HDlive imaging of a giant omphalocele.

Abstract

Omphalocele is a ventral abdominal wall defect with herniation of abdominal contents that results from failure of the lateral ectomesodermal folds to join in the midline of the abdomen during the third and fourth weeks of gestation. It occurs in approximately 1 in 4000–7000 live births1, 2. The term ‘giant omphalocele’ has been used to refer to defects with a diameter that exceeds 5 cm, or those that contain liver in the herniated sac3. Omphalocele, and giant omphalocele in particular, is diagnosed readily with two-dimensional (2D) prenatal ultrasound. We report here a case of fetal giant omphalocele in which the herniated sac was found to contain multiple small bowel loops and almost the entire liver on HDlive imaging. A 30-year-old primigravida was referred to the Fetal and Pregnancy Health Program at Lucile Packard Children's Hospital Stanford because of a prenatal diagnosis of fetal giant omphalocele. Amniocentesis was performed and karyotype and microarray results were normal. Examination of the fetus by ultrasound and magnetic resonance imaging (MRI) revealed an isolated abdominal wall defect with small bowel and nearly the entire liver herniating through the defect. 2D and three-dimensional ultrasound images were obtained subsequently at 37 weeks' gestation using HDlive rendering mode on a GE Voluson E10 ultrasound machine (GE Healthcare Ultrasound, Milwaukee, WI, USA) (Figure 1). The border of the herniated sac extended to the anterior abdominal wall and, consequently, delivery was performed by a low vertical Cesarean section in order to reduce the risk of rupture of the omphalocele sac. A 3560-g neonate was delivered, with Apgar scores of 8 at both 1 and 5 min and an intact omphalocele sac (Figure 2). In the USA, the prevalence of fetal omphalocele at delivery has remained constant, at 1.92 per 10 000 live births, between 1995 and 20051. Omphalocele is often associated with other structural anomalies, most commonly cardiac defects, aneuploidy (such as trisomies 18 and 13 and Turner syndrome), genetic syndromes (such as Beckwith–Wiedemann syndrome) and other multiorgan syndromes (such as Pentalogy of Cantrell and limb–body wall defects)1, 2, 4. In a recent study of 2308 cases of omphalocele at birth, only 22% were isolated1. The diagnosis of ‘giant omphalocele’, often defined as either omphalocele with liver herniation or a defect measuring > 5 cm, is less frequently reported. Complications of giant omphalocele include abdominal wall hernia, gastrointestinal obstruction, sepsis, congestive heart failure and pulmonary morbidity including pulmonary hypertension, atelectasis and need for respiratory support3, 5. A study by Danzer et al. found that an observed-to-expected total lung volume (O/E-TLV) below 50% on prenatal MRI was associated with significant postnatal morbidity, including a longer duration of ventilatory support6. In our case, prenatal MRI showed an O/E-TLV of 39%. Prenatal HDlive imaging was first described 5 years ago and appears to be a useful adjunct to prenatal 2D ultrasound imaging of the fetal heart, face and oral cavity, limbs and the placenta7, 8. Its benefit over 2D ultrasound imaging is its ability to increase depth perception. In our case, HDlive view was complementary to 2D ultrasound in delineating the herniated viscera, particularly the contours of the herniated organs, and was highly representative of the viscera that could be seen through the omphalocele sac after delivery.