You can search published articles.

Journal Information

Online ISSN


​Cihat Şen, ​Nicola Volpe

Cecilia Villalain, Daniel Rolnik, M. Mar Gil

Managing Editors
Murat Yayla

Statistics Editor
Resul Arısoy

Antepartum course and postpartum management of cases with mild fetal pyelectasis at second trimester

Murat Muhcu, Gökhan Gönen, İlker Akyol, Özgür Dundar, Levent Tütüncü, Ali Rüstü Ergür, Vedat Atay, Ercüment Müngen , Yusuf Ziya Yergök

Article info

Antepartum course and postpartum management of cases with mild fetal pyelectasis at second trimester. Perinatal Journal 2007;15(2):56-60

Author(s) Information

Murat Muhcu1,
Gökhan Gönen1,
İlker Akyol2,
Özgür Dundar1,
Levent Tütüncü1,
Ali Rüstü Ergür1,
Vedat Atay1,
Ercüment Müngen 1,
Yusuf Ziya Yergök1

  1. GATA Haydarpaşa Eğitim Hastanesi, Kadın Hastalıkları ve Doğum Servisi- İstanbul TR
  2. GATA Haydarpaşa Eğitim Hastanesi, Üroloji Servisi- İstanbul TR
Publication History
Conflicts of Interest

No conflicts declared.

Mild fetal pyelectasis is the most frequent finding during antenatal ultrasonographic monitoring of the urogenital system. We aimed to find out the natural history of mild fetal pyelectasis detected at second trimester, and its implications on the postnatal pathologies of urinary system.
Antenatal fetal pyelectasis was detected in 46 of the 2470 pregnancies (1.9%). Pyelectasis was bilateral in 14 cases. Fetal pyelectasis normalized antenatally in 14 fetuses (30%) whereas pyelectasis could be identified at birth in 32. Pyelectasis normalized in 3 of 32 babies within 1 week after delivery. During the followup of the remaining 29 babies for at least 4 months; normalization, VUR, obstructive uropathy were detected in 10, 4 and 5 babies respectively. Ten babies are being followed expectantly by the Department of Urology.
We reviewed the charts of pregnant women who delivered at our department during the last three years. Cases in whom fetal anteroposterior renal pelvic diameter exceeded 5 mm during 18th to 28th gestational weeks, and who were followed for at least 4 months after delivery were included in the study.
Prenatal detection of fetal pyelectasis provides the probability of timely treatment to prevent progressive renal functional deterioration. Fetuses with pyelectasis must be monitored closely during pre and postnatal period. Postnatal management is very flexible, and experienced Pediatric Urologists should be involved.

Fetal pyelectasis, hydronephrosis, urogenital system, congenital anomaly

Congenital urogenital system anomalies are commonly encountered during antenatal period and mild fetal pyelectasis is the most commonly detected pathological ultrasound finding during pregnancy (1,2). Mild fetal pyelectasis or minimal hydronephrosis is defined when the anteroposterior diameter of the renal pelvis is between 5-10 mm and the reported incidence varies between 1.1-3.3% (3-5). The importance of pyelectasis arises from its association with fetal aneuploidies and its relation to the urogenital anomalies developed later in pregnancy (6). Fetal pyelectasis is highly associated with urogenital anomalies, however, there is no correlation between urogenital pathologies and the magnitude of the dilatation of the renal pelvis.
The aim of this study was to show the relationship between the course of mild fetal pyelectasis and postnatally detected urinary system anomalies.
In this study, 46 cases in which fetal pyelectasis more than 5 mm was detected on prenatal ultrasound between 18 and 28 weeks of gestation during the last three years were evaluated retrospectively. All cases delivered in our department and had a postnatal follow up period of more than 4 months. Cases with associated fetal structural or chromosomal abnormalities were excluded from the study. Pregnant women with normal amniotic fluid who had unilateral or bilateral mild fetal pyelectasis detected on at least one examination were included in the study.
In all neonates, the first ultrasonografic examination was performed during the period between day 3 and day 7 after the delivery. The second ultrasonography was performed one month after the delivery and the third three months. The first examination was performed in order to detect the neonates in whom urgent surgical intervention was required. The results of the second control and the third one performed not more than 3 months after the delivery in persistent cases demonstrated the course of the pyelectasis and were compared with prenatal findings. In addition, the cases with pyelectasis at delivery underwent a voiding cystoureterography at urology depertment.
Prenatal examinations were performed at intervals of 4 weeks. The course of the pyelectasis at antenatal period were divided to three groups depending on the anteroposterior diameter of the pelvis renalis:
•Not change
•The anteroposterior diameter exceeding 10 mm: worsening
•The anteroposterior diameter decreasing to < 5 mm: improving
During the last three years, 2470 pregnancies were followed in our unit and in 46 cases (%1.9), fetal pyelectasis was diagnosed antenatally. Fetal pyelectasis was bilateral in 14 cases (%30.4). Fetal pyelectasis was not observed in 14 pregnancies during subsequent prenatal ultrasound examinations. During antenatal follow-up, the anteroposterior diameter of the renal pelvis was stable in 27 cases, whereas it was increasing in five cases during follow-up ultrasound examination. Pyelectasis was diagnosed in 1.2 % (32 cases) of the babies at birth. In five cases out of these 32 babies (15.6%), percutan nephrosthomy was necessary due to obstructive uropathy during the first four months of the postnatal follow-up. Pyelectasis was persisted in 29 cases after the first month of the life and in four of them (13.8 %, 8.7% of the all antenatally diagnosed pyelectasis), vesicoureteral reflux (VUR) was diagnosed, therefore, further therapy and follow-up were planned at the urology department. Anteroposterior diameter of the renal pelvis was increasing in five babies and surgical intervention was necessary in three of them, whereas surgical treatment was needed in two cases out of 27 babies with stable anteroposterior diameter of the renal pelvis. There were statistically significant difference between two groups (p=0.003). The course of pyelectasis after the birth was presented in Figure 1 and demographic characteristics was summarized in Table 1.
Mild pyelectasis is considered as a clinically insignificant physiologic condition in some studies. However, up-to-date studies stress its relationship with irreversible renal deterioration if remains uncorrected.
If fetal pyelectasis is ignored, diagnosis of a rare but curable pathology may be misssed, and treatment of possible deterioration is delayed. On the other hand, overzealous management is costly, and causes anxiety. Physiologic pyelectasis resulting from maternal hydration and hormonal alteration due to pregnancy is more frequent than pathologic pyelectasis (7).
Mild pyelectasis is one of the most frequent findings of 2nd and 3rd trimester. Ultrasound investigations, fetuses with this diagnosis need close perinatal followup. However, clinical significance of this condition has not been fully determined yet. Studies show that pyelectasis diagnosed during 2nd trimester mostly regresses prenatally or within the first year of life. A single fetal renal ultrasound evaluation might have detected a physiologic pyelectasis (8). As a matter of fact, many studies have shown that mild pyelectasis mostly regresses spontaneously. Sairam et al found that mild pyelectasis resolves at a rate of 80% (9). Persutte el al reported similar findings (10). In our series, there was no sign of urinary obstruction in 71.9% of the cases who had persistent pyelectasis for 4 months postnatally. In a recent study by Woodward and Frank postnatal diagnoses of cases with antenatally detected hydronephrosis were as follows: temporary hydronephrosis in 48%, physiologic hydronephrosis in 15%, ureteropelvic stenosis in 11%, vesicoureteric reflux in 9%, megaureter in 4%, multicystic dysplastic kidney in 2% and ureterocele in 2% (11). In our series, urinary obstruction was found in 10% of all cases, and they were managed by the Department of Urology; first by placing percutaneous nephrostomy and then by performing surgery, thereby preventing a possible upper tract deteroration at an early stage. Those with VUR were also treated appropriately. All of those in whom surgery was indicated were the ones with progressive fetal hydronephrosis. Furthermore, these patients showed progressive dilatation after birth as well. Three of them had AP renal pelvic diameter of more than 10 mm. Surgery indication was significantly less frequent in cases with no progressive dilatation. Kent et al found that all patients eventually requiring surgery had pelvic diameters more than 7 mm and this was increased at the next ultrasound evaluation.
All these studies suggest that detection of prenatal pyelectasis is important. Since patients with hydronephrosis are often asymptomatic, diagnosis and corrective surgery might be delayed. Therefore, perinatologists would have a significant impact on the protection of renal function in these cases.
Despite the fact that importance of the diagnosis of prenatal hydronephrosis is well perceived, some points in the management of mild hydronephrosis need more clarification:
•Is prenatal evaluation of pyelectasis capable of prognosticating the postnatal outcome?
•Is there any relationship between the first and following renal pelvic diameters?
•How many prenatal exams are required and what is the best scheme for prenatal followup?
As a conclusion, prenatal followup of renal pelvic diameter may help prognosticate the postnatal outcome (12), and may provide the chance for a timely surgery that prevents the progressive renal deterioration. Fetuses with pyelectasis should be closely followed pre- and postnatally. Yet, it appears that the course of dilatation is more important than its existence alone. Postnatal management is very flexible and case-oriented, and all the affected cases must be referred to Pediatric Urologists.
1.Livera LN, Brookfield DSK, Egginton JA, Hawnaur JM. Antenatal ultrasonography to detect fetal abnormalities: a prospective screening programme. BMJ 1989; 298:1421–3
2.Blyth B, Snyder HM, Duckett JW. Antenatal diagnosis and subsequent management of hydronephrosis. J Urol 1993; 149: 693–8
3.Scott JE, Wright B, Wilson G, Pearson IA, Matthews JN, Rose PG. Measuring the fetal kidney with ultrasonography. Br J Urol 1995; 76: 769–74
4.Mandell J, Blyth BR, Peters CA, Retik AB, Estroff JA, Benacerraf BR. Structural genitourinary defects detected in utero. Radiology 1991;178:193-196.
5.Gunn TR, Mora D, Pease P. Antenatal diagnosis of urinary tract abnormalities by ultrasonography after 28 weeks’ gestation: incidence and outcome. Am J Obstet Gynecol 1995; 172: 479–86
6.Signorelli M, Cerri V, Taddei F, Groli C, Bianchi UA. Prenatal diagnosis and management of mild fetal pyelectasis: implications for neonatal outcome and follow-up. Eur J Obstet Gynecol Reprod Biol 2005;118:154–9.
7.Callen PW, editor. Ultrasonography in Obstetric and Gynecology. 4th edition. Philadelphia, PA7 W.B. Saunders Company;,2000.
8.Anderson NG, Allan RB, Abbott GD. Fluctuating fetal or neonatal renal pelvis: marker of high-grade vesicoureteral reflux. Pediatr Nephrol 2004;19:749– 53.
9.Sairam S, Al-Habib A, Sasson S, Thilaganathan B. Natural history of fetal hydronephrosis diagnosed on mid-trimester ultrasound. Ultrasound Obstet Gynecol. 2001 Mar;17(3):191-6.
10.Persutte WH, Koyle M, Lenke RR, Klas J, Ryan C, Hobbins JC. Mild pyelectasis ascertained with prenatal ultrasonography is pediatrically significant. Ultrasound Obstet Gynecol. 1997 Jul;10(1):12-8.
11.Woodward M, Frank D. Postnatal management of antenatal hydronephrosis. BJU International 2002;89:149– 56. 12.Podevin G, Mandelbrot L, Vuillard E, Oury JF, Aigrain Y. Outcome of urological abnormalities prenatally diagnosed by ultrasound. Fetal Diagn Ther 1996; 11: 181–90
Table 1.
Demographic characteristics.
Figure 1.
Pyelectasis follow-up.