一 377 一

J． Tokyo Med． Univ．， 65（4）： 377－383， 2007

総 説

Diagnostic imaging for inguinal and pelvic hernia

Fumio KOTAKEi）， Yosinori WATANABE2）， Motoi NISHIMURA2） Keijj MORIMOTO’）， Taizou OZUKI’）

i）Department of Radiology， Tokyo Medical University， Kasumigaura Hospita1 2）Fourth Department of Surgery， Tokyo Medical University， Kasumigaura Hospital

Abstract

Hernia of the inguinal region is a very frequent condition， accounting for about 80－9090 of all abdominal

hernias． lnguinal hernia involves prolapse of organs into the inguinal region on the ventral side of the inguinal ． lt is subdivided into indirect and di’rect inguinal hernia． Indirect inguinal hernia involves prolapse of intraperitoneal organs through the ． The hernia sac is located outside the inferior epigastric artery． This is the most frequent type of inguinal hernia and often develops in boys during infancy or early childhood and males aged over 50． Diagnosis of this type of hernia is easy when prolapse of intraperitoneal organs into the inguinal canal or scrotum is visible on computed tomography （CT） scans． Direct inguinal hernia involves direct prolapse of intraperitoneal organs fi”om inside the inferior epigastric artery，

without passing through the inguinal canal． This type of hernia， often seen in elderly males， presents only mild symptoms and rarely causes impaction． ln cases with this type of hernia， the inferior epigastric artery can be identified by contrast－enhanced CT， but multidetector－row CT is more usefu1 for the diagnosis ofdirect inguinal

hernia since it can yield coronal images through multiplanar reconstruction． Hernia involving prolapse of intraperitoneal organs through the femoral canal on the dorsal side of the inguinal ligament is called femoral hernia． lt causes a mass to be formed in the inguinal regi’on． lt is often seen in females after middle age and has a high probability of impaction． Richter’s hernia is also frequently

seen in cases of femoral hernia． Special attention is needed in cases of this type of hernia， since only minimal symptoms of ileus are presented even when necrosis ofthe intestinal wall has developed． Distinction ofthis type of hernia from direct inguinal hernia is possible if the hernia sac is visible on the dorsal side of the inguinal

ligament on CT scans． Obturator hernia is a type of pelvic hernia． On external appearance， this type of hernia causes no mass．

Therefore， diagnostic imaging is important for its diagnosis． This type of hernia is often seen in elderly and slim

females． Because the hernia orifice is sharp and solid for this type of hernia， impaction is likely to occur．

Carefu1 observation is needed as Richter’s hernia is also frequently seen in cases of obturator hernia． Obturator hernia is diagnosed easily by CT scan， as the prolapsed intestine is often visible between the pectineal muscle and the external obturator muscle． When conducting CT scans for the diagnosis of this type of hernia， it is essential to take images down to the lower margin of the ischial bone to see the obturator canal．

Received May 24， 2007， Accepted June 25， 2007 Keywords： lnguinal hernia， Pelvic hernia， Computed tomography Corresponding author： Fumio KOTAKE， Department of Radiology， Tokyo Medical University， Kasumigaura Hospital 3－20－1 Ami－machi chuo， lnashikigun， lbaraki 300－0395， Japan Tel：029－887－1161（ext 7120） Fax：029－988－1512 E－mail：kotake＠tokyo－med．ac．jp

（1） 一 378 一 THE JOURNAL OF TOKYO MEDICAL UNIVERSITY Vol．65 No．4

Introduction

Hernia of the inguinal region is very frequent， i accounting for about 80－90％ of all abdominal hernias． It can be divided into indirect inguinal hernia， direct inguinal hernia and femoral hernia， all of which present A as bulges in the groin area． Preoperative diagnosis of this type of hernia is sometimes difllcult． A precise diagnostic imaging is essential for preoperative diagnosis of this condition． Pelvic hernia can be divided into obturator hernia， sciatic hernia and perineal hernia． Since pelvic hernia has no mass on external appearance， diagnostic imaging is an important means for its diagno－ sis． Plain abdominal X－ray， ultrasonography， hernio－ graphy， CT and magnetic resonance imaging （MRI） of Fig．1 Location of inguinal hernia and femoral hernia A： indirect inguinal hernia B： direct inguinal hernia these modalities， ultrasonography’） and herniography2）3） C： femoral hernia （cited from Reference 4）． have been repoited to be usefu1 for the diagnosis of this type of hernia． CT is superior to the other modalities because it allows simple and rapid examination and is usefu1 when checking the contents of hernia or its continuity to the intraperitoneal structures． For this reason， this study will outline representative types of hernia in the inguinal region and the pelvis， focusing on CT findings． 1． Anatomy of the inguinal region by imaging Figure 1 illustrates the anatomical relationship of the area affected by hernia in the inguinal resion‘）． The inguinal ligament is a part of the aponeurosis of the extemal abdominal oblique muscle； it is the thickened area spanning from the anterior superior iliac spine to the pubic tubercle． On CT scans， this ligament is depicted as a linear shadow in rich subcutaneous fat， while it is less clear in slim individuals（Fig．2a）． Also， in the latter cases， better images may be obtained by thin slice imaging． Recently， multidetector－row CT （MDCT） has often been used． With this technique， imaging is easier than before， since the required areas can be presented as thin slice images at the end of imaging （Fig． 2b）． lnguinal hernia， is a type of hemia in which ・llSi，Ni一“醗’ prolapse of the intraperitoneal organs， occurs into the inguinal region on the ventral side of the inguinal ．叉．糠麟怨，． ligament． lnguinal hernia can be divided into indirect G 嚇藁三．’ 鶴． inguinal hernia and direct inguinal hernia． The term ll；K “femoral hernia” is used to indicate the hernia character－ ized by prolapse of organs through the femoral canal on 癒 訓． 響ぜ貿翼 the dorsal side of the inguinal ligament． The inguinal canal is anteriorly surrounded by the transverse muscle of the and internal oblique

muscle and posteriorly surrounded by the inguinal liga－ Fig．2 The inguinal ligament（arrow）is not clear on the 10－mm ment． The spermatic cord passes through this canal in slice， but is clearer on the reconstructed 1－mm－thick males， while the round ligament of the passes lmage． a： 10－mm－thick slice CT image of the right inguinal through it in females5）． ln cases of indirect inguinal reglon hernia， prolapse of the intraperitoneal organs takes place b： Reconstructed 1－mm－thick CT image of the right via the inguinal canal in the inferomedial direction． inguinal region

（2） Oct．， 2007 F． KOTAKE， et al： Diagnostic imaging for inguinal and pelvic hernia 一 379 一

野 覧1∫ 課

饗．・ ．．・．・∫亀勢ll！ Iy．2，

Fig．3 The inferior epigastric artery （arrow） is clear on the arterial phase contrast－enhanced CT image． The course of the inferior epigastric artery is clear on the MIP coronal image． a： Transverse arterial phase contrast－enhanced CT image at the femoral head level b： Coronal image with MIP

with fat， and the obturator aiteiy and vein are visible within it （Fig． 4）． The term “obturator hernia” is used to indicate a type of hernia in which the obturator canal

serves as the hernia orifice． 2． 1ndirect i皿guinal hernia The term “indirect inguinal hernia” is used to indicate the type of hernia in which the intestine or other intraperitoneal organs show partial prolapse from the via the internal inguinal ring and the inguinal canal towards the external inguinal ring， scrotum， or large pudendal lip． This is the most fre－ quent type of hernia affecting the inguinal region． lt develops mostly during childhood， particularly during Fig．4 Contrast－enhanced CT at the level of pubic symphysis infancy and early childhood8）． This type of hernia The obturator artery and vein （arrow） are visible within the obturator canal． occurs more frequently i n males than in females， with the male／female ratio being 8：1． ln boys， this hernia often

With this type of hernia， the contents of the hernia and occurs on the right side． ln girls， the incidence of this hernia sac are located outside the inferior epigastric hernia does not differ between right and left sides． ln arteiy （a branch from the external iliac artery）． ln cases adults， this hernia often develops after age 50． of direct inguinal hernia， prolapse occurs directly inside On CT scans， the internal inguinal ring （located the inferior epigastric artery， without passing through the lateral to the rectus abdominis muscle） shows bulging on inguinal cana16）7）． Although identification of the infe－ the medial anterior part of the external iliac artery and rior epigastric artery is possible with contrast－enhanced vein （Fig． 5a）， accompanied by dilatation of the inguinal CT （Fig． 3a）， MDCT is more usefu1 for diagnosis of this canal（Fig．5b）． ln males， the diagnosis of this hernia is type of hernia since it can yield coronal images with easy if asymmetry relative to the contralateral inguinal multiplanar reconstruction （MPR） or maximum inten－ canal is checked． The prolapse into the scrotum can sity projection（MIP）（Fig．3b）． However， it is rare that also be visualized clearly （Fig．5c）． ln females， contrast－enhanced CT is performed for diagnosing identification of the round ligament of the uterus is hernia of the inguinal region． ldentification of the sometimes difficult， but the diagnosis of this hernia is inferior epigastric artery is often difficult by plain CT possible by checking its location and continuity to the scans alone． intestine within the peritoneal cavity9）． The contents of The obturator canal is a passageway through which the hernia and the hernia sac are often located l ateral to the obturator arteiy and the obturator nerve run． This the inferior epigastric artery． Distinction of undescend－ canal has a diameter less than 1 cm and a length between ed testis from this type of hernia is diMcult by diagnostic 1 and 2 cm． lf the medial anterior part of the hipbone imaging alone （Fig． 6）． However， medical history and is observed downwards on CT images， a pit leading to absence of testis in the scrotum on the affected side are the lateral side of the bone is visible． This pit is filled useful for differential diagnosis． The lack of continuity

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蓄 IY，1 蘇’ 、誕1醜・

蕊 ・Fl’懲

槻’ 轣D．

Fig．6 Undescended testis （81－year－old man） A mass is noted in the right inguinal canal （arrow）． lt can be distinguished from indirect inguinal hernia because the right testis is absent in the scrotum and that the mass is not contiguous to the intraperitoneal struc－

tures．

幾， ．曇藤 みきぐゆ レ1 i，ILti・il ，；i；

、鎌，．難1 ：’t’t；“ 錫 簿難 樋 懇 ・露盤 塁驚彦雛．．．

》鰭 Fig．5 lndirect inguinal hernia （64－year－old man）

1’／Tii－11kl，L，vii’li・ a： Plain CT at the femoral head level 婆 b： Plain CT at the level of the pubic symphysis c： Plain CT at the level of scrotum 残： Bulging ofthe internal inguinal ring （arrow） is visible on the lateral side of the right rectus abdominis muscle． The right inguinal canal is markedly dilated compared to the left counterpart（arrowhead）． Prolapse of the intes－ r鴇’ tine and fat tissue is visible from the inguinal canal into the scrotum．

to the intraperitoneal structures on CT images is also usefu1． Fig．7 Direct inguinal hernia （53－year－old man） 3． Direct inguinal hernia a： Contrast－enhanced CT at the femoral head level b： Contrast－enhanced CT （coronal image with MIP） In cases of direct inguinal hernia， intraperitoneal A mass is visible subcutaneously on the medial side of organs protrude from the medial inguinal fossa via the bilateral inguinal regions （arrowhead）． The mass is external inguinal ring into subcutaneous tissue， without located on the ventral side of the inguinal ligament and passing through the inguinal cana17）． The area affected on the medial side of the inferior epigastric artery by this type of hernia is called the “Hasselbach triangle，” （arrow）．

（4） Oct．， 2007 F． KOTAKE， et al： Diagnostic imaging for inguinal and pelvic hernia 一 381 一

where the inferior epigastric vessels serve as the super－ olateral border， the outer margin ofthe rectus abdominis muscle serves as the medial border， and the inguinal ligament serves as the lower border‘）． Direct inguinal hernia often occurs in elderly individuals with loose muscles． lt accounts for about 100／o of the inguinal hernias seen in adults． lt often develops in elderly males and is bilateral in many cases． lts symp－ toms are mild， and impaction is rare． On CT scans， a mass is visible in the subcutaneous tissue on the medial side of the inguinal region （ventral side of the inguinal ligament）（Fig．7a）． The contents of the hernia and the hernia sac are located at the medial side of the inferior epigastric artery （Fig． 7b）． 4． Femoral hernia In cases of femoral hernia， prolapse of intraperitoneal Fig．8 Femoral hernia （57－year－old woman） organs takes place along the medial side of the femoral A mass is visible in the right inguinal region （arrow－ vein， i．e．， from the femoral ring （dorsal to the inguinal head）． lt is located on the dorsal side of the inguinal ligament） via the femoral canal and saphenous opening ligament（arrow）． No sign of ileus is noted． Richter’s hernia is diagnosed at surgery． to subcutaneous tissue． ln patients with this type of hernia， the hernia sac is located in subcutaneous tissue on the upper anterior part of the thigh， making its distinction from direct inguinal hernia sometimes difllcult． Of all cases of femoral hernia， more than 80％ are middle－aged or elderly females． lt accounts for slightly more than 10％ of all hernias of the inguinal region． Because the hernia orifice is small and the 謬無、．、 、窪～灘隅隅読罵；， surrounding tissue is tough， impaction occurs at a high probability in cases of femoral herniaiO）． Richter’s 醗藻鰹， hernia， characterized by impaction due to strangulation ofthe intestinal wall on the non－attached side 1鶏瀦譲鷺・ alone is also seen frequently in cases of femoral hernia． 一．τ㌔．・7「磨9焦婆撃， Symptoms of ileus are sometimes minimal even when 願糖議■’ the intestinal wall has become necrotici’）． Careful observation is necessary as this can cause a delay in Fig．9 Femoral hernia （81－year－old woman） diagnosis． On CT scans， the hernia sac is located on A mass （arrowhead） is visible on the ventral side of the the dorsal side of the inguinal ligament， allowing this inguinal ligament of the right inguinal region （arrow）． type of hernia to be distinguished easily from direct The woman was initially suspected of having direct inguinal hernia． During surgery， however， she was inguinal hernia （Fig． 8）． However， if the femoral her－ found to have femoral hernia in which the hernia sac nia becomes large， it is sometimes seen that the hernia protruded below the inguinal ligament， its tip extending sac protrudes from below the inguinal ligament and its through subcutaneous tissue to appear on the ventral side tip extends upwards through subcutaneous tissue， pos－ of the inguinal ligament． sibly reaching the level above the inguinal ligament （Fig． 9）． ln such cases， distinction from direct inguinal the obturator foramen due to decrease in fat tissue hernia is diMcult． constituting the obturator canal’3）i‘）． Because the her－ 5． Obturator hernia nia orifice is sharp and tough， impaction is likely to In cases of obturator hernia， prolapse of the organs occur． Richter’s hernia is also seen in cases of obturator takes place via the obturator canal into the extrapelvic hernia， and only minimal signs of ileus are sometimes space． With this type of hernia， the small intestine most seen even in the presence of necrotic intestinal wall． frequently protrudes， followed by the colon， greater Detection of this hernia tends to be delayed because this omentum， ， uterus， etc．’2）． This type of hernia is area is covered by pectineal muscles and visual detection often seen in slim females， but its absolute incidence is is difllicult unlike with inguinal or femoral hernia． On Iow． A possible responsible factor for this hernia is plain abdominal X－ray， dilatation of the small intestine age－related loosening of pelvic muscles and dilatation of is often seen． The abnomal air is sometimes seen on the

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Conclusion

f． ，，kfl． The features on diagnostic imaging have been out－ ．麟． lined above for representative types of hernia of the ；・． u鱗 簿縣． inguinal and pelvic regions． CT is usefu1 as a means of differential diagnosis of hernia of the inguinal region． Clinical diagnosis of obturator hernia is difficult， but

．．．嚥・．鳥ピ ξ智． treatment is possible with removal of strangulation ・磯・．、・・， yノ 漏…’ ’ ． alone， without enterectomy， if the disease is diagnosed and treated at an early stage． However， the delay in diagnosis or treatment can lead to fatal outcome． ln this sense， CT can play a significant role in the diagnosis

of this type of hernia．

References 臨．

1） －臨1・ Rettenbacher T， Hollerweger A， Macheiner P， Gritz－ 蓬 mann N， Gotwald T， Frass R， Schneider B： Abdominal wall hernias：Cross－section imaging ・灘 signs of incarceration determined with sonography． Am J Roentogenol 177： 1061－1066， 2001 2） Ducharme JC， Bertrand R， Chacar R： Is it possible to diagnose inguinal hernia by X－ray？： a prelimi－ nary report on herniography． J Can Assoc Radio1 18： 448－451． 1967 ’ 3） Gullmo A： Herniography： the diagnosis of hernia in the groin and incompetence of the pouch of Douglas and ． Acta Radiol Suppl 361： 1－76， 1980 4） Matsuno S， Hatakeyama K， Kanematsu T： Com－ prehensive anatomy for gastroenterological surgery： esophagus， stomach， duodenum， abdominal wall and hernia （ln Japanese） 128－143 Medical view （Tokyo）， 1999

Fig． 10 Obturator hernia （89－year－old woman） 5） Van den Berg JC， Valois JC de， Go PMNYH， a： Plain abdominal X－ray in the standing position Rosenbusch G： Radiological anatomy of the groin b： Plain CT at the level of the pubic symphysis resion． Eur Radio 110： 661－670， 2000 On the plain abdominal X－ray， taken in the standing 6） Wechsler RJ， Kurtz AB， Needleman L， Dick BW， position， a niveau was noted in the small intestine， Feld RI， Hilpert PL， Blum L：Cross－sectional suggesting ileus． The abnormal air was detected on imaging of abdominal wall hernias． AJR 153： the medial side of the left ischial bone （arrowhead）． 517－521， 1989 On CT scans， a mass is visible between the pectineal 7） muscle and the external obturator muscle （arrow）． Zarvan NP， Lee FT， Yandow DR， Unger JS： Abdominal hernias：CT finding． AJR 164：1391L 1395， 1995 medial side of the ischial bone outside the pelvis with 8） Boocock GR， Todd PJ： lnguinal hernias are com－ carefu1 observation （Fig． 10a）， which is usefu1 for diag－ mon in preterm infants． Arch Dis child 60： 669－ nosis． CT－based diagnosis of obturator hernia was first 670， 1985 reported in 1983 by Meziane et al．i5）． On CT scans， the 9） Araki T： CT of acute abdomen． （ln Japanese） 2－18 prolapsed intestine is often detected between the Medical sciences international （Tokyo）， 2002 pectineal muscle and the external obturator muscle， 10） Fujii M， lwama Y， Kaji Y， Tomita M， Kuwata Y， allowing easy diagnosis （Fig．10b）i6）i7）． CT is very Kanegawa K， Hase M， Sugimura K： Diagnostic usefu1 and its diagnostic value is high． However， CT－ imaging of inguinal and pelvic hernia． （ln Japanese based diagnosis is possible only when imaging covers the with English abstract） Jpn J Clin Radiol 48： 729－ level of the obturator canal． For this reason， it is 739， 2003 essential to take images down to the lower margin of the 11） Kadirov S， Sayfan J， Orda R： Partial enterocele ischial bone when conducting CT scans for patients with （Richter’s hernia）． Eur J Surg 161： 383－385， 1995 ileus． 12） Gray SW， Skandalakis JE， Soria RE， Rowe JS：

（6） Oct．， 2007 F． KOTAKE， et al： Diagnostic imaging for inguinal and pelvic hernia 一 383 一

Strangulated obturator hernia． Surgery 75： 20－27， amen hernia． Gastrointerst Radiol 8：375－377， 1974 1983 13） Yip AWC， Ahchong AK， Lam KH：Obturator 16） Nishina M， Fujii C， Ogino R， Kobayashi R， Ko－ hernia：acontinuing diagnostic challenge． Surgery hama A： Preoperative diagnosis of obturator hernia 113： 266－269， 1993 by computed tomography in six patients． J Emerg 14） ljiri R， Kanamaru H， Yokoyama H， Shirakawa M， Med 20： 277－280， 2001 Hashimoto H， Yoshino G： Obturator hernia： the 17） Terada R， lto S， Kidogawa H， Kashima K， Ooe H： usefulness of computed tomography in diagnosis． Obturator hernia：the usefulness of emergent Surgery 119： 137－140， 1996 computed tomography for early diagnosis． J Einerg 15） Meziane MA， Fishman EK， Siegelman SS： Med 17： 883－886， 1999 Computed tomographic diagnosis of obturator for一

鼠径部・骨盤部ヘルニアの画像診断

小 竹 文 雄1） 渡辺善徳2） 西村 基2） 森 本 恵爾1） 小槻泰三1） 1）東京医科大学霞ヶ浦病院放射線科 2）東京医科大学霞ヶ浦病院第四外科

【要旨】鼠径部のヘルニアは非常に頻度の高い疾患で腹部ヘルニアの約80～90％を占める。鼠径靱帯の腹側で鼠径部に脱 出するヘルニアが鼠径ヘルニアで間接鼠径ヘルニアと直接鼠径ヘルニアとがある。鼠径管を通って腹腔内臓器が脱出する のが間接鼠径ヘルニアでヘルニア嚢が下腹壁動脈の外側にみられる。鼠径部ヘルニアの中で最も多く、乳幼児の男児と50 歳以降の男性に好発する。CTでは鼠径管内や陰嚢内への腹腔内臓器の脱出が認められれば診断は容易である。一方、下 腹壁動脈の内側から鼠径管を通らずに直接脱出するのが直接鼠径ヘルニアである。高齢男性に多いが、自覚症状は軽度で 嵌頓することはまれである。下腹壁動脈の同定は造影CTを施行すれば可能であるが、多列検出器型CT（MDCT）で撮影 すれば多断面再構成法（MPR）により冠状自身も可能となり診断に有用となる。 鼠径靱帯の背側で大腿管を通って脱出するヘルニアを大腿ヘルニアといい、鼠径部に腫瘤を形成する。中年以降の女性 に多く、嵌頓する確率が高い。Richter’s herniaも多く、腸管壁が壊死していてもイレウス症状が軽微なこともあり注意が 必要である。CTでは鼠径靭帯の背側にヘルニア嚢が認められ、直接鼠径ヘルニアと鑑別が可能となる。 骨盤部ヘルニアである閉鎖孔ヘルニアは外見上では腫瘤を認めないため、画像診断が重要となる。高齢でやせた女性に 多いが、ヘルニア門が鋭利で強固なため嵌頓を来しやすい。また、Richter’s herniaも多く認められ、注意が必要である。 CTでは恥骨筋と外閉鎖筋の間に脱出した腸管が認められることが多く診断は容易であるが、閉鎖管レベルまで撮像され ないと診断できないため、坐骨下縁まで撮像することが肝要である。

〈キーワード〉鼠径部ヘルニア、骨盤部ヘルニア、CT

（7）