Ultrasound Diagnosis of a Fetal Omphalocele in an Atlantic Bottlenose Dolphin (Tursiops truncatus)
Fetal abdominal wall defects are routinely diagnosed with ultrasound in human medicine. An omphalocele is an abdominal wall defect at the base of the umbilical cord resulting in herniation of abdominal contents. In 2005, a routine pregnancy ultrasound exam of a multiparous (six previous live births) Atlantic bottlenose dolphin showed an approximately 16 week old fetus with an omphalocele. At that time, the fetal biparietal diameter (BPD) was 3.1 cm and the omphalocele measured approximately 2 cm in diameter at the widest point. Throughout the pregnancy, the omphalocele was closely monitored with a maximum diameter of 11.2 cm at approximately 51 weeks gestation (BPD was 12.2 cm). Ultrasound allowed visualization of the omphalocele contents, which included a portion of the liver and intestinal loops. Doppler was utilized to study the blood flow within the omphalocele as well as diagnose an associated anomaly of the umbilical cord, which contained three vessels instead of four. An anesthetic and surgical plan was prepared to repair the defect immediately after birth. Unfortunately, the omphalocele ruptured during delivery and the calf was stillborn. Gross necropsy confirmed the ultrasound diagnoses of fetal omphalocele with herniated liver and intestinal loops as well as a three vessel umbilical cord. Routine pregnancy ultrasound examinations provide useful data on fetal and maternal health. Although the calf did not survive, a prenatal diagnosis allowed us to formulate a comprehensive medical plan and be as prepared as possible for the potential parturition outcomes.
The authors thank Dr. Sam Ridgway, senior scientist of animal care, and Dr. Kurt Benirschke for their valuable input on the case. Dr. Mark Xitco and Mr. Scott Price provided critical administrative and logistical support of the medical care plan. We also thank the managers, veterinary support staff, and animal trainers at the Navy Marine Mammal Program that assisted in all aspects of animal care and preparation for parturition.