The rectus abdominis is enclosed in a sheath formed by the aponeurosis of the internal and external obliques and transversus abdominis. The posterior sheath ends at a point midway between the umbilicus and pubic symphysis at the linea semicircularis or arcuate line (Fig. 5-3). Superior to the arcuate line, the internal oblique aponeurosis divides at the lateral margin of the rectus into two lamellae: one passing anterior to the rectus and blending with the aponeurosis of the external obliques to become the anterior rectus sheath and the other passing posterior to the rectus and blending with the aponeurosis of the transversus abdominis (known as the inguinal falx or the conjoint tendon) to form the posterior sheath (Fig. 5-4, A).17 Inferior to the arcuate line, the aponeurosis of all three muscles passes anterior to the rectus (Fig. 5-4, B), and thus the posterior border of the recti is separated from the peritoneum only by the transversalis fascia.17 The drawing by Netter20 of the internal view of the anterior abdominal wall shows how, when the transversalis fascia is cut, the posterior aspect of the rectus abdominis is directly exposed inferior to the arcuate line (Fig. 5-5). At the medial border of the rectus, the anterior and posterior rectus sheaths merge again at the linea alba.17
The obliquus externus abdominis, more commonly referred to as the external oblique, is the largest and most superficial of the abdominal muscles; its muscular portion occupies the anterior lateral abdomen, and its aponeurosis occupies the anterior abdominal wall (Fig. 5-6).17 It originates with eight fleshy digitations from the external surfaces and inferior borders of ribs 5 to 12, as well as the adjacent serratus anterior and latissimus dorsi muscles. Fibers from the lower ribs pass inferiorly in a nearly vertical fashion to insert onto the anterior half of the outer lip of the iliac crest, whereas fibers from the middle and upper fibers are directed inferior and medial to become an aponeurosis.17 The external oblique aponeurosis blends with the contralateral aponeurosis, covering the entire anterior abdomen. Superiorly, the fibers of the external oblique muscle communicate with the pectoralis major. In the middle, its fibers interlace with the contralateral obliques to form the linea alba. The inferior fibers attach to the pubic tubercle and pectineal line (Fig. 5-7).17
Acting bilaterally, the external oblique muscle flexes the trunk and posteriorly tilts the pelvis (Fig. 5-8). When it acts unilaterally, or if one side is stiffer than the other, lateral flexion and contralateral rotation of the trunk result.21–26
The inguinal (Poupart) ligament is the portion of the external oblique aponeurosis extending between the anterior superior iliac spine (ASIS) and the pubic tubercle, and it is a thick band that folds inward (Fig. 5-9).17 The lacunar (Gimbernat) ligament (see Fig. 5-9) is a distal portion of the external oblique aponeurosis that is reflected from its pubic tubercle attachment to connect to the pectineal line. The lacunar ligament is approximately 1.25 cm long—larger in males than in females—and it has an almost horizontal orientation in an erect posture. The lacunar ligament is triangular, with its apex at the pubic tubercle, its posterior margin attaching to the pectineal line, and its anterior margin attaching to the inguinal ligament. The lacunar ligament forms the medial boundary of the femoral ring (discussed later in this chapter).17
The pectineal (Cooper) ligament is another fibrous extension from the lacunar ligament (see Fig. 5-9) that extends laterally from the base of the lacunar ligament to attach along the pectineal line. The pectineal ligament helps to reinforce the pectineal fascia, as well as the linea alba.17
From its pectineal line attachment, a few fibers from the external oblique aponeurosis pass superiorly and medially, behind the medial crus of the subcutaneous inguinal ring, to form a thin triangular fibrous band called the reflected inguinal ligament (triangular fascia) (see Fig. 5-7).17 The reflected inguinal ligament blends with the lacunar ligament and the medial inferior crus of the subcutaneous inguinal ring to help reinforce the subcutaneous inguinal ring. The reflected inguinal ligament also blends with the contralateral reflected inguinal ligament to reinforce the distal linea alba,17 and it is discussed later in this chapter.
The obliquus internus abdominis muscle, also known as the internal oblique, is deep to the external oblique and forms the second abdominal layer (Fig. 5-10). Its fibers originate from the lateral half of the inguinal ligament, from the anterior two thirds of the middle lip of the iliac crest, and from the posterior lamella of the lumbodorsal fascia.17 The portion of the internal oblique that originates most posteriorly passes almost vertically and superiorly to insert onto the cartilages of the tenth, eleventh, and twelfth ribs to become continuous with the internal intercostal muscle. Internal oblique fibers originating from the middle third of the iliac crest run obliquely superiorly and medially. They culminate in an aponeurosis that divides at the lateral border of the rectus to become the anterior and posterior lamellae that envelop the rectus. Internal oblique fibers originating from the anterior third of the iliac crest run horizontally, become tendinous, and pass in front to the rectus abdominis to insert into the linea alba.17 The internal oblique fibers originating from the inguinal ligament arch inferiorly and medially across the spermatic cord in the male and the round ligament in the female. These fibers become tendinous, join with the transversus abdominis to form the inguinal aponeurotic falx (conjoint tendon), and insert onto the pubic crest and medial aspect of the pectineal line behind the lacunar ligament immediately behind the subcutaneous inguinal ring (Figs. 5-11 and 5-12).17
Acting bilaterally, the internal oblique flexes the trunk and posteriorly tilts the pelvis (Fig. 5-13). However, unilateral contraction or stiffness leads to lateral flexion and ipsilateral trunk rotation.21–26
The internal and external oblique muscles are effective axial rotators of the trunk, with the external oblique being a contralateral rotator and the internal oblique an ipsilateral rotator. During active axial rotation in one direction, the external oblique on the contralateral side works synergistically with the internal oblique on the ipsilateral side to produce a diagonal line of force through the muscles’ midline through their attachment on the linea alba.21,25,27–29
The deepest abdominal layer is the transversus abdominis, named accordingly because of the nearly horizontal orientation of its fibers (Fig. 5-14). It arises from the lateral third of the inguinal ligament, the anterior three fourths of the inner lip of the iliac crest, the inner surfaces of the cartilages of ribs 6 to 12, fibers from the diaphragm, and the lumbodorsal fascia. The lower fibers curve inferiorly and medially to converge with the internal oblique to form the conjoint tendon and insert onto the crest of the pubis and pectineal line (see Figs. 5-11 and 5-12). The rest of the muscle inserts into the linea alba—the upper three fourths passes behind the rectus to blend with the posterior lamella of the internal oblique aponeurosis, and the lower one fourth passes anterior to the rectus.17
The nearly horizontal orientation of the transversus abdominis makes it ideal for compressing the abdomen and stabilizing the lumbopelvic region through its attachments on the thoracolumbar fascia, where it works to limit intersegmental lumbar spine motion.22,30,31 Studies have found that the transversus abdominis contracts milliseconds before the lower extremity musculature before foot strike during running and before upper extremity elevation or throwing motions.32 Several fine-wire electromyography (EMG) studies have found bilateral activation of the transversus abdominis during axial rotation, and thus this muscle appears to function more as a stabilizer for the obliques than as a torque generator by stabilizing the ribs, linea alba, and thoracolumbar fascia.25,33,34
A few additional muscles are present in the abdominal region. The pyramidalis is a small triangular muscle located in the inferior abdomen anterior to the rectus abdominis and enclosed in the same sheath (see Fig. 5-2). It originates at the anterior pubis and anterior pubic ligament (see Fig. 5-1), and it passes superiorly, where it diminishes in size and eventually inserts into the linea alba midway between the umbilicus and the pubis (see Fig. 5-2). The pyramidalis functions to tense the linea alba.17
The cremaster is a thin muscle consisting of fasciculi originating from the middle of the inguinal ligament, where its fibers are continuous with the internal oblique and sometimes the transversus (see Fig. 5-2).17 It passes along the lateral aspect of the spermatic cord and descends with it through the subcutaneous inguinal ring to form a series of loops that unite to form the cremasteric fascia covering the spermatic cord and testis (Fig. 5-15). The fibers then ascend along the medial side of the spermatic cord to insert on to the pubic tubercle and crest and onto the front of the sheath of the rectus abdominis.17
Incidence
Although athletic communities anecdotally purport that abdominal injuries are fairly common, few epidemiologic studies support their incidence.19,22,35 Abdominal injuries have been documented primarily through published case studies in throwing and racquet sports including baseball, tennis, handball, and cricket, as well as in soccer.14,18,19,36–39
A 19-year retrospective review of the Major League Baseball disabled list35 reported that abdominal muscle strains constituted 5% of all baseball injuries, with 92% of these injuries specially classified as internal or external oblique or intercostal strains, 1% classified as rectus abdominis strains, and 7% classified as general “abdominal muscle strains.” In addition, 44% of abdominal strains occurred in pitchers and 56% in position players, and although an upward trend of more abdominal strains within this 20-year period was noted, the injury rate remained fairly constant in the past decade.35 A prospective study of English professional soccer teams40 reported that torso injuries constituted 7% of all injuries, and a study of youth soccer players found that abdominal injuries constituted 1% of all injuries.41
Presentation of Abdominal Strain
Internal oblique abdominal strains, also referred to as side strains, typically manifest with sudden, sharp onset of anterolateral pain along the anterolateral inferior border of one or more of ribs 9 to 12, with localized tenderness and pain on muscular contraction or passive stretching that may arise during deep inspiration.36,37,39 The pain typically manifests after or during throwing, swinging, or twisting movements, and it often results in forced withdrawal from athletic competition.14,36,37,39,42,43 The injury site and pain are typically on the contralateral side of the dominant arm,18,19,35,36 and the pain often appears when the athlete is asked to perform resisted ipsilateral side flexion to the painful side when starting from either contralateral side flexion or neutral.36 Only one case of an external oblique strain in a professional soccer player has been documented, and the injury manifested in a manner very similar to that of the internal oblique strain as discussed.14
Strains of the internal oblique often involve the anterolateral fibers where the muscle inserts into the eleventh rib.36,39,44,45 These muscle fibers are primarily responsible for lateral trunk flexion, and the tearing is thought to occur during the late cocking and early acceleration stages of throwing, when the nondominant arm is torqued backward from a hyperextended position to allow the dominant arm to follow through and release the ball.37 EMG studies have found that muscle activity in the contralateral obliques and transversus abdominis increases 75% to 100% during the acceleration phase of throwing, ball release, and follow-through.46
Rectus abdominis strains typically manifest with anterior abdominal wall pain below the umbilicus.18,19,22 Edema may be present, along with point tenderness distal to the umbilicus and muscle guarding. Passive trunk flexion often relieves or decreases acute pain, whereas active contraction with resisted trunk or hip flexion or passive trunk extension exacerbates symptoms.22,47 Abdominal pain that is constant or increased with isometric abdominal contraction is termed the Carnett sign and is used in the differential diagnosis to distinguish abdominal muscular disorders from intraabdominal injury.48 Thomson and Francis48 reported that a positive Carnett sign corresponded to normal laparotomy findings, thus ruling out intraabdominal disorders, in 23 of 24 emergency department admissions of patients with acute abdominal pain. Abdominal wall injuries caused by direct trauma may result in muscular hematoma and complaints of abdominal pain accompanied by nausea and vomiting. Rectus sheath hematomas often manifest with a bluish discoloration in the periumbilical region, known as the Cullen sign, approximately 72 hours after the injury.22,47
Imaging
Although abdominal strains can be diagnosed by clinical sign and symptom presentation, imaging can help determine the exact site, status, and severity of the injury.39 Increased use of magnetic resonance imaging (MRI) has led to specific documentation of abdominal injuries, especially in professional athletes.18,35 MRI can be used to identify the anatomic site of injury accurately, as well as to rule out additional lesions such as osteochondral injuries.37
Diagnostic ultrasound examination is typically easily accessible and less costly than MRI, and it appears to be a sensitive and valuable tool for detecting abdominal strains.18,39,45 A case series report using ultrasound to diagnose rectus sheath hematomas found sensitivities ranging from 100% to 30%.49 This wide variation of false-negative results from 0% to 70% suggests that the examination depends on the operator’s expertise. A positive ultrasound result is characterized by disruption of the normal echogenic fibrillar pattern or muscle fibril disruption, edema, and hemorrhage 10 to 28 mm below the umbilicus.18,19,45
Etiology
Abdominal wall injuries can occur as a result of direct trauma,22,47 during an abrupt movement of the torso such as during throwing, spiking, or serving, or they can be caused by repetitive trunk rotation in sports such as golf or racquet sports.22 The most common mechanism of injury is sporting activity in which trunk rotation is critical for generating power. The abdominal muscles are integral for transferring forces from the lower extremities to the upper extremity during throwing or racquet sports, and they work eccentrically to decelerate the trunk.35,37,45,46,50–53 EMG analysis of professional baseball players documented that batting and pitching activities require the abdominal muscles not only to function to stabilize the trunk, but also to create axial torque.46,53 These high-demand, volitional movements require an intricate balance of muscle concentric and eccentric activity. Thus, any asymmetry of muscular strength or length can significantly affect other muscles, and injuries are often the result of excessive, unbalanced eccentric muscle contraction. Investigators have suggested that after a muscular strain, the muscle is weaker and thus at increased risk for further injury compared with normal muscle.15 Evidence does suggest that recurrence of abdominal muscle strain is common.36
Treatment
Treatment of abdominal muscle strains can be divided into phases according to injury presentation. During the acute inflammatory phase (typically from injury to 72 hours), rehabilitation often includes rest, ice, electrotherapy, and antiinflammatory medication.19,36 Patients may also obtain relief with either a compression support device or taping (Fig. 5-16). Athletes are progressed according to symptom presentation, with special attention paid to the absence of pain reported with activities. After approximately day 4, athletes can start gentle isometric abdominal contraction as long as no pain is reported with muscular activity, and modalities such as electrotherapy and ice are continued. When no signs of edema or inflammation are noted, soft tissue massage can be incorporated, especially in areas surrounding the focal injury site.
When pain with active contraction and daily activities is no longer present, patients can begin gentle concentric strengthening exercises, light stretching, and conditioning, with the focus on correcting any muscular strength and length imbalances. Exercises are gradually progressed to include eccentric exercises, core strengthening, and plyometric exercise, with the focus on returning to sport-related activities as the patient tolerates.19,36 Reported recovery time to return to sport has been 1 to 70 days in cricket bowlers,36 4 to 6 weeks for elite tennis players,18,37 and 27 to 33 days for professional baseball pitchers.39
In professional sports, athletes are often given an ultrasound-guided corticosteroid injection at the injured site.36,39 Stevens and colleagues39 reported that corticosteroid injections enabled professional baseball pitchers to return to pitching at full speed in a mean of 21 days and return to able status in a mean of 30.7 days, compared with the typical recovery time of 6 to 10 weeks,44 with no reinjury reported in long-term follow up. Corticosteroid injections for the treatment of muscular injuries are controversial because of concerns about incomplete healing, rupture, and risk of infection.39 However, in rat studies, a single dose of dexamethasone given to an acutely strained muscle facilitated recovery of contractile tension without adverse effects.54 A retrospective review of corticosteroid injections for severe hamstring injuries in professional football players found no adverse side effects, decreased time before return to play, and lessened game and practice time missed.55 Also becoming increasingly more common in professional sports is platelet-rich plasma (PRP) injections of a growth factor that is thought to stimulate and enhance tissue healing.56,57 Despite anecdotal evidence and increased popularity, evidence is lacking that PRP injections hasten healing.14,58 Athletes are often withheld from participating in their sport until they are able to perform the skills necessary for the sport with appropriate intensity.22
Abdominal Wall Hernias
Anatomy of the Inguinal Canal
The inguinal canal is an oblique canal measuring approximately 4 cm long that runs parallel and a little superior to the inguinal ligament (Fig. 5-17). Throughout its length, the inguinal canal is bounded anteriorly by the aponeurosis of the external oblique, with a small contribution from the internal oblique in its lateral third. The transversalis fascia forms the posterior wall of the inguinal canal, with medial reinforcement by the conjoint tendon and reflected inguinal ligament. The floor is formed by the superior surface of both the inguinal and lacunar ligaments, and the roof is formed by the arching fibers of the internal oblique and transversus abdominis muscles. The sides of the inguinal canal are reinforced by intercrural (medial and lateral crura) fibers (Fig. 5-18).17
The inguinal canal has two openings: a superficial (external) inguinal ring and a deep (internal) inguinal ring. The superficial (external) ring is a slitlike opening in the distal aponeurosis of the external oblique muscle just superior and lateral to the pubic crest (see Fig. 5-7). The ring is somewhat triangular, measuring approximately 2.5 cm. It is bound inferiorly by the pubic crest, on either side by margins of the external oblique aponeurosis named the medial and lateral crus, and superiorly by a series of curved intercrural fibers. The strong inferior crus forms the floor of the ring and consists of the inferior portion of the inguinal ligament that inserts onto the pubic tubercle and on which the spermatic cord or round ligament rests. The superior crus attaches to the front of the pubic symphysis and interfaces with the contralateral superior crus.17
At the proximal end of the inguinal canal is the deep (internal) inguinal ring, also known as the abdominal inguinal ring (see Fig. 5-17). It is located midway between the ASIS and the pubic symphysis, approximately 1.25 cm above the inguinal ligament (see Fig. 5-12). It is bordered superiorly and laterally by the transversus abdominis and inferiorly and medially by the inferior epigastric vessels.17 The deep inguinal ring is an opening in the transversalis fascia for the passage of the spermatic cord and ilioinguinal nerve in males and the round ligament of the uterus and ilioinguinal nerve in females .59,60 Netter’s20 internal view of the anterior abdominal wall shows the orifice in the transversalis fascia (see Fig. 5-5). The deep inguinal ring is much larger in male than in female anatomy, and in males the fascial opening continues as a thin membrane, called the internal spermatic fascia, that envelops the spermatic cord and testis (see Fig. 5-12).17
Another important anatomic area of the abdominal wall is the inguinal triangle, also known as the Hesselbach triangle (see Fig. 5-5). The Hesselbach triangle is bounded laterally and superiorly by the inferior epigastric vessels, medially by the lateral border of the rectus abdominis, and inferiorly by the inguinal ligament, and it is located medial to the deep inguinal ring.17
The femoral artery exits inferior to the inguinal ligament midway between the ASIS and the pubic symphysis (Fig. 5-19). The first 4-cm segment of the femoral artery is enclosed together with the femoral vein within the fibrous femoral sheath (see Fig. 5-19), a continuation of the abdominal transversalis fascia downward and posterior to the inguinal ligament. The femoral vessels are surrounded anteriorly by this femoral sheath and posteriorly by the iliac fascia. The femoral sheath is shaped like a short tunnel that becomes narrow and fuses approximately 5 cm below the inguinal ligament and is reinforced anteriorly by a fibrous band called the deep crural arch (Fig. 5-20). The femoral sheath is compartmentalized vertically to contain the femoral artery laterally and the femoral vein in the middle, whereas the medial compartment is termed the femoral canal. The conical femoral canal measures approximately 1.25 cm and is bounded anteriorly by the inguinal ligament, posteriorly by the pectineus muscle, medially by the lacunar ligament, and laterally by the femoral vein’s fibrous sheath.17
Types and Incidence of Abdominal Hernias
The diagnosis of abdominal wall hernia is made in 1.7% of the population and in 4% of persons older than 45 years of age.61 Inguinal hernias account for 75% of all abdominal wall hernias, whereas the other 25% are noninguinal, including umbilical, epigastric, incisional, and femoral hernias.61,62
Although the exact incidence and prevalence of inguinal hernias are unknown, the incidence of inguinal hernia repair is 27% in men and 3% in women.63–66 The two classes of inguinal hernias are direct and indirect. Both types of hernia protrude through the inguinal canal and exit through or near the superficial inguinal ring, but the point of entry into the inguinal canal differs.60,66 At its point of entry, direct hernias protrude within the Hesselbach triangle, medial to the epigastric vessels, whereas indirect hernias protrude through the deep inguinal ring, lateral to the epigastric vessels (Fig. 5-21).17,60,63 In males, 50% of inguinal hernias are indirect, and 40% are direct. In females, 70% of inguinal hernias are indirect, 10% are direct hernias, and 20% are femoral hernias.64,66,67
An indirect inguinal hernia occurs when a sac containing peritoneum contents protrudes through the deep inguinal ring. An indirect inguinal hernia is also known as a congenital hernia because the cause is embryonic failure of the processus vaginalis to close. This type of inguinal hernia is more prevalent and is typically diagnosed in younger patients; most patients younger than 25 years of age who present with a hernia have an indirect hernia.63
Boys and men are more likely to develop an indirect inguinal hernia than are girls and women because the testicles and blood vessels pass through the inguinal canal before birth, thus making the deep ring less likely to close completely and making the ring larger.63 The incidence of indirect hernias is increased in persons with a close family history of the condition.63,66,68–70 Although an indirect inguinal hernia is often congenital, it may also result from an increase in intraabdominal pressure during strenuous activities such as lifting or straining during sports or with a medical condition leading to increased pressure on the region such as a chronic cough, chronic constipation, excess weight, or pregnancy.63,66,70–72 Smoking is also a risk factor.66,73,74 In male patients, indirect hernias are always covered by internal spermatic fascia, so if an inguinal hernia is located within the male scrotum, it is an indirect hernia.17
The protruding abdominal sac of an indirect inguinal hernia may become pinched during exercise and straining, thereby causing pain. If the abdominal sac becomes pinched and the blood supply to the hernia is compromised, the hernia become “incarcerated” or “strangulated.”60,63 The incidence of incarceration or strangulation is estimated to be 0.3% to 3% per year, depending on the definition.66,75–78 Strangulation occurs 10 times more often in indirect inguinal hernias than in direct hernias because of a comparably smaller orifice.66,79–81 Hernia incarceration or strangulation can lead to intestinal obstruction, resulting in potential ischemia, gangrene, and even death, and thus requires emergency surgery. Emergency surgical treatment of a strangulated inguinal hernia has a higher associated mortality than elective surgical treatment of inguinal hernia (>5% versus <0.5%).82,83
Direct inguinal hernias occur when retroperitoneal fat herniates through the transversalis fascia secondary to weakness or tearing of the transversalis fascia within the Hesselbach triangle. This tearing may result from increased intraabdominal pressure during strenuous activities such as lifting or straining or in sport. Thus, direct inguinal hernias are acquired and are more common in 40- to 50-year old persons.60,63,66
Femoral hernias occur when peritoneum protrudes into the femoral sheath or canal posterior and inferior to the inguinal ligament as a result of weakness of the transversalis fascia.62 Femoral hernias are extremely rare, accounting for only 3% of all hernias and found primarily in women.66,67 Femoral hernias account for one fifth to one third of all groin hernias in women, but only 2% in men,67,84 and 50% of men with a femoral hernia have a concomitant direct inguinal hernia, compared with only 3% of women.85 It is speculated that femoral hernia is more common in women compared with men because of its association with pregnancy and childbirth.86 In addition, a prospective fresh-cadaver study of women who had undergone femoral hernia repair87 found that the distances between the pubic tubercle and the medial margin of the femoral vein and between the inguinal and Cooper ligaments were much larger in these subjects compared with subjects who did not undergo repair. This finding suggests that the wider bone structure in women may lead to stretching of the fascia, with eventual weakening the fascia and predisposition to femoral hernia.
Diagnosing a femoral hernia is challenging because the hernia is often asymptomatic until strangulation or incarceration occurs.62 The typical presentation of a femoral hernia comprises “achy” abdominal pain, signs of intestinal obstruction,84 and a small nonreducible palpable bulge below the inguinal ligament lateral and inferior to the pubic tubercle.67,88 Given the challenge of diagnosis using clinical signs and symptoms, imaging is often necessary, including ultrasound, MRI, and computed tomography (CT). Although all imaging techniques have high accuracy in diagnosing a femoral hernia,62 ultrasound is most typically used because of its high accuracy (up to 100% sensitivity and specificity),89 wide availability, low cost, and reduced exposure to radiation.62
Because femoral hernias are more likely to become incarcerated or strangulated as a result of their narrow orifice, and because they have a 10-fold risk of mortality, immediate surgical repair is advised.62,67,88,90 Repairs typically consist of closure with nonabsorbable sutures that may be reinforced using the pectineal (Cooper) ligament.84 The recurrence rate after femoral hernia repair is only 2%.85 Postoperative return to activities is similar to that after inguinal hernias (discussed later), including limiting strain to the area for 2 to 3 weeks and gradual return to activities that avoid symptom reproduction.62,91
Umbilical hernias manifest near the naval in an area naturally weakened by the vessels of the umbilical cord.17 These hernias often appear in infants soon after birth, and 95% resolve spontaneously by age 3 to 4 years.92 Umbilical hernias can also manifest in adults in response to excessive pressure from being overweight or from coughing or pregnancy,62,93 and in the athletic population, they can manifest from increased abdominal pressure in activities such as powerlifting.94 Umbilical hernias are typically asymptomatic, and they appear as a nonpainful palpable bulge at the umbilicus in adults.95 Although they rarely become incarcerated, umbilical hernias in adults and unresolved hernias in infants are often treated surgically to prevent worsening and possible incarceration. Umbilical hernias have a high success rate when treated operatively; treatment involves defect closure and suture placement or a mesh prosthesis.96 Postoperative guidelines are similar to those for femoral hernias and inguinal hernias, as subsequently discussed.
Presentation of Inguinal Hernias
Clinical examination typically suffices in the diagnosis of an inguinal hernia because diagnosing an inguinal hernia by means of a physical examination has a sensitivity of 75% to 92% and a specificity of 93%.97,98 Indirect and direct inguinal hernias result in a palpable bulge with increased abdominal pressure in the groin at the top of, or within, the scrotum (Fig. 5-22). This small bulge is elicited during examination by palpating the inguinal canal and asking the patient to cough while standing. The hernia is reducible if it appears intermittently, such as during standing or straining, and can be manually pushed back into the abdominal cavity with minimal pressure or when the patient lies supine, in contrast to an irreducible hernia, which remains outside the abdominal cavity permanently even with pressure.60,63 A direct hernia protrudes directly forward and appears as a symmetrical, circular swelling, whereas an indirect hernia has a more oblique route and thus appears as a more elliptical swelling. However, differentiating between direct and indirect inguinal hernias clinically by using anatomic landmarks is unreliable and is necessary only to rule out a femoral hernia because treatment is identical for both direct and indirect inguinal hernias.79–81
Pain from an inguinal hernia, if present, is typically described as a deep, aching pain in the inguinal or scrotal region.63 However, approximately one third of patients electing to undergo surgical hernia repair have no pain and little to no limitation of daily activities.60,77 A study of 323 patients undergoing inguinal hernia repair found that, before the operation, at rest 27% had no pain, 54% had “mild pain” (<10 on a 1- to 100-point scale), and 1.5% had severe pain (>50 out of 100), and during movement 16% had no pain, 42% had mild pain, and 10% had severe pain. In addition, no association was observed between pain intensity and location type of hernia.99
Imaging
If a patient has obscure or vague pain, or has intermittent swelling not palpable during examination, a diagnostic investigation is recommended.66 Ultrasonography is a useful noninvasive adjunct to the physical examination; its specificity of 81% to 100% and sensitivity of 33% to 100% compared with surgical exploration in the diagnosis of an inguinal hernia suggests that the accuracy of this technique depends on the examiner’s experience.97,100–103 MRI has a sensitivity of 95% and a specificity of 96% and is also useful in diagnosing inflammation, tumors, and other musculotendinous dysfunctions.66,104 A CT scan has a limited place in the diagnosis of an inguinal hernia even though its sensitivity is 83% and its specificity is 67% to 83%.66 Herniography is a radiographic diagnostic technique using fluoroscopy-guided injection of a contrast medium into the peritoneal cavity.105,106 Herniography is highly reliable for detecting inguinal hernias104–107; moreover, it has a reported sensitivity of 100% and a specificity of 98% to 100%.107 In the diagnosis of hernias, herniography has been found to be superior to MRI, possibly because of the difficulty of having the patient perform a Valsalva maneuver (forced expiration against a closed glottis) while statically supine.104 However, herniography has limited use in the United States as a result of potential complications including accidental bowel puncture, despite a reported 1% incidence of complications,106,108 given that less invasive techniques with nearly equal accuracy are available. All things considered, the typical diagnostic investigative course of action is to first perform an ultrasound examination; if findings are negative, then perform an MRI with a Valsalva maneuver, and if MRI results are negative, perform herniography.66
Treatment
Minimally symptomatic direct and indirect inguinal hernias are typically initially treated with “watchful waiting” to assess whether they become more symptomatic.66 Given that historically most diagnosed inguinal hernias are operated on, the natural course of an untreated inguinal hernia is rarely documented.66 Studies have found similar outcomes between men with minimally symptomatic inguinal hernias that were surgically repaired compared with men who were treated with watchful waiting.75,109 This finding suggests that watchful waiting is a reasonable option for men with minimally symptomatic inguinal hernias, and if the hernia becomes more painful or the pain interferes with normal activities, than repair is suggested.75,109 The primary rationale for watchful waiting as the first course of treatment is to avoid potential postoperative pain syndrome, or inguinodynia—pain or discomfort lasting longer than 3 months after the surgical procedure—a somewhat common complaint after surgical repair of inguinal hernias. Studies report that 3% to 6% of patients undergoing hernia repair have severe pain, and 30% have mild pain, 1 year after inguinal hernia repair.82,110,111 Thus, investigators have suggested that patients with moderate to severe pain undergo surgical repair, whereas patients with no pain should undergo a trial of watching waiting because the repair may make their pain worse.99
Evidence-based guidelines suggest that all men who are older than 30 years of age and who have a symptomatic inguinal hernia should be operated on to reduce symptoms and prevent complications such as incarceration or strangulation.66 Inguinal hernia repair is one of the most frequently performed surgical procedures in the United States, with an estimated 600,000 operations performed annually.112,113 Surgery can be laparoscopic/endoscopic or open. A review of the literature reveals that, compared with open repair, laparoscopic procedures result in longer operation times but less severe postoperative pain, fewer complications, and a quicker return to normal activities.114,115 Surgical procedures include the following: herniotomy, in which the hernia sac is removed without any repair; herniorrhaphy, which is repair without any reinforcement; and hernioplasty, which consists of herniotomy combined with reinforcement using the patient’s own tissue (autogenous) or a heterogeneous material such as mesh.116 The procedure used is selected based on the surgeon’s preference and the hernia presentation. The mesh is typically a synthetic nonabsorbable polypropylene flat mesh.66 Laparoscopic hernioplasty using mesh repair results in fewer recurrences than techniques not using mesh and also reduces the incidence of chronic inguinodynia.117–119 Either the open or endoscopic mesh repair is a recommended option for treating a unilateral inguinal hernia because both procedures have similar outcomes, provided the surgeon is experienced in that procedure.118,120 Endoscopic techniques are technically more demanding and thus are more dependent on the surgeon’s experience.91,121
The Lichtenstein technique is the best evaluated and most popular of the open mesh techniques. It has been associated with low morbidity, can be performed as a same-day surgical procedure using local anesthesia, and has low recurrence rates (≤4%) in long-term studies.122,123 Although endoscopic mesh techniques require a longer operation time than the open mesh procedure, they result in a lower incidence of wound infection and hematoma formation, have a faster recovery time and thus earlier return to normal activities, and have a reduced incidence of chronic inguinodynia compared with the open mesh techniques.117,124 Endoscopic mesh repair is chosen for treating inguinal hernias in women because they have a higher risk of hernia recurrence following an open repair125,126 and a greater risk of presenting with a concomitant femoral hernia, thus suggesting that endoscopic mesh repair should be used to cover both inguinal and femoral hernias simultaneously.66
If a nonmesh procedure is selected, the Shouldice technique, a modern version of the original Bassini procedure, has been found to be the most effective.127 The Shouldice technique involves repairing the posterior wall of the inguinal canal and the internal ring by suturing several layers with a continuous nonsoluble monofilament suture; it has considerably better outcomes than other nonmesh techniques and results in a lower recurrence rate (15% versus 33%).128
Postsurgical Considerations and Rehabilitation
Inguinal hernia repair can be easily performed as a same-day surgical procedure, regardless of the technique used.66 Typical postoperative recovery for an anterior open approach without mesh is 6 weeks.129 Research reveals that patients recover 4 days earlier on average after an open mesh procedure than after a conventional nonmesh open repair, and they recover 7 days earlier on average following an endoscopic mesh operation than after an open mesh technique.117–120,124,130–135
Following inguinal hernia repair, patients were historically informed to resume activities as their symptoms allowed but to avoid heavy weight lifting for 2 to 3 weeks.66 This limitation of heavy physical lifting was based primarily on expert opinion and low-level evidence suggesting that physical strain leads to an increase in intraabdominal pressure that subsequently causes inguinal hernias and thus possible reinjury.66,136,137 This opinion led to ambiguous guidelines to avoid “heavy weight lifting” for 2 to 3 weeks without specifying the threshold of heavy lifting.66,136,137 Current research suggests that after an initial 3-week period of reduced protected activity to allow wound healing, no difference in hernia recurrence is noted among groups informed to resume all occupational and recreational activities without restrictions, those informed to return to activity but reduce strain for an additional 2 to 3 weeks, and those remaining inactive for 3 months.138–140 Thus, no evidence exists of a relationship between an increase in intraabdominal pressure with activities and hernia recurrence.136,137 Mesh reconstruction of an inguinal hernia that is placed through an open or laparoscopic procedure has full loading strength immediately after wound closure that is not endangered by physical activity of any type, including heavy lifting.136 Therefore, physical activity of any type, including heavy lifting, does not endanger the repair. The only limiting factor for resumption of activity after herniotomy is not recurrence risk, but pain.82,136,141–143 Because laparoscopic hernia repair is associated with less postoperative pain,120,144,145 laparoscopic repair facilitates earlier resumption of work and daily activity.66,145 Thus, current evidence suggests that patients be allowed to return to their regular activities, regardless of the physical strain involved, immediately after healing of the skin wound if analgesics are administered.136 Because most inguinal hernias are treated surgically, guidelines governing conservative rehabilitation are few or absent.
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