Abstract. We report a case of colon atre- sia diagnosed pre-natally at 32 weeks' gestation. The fetal transverse colon was dilated. Complete atresia of the middle.
Pediatr Radiol (1993) 23:63-64
Pediatric Radiology 9 Springer-Verlag 1993
Prenatal diagnosis of colon atresia N. Anderson 1, T. Malpas 2, R. Robertson 3 1Department of Radiology, Christchurch Hospital, Christchurch, New Zealand 2Department of Paediatrics, Christchurch Hospital, Christchurch, New Zealand 3Department of Surgery, Christchurch Hospital, Christchurch, New Zealand Received: 20 July 1992/Accepted: 17 September 1992
Abstract. We report a case of colon atresia diagnosed pre-natally at 32 weeks' gestation. The fetal transverse colon was dilated. Complete atresia of the middle transverse colon was confirmed after birth. Small bowel dilatation (and clinical obstruction) did not develop until after 24 h of age.
Fig. 1. Transverse image of fetal upper abdomen at 331/2weeks gestation with dilated transverse colon (25 mm diameter). TC, transverse colon; sp, spine
colon was prominent, 18 mm in diameter. Ten days later, the dilatation of the transverse colon had increased to 25 mm (Fig. 1). There was still no other fetal abnormality. Amniotic fluid volume remained normal. A normal male infant was delivered by caesarian section for obstructed labour at 38 weeks gestation, weighing3000 g. There were no dysmorphic features. A mass was palpable in the upper abdomen. Abdominal X-ray at 1 h of age showed displacement of gas-filled, nondilated bowel to the left, and at 10 h a further X-ray showed a distended, gas-filled structure lying in the upper abdomen (Fig. 2). A contrast enema demonstrated atresia in the middle transverse colon associated with a distal microcolon (Fig. 3). At laparotomy complete atresia of the middle transverse colon, without a connecting fibrous band, was confirmed, and a primary end-to-end anastomosis was performed. Recovery was complete and uncomplicated.
Fig.2. Supine abdominal film of infant at 10 h of age. A dilated transversely oriented bowel loop in the expected position of the transverse colon is seen. Small bowel dilatation has not yet developed. S, stomach
Discussion
Fig. 3. Water-s~ barium enema reveals a micr~176176 ~ in the middle transverse colon. There is a hook-like appearance to the atretic end point. Meconium in the dilated proximal transverse colon can be seen. Curved arrow, bend of hook; Straightarrow, tip of hook
Colon atresia comprises 5-10 % of gut atresias. It may take the form of memb r a n o u s atresia, atresia with a thin con-
Colon atresia comprises 5 - / 0 % of gut atresias [1]. If dilated bowel loops are detected prenatally, the diagnosis is usually
Correspondence to: N. Anderson
small bowel atresia. Prenatally detected dilated colon usually is due to anorectal atresia [2] but has been seen in Hirschsprung's disease [1 ] and in a case ofmeconium plug syndrome associated with cystic fibrosis [3]. To our knowledge, prenatal ultrasound diagnosis of colonic atresia has not b e e n reported previously.
Casereport A 25-year-old white woman in her third pregnancy (two previous pregnancy terminations) developed vaginal bleeding at 13 weeks. As the placenta was low-lying at that time, a follow-up examination was performed at 32 weeks. The fetal transverse
64 necting fibrous band, complete atresia without a connecting band, or multiple atresia [4]. The aetiology is believed to be a vascular insult [5]. Postnatally, the diagnosis is cornfirmed with a colonic contrast study. The colon proximal to the point of atresia frequently is massively dilated with a microcolon distal to the atretic segment. There is commonly a hook-like appearance on the microcolon side of the atresia [4], as seen in our case. Prenatally, the normal colon diameter increases in a linear fashion, from an upper limit of normal of 7 m m at 25 weeks to 18 m m at term [2]. At prenatal ultrasound the colon has a relatively characteristic appearance, with the haustrae readily apparent and the colon coursing at the periphery of the abdomen. In our case, on the 32-week scan,
the position and appearance of the dilated bowel segment indicated that it was transverse colon. The diameter was 18 mm, well above the upper limits of normal for this stage of gestation, and progressive dilatation to 25 m m was demonstrated 10 days later. It is of interest that the marked bowel dilatation involved the colon proximal to the atretic segment, but that small bowel dilatation (and clinical obstruction) did not develop until after 24 b of postnatal life. If colon atresia is suspected prenatally, we recommend that oral feeding should be withheld after birth. A water-soluble contrast enema should be given at some time within the first 24 h of life to confirm the diagnosis. There is no immediate urgency with this investigation, as clinical obstruction takes over 24 h to develop.
References 1. Nyberg DA (1990) Intra-abdominal abnormalities. In: Nyberg DA, Mahony BS, Pretorius DH (eds) Diagnostic ultrasound of fetal anomalies: text and atlas. Year Book Medical Publishers, Chicago, p 342 2. Harris RD, Nyberg DA, Mack LA, Weinberger E (1987) Anorectal atresia: prenatal sonographic diagnosis. A JR 149:395 3. Nyberg DA, Hastrup W, Watts H et al (1987) Dilated fetal bowel: a sonographic sign of cystic fibrosis. J Ultrasound Med 6: 257 4. Swischuk LE (1989) Colon agenesis, atresia, and stenosis. In: Swisehuk LE (ed) (1989) Imaging of the newborn, infant, and young child, 3rd edn. Williams and Wilkins, Baltimore, p 505 5. Louw JH (1964) Investigations into the etiology of congenital atresia of the colon. Dis Colon Rectum 7:471
