Table 1 Summary of characteristic for studies included in the meta-analysis

Ulvik[8]

1995

Norway, Europe

Journal of Urology

September 1984-December 1994

27 (20–41)

4–14 weeks in 3; 15–28 weeks in 9; 29–37 weeks in 12

KUB 1 positive in 6; US 3 positive in 21 (hydronephrosis 21 in 21)

Not mentioned

Not mentioned

Scarpa[9]

1996

Italy, Europe

Journal of Urology

3-years period

24 (16–30)

20–34

US\symptoms\urinalysis

Not mentioned

Not mentioned

Parulkar[10]

1998

America, North America

Journal of Urology

January 1984-November 1995

27 (< 18y 2; 18-20y 4; 20-30y 43; 30-40y 21)

First trimester in 3; second trimester in 23; third trimester in 44

US 40 positive in 65; IVP 5 positive in 5

Not mentioned

US 0.7 (0.4–1.6); IVP 0.55 (0.4–0.7)

Lemos[11]

2002

Brazil, South America

International Braz J Urol

Not mentioned

28 (20–34)

18 (12–34)

US 12 positive in 12; ureteroscopy 13 positive in 14

Proximal ureter in 1; medium ureter in 4; distal ureter in 12; 1 missed

6 (4–12)

Rana[12]

2009

Pakistan, Asia

Urology

1997—2007

22 (18–27)

20 (14–34) First trimester in 1; second trimester in 11; third trimester in 7

US in 11; KUB in 1

Proximal ureter in 11; distal ureter in 8;

11 (8–18)

Elgamasy[13]

2010

Egypt, Africa

BJU International

June 2003- June 2008

25.9 (18–38)

25.9 (24–30)

US 12 positive in 15; RU 14 positive in 15,

Proximal ureter in 2; medium ureter in 2; distal ureter in 10;

Not mentioned

Liu[14]

2011

China, Asia

Journal of Huazhong University of Science and Technology-Medical Sciences

January 2004—December 2009

26.7 (18–37)

23.45 (4–38)

US in 24

6 bilateral; 8 left; 10 right (surgery group)

Not mentioned

Polat[15]

2011

Turkey, Asia

Urological Research

2007–2009

25 (19–34)

30 (23–35) second trimester in 8; third trimester in 8

US in 11

Proximal ureter in 5; distal ureter in 6;

9.45 (5–12)

Atar[16]

2012

Turkey, Asia

International Journal of Surgery

December 2010-July 2011

26 (19–40)

24 (16–33)

US for 8, ureteroscopy for all

Proximal ureter in 5; medium ureter in 5; distal ureter in 7; no stone in 2

8 (5–19)

Bozkurt[17]

2012

Turkey, Asia

Urological Research

April 2005-Nocember 2010

27.8 (20–39)

24 (15–34)

US 16 positive; all 32 positive underwent URS

Proximal ureter in 8; medium ureter in 9; distal ureter in 10; no stone in 5

8 (5–19, in 16 US positive cases)

Hoscan[18]

2012

Turkey, Asia

Urology

2001–2011

24 (17–37)

26 (12–38)

URS 34 positive in 57

Proximal ureter in 8; medium ureter in 6; distal ureter in 20

7 (4–13)

Johnson[19]

2012

America, North America

Journal of Urology

Not mentioned

27

24.7

Low dose CT in 23; US in 18; MRI in 5

Not mentioned

7.8 (3–25)

Abdel[20]

2013

Egypt, Africa

Urology Annals

April 2008-March 2011

23 (19–28)

25 (16–35)

Clinical presentation and US; MRI in 3

Proximal ureter in 2; medium ureter in 5; distal ureter in 10

17 (12–21)

Bozkurt[21]

2013

Turkey, Asia

Urolithiasis

April 2005-Setemper 2011

27.41 ± 5.79

23.2 ± 4.6 (13–34)

Clinical presentation, presence of microscopic hematuria in urinalysis and US

Proximal ureter in 13; medium ureter in 13; distal ureter in 15

9.78 ± 3.47

Song[22]

2013

China, Asia

International Journal of Gynecology and Obstetrics

April 2001—July 2012

27.2§

26.5§

US 23 positive in 54; MRI 25 positive in 31

Proximal ureter in 10; distal ureter in 44

13.14 (7–22)

27.1¶

26.3¶

Keshvari[23]

2013

Iran, Asia

Nephro-Urology Monthly

June 2003-April 2011

23 ± 2 (19–34)

24 ± 3 (12–36) First trimester in 2; second trimester in 26; third trimester in 16

US in 44; IVP in 2

Proximal ureter in 2; medium ureter in 10; distal ureter in 36

Not mentioned

Ngai[24]

2013

Iraq, Asia

Arab Journal of Urology

March 2008-March 2010

27.2 (18–38)

First trimester in 5; second trimester in 15; third trimester in 10

US showed hydronephrosis in 30, stone in 12

Not mentioned

Not mentioned

Adanur[25]

2014

Turkey, Asia

Archivio Italiano di Urologia e Andrologia

January 2005-December 2012

25.4 (18–41)

24.8(7–33)

US in 6; ureteroscopy for all

Proximal ureter in 6; medium ureter in 5; distal ureter in 8

9.2 (6–13) in 6 with US

Georgescu[26]

2014

Romania, Europe

Chirurgia

January 2006-January 2012

27.2 (20–37)

First trimester in 6; second trimester in 32; third trimester in 16

US stone 18 positive in 54

Proximal ureter in 11; medium ureter in 8; distal ureter in 14

8 (4–16)

Not mentioned

Teleb[27]

2014

Egypt, Africa

Arab Journal of Urology

October 2006-December 2013

26.6 (SD 4.65)§

24.1 (SD 5.44)§

US 31 positive in 43

Middle ureter in 9§; distal ureter in 13§

Not mentioned

25.5 (SD 4.26)¶

25.7 (SD 4.95)¶

Middle ureter in 7¶; distal ureter in 14¶

Wang[28]

2014

China, Asia

Urology

February 2006-Setemper 2012

26 (17–39)

29(17–39) First trimester in 2; second trimester in 36; third trimester in 49

US in 79, MRI in 8,

Left side in 48, Right side in 39

8 (5–19)

Fathelbab[29]

2016

Egypt, Africa

African Journal of Urology

April 2006-October 2013

23 (19–37)

First trimester in 4; second trimester in 23; third trimester in 14

Diagnostic ureteroscopy 36 positive in 41

Proximal ureter in 7; distal ureter in 29

8.9 (5–16)

Zhang[30]

2016

China, Asia

PLoS ONE

March 2009-Setember 2014

25.5 ± 4.6 (16–41)

9–36

US and diagnostic ureteroscopy positive in 86 (only ureteroscopy in 24), negative in 31

Not mentioned

8.2 ± 0.6

Abedi[31]

2017

Iran, Asia

Journal of Lasers in Medical Sciences

January 2007-June 2016

29.3

27.3 (13–31) First trimester in 9; second trimester in 24; third trimester in 12

Clinical manifestations, urinalysis and US

Poximal ureter in 5; distal ureter in 40

7.84 (5-9 mm)

Tan[32]

2018

China, Asia

European Journal of Obstetrics and Gynecology and Reproductive Biology

January 2005-June 2015

26.7 ± 8.9§

27.5 ± 11.2§

US

Proximal ureter in 10; medium ureter in 12; distal ureter in 31

Not mentioned

27.4 ± 10.2¶

25.9 ± 9.7¶