* Ultrasound Division, ASL Roma B, Rome, Italy.
** Department of Pediatrics, Policlinico Umberto I, Università “La Sapienza” Rome, Italy.
*** Prenatal Diagnosis Centre, Obstetrics and Gynecology Department, Policlinico Umberto I, Università “La Sapienza” Rome, Italy.
**** Ultrasound Division, Ceprano Hospital, Ceprano, Italy.
Introduction
Duodenal atresia represents a complete obliteration of the duodenal lumen and duodenal stenosis represents a severe narrowing and incomplete obstruction of the duodenal lumen. These pathologies are considered as one common entity representing a similar spectrum of intrauterine events. Regardless of severity of the stenosis, the proximal intestinal segment is typically dilated and the distal segment empty; these are hallmarks of duodenal atresia. Although obstruction may occur anywhere within the duodenum, it is most common in the first or second part of the duodenum, most often in the vicinity of the ampulla of Vater. Stenosis may manifest as a stricture or a perforated intraluminal diaphragm. There is usually a single perforation within the diaphragm which is centrally located within the lumen of the duodenum, although variations have been reported. A windsock abnormality is a thin diaphragm that has ballooned distally as a result of peristalsis.
One half of the affected neonates are born prematurely. Polyhydramnios occurs in approximately 40% of neonates with duodenal obstruction. Duodenal atresia or stenosis is most commonly associated with trisomy 21. Both anomalies can be associated with other GI and biliary tract abnormalities such as malrotation, esophageal atresia, ectopic anus, annular pancreas, gallbladder or biliary atresia, vertebral anomalies, as well as with congenital abnormalities of other systems.
Ultrasound findings
The use of ultrasonography enables to identify many cases of duodenal obstruction prenatally. Duodenal obstruction is characterized by a double-bubble sign. The first bubble corresponds to the stomach and the second to the postpyloric and prestenotic dilated duodenal loop. This configuration most commonly occurs with duodenal atresia and an annular pancreas, less with duodenal stenosis. Prenatal diagnosis and counseling with a pediatric surgeon provides parents an opportunity to discuss plans for postnatal care and management. Few cases of prenatal diagnosis of duodenal stenosis have been reported, some in the first trimester. Most of them were associated with esophageal atresia. In most cases, diagnosis is made in the first few hours or days after delivery.
Case report
This is a case of a 25-year-old G2P1 with non-contributive personal and family history who was referred to our department at 21 weeks of gestation for a second trimester anomaly scan. First trimester ultrasound performed at 10 weeks of gestation was reported as normal.
We noticed an increased amount of the amniotic fluid, AFI=25 cm. The stomach was overdistended. A fluid filled elongated structure was visualized to the right near midline at the same level as the lower portion of the stomach. This cystic structure did not show any flow on color Doppler and did not communicate with other abdominal or pelvic structures. No other anomalies were detected.
10 minutes later, the stomach and the fluid filled structure in the midline dilated even more and a thin communication between them became apparent. We presumed that the thin communication was the pylorus and the fluid filled structure represented a postpyloric and prestenotic dilated duodenal loop.
The patient was scanned again 90 minutes later with the same findings: dilated stomach and fluid filled structure were visualized separately at first, after while a thin communication became apparent and midline cyst was dilating. Our differential diagnosis included duodenal atresia/stenosis or annular pancreas.
Amniocentesis revealed a normal 46,XY karyotype. After an extensive surgical counseling, the patient opted for pregnancy continuation. The pregnancy was monitored at a tertiary-care centre. Fetal echocardiography performed at 25 weeks was normal. Follow-up scans showed normal fetal growth and normal amount of the amniotic fluid, AFI 15 cm. Fetal MRI was performed at 29 weeks and confirmed the ultrasound findings. No associated fetal anomalies were detected.
The patient delivered via cesarean section at 37 weeks a male neonate of 2390 grams and Apgar score 9/9 at 1st/5th minutes respectively.
Physical examination after delivery did not show distended abdomen. Plain abdomen X-ray showed a normal pattern of gas. During the first hours of life the newborn passed meconium and the nasogastric tube drained only clear fluid.
The next day the neonate started with bilious vomiting, and underwent an upper gastrointestinal contrast study which showed a delayed gastric emptying and a dilated first portion of the duodenum. The rest of the duodenum showed a markedly reduced diameter. These findings were consistent with our prenatal suspicion of duodenal stenosis.
On the next day, neonate underwent a right upper quadrant transverse laparotomy. During the surgery the proximal duodenum appeared dilated although there was no discontinuity of the bowel. Malrotation was excluded. After the duodenotomy, a perforated intraluminal diaphragm was found with the ampulla on its medial portion. The diaphragm was therefore incised on its lateral portion, and a transverse duodenoplasty was performed after the exclusion of distal stenosis by irrigation of the distal bowel with the saline solution.
The postoperative course was uneventful, there was no hyperbilirubinemia and the baby passed meconium on the second day after surgery. Oral feeding was initiated and well tolerated from the day 7. Finally, the baby was discharged from the hospital on postoperative day 19, it's weight was 2.950 grams.
At 7 months’ follow-up, the baby boy was doing well, his weight was 8.000 grams and he remained free of any symptoms.
Images 1,2: Image 1 shows a markedly dilated stomach. Image 2 shows a cystic structure in the midline which dilates while the stomach empties.