PMC8137300_01
Fetal ultrasonography and the change of fetal bowel. Fetal images. (a) The distal rectal pouch shows dilated bowel with intraluminal calcifications (arrowheads) at 20 weeks. R indicates distal rectal pouch. The arrowheads indicate bowel calcifications. (b) The echogenic center (dotted circle) is not detectable at 20 weeks, which indicates that anal mucosa is invisible. (c) Fetal bowel dilation at 26 weeks. (d) Fetal bowel dilation at 31 weeks. (e) Fetal bowel dilation at 32 weeks. (f) Thoracic compression by bowel dilation at 31 weeks. The arrowheads indicate the diaphragm.
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Fetal ultrasonography showing a distended colon with the presence of bowel calcifications, distal rectal pouch, and undetectable anal mucosa indicated the presence of intermediate- or high-type imperforate anus with rectourethral fistula (Figures 1(a) and 1(b)). Fetal ultrasonography showed further progression of bowel dilation obviously seen from 26 weeks of gestation, which leads to thoracic compression, and amniotic fluid suddenly decreased after 28 weeks of gestation despite a fluid-filled bladder without hydroureter or hydronephrosis, which implied the presence of fetal urine outflow obstruction but not a decrease in urine production (Figures 1(c)-1(f), Table 1).
Fetal MRI. Fetal T2-weighted magnetic resonance imaging at 30 weeks showing small lungs with bowel dilation and oligohydramnios. The arrowheads indicate the diaphragm.
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MRI was performed at 30 weeks of gestation to assess pulmonary development, which indicated possible pulmonary hypoplasia (Figure 2).
Neonatal chest X-ray and cystourethrography: (a) chest X-ray on day 1 showing poor lung expansion and abdominal expansion; (b) cystourethrography showing a patent rectourethral prostatic fistula into the rectal pouch and a patent urethra. The arrowheads indicate urethral stenosis distal to rectourethral fistula. The arrow indicates rectourethral prostatic fistula.
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The neonate required immediate intubation and high-frequency oscillatory ventilation accompanied with inhaled nitric oxide treatment due to severe respiratory failure with persistent pulmonary hypertension (Figure 3(a)). On 36 days after birth, cystourethrography revealed high-type imperforate anus with patent rectourethral fistula, nonobstructive lower urinary tract, and urethral stenosis distal to the rectourethral fistula (Figure 3(b)).