Ultrasonography for inguinal hernias in boys

Ultrasonography By Ke-Chi

Chen,

Chih-Chun

for Inguinal Chu,

Taiwan,

&wkground/furpose: tion alone no longer of inguinal hernia. and safe diagnostic

Ting-Ywan

Republic

History taking and physical examinameet the surgeon’s need in the diagnosis Ultrasonography (US) provides a good tool for inguinal hernias in boys.

Methods: From 1995 to 1997, 244 boys with inguinal hernias (41 bilateral and 203 unilateral), received preoperative US on both groins to confirm the diagnosis. Those with positive US findings, such as viscera or fluid in inguinal canal or widening of the internal inguinal ring, underwent surgery. Results: The accuracy of diagnosis assessment were 97.9% and 84%, 95% of widening of internal inguinal

with US and clinical respectively. More than rings (>4 mm) proved to

H

ISTORY TAKING and physical examination play important roles in the diagnosis of inguinal hernia in children but do have limitations. It is not always possible to distinguish an inguinal hernia in a child before surgery, especially when the child is obese or irritable. When a child presents with unilateral inguinal hernia, although the incidence of an occult hernia on the opposite side is high, it is stressful to discuss the possibility of contralateral exploration with his parents when there is no evidence of the coexisting hernia. Ultrasonography can help surgeons make the decision to explore the asymptomatic side. We believe that the more information we obtain before operation, the less morbidity and mortality occurs. For a better prognosis and to eliminate inappropriate operations, history taking and physical examination alone no longer meet the surgeon’s needs. We have used ultrasonography as a diagnostic tool to determine the nature of childhood inguinal hernia since 1993 and have had excellent results. Since then, US has been used at our hospital as a routine study in children with inguinal hernia. Ultrasonography not only shows the herniated viscera or fluid in the processus vaginalis (PV) but also measures the size of the cord. We found that in

From the Division of Pediatric Surgevy Department of Surgery, Department of Radiology, Tri-Service General Hospital and the Department of Medical Imaging, Cheng Hsin Medical Centel; Taipei, Taiwan, Republic of China. Address reprint requests to Dr Ke-Chi Chen, Division of Pediatric Surgery, Department of Surgery, Tri-Service General Hospital, No 8, See 3, Tin&how Rd, Taipei, Taiwan 100, ROC. Copyright 0 1998 by WB. Saunders Company 0022-3468/98/3312-0011$03.00/0 1784

Hernias Chou,

and

in Boys

Ching-Jiunn

Wu

of China

be hernias. There were two direct inguinal femoral hernias, which were misdiagnosed nation, but proved to be diagnosed correctly Conclusions: US serves as a noninvasive diagnostic tool for inguinal hernias in the upper limit of the normal diameter ring, an occult inguinal hernia can be surgery. J Pediatr Surg 33:1784-1787. Copyright ders Company. INDEX inguinal

WORDS: Ultrasonography, ring, femoral hernias.

hernias and two by clinical examiby US.

and highly accurate boys. Using 4 mm as of the internal inguinal easily detected before o 1998

inguinal

by W.B.

hernias,

Saun-

internal

boys, regardless of the age, any inguinal canal with a diameter more than 4 mm at the level of internal ring is very likely to have a hernia.’ In addition to checking for contralateral inguinal hernia, US provides the advantage of an accurate diagnosis of both direct inguinal hernia and femoral hernia, which are often misdiagnosed by clinical examination. MATERIALS

AND

METHODS

From October 1995 to October 1997,244 boys with inguinal hernias, 41 bilateral and 203 unilateral, underwent diagnosis by clinical examination at the outpatient department and the baby room. Their ages ranged from 3 days to 13 years with a mean of 32.6 months. All received preoperative US on both groins to confirm the diagnosis. There were 285 symptomatic and 203 asymptomatic groins involved in this study. An Acuson 128XP/lO computed sonography machine (Acuson, Mountain View, CA) with a 7.0 MHz linear-array transducer was used. All US were performed by the same experienced pediatric radiologist. US was performed with the patient in the supine position with the transducer gently placing on the groin. Scanning was performed in the sagittal plane beginning at the scrotum and moved upward to the region of the internal ring of the inguinal canal. Care was taken to identify the tubular hypoechoic structures of the inguinal canal proximal to the peritoneal cavity. Inferior epigastric vessels could be identified by color Doppler scanning. These vessels are considered landmarks of the site of the internal ring of the inguinal canal. After the entire inguinal canal from the external ring to the internal ring was visualized, the width of the inguinal ring was measured. All measurements were made while the patient was both at rest and straining (eg, standing, crying, coughing, or bearing down). For purposes of this study, a patent PV was considered as a potential hernia sac and was included in the category of “hernia.” The US criteria for the diagnosis of “inguinal hernia” were the following: (1) the presence of bowel loops or omentum in the inguinal canal (Fig I),, (2) the presence of fluid in the PV (Fig 2), (3) no bowel loops, omentum, or fluid in the PV, but widening of the cord at the level of internal ring (Fig 3). The width of the cord at the level of internal inguinal ring over 4 mm is considered an occult hernia. If the hernia is JoornalofPediatric

Surgery,Vol33,

No 12 (December),

1998: pp 1784-1787

ULTRASONOGRAPHY

Fig 1. canal.

Indirect

FOR INGUINAL

inguinal

hernia

that

1785

HERINAS

has bowel

loops

in the inguinal

bulging out from below the inferior epigastric vessels, a direct inguinal hernia is suspected. If a hernia is based below the inguinal ligament, a femoral hernia is considered. All boys subsequently underwent surgical exploration on the groins with positive US findings.

RESULTS

The US findings in groins of 244 boys are summarized in Table 1. The US of the 285 symptomatic groins showed 91 (32%) inguinal canals with visceral hernia, 52 (18%) fluid hernia, 118 (41%) widening of the internal inguinal ring, four (1.4%) different forms of hernia (two boys with unilateral direct inguinal hernia and one boy with bilateral femoral hernia), and 20 (7%) groins with no hernia. On the 203 asymptomatic groins, there were 11 (5.4%) inguinal canals with visceral hernia, 16 (8%) fluid hernia, 38 (19%) widening of the internal inguinal ring, and 138 (68%) groins with no hernia at all. All boys with positive US findings received surgical exploration on the groins.

Fig 3. Indirect inguinal hernia that has a widening cord at the level of the internal inguinal ring. Arrowheads show the landmark of the internal inguinal ring.

Among 203 boys with unilateral symptomatic hernia, 198 underwent operations (57 bilateral and 141 unilateral explorations), and five received no operation according to US findings. Therefore, 57 boys (28%) with a unilateral clinical hernia were found to have another contralateral hernia on US examination that was missed during the clinical examination. About eight (4%) boys with a unilateral clinical hernia that showed negative findings on US examination underwent surgery for contralateral hernia. Among 41 boys with clinically bilateral inguinal hernia, 35 received bilateral groin explorations, five received unilateral explorations, and one received no operation because of negative US findings on both sides. Among 488 groins, including symptomatic and asymptomatic groins, there were 410 groins with correct clinical diagnosis and 78 groins with incorrect clinical diagnosis; therefore, the accuracy was 84%. Among 330 operated groins, there were 323 groins with correct US diagnosis and seven groins with incorrect US diagnosis; therefore, the accuracy was 97.9%. The groins with negative US findings did not undergo surgical exploration. All groins with bowel loops or omentum hemiation or fluid accumulation in the inguinal canal proved to have patent processus vaginalis. In the group of widening of internal inguinal ring (>4 mm), there was patent processus vaginalis found in 114 of 118 groins on symptomatic sides and 35 of 38 groins on asymptomatic sides. The accuracy of US in the group of widening of the internal inguinal ring was 95.5%. In the other groups, including visceral hernia, fluid hernia, direct inguinal hernia, and femoral hernia, the accuracy of US diagnosis was 100%. DISCUSSION

Fig 2. Indirect patent processus

inguinal vaginalis.

hernia that demonstrates H, cord hydrocele.

fluid

in the

Routine bilateral explorations of the inguinal canals in children, regardless of clinical findings for inguinal

1786

CHEN

Table

1. Ultrasonographic Symptomatic

Findings

(n = 285)

in Groins

of 244 Boys

Asymptomatic

in = 203)

Unilateral (n = 203)

Bilateral (II = 82)

hernia

64

27

Fluid hernia Widening of the internal

33 91

19 27

2D 13

2F 7

0 138

US Findings

Visceral

inguinal

ring

Others Negative Abbreviations: D, direct boy; OR operation.

inguinal

hernia,

two

boys

with

unilateral

direct

hernia, have been used by surgeons for decades2w5 Although the incidence of a coexisting hernia on the asymptomatic side is quite high, there is no need for routine bilateral explorations in all patients.6 At our hospital, intraoperative nonpuncture laparoscopic examination and preoperative US have been used to eliminate the unnecessary surgical explorations since 1991 and 1993, respectively. 7,8~1The two methods have proven to be good diagnostic tools in detecting the contralateral hernia? However, US offers the advantage against the intraoperative nonpuncture laparoscopic examination, eg, (1) the US is a rapid, reliable, convenient, noninvasive screening technique; (2) the surgeon can obtain more information before surgical explorations; (3) laparoscopy induces pneumoperitoneum, which may distort the anatomic positions of the inguinal canal and visceralO-‘l; however, US does not; (4) US provides dynamic, twodimensional images. A patent processus vaginalis, although it might disappear itself, still has the potential to develop into a hernia in all age groups. The widening of the internal ring (>4 mm) seen on US examination has the positive rate of surgery of about 95% and usually proves to be a patent processus vaginalis or hernia. In this study, all inguinal canals with a herniated viscera or fluid accumulation were shown to have hernias, and more than 95% of the group with widening of the internal inguinal ring were shown to be indirect inguinal hernias. In a recent study by Erez et all2 it was shown that US was 92% accurate in demonstrating the presence or absence of inguinal hernias in 200 children. At our hospital, we demonstrated that, regardless of age, when using 4 mm as the upper limit of the normal diameter of the internal inguinal ring, we were able to detect the cases of clinically unsuspected contralateral inguinal hernia.’ An accuracy of 95% was achieved when the same criteria to suggest a normal inguinal canal are applied.

Ultrasonography Positive OP Finding

Finding

Accuracy (%)

11

102

102

100

16 38

68 149

68 156

100 95.5

2D2F -

2D2F 158

Tota I (n = 203)

inguinal

ET AL

hernia;

F, femoral

hernia,

two groins

with

100 -

femoral

hernia

in a

One hundred fifty-eight groins had negative findings on ultrasonographic examination, and did not undergo any operation. Because it is not fair to perform surgical exploration on the groins without any positive ultrasonographic findings, the false-negative rate of ultrasonography cannot be assessed in this study. However, the false-negative rate of ultrasonography in diagnosis of inguinal hernias is about 2% in a previous study at our hospital.’ Using the same criteria, the high accuracy of ultrasonography in the diagnosis of inguinal hernias is believable even with no false-negative data. In addition to detecting the contralateral occult hernia, US can also distinguish some rare forms of groin hernias, such as direct inguinal hernia and femoral hernia, from indirect inguinal hernia. Without US findings, surgeons may miss these hernias during operation. Direct inguinal hernia rarely is encountered in children and usually presents as a recurrent hernia after repair of a congenital indirect hemia.13 Femoral hernias are also rare in children with an incidence of 0.4% to 0.8%.14-16 In 1965, Fonkalsrud et alI7 have shown 25 pediatric patients during the past 17 years, 12 with a femoral hernia and 13 with a direct inguinal hernia; the correct preoperative diagnosis was made in only eight (32%). Others reported the preoperative accurate diagnostic rate for femoral hernias was 15% to 90%.18-20 In this study, US can provide a 100% accurate preoperative diagnosis of both direct inguinal hernias and femoral hernias, which are often misdiagnosed by clinical examination. It is clear that US can offer the benefits in confirming the clinical examination and diagnosis of the contralateral inguinal hernia, which might be missed by physical examination if there is already an established clinical diagnosis of hernia. Therefore, we highly recommend the use of US as a routine diagnostic tool in pediatric patients with inguinal hernias.

REFERENCES 1. Chou TY, Chu CC, Diau GY, et al: Inguinal hernia in children: US versus exploratory surgery and intraoperative contralateral laparoscopy. Radiology 201:385-388, 1996 2. Moss RL, Hatch EI: Inguinal hernia repair in early infancy. Am .I Surg 161596-599, 1991 3. Clansen EG, Jake RJ, Binkley FM: Contralateral inguinal explora-

tion of unilateral 1958 4. Kiesewetter treated bilaterally? 5. Rothenberg children. Surgery

hernia

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WB, Prenzen L: When should hernia JAMA 171:287-290, 1959 RE, Bamett T: Bilateral hemiotomy 37:947-950, 19.55

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ULTRASONOGRAPHY

FOR INGUINAL

HERINAS

6. Uno T, Mochida T, Wada H, et al: Ultrasonic exploration of the contralateral side in pediatric patients with inguinal hernia. Surg Today 22:318-21, 1992 7. Chu CC, Chou CY, Hsu TM, et al: Intraoperative laparoscopy in unilateral hernia repair to detect a contralateral patent processus vaginalis. Pediatr Surg Int 8385-388, 1993 8. Chu CC, Diau GY Diagnostic laparoscopy in childhood hernia repair. J Surg Assoc ROC 27:2668-2672, 1994 9. Lawrenz K, Hollman AS, Carachi R, et al: Ultrasound assessment of the contralateral groins in infants with unilateral inguinal hernia. Clin Radio1 49:546-548, 1994 10. Powell RW Intraoperative diagnostic pneumoperitoneum in pediatric patients with unilateral inguinal hernias: The Goldstein test. .I Pediatr Surg 20:418-421, 1985 11. Gurses N, Bemay F, Demirbilek S, et al: Intraoperative diagnostic pneumoperitoneum in pediatric patients with unilateral inguinal hernias: The Goldstein test. Pediatr Surg Int 9:70-72, 1994 12. Erez I, Kovalivker M, Schneider N, et al: Elective sonographic

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evaluation of inguinal hernia in children: An effective alternative to routine contralateral exploration. Pediatr Surg Int 28: 1026-1027, 1993 13. Viidii T, Marshall DG: Direct inguinal hernias in infancy and early childhood. J Pediatr Surg 15:646, 1980 14. Coley WB: Operative treatment of hernia. Ann Surg 68:255-268, 1918 15. Rutherford R: Femoral hernia in children. Lancet 2:498, 1927 16. Fosburg RG: Femoral hernia in infancy and childhood. Am .I Surg 109:470-4751965 17. Fonkalsmd EW, deLorimier AA, Clatworthy HW Femoral and direct inguinal hernias in infants and children. JAMA 192:597-599, 1965 18. Tam PKH, Lister J: Femoral hernia in children. Arch Surg 119:1161-1164, 1984 19. Burke .I: Femoral hernia in childhood. Ann Surg 166:287-289, 1967 20. Marshall DG: Femoral hernias in children. J Pediatr Surg 18:160-162, 1983