Babies with trisomy 13 (Patau's syndrome) have a median survival of 2.5 days, with only 5% surviving beyond 6 months. There are three cases of trisomy 13 with anorectal malformation in the English literature; a partial trisomy of chromosome 13q and 20p,1 a mosaic form (46,XX,t(13q13q)/46,XX,−13,+r(13))2 of trisomy 13 and a third case in which the form of trisomy 13 was not described.3 We report a case of full trisomy 13 with an unusual anorectal malformation.
A boy delivered at 36 weeks' gestation had antenatal scans showing a cleft lip and a large ventricular septal defect with an over‐riding aorta. He was below the third centile for weight and head circumference. He had a small occiput with occipital and parietal scalp defects, micro‐ophthalmia, a cleft lip and palate, fisted hands, rocker‐bottom feet, micropenis, an impalpable right testis and an imperforate anus. Echocardiography showed a patent ductus arteriosus and coarctation of the descending aorta in addition to a ventricular septal defect and an over‐riding aorta. Fluorescent in situ hybridisation and karyotype analysis confirmed trisomy 13 with a Robertsonian translocation of the extra chromosome 13 to chromosome 14.
On day 2, he had increasing abdominal distension and pain. A plain abdominal film showed a hugely distended colon with no gas beyond the pelvic brim (fig 1). Importantly, the gas pattern in the sigmoid colon was limited to the left iliac fossa, whereas distension of the sigmoid typically displaces the sigmoid colon to the right in imperforate anus.
Despite the short life expectancy, we performed a colostomy under general anaesthesia for the palliative relief of intestinal obstruction at 64 h. At laparotomy, his distended sigmoid colon had no mesentery, and it was difficult to mobilise. This is unusual. A flush colostomy was therefore formed in the anterior wall of the sigmoid colon. He was comfortable postoperatively, but developed increasing respiratory distress and died at 84 h. No postmortem examination was performed, and we do not know whether there was a fistula to the urinary tract.
Interestingly, in a study of 1992 patients with anorectal malformation, 5% had trisomy 21 but none had trisomy 13.4 Of the 1992 patients, 238 had no fistula and 40% of patients without fistulas had trisomy 21. In a smaller study of 103 patients with anorectal malformation, one had trisomy 13.3 Trisomy 13 with a coexisting anorectal malformation could be a chance occurrence. Alternatively, a genuine association between trisomy 13 and anorectal malformations exists, and the unusual anorectal anomaly in this case supports this hypothesis.
Footnotes
Competing interests: None declared.
References
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