Intraluminal colonic calcifications associated with anorectal atresia. Prenatal sonographic detection.

Abstract

Intra-abdominal meconium calcifications in the fetus can be detected with sonography.t-3 Fetal peritoneal calcifications are usually related to meconium peritonitis secondary to bowel perforation; intraluminal calcifications (enterolithiasis) are relatively rare but are often associated with bowel obstruction. 2.3 Sonographic characteristics clearly reveal the presence of calcified meconium and may distinguish intraluminal from peritoneal foci. The following is a report of two cases of prenatal detection of calcified intraluminal meconium associated with anorectal atresia. Sonographic signs useful in the antenatal diagnosis of enterolithiasis are described. To our knowledge, these have not been previously reported. CASE REPORTSCase 1 A multiparous 37-year-old woman without significant medical history presented to the obstetrics service with a 2-day history of dysuria and lower abdominal cramping. Sonography demonstrated a 30-week gestation and oligohydramnios. Fetal survey revealed a small thorax, right hydrone- phrosis, nonvisualization of the left kidney, and a dilated loop of bowel in the midabdomen. The bowel loop "mass" contained multiple coarse, highly reflective foci, 4-to 6-mm in diameter, compatible with calcifications (Fig. 1). Peristalsis in this segment was present. Four days later the patient delivered a 1,575-g girl with Apgar scores of 4 and 6. Delivery was com• plicated by breech presentation and amnionitis. The baby was noted to have multiple congenital anomalies and expired 5 hours postpartum. Postmortem examination demonstrated imperforate anus, bilateral renal hypoplasia with right uretero~ pelvic junction obstruction, Potter's facies, choledochal cyst, imperforate vagina, urachal cyst, and a colon that ended blindly against the dorsal aspect of the latter. Several mesenteric bands surrounded a distal loop of dilated sigmoid colon. Specimen radiographs of the meconium within the loop demonstrated scattered calcifications. No connection between the urachal sac and colon was identified. The infant's karyotype was 46,XX. An abdominal radiograph performed after expiration identified scattered left hemiabdominal calcifications confined to a focally dilated loop of colon (Fig. 2).Case 2 A 33~year-old gravida 1, para 0 woman with no significant medical history was suspected of carrying a growthretarded fetus. Sonography demonstrated a 32-week gestation. The fetal abdomen contained multiple coarse hyperechoic foci within dilated loops of bowel (Fig. 3). Active peristalsis of these loops was observed. A fetal sonogram 3 weeks later demonstrated normal interval growth and multiple coarse intra-abdominal calcifications confined to the dilated bowel that measured 4.5 em in diameter in the periphery of the fetal abdomen. A 2,296-g boy was delivered by cesarean section following a nonreactive stress test. Apgar scores were 9 and 9. Neonatal evaluation demonstrated imperforate anus, hypospadias, rectovesical fistula, malpositioned thumbs, and mul-

Fetal magnetic resonance imaging in the antenatal diagnosis and management of hydrocolpos

“…Digestive malformations may be difficult to identify by fetal ultrasound examination alone. The diagnosis may be presumed if ultrasound examination reveals a dilated colon19, atypical anal appearance20, or intraluminal colonic calcifications in the third trimester associated with a urinary fistula21. However, most anorectal atresias are not detected antenatally.…”

Prenatal diagnosis of enterolithiasis: a sign of fetal large bowel obstruction.

“…The advent of high-resolution ultrasonography allows an advantageous diagnostic approach and complements neonatal radiologic studies, as ultra~ sonography is extremely useful in demonstrating the intraluminal nature of calcifications, thus ruling out other causes of abdominal calcification in both the fetus 23 .2 4 and the neonate? …”

Fetal defaecation: Is it a normal physiological process?

“…Berdon et al reported five newborn male infants with an imperforate anus and the associated finding of calcified intraluminal meconium in the distal bowel 31 . Similar intraluminal calcifications have been described both in newborns with anorectal malformations 32 –35 and also as an antenatal sonographic finding in the dilated distal bowel of fetuses with anorectal malformations 24 , 26 , 36 . Almost all of these reports have been in males with a fistula between the rectum and the urinary tract, which has led to the speculation that the calcification is due to the mixing of alkaline urine and meconium 31 .…”

“…There have been several previous case reports of antenatal detection of bowel dilatation where the fetus has proven subsequently to have an anorectal malformation 22 –26 . Harris et al reported the antenatal sonographic finding of colonic dilatation in four fetuses with anorectal malformations ranging in gestational age from 26 weeks to 35 weeks.…”