Letter to the Editor Urinary ascites in a fetus with posterior urethral valve: Antenatal diagnosis Tomoyuki Kuwata, 1 Shigeki Matsubara, 1 Shigeru Nakamura 2 and Hideo Nakai 2 Department of 1 Obstetrics and Gynecology and Jichi Perinatal Education Center, and 2 Pediatric Urology, Jichi Medical University, Shimotsuke, Tochigi, Japan Posterior urethral valves are reportedly associated with urine collection in the retroperitoneal or abdominal cavity in 1.0– 8.5% of cases, 1 with the latter, urinary ascites, being less fre- quent. 1 Although the mechanism of urinary ascites is unclear, bladder rupture is one culprit. 1 We read the article by Gürgöze et al., “A rare case of ascites in a newborn: posterior urethral valve”, 2 in which posterior urethral valve caused kidney rupture, not bladder rupture, leading to urinary ascites in a 17-day-old boy. The authors emphasized that in this condition, urinary ascites can be caused by not only bladder rupture, but also urine extravasation from the upper urinary tract, also pre- viously reported to be a culprit of neonatal urinary ascites. 3 The report by Gürgöze et al. 2 ended with, “antenatal ultrasonogra- phy should be performed in all pregnant women”, which was not performed in this case. We agree with this comment. We experienced a similar case of urinary ascites due to urine extravasation from the upper urinary tract associated with posterior urethral valve, but in a fetus, not a neonate. Antenatal ultrasound worked. Ultrasound in the 26th week revealed giant bladder (megacystis) and bilateral hydro- nephrosis in a male fetus (Fig. 1a). In the 28th week, ascites appeared, and the mother was referred. Megacystis and bilateral hydronephrosis, which had been observed 2 weeks previously, were absent. Massive ascites (Fig. 1b) pushed the diaphragm cephalad, compressing the thoracic cavity. Retroperitoneal fluid collection around the left kidney was observed (Fig. 1c). The most probable antenatal diagnosis was as follows: distal urinary tract obstruction, such as posterior urethral valve, caused megacystis and hydronephrosis. Urine was extravasated from the left upper urinary tract, finally leading to urinary ascites. The next day (28 2/7 weeks of gestation), Doppler flowmetry revealed mitral/tricuspid regurgitation, a heart failure sign, possibly caused by thoracic compression by ascites, requiring emergency cesarean section. The male infant weighed 1470 g with 1/5-min Apgar scores of 3/7. Ultrasound revealed massive ascites and fluid retention around the left kidney. Cystoscopy revealed no bladder rupture. Posterior Correspondence: Shigeki Matsubara, MD, PhD, Department of Obstet- rics and Gynecology, Jichi Medical University, 3311-1 Shimotsuke, Tochigi 329-0498, Japan. Email: matsushi@jichi.ac.jp Received 3 June 2010; revised 6 December 2010; accepted 22 December 2010. (b) (a) (c) Fig. 1 Ultrasound findings at (a) 26th and (b,c) 28th week of gestation. (a) Arrowheads and arrow indicate bilateral hydronephrosis and megacystis, respectively. (b) Arrowheads and arrow indicate kidneys and ascites, respectively. Bilateral hydronephrosis (arrowheads in Fig. 1a) disappeared. (c) Asterisk indicates retroperitoneal fluid, suggesting retroperitoneal urinary collection (extravasated urine). Arrow indicates ascites. Arrowheads show the kidney. Note the absence of hydronephrosis. Pediatrics International (2011) 53, 281–282 doi: 10.1111/j.1442-200X.2011.03344.x © 2011 The Authors Pediatrics International © 2011 Japan Pediatric Society