male newborns
Male newborns with recto-perineal fistula do not need a colostomy. They can undergo a posterior sagital anoplasty whereas male babies with evidence of a recto-urinary tract communication should undergo fecal diversion with a colostomy.
In 80–90% of male newborns, clinical evaluation and urinalysis will provide enough information for the surgeon to decide whether the baby requires a colostomy. If none of the clinical signs to determine the location of the anorectal anomaly becomes evident by 24 hours, a cross-table lateral film with the baby in prone position, with the pelvis elevated, and with a radioopaque marker placed on the perineum is performed (Figure 4). This x-ray on rare occasion may show the column of air in the distal rectum to be within 1 cm of the perineum, and if this is the case, the baby can be treated like those with a recto-perineal fistula, and a newborn perineal operation can be performed. If the air column is greater than 1 cm from the perineum, a colostomy is indicated.
A definitive repair in the newborn period avoids a colostomy but there is considerable risk to the urinary tract with this practice because the surgeon does not know the precise anorectal defect. The only way to definitively determine the patient's anorectal defect is to perform a distal colostogram, which of course requires the presence of a colostomy. Without this information an operation in the newborn period is essentially a blind perineal exploration. The surgeon may not be able to find the rectum and may find and damage other, unexpected, structures, such as the posterior urethra, seminal vesicles, vas deferens, and ectopic ureters during the search for the rectum. Finally, without fecal diversion, there is the risk of dehiscence and infection. These complications may compromise the ultimate functional prognosis.
Decision-making for female newborns
The decisions involved in managing the female newborn are less complicated. In 90% of patients, a meticulous perineal inspection will demonstrate the anorectal defect. Waiting 16–24 hours for enough abdominal distension to demonstrate the presence of a rectoperineal fistula or rectovestibular fistula applies to females as well.
The most common anomaly in females is a rectovestibular fistula (Figure 5). Perineal inspection shows a normal urethra, normal vagina, and another orifice, which is the rectal fistula in the vestibule. The safest option for a surgeon without extensive experience in anorectal anomalies when faced with a baby with clinical evidence of a rectovestibular fistula is to perform a diverting colostomy. Colostomy prior to the main repair avoids the complications of infection and dehiscence. Definitive repair of this anomaly in the newborn period should be reserved for surgeons with significant experience repairing these defects. This anomaly has an excellent prognosis and therefore complications that could affect future continence must be avoided.
Unfortunately, the most common referral for redo operations to tertiary centers that care for anorectal anomalies are for patients with rectovestibular fistulas who underwent a failed primary repair in the newborn period.
Occasionally, the fistulas are big enough to decompress the gastrointestinal tract, and may be dilated to facilitate fecal drainage until the baby is older and a definitive repair is performed. Definitive repair involves a posterior sagittal approach. The most delicate part of this operation is the separation of the rectum and vagina, which share a common wall. Females like males can have a rectoperineal fistula and for them an anoplasty in the newborn period should be performed. Like in males, less than 5% of female babies have no clinical evidence of the location of the rectum after 24 hours. They may have imperforate anus with no fistula. A cross-table lateral x-ray should be performed, and will help determine the need for a colostomy.
B. Treatment
Surgery
As discussed previously, the surgeon must decide in the newborn period whether the child requires fecal diversion with a colostomy, or can undergo a primary repair procedure.
• Colostomy
The preferred colostomy is a descending colostomy, i.e. made from the descending portion of the colon located in the lower-left quadrant of the abdomen, with separated stomas [18]. The proximal stoma is connected to the upper gastrointestinal tract and drains stool. The distal stoma, also called a mucous fistula, is connected to the rectum and will drain small amounts of mucus material. The advantages of this type of colostomy are many: 1) it defunctionalizes only a small portion of distal colon, 2) in cases of large rectourinary fistulae in which the patient passes urine into the bowel, the urine comes out easily through the mucous fistula, avoiding problems of hyperchloremic acidosis due to urine absorption. Urinary tract infections are also avoided, 3) it is relatively easy to wash and clean the part of the colon distal to the colostomy, 4) distal colostograms are easy to perform, 5) the sigmoid loop is kept distal to the colostomy which provides enough length to reach the perineum during the definitive pull-through procedure, 6) the separated stomas prevent spillage of stool from proximal to distal bowel, which avoids impacted distal stool and urinary tract infections, 7) there is a low incidence of prolapse with this technique. Proximal stoma prolapse in a normally rotated colon should not happen with this technique because the colon is well fixed to the retroperitoneum just before the colostomy rises to the skin level. The distal stoma may prolapse because it is in a mobile portion of the colon. To avoid this, the distal stoma must be made intentionally small, as it will be used only for irrigations and radiologic studies. When performing the colostomy in the newborn, the distal bowel should be irrigated to remove all of the meconium. This prevents formation of a megasigmoid, which may be responsible for the future development of constipation.
Several pitfalls exist with regard to the creation of the colostomy. 1) If the colostomy is placed too distal, it will interfere with the pull-through. 2) During attempts to perform a transverse colostomy, cases of inadvertent sigmoid colostomy placed in the right upper quadrant have occurred. Anchoring of the sigmoid in the right upper quadrant would interfere with the pull-through procedure. 3) A loop colostomy does not completely divert the stool and allows for distal stool impaction and urinary tract infections. 4) Transverse colostomies produce megarectum [19].
• Posterior sagittal approach
◦ Anorectal repair
The repair of an anorectal malformation requires a meticulous and delicate technique and a surgeon with experience in the management of these defects. The posterior sagittal approach is an ideal method of defining and repairing anorectal anomalies. If the baby growing well, the repair can be performed at 1–2 months of age. Detailed surgical procedure can be found in the following references: [1, 2, 5, 6].
Ninety percent of male patients can be approached with a posterior sagittal approach alone, while 10% require an abdominal component (with laparotomy or laparoscopically) to mobilize a very high rectum. All female malformations, with the exception of about 30% of cloacas can be repaired with this approach. In 30% of cloacas, the rectum or vagina is so high as to require an abdominal approach as well [20].
◦ Rectobladder neck fistula
In the rare case of a true supralevator malformation (rectobladder neck fistula), the operation involves both a posterior sagittal incision and an abdominal component, which can be done with laparoscopy or laparotomy (Figure 6).
◦ Imperforate anus without fistula
In patients with imperforate anus without fistula, the same meticulous dissection is required to separate the distal rectum from the urinary tract as in patient with rectourinary fistulae because the rectum and urethra still share a common wall.
◦ Rectovestibular fistula
In cases of rectovestibular fistula, the posterior sagittal incision can be shorter than in male patients with rectourethral fistulae. Often the entire levator mechanism needs not be divided and only the external sphincter, muscle complex, and part of the lower portion of the levator mechanism need to be divided. The rectum and posterior vagina share a common wall, and it is this separation that is the most difficult part of the operation. Once the rectum is completely mobilized, a perineal body is constructed, and the rectum is placed within the limits of the sphincter mechanism [21].
◦ Rectal atresia
A very rare malformation, rectal atresia, occurs in 1% of cases. The anal canal is normal and externally the anus appear normal. However, there is a blockage 1–2 cm from the anal skin, usually found when the nurse tries to pass a thermometer. These babies should undergo colostomy at birth, and then their definitive repair involves a posterior sagittal approach and an end-to-end anastomosis between the upper rectal pouch and the anal canal.
◦ Persistent cloacas
The repair of persistent cloacas represents a serious technical challenge that should be performed in specialized centers by pediatric surgeons dedicated to the care of these complicated patients [22]. This malformation represents a wide spectrum of defects by itself. The defect involves fusion of the rectum, vagina, and urethra together to form a common channel (Figure 7). The length of this common channel can range from 1 to 10 cm. The rectum and vagina share a common wall and the vagina and urinary tract likewise have a common wall. The goals of surgical treatment are to achieve bowel control, urinary control, and normal sexual function. Sometimes all three goals are achieved, sometimes only two, often only one, and occasionally none [23].
Prognostic factors include the quality of the sacrum, the quality of the muscles, and the length of the common channel. We have arbitrarily defined two groups of patients. The repair of patients with a common channel less than three cm is reproducible and is feasible for most pediatric surgeons. For patients with a common channel greater than three cm, the repair should be performed at a specialized center by a surgeon with experience managing the urologic anomalies and able to performing complex vaginal reconstructions. If the common channel is less than 3 cm, the posterior sagittal approach without an abdominal approach can be used to repair the defect.
For patients with a common channel greater than three cm, a laparotomy is usually required. Often the vagina and urinary tract must be separated trying to gain length, and the urethra must then be reconstructed. The surgeon must be prepared to open the bladder and to reimplant the ureters if necessary. Complex vaginal mobilizations are often required and frequenly a vaginal replacement with small intestine or colon is necessary. The pullthrough of the rectum is similar to other anorectal malformations. It is the repair of the vagina, the urethra, and the associated urologic defects that represents the main surgical challenge. A large vagina can be an advantage during the definitive repair because the surgeon can more easily mobilize it and has more alternatives for the vaginal repair. About 50% of patients have various degrees of vaginal or uterine septation. These can be totally or partially repaired during the main operation. The precise gynecologic anatomy must be ascertained either during the main repair or during colostomy closure (if a laparotomy was not required during the main repair). We have learned that approximately one third of our patients have obstructed Mullerian structures which can lead to severe problems resulting from retrograde menstruation. Predictions of future problems such as amenorrhea in cases of atretic uteri, or hydrometrocolpos and retrograde menses can be made in the newborn period. Presentations of pelvic pain or amenorrhea as teenagers should prompt the assumption of anomalous gynecologic structures.
• Laparoscopically assisted anorectal approach
The laparoscopically-assisted anorectal approach consists in mobilizing and bringing the rectum through the pelvic floor sphincter muscles through a minimal posterior incision. Perianal dissection towards the laparoscopic light source favours accurate placement of a trocar to pull the rectum through the external sphincter muscle complex. Laparoscopically-assisted anorectal repair can either be performed in the newborn period without a colostomy or in a stage-approach. This new technique, described by KE Georgeson et al. needs further long-term evaluation in terms of fecal continence [24, 25].
• Anterior sagittal approach
Anterior sagittal approach, involving anterior perineal dissection (from the base of the scrotum to the posterior part of the anoderm), is used by some surgeons, with the aim of preserving the internal anal sphincter [26]. But it should be noticed that this approach might damage the vesical nerve plexus when the rectourethralfistula is dissected up to its junction with the urethra. Furthermore, an internal sphincter saving technique has been devised when performing the posterior sagittal approach.
Post-operative management
• Anoplasty
The posterior sagittal incision is relatively painless. In patients with a rectourethral fistula, the foley catheter stays in place for about 5–7 days, and occasionally longer. At two weeks postoperatively, anal calibration is performed, followed by a program of anal dilitations. The anus must be dilated twice daily and every week the size of the dilator is increased. The final size to be reached depends on the age of the patient. Once the desired size is reached, the colostomy can be closed. Dilatations are a vital part of the postoperative management to avoid a stricture at the anoplasty. After colostomy closure, severe diaper rash is common because the perineal skin has never before been exposed to stool.
• Functional Disorders
◦ Constipation
The most frequent functional disorder encountered after treatment for imperforate anus in which the rectum has been preserved is constipation [26–28].
It is also the most important problem to avoid after definitive repair for female patients with rectovestibular or rectoperineal fistula and for male patients with rectobulbarurethral fistula, imperforate anus without fistula, and rectoperineal fistula. Failure to avoid constipation can result in megarectum and megasigmoid, and can lead to fecal impaction and overflow incontinence. The origin of the problem of constipation is unknown. It was originally thought that the perirectal dissection caused a degree of denervation that resulted in constipation. However, on careful review of the largest series of these patients, it became clear that those with the most benign defects and thus the least amount of perirectal dissection had the worst constipation.
The presence of a megarectum prior to the pull-through does correlate with postoperative constipation. Megarectum is more common in patients for whom a transverse or loop colostomy was performed in the newborn period. Constipation appears to be a hypomotility disorder secondary to chronic bowel dilatation. Or, perhaps it is the hypomotility that causes dilatation, which in turn results in constipation, creating a vicious cycle.
When a patient with a megasigmoid has been shown to be fecally continent, resection of the sigmoid has been found to dramatically reduce the patient's laxative requirements. The descending colon with normal caliber and normal motility is anastomosed to the rectum at the peritoneal reflection. This applies for a select group of patients with enormous daily laxative requirements to keep their colons clean. Performance of a new pull-through operation should be avoided so that the patient's rectal reservoir is preserved. Loss of the rectal reservoir could lead to a worse problem of incontinence with a patient who now has diarrhea.
The key in these patients is to manage constipation proactively and avoid it after the pull-through procedure. The patients must be followed regularly, and laxatives and dietary manipulations are begun at the first sign of constipation.
Occasionally constipation becomes so severe that patients develop chronic fecal impaction and constant soiling. Patients like this are often referred with "fecal incontinence." However, if the patient has a good prognosis type of anorectal anomaly, often this incontinence is actually overflow pseudoincontinence. Once the constipation is managed, they become continent.
◦ Continence
Less frequently than constipation, some patients may experience soiling. While in a patient with a good prognosis, this may be overflow incontinence, it may also represent true fecal incontinence in cases of very high imperforate anus or poor muscles and an abnormal sacrum. A contrast enema is helpful in differentiating these two groups of patients. Patients with real incontinence require a bowel management program, which involves cleaning of the child's colon once a day by the use of a suppository, an enema or a colonic irrigation [29].
Giving the enema after the main meal of the day allows a more efficient cleansing of the bowel by taking advantage of the gastrocolic reflex. Antegrade enema procedures, whereby enema is introduced in a conduit via appendicocecostomy, has been devised to help the patient clean its bowel [30, 31]. The artificial bowel sphincter and electrically stimulated gracilis neosphincter are two relatively new techniques that have been used for the treatment of patients with severe refractory fecal incontinence.
Patients who have undergone abdominoperineal operations for imperforate anus that included resection of the rectum suffer from a tendency to have diarrhea due to a lack of a rectal reservoir. These patients' incontinence is much harder to manage because they pass stool constantly.
Bowel movement pattern prior to potty-training may give an important clue as to the child's potential for continence. For example, a one-year-old child who has undergone a pull-through for imperforate anus and has one to three bowel movements per day with no soiling in between has a great potential for future fecal continence. The child shows signs that he is "feeling" while having a bowel movement as he pushes. On the other end of the spectrum, a child who suffers from fecal incontinence passes stool constantly without any evidence of pushing or feeling. A child with a normal bowel movement pattern is trainable, whereas a child with the second pattern will likely need a bowel management program. For that child, one should not expect him to achieve voluntary bowel control.
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