Prenatal diagnosis of urinoma and dilated azygous vein

OBJECTIVE: We present a case which presented a diagnostic challenge and highlighted a previously unreported interesting developmental finding on antepartum ultrasound with postnatal follow up METHODS: A primi-gravid patient... [ view full abstract ]

OBJECTIVE: We present a case which presented a diagnostic challenge and highlighted a previously unreported interesting developmental finding on antepartum ultrasound with postnatal follow up
METHODS: A primi-gravid patient was followed with serial ultrasound from 11 weeks until preterm delivery at 34 weeks. A fetal intra-abdominal mass was found during the anatomic scan at 22 weeks and subsequently diagnosed as an urinoma. The mass progressively expanded and displaced the intraabdominal contents with the liver displaced into the left side of the fetal abdomen. The fetal condition was followed and the subsequent changes in the venous drainage and cardiac findings were documented.
RESULTS: The patient had a normal 11 week dating scan. The anatomic survey scan at 22 weeks demonstrated a right sided cystic mass 3.7 cm in diameter which deflected the R kidney medially. The umbilical vein drained normally into the portal system and flow in the DV was normal. The fetal heart including 3 vessel views was normal. Over the next month, the cyst grew to over 7 cm in diameter and the abdominal circumference was greater than the 97% for GA. The fetal liver was gradually displaced into the left abdomen by the progressively enlarging cyst. The size of the mass raised the concerns about a possible abdominal dystocia with attempting vaginal delivery as well as the possibility of either in utero or intrapartum vascular decompensation due to progressive compression of the venous return to the heart. A fetal MRI was obtained to confirm the fetal anatomic relationships. The fetal echocardiogram demonstrated that the azygos system dilated but no other abnormalities were noted
The patient delivered vaginally at 34 weeks and postnatal evaluation of the neonate confirmed a urinoma from a ruptured renal pelvis and a normal neonatal heart The infant had a laparoscopic nephrectomy and removal of the retroperitoneal cyst. With decompression of the abdominal cyst, the normal drainage on the IVC and normal echocardiographic findings were documented.
DISCUSSION: When a dilated azygos vein is identified on antenatal scanning, it is often a marker for disruption of the normal embryological formation of the abdominal visceral venous drainage associated with heterotaxy. Compensatory dilation of the azygos vein will develop when there is an interruption of the inferior vena cava (IVC) as a result of the right sub cardinal vein failing to anastomose with the hepatic sinusoids to form the hepatic segment of the IVC. This is a frequent finding with left atrial isomerism. In our case the abdominal venous drainage and cardiac findings were normal in the early second trimester. A retroperitoneal cystic mass developed as a result of a urinoma formation and the progressively enlarging mass gradually displaced the right sided abdominal viscera including the liver to the left of the midline. By 26 weeks gestation the mass had compressed the IVC drainage of the lower body resulting in a dilation of the azygos vein behind the heart and a dilated azygos arch emptying into the superior vena cava. Prenatal diagnosis of a urinoma has been previously reported as a complication in a number of obstructive renal conditions. The progressive dilation of the azygous vein has not been previously reported in association with this condition.
CONCLUSIONS: This case illustrates how compression of the IVC by a retroperitoneal mass led to a compensatory dilation of the azygos system. This case offered the opportunity to follow the sequential developmental evolution of the renal abnormality with advancing gestational age and demonstrated the compensatory adaptation of the fetal cardiovascular system to the gradual obstruction of the normal venous return to the heart from the lower body. It is interesting that despite the compression of the portal system and IVC, The high velocity flow in the Ductus Venosis remained unaffected and the fetus never developed any signs of cardiac decompensation despite the obvious change in the intraabdominal venous return due to the progressively enlarging mass. This case was presented in our fetal board conference and highlights several issues with care coordination in a rural setting.