Characteristic Locations of Inguinal Region and Anterior Abdominal Wall Hernias: Sonographic Appearances and Identification of Clinical Pitfalls

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1 Sonography of Inguinal Region and bdominal Wall Hernias Gastrointestinal Imaging Pictorial Essay David. Jamadar 1 Jon. Jacobson 1 Yoav Morag 1 Gandikota Girish 1 Qian Dong 1 Mahmoud l-hawary 1 Michael G. Franz 2 Jamadar D, Jacobson J, Morag Y, et al. Keywords: gastrointestinal radiology, hernia, sonography DOI: /JR Received May 26, 2006; accepted after revision September 12, Department of Radiology, TC2910, University of Michigan Hospitals, 1500 E Medical Center Dr., nn rbor, MI ddress correspondence to D.. Jamadar. 2 Department of General Surgery, University of Michigan Hospitals, nn rbor, MI JR 2007; 188: X/07/ merican Roentgen Ray Society Characteristic Locations of Inguinal Region and nterior bdominal Wall Hernias: Sonographic ppearances and Identification of Clinical Pitfalls OJECTIVE. The purpose of this article is to show the typical locations of anterior abdominal wall and inguinal region hernias and to illustrate their sonographic appearances and describe pitfalls in clinical diagnosis of hernias that may be resolved with sonography. CONCLUSION. wareness of the expected locations of anterior abdominal wall hernias and potential clinical pitfalls allows an accurate diagnosis of a hernia and helps in differentiating a hernia from other abnormalities. here are a variety of hernias that T may occur through the anterior abdominal wall. These include inguinal hernias (which may be femoral, direct inguinal, or indirect inguinal), spigelian hernias, umbilical and paraumbilical hernias, and epigastric hernias. Incisional hernias may occur after incisions through the anterior abdominal wall. On clinical examination, it may be difficult to diagnose a hernia with certainty. In addition, when a diagnosis of hernia is made, it may be difficult to differentiate between two hernias that occur close together anatomically [1]. Occasionally, a patient who presents clinically with a diagnosis of a hernia may be found to have another cause for the symptoms. Sonography may be useful not only in providing the diagnosis but also in identifying the variety of hernia and providing additional information such as the contents of the hernia and the extent of reducibility of the hernia contents. These observations may affect surgical decision making and reconstruction. We describe the use of sonography in evaluation for anterior abdominal wall hernias and the expected location of these hernias. We show a spectrum of abnormalities that may simulate a hernia on clinical examination. Technical Considerations ecause abnormality is confined to the anterior abdominal wall, using a high-frequency linear transducer is optimal, at least a 7-MHz transducer. Knowledge of the surface anatomy of the expected location of the common anterior abdominal wall hernias is important (Fig. 1) because such knowledge provides an anatomic framework around which to work. The patient is initially scanned in the supine position and then examined in the upright position. Upright scanning is particularly important for evaluation of a femoral hernia. The examination of the inguinal region has been described in the literature [2]. The inferior epigastric artery is identified where it passes under the lateral border of the rectus abdominis muscle. From there it can be followed inferiorly to its origin from the external iliac artery (EI), which is just cranial to where the inguinal ligament crosses the EI. The inguinal ligament and the EI are two anatomic structures that allow differentiation between a direct inguinal, indirect inguinal, and femoral hernia. The deep inguinal ring lies lateral to the origin of the inferior epigastric artery above the inguinal ligament, whereas the neck of a femoral hernia lies below the inguinal ligament and usually medial to the femoral vein. The anterior abdominal wall can be incrementally scanned from the epigastrium to the pubic symphysis. The Valsalva maneuver should be liberally used. hernia may sometimes be better appreciated during relaxation immediately after a Valsalva maneuver, when the hernia contents may be seen to return to their pre-valsalva location, rather than during the Valsalva maneuver itself. Scanning patients in the supine and in an upright position or during a particular maneuver that patients associate with their hernias may facilitate detection. Evaluation for an incisional hernia may be challenging because the incision and the tis JR:188, May 2007

2 Sonography of Inguinal Region and bdominal Wall Hernias sue distortion by the application of sutures in closing the incision may result in asymmetry and abnormal movement during a Valsalva maneuver. Typically, the visible skin incision is an indication of the approximate incision through the deeper tissues, but this is not always the case [3] (Fig. 2). The skin incision may be shorter than the peritoneal incision, necessitating routine sonographic evaluation beyond the limits of the visible skin scar (Fig. 2). Incisional hernias may also occur lateral to the surgical scar where the suture passed through the muscle and fascia (Fig. 2). Last, an incision near an anatomic location where a hernia may occur necessitates differentiation from an incisional hernia. This may occur, for example, with an appendectomy scar and an inguinal hernia (Fig. 3). nterior bdominal Wall Hernias bdominal wall hernias are diagnosed on sonography by visualizing abdominal contents moving either through an abdominal wall defect or bulging due to abnormal thinning of the anterior abdominal wall. The abdominal contents may appear echogenic due to fatty tissue or bowel. The presence of peristalsis indicates the latter. Fluid and gas may also be seen in the bowel lumen, and fluid may be seen in the hernial sac and surrounding the herniated contents. The Valsalva maneuver and often upright positioning are usually required to detect a hernia. Inguinal hernias include the indirect inguinal hernia, in which the origin is lateral to the inferior epigastric artery and superior to the inguinal ligament (Fig. 4); the direct inguinal hernia, which is located medial to the inferior epigastric artery and superior to the inguinal ligament (Fig. 5); and the femoral hernia, located inferior in relation to the inguinal ligament and usually medial to the femoral vein (Fig. 6). The uncommon spigelian hernia occurs along the linea semilunaris (the lateral border of the rectus abdominis) just superior to the inferior epigastric artery where this artery passes under the lateral border of the rectus abdominis muscle (Fig. 7). Epigastric hernias occur anywhere between the xiphoid process and the umbilicus and initially consist of extraperitoneal fat that has protruded through the linea alba (Fig. 8). n umbilical hernia usually occurs in children through a weak umbilical scar (Fig. 9), whereas a paraumbilical hernia occurs through the linea alba just above the umbilicus (Fig. 10) or, less commonly, just below the umbilicus. Divarication (or separation) of the rectus abdominis muscles (Fig. 11) occurs along the linea alba and is due to stretching and thinning of the linea alba along its length. This may be seen in elderly multiparous women. The Valsalva maneuver results in separation of the right and left rectus abdominis muscles and bulging of the attenuated linea alba. The incisional hernia presents different diagnostic problems depending on the anatomy of the incision and the specific layer of abdominal wall closure that has failed (Fig. 12). n understanding of the specific incision and careful evaluation with the Valsalva maneuver are essential to detect these hernias. In general, complications of hernias include an irreducible hernia, an obstructed hernia, and a strangulated hernia. n irreducible hernia is one in which the contents cannot be reduced in the absence of any other complication. n obstructed hernia is one in which a loop of viable bowel within the hernia becomes obstructed. strangulated hernia is one in which there is vascular compromise to the bowel within a hernia. Clinical Pitfalls in Hernia Evaluation Sonography can be useful to rule out hernia in situations in which this disease is erroneously suspected by the clinician. trophy of the anterior abdominal wall muscles, as may occur after a surgical incision or after transverse rectus abdominis myocutaneous flap surgery, with displacement of the muscles may allow an intraabdominal viscus to be more easily palpable and present clinically as a possible hernia (Fig. 13). Focal spasm in an abdominal wall muscle may present as a painful transient mass (Fig. 14), whereas an incised abdominal wall muscle that has not healed completely may present as a focal bulge after abdominal wall contraction during the Valsalva maneuver (Fig. 15). normal structure may be noticed for the first time and present as a mass (Fig. 16). The xiphoid process may become noticeable after weight loss and present as an epigastric mass. In this anatomic location, an epigastric hernia may be simulated. Enlarged lymph nodes are often found in the inguinal region. lthough normal inguinal lymph nodes may have a short-axis diameter that measures up to 1.5 cm [4, 5], malignancy may be present even if the node is not enlarged. Even nodes thought to be normal in size may raise concern for an inguinal hernia (Fig. 17). saphenous varix (Fig. 18) is a specific diagnosis that can be confused clinically with a femoral hernia, particularly if it is thrombosed [6]. This focal dilatation of the saphenous vein proximal to its passage through the cribriform fascia in the groin may be differentiated from a femoral hernia on sonography [7]. hematoma (Fig. 19) or a focal fluid collection (Fig. 20) may present deep in relation to an incision as a mass. These can be differentiated from an incisional hernia by their location within the abdominal wall and the absence of movement during a Valsalva maneuver. n endometrioma (Fig. 21) after surgery due to endometrial seeding of the surgical incision has been well described [8] and may present as a mass. This is also differentiated from an incisional hernia with sonography by its location within the abdominal wall, indistinct margins, and absence of movement during a Valsalva maneuver. Conclusion Knowledge of the variety of anterior abdominal wall hernias and their typical locations and an understanding of the anatomy of surgical scars are essential to identify anterior abdominal wall and inguinal hernias. wareness of the processes that simulate hernias clinically can aid in providing an accurate diagnosis. References 1. radley M, Morgan D, Pentlow, Roe. The groin hernia: an ultrasound diagnosis? nn R Coll Surg Engl 2003; 85: Jamadar D, Jacobson J, Morag Y, et al. Sonography of inguinal region hernias. JR 2006; 187: Kisielinski K, Conze J, Murken H, Lenzen NN, Klinge U, Schumpelick V. The Pfannenstiel or socalled bikini cut : still effective more than 100 years after first description. Hernia 2004; 8: bang Mohammed DK, Uberoi R, de Lopes, Monaghan JM. Inguinal node status by ultrasound in vulva cancer. Gynecol Oncol 2000; 77: Grey C, Carrington M, Hulse P, Swindell R, Yates W. Magnetic resonance appearance of normal inguinal nodes. Clin Radiol 2000; 55: Patel K, Thwaini H, Cooper JC, Spooner SF. Thrombosed sapheno-varix presenting as an incarcerated femoral hernia in a postpartum woman. J Obstet Gynaecol 2003; 23: Wales LR, zose. Saphenous varix: ultrasonic diagnosis. J Ultrasound Med 1985; 4: Kocakusak, rpinar E, rikan S, Demirbag N, Tarlaci, Kabaca C. bdominal wall endometriosis: a diagnostic dilemma for surgeons. Med Princ Pract 2005; 14: JR:188, May

3 Fig. 1 Illustration of anterior abdominal wall shows usual anatomic location of various anterior abdominal wall hernias. Red line in right lower quadrant indicates inferior epigastric artery. E = epigastric hernia; P = periumbilical hernia; U = umbilical hernia; Div = infraumbilical divarication of the rectus abdominis muscles, which may be seen along entire extent of linea alba; S = spigelian hernia; I = indirect inguinal hernia; D = direct inguinal hernia; F = femoral hernia. Fig year-old man with clinically diagnosed right groin hernia. Sonography cranial and parallel to inguinal ligament revealed indirect inguinal hernia adjacent to appendectomy scar (not shown). Preoperative diagnosis modified surgical approach. Sonogram after Valsalva maneuver shows hernia (H) and inferior epigastric artery (arrow). Right side of image is medial side of structures on sonogram. Fig. 2 Illustration of anterior abdominal wall shows three surgical incisions, two in which skin incision may not accurately reflect incision through deeper tissues. Lower abdominal Pfannenstiel incision (bikini cut) is curvilinear cutaneous and subcutaneous incision (), but vertical component of incision is between rectus abdominis muscles, with potential for incisional hernia (vertical rectangle). Subcostal skin incision () is often shorter than deeper incision with extension along line of incision both medially and laterally. There is potential for hernia (ovals). Third, midline vertical incision (C) shows suture perforations (circles) on either side, a site for incisional hernias (curved arrow). Fig year-old woman with right indirect inguinal hernia. In sonogram with scanning cranial and parallel to inguinal ligament, inferior epigastric artery (curved arrow) marks medial boundary of deep inguinal ring and neck of this hernia (H). Lateral boundary (straight arrow) is less clearly seen. Right side of image is medial side of structures on sonogram JR:188, May 2007

4 Sonography of Inguinal Region and bdominal Wall Hernias Fig year-old man with new inguinal and suprapubic fullness and direct inguinal hernia., Pre-Valsalva maneuver transverse oblique sonogram shows external iliac artery (), inferior epigastric artery (curved arrow), superior pubic ramus (arrowheads), and echogenic superficial boundary of hernia (straight arrows) not clearly demarcated. V = femoral vein., Post-Valsalva maneuver transverse oblique sonogram shows echogenic boundary of hernia (straight arrows), which originates medial to inferior epigastric artery (curved arrow). = external iliac artery. Fig year-old man with right femoral hernia. Sonogram caudad and parallel to inguinal ligament shows femoral vein (arrows) distorted and displaced ventrally by retrovascular femoral hernia (H). Femoral artery () is lateral in relation to hernia. Fig year-old woman with left spigelian hernia. Transverse sonogram along linea semilunaris shows lateral border of rectus abdominis (R) and flank muscles (F) and between them, bowel () and extraperitoneal fat (EF) of hernia. JR:188, May

5 Fig year-old woman with epigastric hernia. Longitudinal sonogram along linea alba shows defect (arrows) in linea alba through which extraperitoneal fat herniates. Hernia (H) shows no movement during Valsalva maneuver, which is not unusual for these hernias when small. Fig. 9 4-month-old boy with umbilical hernia. Transverse sonogram at umbilicus shows both medial margins of rectus abdominis muscles (R), between which is umbilical hernia (H). Fig year-old man with supraumbilical fullness and paraumbilical hernia. Transverse sonogram shows defect in linea alba through which extraperitoneal fat herniates (arrows). Rectus abdominis muscles (R) can be seen on either side of defect JR:188, May 2007

6 Sonography of Inguinal Region and bdominal Wall Hernias Fig year-old woman with infraumbilical divarication of rectus abdominis., Pre-Valsalva maneuver transverse sonogram shows both rectus abdominus muscles (R) closely approximated to midline. rrowheads show medial extent of rectus abdominis muscles., Post-Valsalva maneuver transverse sonogram shows separation of rectus abdominis muscles (R). rrowheads show medial extent of rectus abdominis muscles. Fig year-old woman with right upper quadrant discomfort medial to cholecystectomy incision with incisional hernia (corresponds to medial right upper quadrant incisional hernia illustrated in Fig. 2). Transverse oblique sonogram shows extraperitoneal fat (F) and hernia (H) between posterior rectus abdominis (R) and adjacent fascia defect (arrows). This unusual hernia was not appreciated at laparoscopy, and repeat open surgery was performed to repair hernia, with resolution of symptoms. JR:188, May

7 Fig year-old woman with complicated bilateral transverse rectus abdominis myocutaneous flap surgeries and absence of both rectus abdominis muscles who presented with palpable left upper quadrant mass for exclusion of incarcerated hernia. Sonograms show palpable abnormality secondary to abdominal wall atrophy. No hernia is seen., Oblique sonogram shows spleen (S), which is palpable and simulates mass. K = kidney., Very thin anterior abdominal wall is better appreciated by close proximity of underlying bowel (). Note centimeter scale to right of image. Fig year-old woman with history of transient painful swelling in right epigastrium and muscle bulge from focal spasm., Pre-Valsalva maneuver longitudinal sonogram shows right proximal rectus abdominis muscle (arrows) directly under focal discomfort., Post-Valsalva maneuver longitudinal sonogram in same location as shows right proximal rectus abdominis muscle bulging focally (arrows), clinically simulating hernia JR:188, May 2007

8 Sonography of Inguinal Region and bdominal Wall Hernias Fig year-old man with focal discomfort and bulge adjacent to right paramedian appendectomy scar, presumed secondary to postsurgical tissue scarring., Longitudinal sonogram over right rectus abdominis muscle (M) shows focal hyperechoic scar (S) at location of patient discomfort., Transverse sonogram shows rectus abdominis muscle (M) and focal hyperechoic scar (S). Fig year-old man with prominent xiphoid process. Sagittal midline epigastric sonogram shows hypoechoic cartilaginous xiphoid process (X), which has ventral curve. Tip (arrow) is closest to overlying skin and under palpable abnormality. Fig year-old woman with right inguinal lymph nodes. Sonogram caudad and parallel to inguinal ligament shows lymph node (arrows), with fatty hilum (Hi) medial to femoral artery () and femoral vein (V). JR:188, May

9 Fig year-old woman with left saphenous varix. Sonogram over proximal long saphenous vein shows focal variceal dilation (V) along proximal long saphenous vein (VV) just before it traverses cribriform fascia to anastomose with femoral vein (F). Fig year-old woman with wound abscess. Longitudinal sonogram shows tubular structure with hypoechoic contents () with thick and irregular walls (curved arrows) of wound abscess. Wavy echogenic structure (straight arrows) deep in relation to abscess is abdominal wall mesh from prior midline vertical incisional hernia repair. Fig year-old woman with right groin hematoma. Transverse sonogram shows heterogeneous, predominantly hypoechoic mass (Hem) in superficial tissues. Fig year-old woman after caesarian section with subcutaneous endometrioma. Longitudinal sonogram over scar shows ill-defined heterogeneous mass with indistinct margins and minimal vascularity of endometrioma (E) superficial to rectus abdominis muscle (R) JR:188, May 2007