The spectrum of anorectal malformations in Africa

Abstract

Anorectal malformations (ARM) remain a significant birth defect with geographic variation in incidence, individual phenotypes and regional geographic subtypes. Although early studies indicated a low incidence in Black patients, there is a great paucity of knowledge as to the types, frequency and incidence of ARMs encountered in the African continent and their associated anomalies. Current evidence suggests a significant clinical load. This study set out to evaluate ARM in Southern and other parts of Africa to define the clinical load of ARM. We retrospectively collected data on 1,401 ARM patients from six South African Paediatric Surgical units plus representative samples from five other African countries from West, Central and Southern Africa. Data included ethnic group, age, gender as well as the anatomical pathology, classification and presence or absence of associated anomalies. ARM lesions classified by the Wingspread classification plus an analysis of fistula position was carried out in evaluable cases for purposes of comparison. South African centres reported a higher prevalence of cloacae and vestibular fistulae, whereas rectovaginal, recto prostatic and anorectal malformation without fistula were more prevalent in the Northern African group. 76% of 1,401 patients were ethnically Black African [gender ratio = 2 (vs gender ratio 1.38 overall)] and 49.8% were “low” lesions (Wingspread classification). High or intermediate lesions were mostly males (72%). Anal stenosis was most prevalent in black males and non-Black females. Fistulae were identified in 95% with 682 (52%) being low (perineal/covered anus/vestibular) fistulae. Perineal fistulae had a male predilection (n = 260; 20%), whereas vestibular fistulas (n = 416; 32%) was strikingly frequent in black females (55%). Of the remainder, 15 fistulae were rectovesical (1.2%), 544 recto-urethral or prostatic (42%), 16 recto-vaginal (1.2%). In addition, there were 43 cloacal lesions (3.3%). Isolated rare ARM anomalies included “Pouch” colon (2) and H-type fistula (2). Isolated lesions occurred in 81% but 163 associated anomalies were identified in 114 patients. These included chromosomal lesions (10), genito-urinary anomalies (50), genital (16), cardiac (31), skeletal anomalies (33), gastro-intestinal malformations (28). Other anomalies included CNS anomalies (14), anterior abdominal wall defects (2) and facial (8) abnormalities and neuroblastoma (1). The ARM is not uncommon in Black African populations and constitutes a significant clinical load to surgical practice in Africa. Ethnic differences appear to exist and vestibular fistulae predominate in black females. Cloaca (3.3%) did appear to be more prevalent. Isolated lesions are frequent but the types of associated anomalies appear similar to other series except chromosomal syndromes. This study illustrates the need for more objective data from developing countries to assess geographical differences.