Table 2.
Index test characteristics and diagnostic test criteria of the included studies (n = 14)
| Author, year | Index test | Transducer | Examination | Diagnostic criteria for contralateral PPV or inguinal hernia | WLIRa of contralateral hernia |
|---|---|---|---|---|---|
| Chen, 1998 | Ultrasound | 7.0 MHz linear array transducer | At rest and straining | (A) Presence of bowel loops or omentum in inguinal canal (B) Presence of fluid in processus vaginalis (C) No bowel loops, omentum or fluid in processus vaginalis, but widening of the cord at the level of internal ring. WLIR > 4 mm is considered an occult hernia |
PPV > 4 mm |
| Chou, 1996 | Ultrasound | 7.0 MHz linear array transducer | At rest and straining | (A) Diameter of internal inguinal ring > 4 mm (B) Presence of fluid in the processus vaginalis (C) Presence of bowel loops or other peritoneal structures in the inguinal canal |
PPV > 4 mm |
| Erez, 1996 | Ultrasound | 7.0 MHz linear array transducer | At rest, no straining | The presence of fluid, characterised by a homogeneous and more hypoechoic appearance, wider than a PPV | PPV > 3 mm (< 1 year) PPV > 4 mm (1–2 years) PPV > 5 mm (> 2 years) |
| Hasanuzzaman, 2011 | Ultrasound | 7.5 MHz linear array transducer | At rest and straining | CPPV that was not detectable at rest could be visualised as a hydrocele owing to the inflow or peritoneal fluid into a processus vaginalis on straining | Unclear |
| Hata, 2004 | Ultrasound | 7.5 MHz linear array transducer | At rest and straining | (A) Hydrocele, owing to inflow of physiologic ascites into the processus vaginalis, detectable while straining (B) Expanded processus vaginalis owing to the protrusion of a viscus, detectable while straining (C) Hydrocele > 10 mm in longitudinal length |
Unclear |
| Kaneda, 2015 | Ultrasound | 10.0 MHz linear array transducer | At rest, no straining | Major axis of the contralateral PPV in millimetres | Unclear |
| Kazez, 1998 | Ultrasound | 5.0 MHz linear array transducer | Unclear | (A) PPV: 2–3 mm (B) Hernia: > 4 mm |
PPV > 4 mm |
| Kazez, 2001 | Ultrasound | 7.5 MHz linear array transducer | Unclear | (A) PPV: 2–4 mm (B) Hernia > 4 mm |
PPV > 4 mm |
| Kervancioglu, 2000 | Ultrasound | 7.5 MHz linear array transducer | At rest, no straining | (A) Presence of fluid, bowel loops or omentum in the inguinal canal (B) PPV width ≥ 4 mm (C) Extension of bowel loops or omentum into the scrotum |
PPV > 4 mm |
| Lawrenz, 1994 | Ultrasound | 7.0 MHz linear array transducer | At rest and straining | (A) PPV (B) PPV and hydrocele |
Unclear |
| Shehata, 2013 | Ultrasound | 10.0 MHz linear array transducer | At rest and straining | (A) PPV with intra-abdominal organ observed in inguinal canal (B) PPV seen as a cyst at the internal ring of the inguinal canal (C) PPV is widened with increases in abdominal pressure and length of the PPV > 20 mm |
Unclear |
| Toki, 2003 | Ultrasound | 10.0 MHz annular array transducer | At rest and straining | (A) PPV with intra-abdominal organ observed in inguinal canal (B) PPV is cyst-like, exceeding 20 mm along the major axis at the internal ring of the inguinal canal (C) PPV is widened with abdominal pressure increment and length of the PPV ≥ 20 mm (D) PPV contains moving fluid without PPV widening |
Unclear |
| Uno, 1992 | Ultrasound | 3.75 MHz convex array transducer | Unclear | Unclear | Boys ≥ 7 mm Girls ≥ 4 mm |
| Zaidi, 2017 | Ultrasound | 7.5–11.0 MHz linear array transducer | Unclear | Inguinal hernia/PPV if maximum observed diameter of the inguinal canal at the internal ring ≥ 4.5 mm | PPV ≥ 4.5 mm |
PPV patent processus vaginalis, WLIR width of low echoic region of the internal ring
aWLIR of contralateral side as criteria for diagnosis of contralateral PPV or inguinal hernia