One Hundred Three Consecutive Patients With Anorectal Malformations and Their Associated Anomalies

Objective  A long-term retrospective analysis of 103 infants with anorectal malformations (ARMs) was conducted to describe any associated congenital anomalies and surgical classifications.

Design  Retrospective medical record review.

Setting  This case series was conducted on all infants with ARMs born at, or referred to, any of 3 major medical centers in Wichita, Kan, for close to a 22-year period.

Patients  The 103 infants in this study represent a consecutive sample of patients with ARMs. Patients were separated into 2 groups: isolated ARMs without associated anomalies (n = 30), and ARMs with associated anomalies (n = 73). The male-female ratio was 2:1.

Main Outcome Measures  Patients with associated anomalies were further classified into groups of ARMs with minor anomalies; major anomalies; chromosomal abnormalities; and malformation syndromes, associations, or sequences. Only anomalies that occurred more than once were reported. Malformations were also classified according to major organ systems.

Results  The incidence of ARMs in our study was approximately 1 in 2500 live births. Additional anomalies were found in 71% of infants with ARMs. Associated anomalies by major organ system included genitourinary anomalies (49%), musculoskeletal anomalies (43%), craniofacial anomalies (34%), cardiovascular anomalies (27%), gastrointestinal anomalies (18%), respiratory anomalies (13%), and central nervous system anomalies (12%). The most common chromosomal abnormalities were trisomies (8%), and ARMs were associated with VATER complex (vertebral defects, anal atresia, tracheoesophageal fistula with esophageal atresia, and radial and renal anomalies) in 11 cases (11%) and VACTERL (vertebral, anal, cardiac, tracheal, esophageal, renal, and limb anomalies) in 4 cases (4%).

Conclusions  Patients with ARMs have a high incidence of associated congenital anomalies. Evaluation of the most commonly affected organ systems in these infants is essential because it is these associated anomalies that account for most of the morbidity and mortality that is associated with this condition.

THE INCIDENCE of anorectal malformations (ARMs) varies from 1 in 1500 to 1 in 5000 live births.^1-5 The surgical and medical management of patients with these malformations can be complex, especially when one considers the high frequency of concomitant anomalies that occur with ARMs. This frequency of additional anomalies in patients with ARMs ranges from 40% to70%.^1,2,4,5 Thorough evaluation of patients with ARMs is essential because it is these coexisting anomalies that account for most of the morbidity and mortality that is associated with this condition.^3,6-8 This article addresses the surgical classification and description of additional anomalies that occurred in a consecutive series of 103 patients with ARMs.

This study encompassed all infants with ARMs who were born at, or referred to, any of 3 major medical centers in Wichita, Kan, from January 1, 1975, to October 16, 1996. Medical records of 103 patients were reviewed retrospectively at these 3 hospitals (Wesley Medical Center, St Joseph Medical Center, and St Francis Regional Medical Center) for all infants admitted during this time period with a diagnosis of anorectal anomalies, anal stenosis, or imperforate anus. Data that was recorded included date of birth, sex, race, maternal age, county and hospital of birth, surgical classification, karyotype results, and any associated anomalies. Associated anomalies were only reported in the results if they were observed more than once (in more than one individual).

Surgical classification of ARMs was conducted in accordance with the Wingspread classification, and anomalies were divided into low, intermediate, high, cloaca, or rare malformations.⁹ Clinical geneticists (S.C.) were consulted in every case, and karyotypes were obtained to confirm chromosomal abnormalities when suspected on physical examination (n = 40) by these geneticists. Other diagnostic procedures were also performed when clinically indicated. Incidence rates for ARMs were calculated for infants born at Wesley Medical Center during the study period. Other anomalies that were associated with ARMs were documented and classified under major organ systems. Recognizable anomaly patterns were also classified into malformation syndromes, malformation associations, malformation sequences, and chromosomal abnormalities whenever appropriate. Major anomalies were defined as those that have serious medical, surgical, or cosmetic consequences, whereas minor anomalies did not have these implications. Statistical analysis consisted of χ² tests conducted with SPSS software version 9.0 (SPSS Inc, Chicago, Ill).

In our patient population, the incidence of ARMs was approximately 1 in 2500 based on all infants born at Wesley Medical Center from January 1, 1975, to October 16, 1996. During this time period, there were 43 births with ARMs of 106 012 total births at this hospital. Sex distribution of all 103 patients with ARMs was 67% male (n = 69) and 33% female (n = 34). The racial composition of these patients was 85% white, 5% African American, and 10% Hispanic and other. The average maternal age was 25.8 years (age range, 15-40 years). Karyotypes were obtained for 39% of the infants (n = 40), and 25% of these findings were abnormal.

Surgical classification of the ARMs was performed according to the Wingspread classification.⁹ The results of this classification broken down by sex are presented in Table 1. A high ARM was found in 58% of males and only 27% of females. Intermediate ARMs were found in 4% of males and 29% of females. Low ARMs were observed in 33% and 38% of males and females, respectively. Rare malformations occurred in only 1% of males and 3% of females. There was 1 female with a cloaca malformation. The Wingspread surgical classifications of all infants are presented in Table 1.

Anomalies that were associated with ARMs were reported by classification into major organ systems (Table 2). Overall, 73 (71%) of 103 infants with ARMs had other associated anomalies. The most commonly observed anomalies were those of the genitourinary system, which were seen in 50 (49%) of the infants with ARMs. Other organ systems with anomalies included the musculoskeletal (44 [43%]), craniofacial (35 [34%]), cardiovascular (28 [27%]), gastrointestinal (19 [18%]), respiratory (13 [13%]), and central nervous system (12 [12%]). Tracheoesophageal fistulas were included under gastrointestinal anomalies. Patent ductus arteriosus and patent foramen ovale were not included in the cardiovascular anomalies because they are common physiologic phenomena in premature infants. Other minor anomalies, including ectodermal skin defects, webbed neck, and Simian creases, were observed in 13% of the infants. Table 2 gives the most commonly observed additional anomalies by organ system.

All 73 patients with additional anomalies were then classified into 1 of 6 categories: (1) malformation syndromes, (2) malformation associations, (3) malformation sequences, (4) chromosomal abnormalities, and those with (5) major anomalies or (6) minor anomalies. There were 16 patients (11 males, 5 females) with minor anomalies who could not be accounted for by a syndrome, sequence, etc. Major anomalies were observed in 27 patients who also did not conform to another diagnostic category. Chromosomal abnormalities were observed in 10 patients (10%). Eight of these patients had trisomies (chromosomes 21, 18, 13); 1 had a ring chromosome 13; and 1 had a derivative chromosome 22. Overall, karyotypes were obtained for 40 patients, and 10 of these were abnormal (25%). Malformation syndromes were observed in 3 patients (3%), and these consisted of cat's-eye syndrome, Opitz syndrome, and Potter syndrome type I. Malformation associations occurred in 15 patients (15%), 11 of which were VATER complex (vertebral defects, anal atresia, tracheoesophageal fistula with esophageal atresia, and radial and renal anomalies) and 4 of which were VACTERL (vertebral, anal, cardiac, tracheal, esophageal, renal, and limb anomalies). Karyotypes were obtained for 11 of the infants with malformation associations, and all findings were normal. Malformation sequences were observed in only 2 patients, and both consisted of caudal regression sequence. Overall, 30 of 73 patients with additional anomalies had defined chromosomal abnormalities or malformation syndromes, associations, or sequences. These 6 categories and their breakdown by patient sex are presented in Table 3.

The 6 categories of malformation classification were also compared with the Wingspread surgical classifications of these patients (Table 4). Results of χ² analysis indicated that patients with major anomalies associated with ARMs were 16.5 times more likely to have a high surgical ARM than patients with isolated ARMs (P<.001). Patients with minor anomalies were also 8 times more likely to have high lesions than patients with isolated ARMs (P<.002). Males were more likely to have high lesions than females; however, this was not statistically significant (P<.065). Overall, patients with additional anomalies were also more likely to have high lesions than patients with isolated ARMs, and the reverse was true for low lesions (odds ratio, 13.8; P<.001).

Anorectal malformations are relatively common congenital anomalies. The incidence of ARMs was approximately 1 in 2500 live births in our patient population, which is within the reported incidence range in the literature.^1-5 It is well known that additional congenital anomalies are often present in patients with ARMs, and it is these coexisting anomalies that account for the high morbidity and mortality associated with this condition.^2-4,6 We observed additional congenital anomalies in 71% of infants affected with ARMs in our population, which is slightly higher than the 30% to 70% incidence of additional anomalies reported in the literature.^1,2,4,5,10 Differences in the percentages of additional anomalies that are observed can be attributed to how exhaustively each patient was evaluated in these studies, as well as by access and utilization of radiological modalities, such as magnetic resonance imaging (MRI) and ultrasound. The male-female ratio in this population was approximately 2:1, which is greater than the reported range of 1.2:1 to 1.8:1 in more recent studies.^2-4,10 Additionally, high ARMs were more common in males than females by a 4 to 1 ratio.

The most common organ system that was affected by additional anomalies was the genitourinary system. Abnormalities in the genitourinary system were observed in 49% of patients with ARMs. Other case series describe similar results, with the frequency of genitourinary anomalies ranging anywhere from 26% to 59% in patients with ARMs.^1,3,4,11-14 Therefore, thorough evaluation of the genitourinary system in patients with ARMs is essential. Most authorities recommend a vesicoureterogram voiding cystourethrogram and ultrasound to study the kidneys and bladder in all patients with ARMs.^3,8,11-14 Musculoskeletal anomalies were observed in 43% of the infants in this case series. The reported range of musculoskeletal anomalies in patients with ARMs is 15% to 44%.^3,4,7,12,13 Findings from physical examination can reveal many of these anomalies in the periphery, and various radiological modalities should be employed to evaluate the lumbosacral spine. Many authorities recommend ultrasonography and radiography, and the spine can also be evaluated during the voiding study, with MRI reserved only for abnormal findings on radiographs or ultrasound.^3,12,14,15 Others recommend an MRI in all patients with ARMs.^16,17 At our institution, we use ultrasonography as a screening tool for lumbosacral anomalies in patients with ARMs with MRI reserved for abnormal findings on ultrasound, as the role of MRI and ultrasound has not been definitively established in infants with ARMs.¹⁸

Cardiovascular anomalies were observed in 27% of the infants in this case series, and we performed screening echocardiograms on all patients with ARMs owing to the frequency of these lesions.^3,7,12,19 We also observed a high incidence of craniofacial, gastrointestinal, respiratory, and central nervous system anomalies in this case series. In addition, 29% of the infants had notable chromosomal abnormalities or malformation syndromes, associations, or sequences. The most common chromosomal abnormality was trisomy 21, and the association between Down syndrome and ARMs has been well described.^10,20,21 Obtaining karyotypes is warranted on individuals with ARMs and any associated malformations to investigate possible chromosomal abnormalities.

In a limited literature review, several syndromes were associated with ARMs, including Townes-Brocks, Johanson-Blizzard, Pallister-Hall, Currarino, cat's-eye, Down, Opitz, deletion 13q, Zellweger, and FG syndromes.^4,5,10,20-23 Malformation associations were observed in 15 patients and consisted of 11 cases of VATER and 4 cases of VACTERL. The expression of these 2 malformation associations shows phenotypic heterogeneity; however, we defined patients with VATER or VACTERL as having 3 or more of the anomalies that are associated with these conditions.^4,5,12,24-26 Other malformation associations and sequences that are associated with ARMs include exstrophy of cloaca sequence, sirenomelia sequence, caudal regression sequence, Klippel-Feil sequence, OEIS complex (omphalocele, exstrophy, imperforate anus, spinal defects), and CHARGE (coloboma [of eyes], hearing deficit, choanal atresia, retardation of growth, genital defects [males only], and endocardial cushion defect) association.^4,5,22

It is well established that high ARMs are more common in males than females and are also more frequently associated with other congenital anomalies than low lesions.^1-4,10 In our study, high ARMs were observed in 58% of males (n = 40) and 27% of females (n = 9). Results of χ² analysis indicated that patients with ARMs and additional anomalies were 13 times more likely to have high lesions than patients with isolated ARMs (P<.001). This is in line with contemporary thought that high ARMs are more complex lesions that are more likely to be accompanied by anomalies in other organ systems also forming between gestational weeks 4 and 8 due to some teratogenic event.⁵

Anorectal malformations are relatively common congenital anomalies that are frequently associated with other congenital anomalies. It is these associated anomalies that account for most of the morbidity and mortality that is associated with ARMs. Therefore, a thorough evaluation of infants born with ARMs is warranted to minimize these complications.

Accepted for publication November 17, 2000.

Corresponding author and reprints: Sechin Cho, MD, Department of Pediatrics, Kansas University School of Medicine–Wichita, 1010 N Kansas St, Wichita, KS 67214 (e-mail: sechincho@compuserve.com).