Clinical review background
While uncommon, anorectal malformations are complex and require individualized care strategies for multiple steps in treatment. The steps, which are unique to the child and important for overall outcomes, include:
- Perioperative evaluation
- Operative reconstruction
- Postoperative care
A main challenge in the study and understanding of patients with anorectal malformations is the wide spectrum of congenital abnormalities that affect the anus, rectum and urogenital tract – from indistinguishable to very severe. This has led to many miscommunications of description and terminology.
The paper authors are Andrea Bischoff, MD, John Bealer, MD, and Alberto Peña, MD from the International Center for Colorectal and Urogenital Care at Children's Hospital Colorado. This summary includes the important decisions that should be made at each stage of patient care, an overview of controversial approaches, and author insights regarding the care of this patient population.
Of male patients can be repaired with posterior sagittal approach
Of patients with anorectal malformation have a cardiac defect
Of patients with anorectal malformation experience fecal incontinence
Preoperative evaluation and management
A classification system used to define anorectal malformations, created by the study authors and accepted by a large body of experts in 2005, is based on prognostic and therapeutic implications.
Types of anorectal malformation by sex
Male (percentage chance of bowel control*)
Female (percentage chance of bowel control*)
Note: In females, the rectum connects to the vagina instead of ending in the urethra or urinary system.
* Provided patients have a normal sacrum, no tethered cord and they receive a technically correct operation without complications.
† Recto-vaginal anomalies are extremely unusual; usually their prognosis is like recto-vestibular fistula.
‡ Cloaca represents a spectrum, those with a common channel length <3 cm have the best functional prognosis.
Typically, the initial neonatal evaluation of patients can distinguish the two defects closer to the perineal skin from the more cephalad defects that connect with pelvic structures. After examination, the following are performed:
- Chest and abdominal radiograph
- Urine analysis in males
- Kidney and lumbosacral spine ultrasound
– Pelvic ultrasound for female patients with cloaca
While there is no consensus on the best imaging modality for precise diagnosis at birth, study authors recommend anatomic diagnosis should be made in the context of neonatal physiology. In addition, the authors believe that most imaging modalities that are used to try to localize the rectum are inaccurate for babies less than 24 hours old.
The perineal fistula, a common malformation with a straightforward repair, causes much confusion as it is often incorrectly referred to as an anterior anus. Rectoperineal fistula patients have typically experienced a straightforward repair and are expected to have an excellent bowel control prognosis, yet many have substantial constipation. The authors note that colorectal surgery has not improved constipation in children they have treated. Clinicians are divided on whether or not colorectal surgery is necessary. Fistula dilation is a non-operative approach but good compliance is necessary and it can be uncomfortable for the child. A potential advantage of the operation is less risk for rectal and sphincter damage for women during childbirth.
Anorectal malformations rarely have life-threatening consequences during the first few days of life but babies often have other anomalies that are life-threatening:
A thorough evaluation to identify associated anomalies is essential.
There has not been specific pediatric surgical volume data on the need to transfer patients to a center with extensive pediatric colorectal surgical experience, but evidence in adults shows outcomes are improved with surgeons who have a large volume.
Mechanical bowel preparation
There is no consensus on the need for or the benefit of perioperative mechanical bowel preparation. The authors believe an individualized approach should be taken for each child and previously outlined their preparatory approach for children.
Study authors do not recommend any preparation for babies that are passing meconium and have not been fed nor for older children who had a colostomy as a baby and later present for an elective sagittal anorectoplasty.
Primary repair vs. colostomy diversion
There are two options for surgical management of virtually all neonates born with an anorectal malformation: perform a repair without a more proximal diversion of the fecal stream with a colostomy or delay repair by performing a colostomy to create a fecal diversion. The decision requires careful consideration of multiple factors, such as:
- Type and complexity
- General condition and maturity of patient
- Presence of associated anomalies
- Experience of surgeon
- General environment for care
Babies born with rectoperineal fistula or rectovestibular fistula have the option of no surgical intervention until the child is larger and more mature, but all urinary fistulas should be closed during definitive repair. Perioperative imaging is an important tool for a surgeon to determine approach. The absence of precise anatomic understanding of the malformation type before a primary repair can have serious consequences.
Another option for less experienced colorectal surgeons is creating a colostomy, which has several advantages including allowing for growth of the patient, referring to another surgeon, and allowing for a high-pressure colostogram later in life.
Management of hydrocolpos
Drainage of a hydrocolpos (present in 30-50% of children) should be included in the operative plan for females with cloacas. Complications of undrained hydrocolpos include:
- Mega ureters
- Compression of the trigone causing megaureters and hydronephrosis
- Possible rupture of hydrocolpos
The use of a transabdominal vaginostomy tube is recommended until a definitive repair is performed.
Definition of the anatomy perioperatively
Regardless of the procedure, operative planning includes whether or not entering the abdominal cavity is necessary or desirable. 90% of male cases do not require abdominal entry and can be repaired with posterior sagittal approach. The abdomen can be accessed by laparotomy or laparoscopy and there is no evidence that either procedure has a better notable functional outcome. While there are several disadvantages to the laparoscopic approach, there may be benefits if an abdominal and perineal approach is necessary.
More evidence on anesthesia's effects on the neonatal brain could impact future surgical procedures for anorectal malformation repair.
For children with anorectal malformations, decades of support and medical management is needed from the second postoperative week with an anal dilation program through constipation or fecal incontinence management and the transition to adult care.
The study authors begin daily dilation on children 14 days after posterior sagittal anorectoplasty until about 6 months after surgery. It is performed by parents with the goal of preventing stricture. While some surgeons question its usefulness, study authors believe daily dilation is invaluable for reconstruction and better prognosis.
Most children born with an anorectal malformation will suffer from chronic constipation, requiring lifelong treatment with laxatives. Aggressive constipation management is crucial to prevent further complications. The first line of defense is emptying the rectum each day using laxatives. Enemas are often used but are not an ideal type of management. Sacral nerve stimulation has been used for idiopathic constipation but has not been evaluated fully for use in anorectal malformations.
Fecal incontinence occurs in at least 25% of children with an anorectal malformation. Sacral nerve stimulation has been used to treat patients with fecal incontinence with mixed results, and the benefit remains unclear. Biofeedback has also been used, but has not shown consistently good results, although study authors believe it might contribute to manometric parameter improvement. Authors recommend bowel management.
Enemas can improve social acceptability for children by artificial prevention of fecal incontinence. Children who suffer from fecal incontinence should begin a formal management program at about three years of age. Bowel management usually takes a week and is individualized for each child. The program first differentiates patients into one of two groups: patients with dilated colon indicating hypomotility and a tendency for constipation; and those with a non-dilated colon, colonic hypermotility and tendency for diarrhea.
Patients with an anorectal malformation require lifelong help and support. When the patient enters adulthood, an adult healthcare provider experienced in pediatric issues of the patient and supported by pediatric sub-specialists is needed.
Children's Colorado and the University of Colorado Hospital are collaborating with patients for smooth transitions from pediatric to adult care.
Prior to the transition to adult care, patients should be encouraged to:
- Have a say in their own care
- Know about their condition
- Administer their own medication and enemas
- Actively participate during consultations
Clinical review conclusions
Children born with anorectal malformations represent a broad clinical spectrum with lifelong medical needs. For the best outcomes, a precise understanding of the individual malformation (and associated anomalies) is necessary. Surgical technique will improve and advance treatment, and high-volume centers with specific expertise will be developed.
The transition of pediatric patients with anorectal malformations to adulthood is an emerging field and will provide new insight on long-term outcomes to help improve the decisions made to treat newborn patients.
Featured in the August 2017 issue of The Lancet Child & Adolescent Health, Volume 1.