Incarcerated Inguinal Hernia in the Elderly: Surgical Implication

Abstract

Inguinal hernia is a very common clinical condition, and its incidence is higher in elderly patients. Different factors are involved in the etiology of the disease, either congenital or acquired. Most inguinal hernias are asymptomatic but may develop complications such as incarceration. Diagnosis, in uncomplicated cases, is easy and based on physical examination. Imaging studies are helpful when the diagnosis is unclear, especially if bowel strangulation is suspected. Elective surgical hernia repair is considered the treatment of choice. However, in elderly patients with a high surgical risk, a watchful-waiting approach is advisable. The choice of surgical technique depends on the experience of the surgeon and the contamination of the surgical field. The classical approach is Lichtenstein open tension-free mesh repair, although laparoscopy has been proposed. The use of mesh in incarcerated inguinal hernia is disputed because of the increased risk of postoperative wound infection. General anesthesia is usually preferred in particular if bowel ischemia is suspected and intestinal resection may be required. However, local anesthesia is expanding its indication since it provides effective anesthesia with less postoperative complications.

1. Introduction

Inguinal hernia is a common clinical condition with a lifetime occurrence of 27–43% in men and 3–6% in women [1, 2]. Its incidence is higher in elderly people due to conditions frequently associated with old age such as constipation, chronic obstructive pulmonary disease (COPD), and prostatism, which are considered risk factors for hernia formation [3, 4].

Inguinal hernia is generally asymptomatic, or minimally symptomatic in most patients [5], although in 5–15% of cases may complicate with incarceration [6, 7]. Moreover, around 15% of incarcerated inguinal hernias may evolve into bowel strangulation, a life-threatening condition requiring intestine resection [8, 9].

Patients operated on for complicated hernia have poor outcomes with high postoperative complications and mortality, ranging from 6 to 43% [7, 10] and from 1 to 7%, respectively [8, 11]. Therefore early diagnosis and prompt surgical repair are critical factors in improving the prognosis of these patients [12, 13]. In typical, uncomplicated cases, diagnosis is easy and can be made by physical examination alone [14, 15]. However, if clinical features are doubtful and patients present symptoms referring to intestinal obstruction, imaging studies play an important role in clearing the diagnosis and in assessing the viability of incarcerated intestine [16, 17, 18, 19, 20].

Although inguinal hernia repair is one of the most common operations performed worldwide, with over 20 million operations per year [21], several methods of treatment have been proposed including conservative approach (watchful-waiting strategy), manual reduction for incarcerated hernia, and, of course, surgical repair, either open or laparoscopic [22, 23, 24, 25].

This chapter aims to describe the diagnostic process, highlight the importance of early detection of bowel ischemia, and summarize the treatment options, especially surgery, its indications, and results.

2. Epidemiology

Groin hernia is the most common abdominal wall hernia and includes inguinal and femoral types, with the former accounting for 96% of cases [2, 26]. The incidence of inguinal hernia is higher in males than in females, with male-to-female ratio of 9:1, whereas femoral type is more common in women [27, 28].

It is estimated that one-fourth of adult men in the United States have a recognizable groin hernia that accounts for 4.7 million ambulatory visits annually [29]. Moreover, it is more common on right side and in 10% of cases is bilateral [15, 28, 30]. Inguinal hernia may evolve into incarceration with an estimated risk ranging from 0.03–3% over a person’s lifetime [31, 32, 33]. Primary hernias are strangulated more than recurrent and the small ones more than the large hernias, with a ratio of 5:1 [12, 34].

Incarceration occurs more frequently during the first 3 months after the diagnosis, with no difference in gender [31]. Overall 5.8–13% of patients operated on for inguinal hernia are treated emergently [1, 32, 33], and around 10–20% of these patients will need a bowel resection [6, 34]. Interestingly, complicated hernia in elderly people shows an increased incidence of necrotic bowel compared with young adults for the same time duration of symptoms [28, 32].

The most frequent anatomical structure found in incarcerated inguinal hernia sac is the intestine, in around 75% of patients, followed by omentum in the remaining 25% [15, 35]. However, other unusual structures have been described such as ovarian in 2.9% of cases, urinary bladder in 0.36% [36], sigmoid diverticulum [37], appendix epiploica [38], Meckel’s diverticulum [39], and even gallbladder [40]. The presence of a vermiform appendix is reported with an incidence of 1% [41], and, although rarely, the appendix may become inflamed (Amayand’s hernia) [42].

3. Etiology

Hernia is a multifactorial condition, and several causes may play a role in its development. Risk factors are usually divided into patient and external factors [Oberg]. Patient risk factors are considered male gender, old age, and low body mass index [43, 44, 45]. Other factors such as constipation, prostate hypertrophy, and COPD are all conditions that increase intra-abdominal pressure that strains the layers of the abdominal wall and may weaken its strength [34, 46]. There is a strong correlation between the processus vaginalis and hernia formation [47]. An indirect inguinal hernia is supposed to be due to a persistent patency of processus vaginalis [48, 49]. Furthermore, an indirect hernia is more common on the right side because the right testis descends later than the left, leaving the right processus vaginalis patent for more time [50]. Patients with collagen vascular disease and connective metabolism disorders (Marfan syndrome, Ehlers-Danlos, and aneurysmal disease) are at increased risk of hernia formation [51, 52, 53]. When comparing different inguinal hernia types, direct hernia shows local collagen tissue alteration and different abdominal fascia architecture, factors that affect the elastic properties of transversalis fascia leading to hernia formation [54, 55].

Among external risk factors, smoking is supposed to increase the risk of recurrence [43], but its role in primary hernia formation is uncertain [44, 56]. Increased intra-abdominal pressure seems to be related to abdominal wall hernia formation, but its effective role is still under scrutiny [33]. Some physical activities, such as jumping, or great physical exertion, are strongly related to hernia formation [57, 58, 59]. However, in other circumstances, factors, such as leisure physical activities, lifting heavy loads, or standing for a long time, although they provoke an increase in intra-abdominal pressure, do not seem to be responsible for hernia development [60].

4. Classification

Abdominal hernia is defined as an abnormal protrusion of a peritoneal sac through the muscoloaponeurotic structures covering the abdominal wall [61]. Classification of abdominal wall hernia is generally based upon anatomic location of the bulge and includes groin, umbilical, epigastric, Spigelian, and obturatoria hernias [30, 62]. In addition, groin hernias can be classified according to etiology (congenital or acquired), anatomic location of the bulge (inguinal and femoral), defect size (small, medium, and large), and integrity of anatomic groin structure [63, 64, 65, 66]. Some of these classifications are complex and difficult to remember; thus, surgeons, in their day-to-day practice, separate inguinal hernias essentially in two types, indirect (lateral) and direct (medial), by their relationship with the inferior epigastric vessels at surgical exploration [64, 67]. Direct hernia protrudes medially to inferior epigastric vessels, whereas indirect type laterally to the vessels [68].

Incarcerated hernia is defined as a hernia in which the sac content cannot be reduced into the abdomen due to a narrow opening orifice or because of adhesions between the sac and its content [23, 69, 70].

Hernia becomes strangulated when the blood supply of the sac content is compromised, and the tissue progresses to necrosis [71].

Unfortunately, the two terms “incarcerated” and “strangulated,” which refer to different clinical conditions, are often used interchangeably with the undesirable consequence of negatively affecting the therapeutic decision-making process [72, 73].

5. Diagnosis

The majority of uncomplicated inguinal hernias are easily diagnosed. Typically, a patient complains of pain or dull discomfort in the groin region that exacerbates during daily living activities [74, 75]. On physical examination, the hernia appears as a lump in the groin which becomes more evident when the patient performs a Valsalva maneuver or gives a cough [76]. In uncomplicated cases, the lump may go away spontaneously, when the patient is lying down, or after a gentle manual pressure over the hernia. Overall, clinical examination in the elective setting results is quite accurate and shows a sensitivity ranging from 74–92% and a specificity of 93% [14].

If the patient complains of moderate–severe groin pain, a complicated hernia should be taken into consideration [15, 23]. Incarcerated hernia may also present with symptoms of bowel obstruction such as nausea, vomiting, diffuse abdominal pain, and bloating [15, 77]. When bowel ischemia has occurred, the patient may show signs of local or general peritonitis, including abdominal tenderness, absent bowel sounds, fever, tachycardia, and systemic inflammatory response syndrome (SIS) [78]. On physical examination, incarcerated hernia will appear erythematous, indurated, swollen, painful to palpation, and irreducible [79, 80]. Therefore, early diagnosis of incarcerated hernia is paramount to improving the patients’ prognosis [81, 82]. A delay in hospital admission of more than 48 hours increases postoperative morbidity and mortality by 24 and 7 times, respectively [83, 84]. Furthermore, patients hospitalized after more than 24 hours following incarceration encompass 81.8% of death cases [85]. Sometimes a delayed diagnosis, especially in elderly people, may be ascribed to inadequate awareness of the problem by the patient who does not seek medical advice [86]. However, in other circumstances, the diagnostic delay may be due to physician mistakes [87]. A study showed that strangulated hernias were misdiagnosed in 3% of patients by general physicians and in 15% by hospital registers [88].

In patients with incarcerated inguinal hernia, it is important to rule out bowel ischemia [89, 90]. Several clinical, radiological, and laboratory criteria have been analyzed in order to predict this complication. Among laboratory parameters, D-dimer level correlates well with bowel ischemia, and this parameter’s high value should increase the suspicion of bowel infarction [91]. On univariate analysis, an elevated serum lactate level greater than 2.0 mmol/L [92] is strongly associated with intestine ischemia, although the test shows a low specificity [93, 94]. Moreover, lactate levels may be false normal up to 8 hours after the onset of bowel necrosis [95]. White blood count (WBC), blood fibrinogen, and serum creatinine phosphokinase (CPK) have been considered valuable predictive parameters for ischemic events occurring in different tissue of the body [96]. Fibrinogen level is increased in patients with incarcerated hernia and seems to show a positive correlation for bowel resection, need for intensive care, and higher risk of mortality [97]. Similar results have been found for CPK [96] and WBC count [80, 98]. In patients who complain of severe groin pain and show an increased level of fibrinogen and high WBC count, a prompt surgical hernia exploration is recommended [99]. Hyponatremia, defined as sodium level less than 135 mg/dl, should raise a strong suspicion of bowel necrosis [100]. Furthermore, the combination of hyponatremia and clinical features of bowel strangulation should dissuade the surgeon from any attempts to perform Taxis maneuver [101]. To conclude, procalcitonin (PTC) is considered a reliable diagnostic serum parameter in several conditions such as infections, systemic inflammatory response syndrome (SIRS), acute pancreatitis, and multiorgan dysfunction syndrome (MODS) [102]. In incarcerated inguinal hernia, PTC is significantly higher in patients with bowel ischemia compared with those without ischemia and in patients with necrosis compared with those without it. Thus, elevated levels of PTC should rise the suspicion of bowel necrosis, and repeated measurements of PTC may help the surgeon to decide if operate and the timing of surgery [89].

Overall, no single serum marker is sensitive or specific enough to diagnose intestinal ischemia, and only the association of two or more factors has proved helpful in predicting the progression of incarcerated hernia toward bowel necrosis [69, 103].

Imaging studies are useful in doubtful diagnosis and in patients with complicated inguinal hernia, particularly if bowel ischemia is suspected [14, 19, 75, 104]. Without intra-abdominal complications, groin ultrasound (US) should be the initial imaging modality to evaluate a suspected incarcerated inguinal hernia [105, 106]. Sonographic signs of incarceration include free fluid in hernia sac and within the dilated bowel loop, intestine thickened wall (> 2,5 cm), and “back-and-forth” peristalsis sign [20, 107, 108]. Moreover, sonographic reduction of Doppler color flow within the bowel loops, the absence of peristalsis, and free air in the intestinal wall are signs of strangulation [104, 109].

Multidetector computed tomography (MDCT) is considered the modality of choice in incarcerated inguinal hernia since it supplies the surgeon with decisive information to clear a doubtful diagnosis, to detect signs of peritonitis, and to evaluate bowel necrosis and its severity [18, 110, 111, 112, 113]. Analysis of the overall diagnostic performance of MDCT for detecting ischemic bowel has shown contrasting results, with a sensitivity reaching almost 100% and, by contrast, specificity reported in some studies as low as 61% [114, 115]. The low specificity rate is probably because some CT signs found in ischemic bowel are also observed in other conditions, especially in inflammatory bowel diseases and peritonitis in which no vascular compromise is involved [16]. CT diagnosis of bowel ischemia is based on the presence of two or more of the following signs: bowel wall thickening, a high attenuation of the bowel wall on unenhanced CT, mesenteric edema, fluid in the hernia sac, asymmetric bowel wall enhancement on IV contrast-enhanced CT, and pneumatosis in advanced stage [103, 116, 117]. In conclusion, in patients with incarcerated inguinal hernia, MDCT allows identifying patients at high risk of bowel necrosis, regardless of surgical risk, and requiring an emergent surgical repair [110, 118, 119, 120].

6. Treatment

Inguinal hernia is a common problem occurring in about 15% of adult men [121], and inguinal hernioplasty is probably the most common operation performed by a general surgeon [122].

The definitive therapy for inguinal hernia is surgery; generally, patients are referred for surgical treatment after diagnosis [23, 123]. The main reason for this strategy is the fear of hernia incarceration, which requires emergency operations [124, 125, 126, 127, 128]. In addition, elective surgical hernia repair is a safe and effective treatment for rare and minor complications, as well as in elderly patients [129, 130].

By contrast, several studies have shown that emergent inguinal hernia repair has a high morbidity and mortality rate, estimated at around 30 and 13,4%, respectively [84, 87, 131, 132].

Therefore, in contemporary practice, the majority of patients, regardless of age and symptoms and who are healthy enough, are referred to surgery [23, 133, 134].

Lichtenstein mesh tension-free technique is the procedure of choice [2, 135, 136, 137, 138] due to its safety and efficacy with a low recurrence rate ranging from 0.002 to 0.48% [87].

However, many elderly people have several comorbidities and present a high surgical risk. A watchful-waiting approach is warranted for this group of patients, particularly if they are asymptomatic or minimally symptomatic [134, 139, 140].

Proponents of this strategy argue that the risk of incarceration is low, occurring in only 2–4% of patients followed up as long as 11.5 years and that only 7% of operations are performed emergently [24, 141, 142]. Furthermore, there is no difference in pain relief between patients operated on and those treated with a watchful strategy [143].

However, despite these positive results, it should be remembered that around two-thirds of patients treated with a watchful-waiting approach cross over to surgery within 10 years mainly because of pain or incarceration of hernia [144, 145, 146].

Things change when a hernia becomes incarcerated since this complication is life-threatening and needs prompt treatment [147, 148, 149].

In high-surgical risk patients without signs of strangulation, a manual non-invasive reduction of incarcerated hernia, performed under analgesia/sedation (Taxis maneuver), is considered a safe and reliable treatment [4, 72, 150]. The procedure can also be performed under US guidelines increasing the safety and efficacy of the technique [151]. The success of this approach is reported in 70% of cases, and it is also considered the treatment of choice in pediatric patients [149]. The advantage of the manual reduction procedure is to avoid emergency operations in critically ill patients with an increased risk of morbidity and mortality [72, 150]. In addition, definitive surgical repair can be scheduled early after a successful Taxis maneuver (“two-stage procedure”), providing better anatomical conditions for operation [47, 152].

Unfortunately, a manual reduction procedure may carry the risk of reducing necrotic bowel into the abdomen, the event that leads to diffuse peritonitis which needs an emergent surgical treatment [153, 154]. However, cases are rare, and since bowel strangulation occurs with a very narrow hernia orifice, the risk of reducing a necrotic bowel is very low [149].

In current practice, the role of manual reduction is still under debate, and, anyway, the procedure should be considered a temporary treatment due to the high incidence of re-incarceration [154]. Furthermore, the technique is not even mentioned in a recent update of different society’s guidelines for the emergency repair of abdominal wall hernias [4, 71, 155].

Incarcerated inguinal hernia associated with intestinal obstruction and/or suspected bowel ischemia represents a mandatory indication for emergent surgery [23, 71, 147]. Unfortunately, complications after urgent repair, particularly in elderly patients, are common, and the reported morbidity and mortality are high, ranging from 19 to 30% and from 1.4 to 13.4%, respectively [131, 156, 157].

Several factors have been investigated in order to predict surgical risk and outcome in this group of patients [84, 85, 158]. Age over 70 years is considered a negative prognostic factor, and it is estimated that postoperative mortality increases 1% with every year of age [8, 159, 160]. However, old age “per se” seems not to be responsible for poor outcomes, but only if it is associated with comorbidities [133, 161] or with a “frailty” status [162]. Cardiovascular disease, diabetes mellitus, COPD, and obesity are also associated with increased postoperative complications [6, 163, 164]. Furthermore, patients with ASA (America Society of Anesthesiologist) III-IV class show mortality 2,5 times higher than those with ASA I-II class [100, 134, 160]. Smoking seems to hinder the oxygenation of the surgical field, impairing the wound-healing process [56, 165, 166].

However, among risk factors, probably the most important is the necrosis of incarcerated bowel, which demands intestine resection [6, 83, 84, 157]. It is estimated that bowel resection increases mortality by 3 to 4 times [28], although this result is disputed by other studies, which show that intestinal resection is a predictor of morbidity but not of mortality [7, 85, 167].

Intestinal ischemia includes different grades of severity, ranging from reversible stage to transmural necrosis with possible wall perforation [168]. This “acute bowel injury,” also in an early phase of its development, leads to bacterial translocation, absorption of bacterial endotoxin, systemic inflammatory response syndrome (SIRS), and may progress to multiorgan dysfunction syndrome (MOS) [71, 169, 170]. Therefore, early diagnosis of ischemic bowel and prompt surgical treatment assume great clinical value in these patients [151, 171].

Incarcerated inguinal hernia may be treated with different surgical approaches, and the choice of the technique depends on several factors including anesthetic considerations, surgeon’s expertise, suspect of bowel necrosis, and contamination of the surgical field [147, 148]. The most common technique, especially in elderly patients, is the open anterior mesh tension-free repair. In this regard, the Lichtenstein procedure has gained great acceptance and has become the technique of choice in emergency settings and high-risk patients [172, 173, 174, 175]. The mesh guarantees excellent repair results, but its use in complicated hernia is controversial due to the increased risk of wound infection [176, 177, 178, 179]. However, several studies have shown that mesh can be safely implanted in complicated hernia without increased risk of wound infection, even in the case of bowel resection [156, 180, 181]. The choice of mesh is crucial for the success of the operation [182, 183]. Polypropylene is the ideal material to be used in contaminated fields since its macroporous structure allows contact among bacteria and the patient’s immune system cells, allowing the recovery from infection [184, 185].

In conclusion, the mesh can be safely used in clean and clean-contaminated surgical fields (CDC Class I-II), whereas its use in cases of bowel perforation and in grossly contaminated-dirty surgical fields (CDC Class III-IV) is not recommended [23, 71, 186].

When mesh is contraindicated, a primary tissue repair is required. Several techniques can be employed such as Bassini, Shouldice, and Mc Vay procedures [187, 188, 189].

The Shouldice technique is considered the most effective procedure, particularly in specialized centers [22, 190]. However, all “pure tissue repair” techniques are burdened with high postoperative morbidity and can show a recurrence rate as high as 34%, especially when employed in an emergency setting [87, 191].

Therefore, to obviate the poor results of the suture tissue repair technique and perform a mesh tension-free repair also in a contaminated field and, at the same time, trying to avoid the risk of wound infection, the use of absorbable mesh has been proposed [192, 193].

The laparoscopic approach has recently become popular, and it is considered a reliable procedure for the repair of bilateral inguinal hernia and recurrent hernia, and also for unilateral inguinal hernia [194, 195, 196, 197, 198]. Furthermore, a series of studies have confirmed that the laparoscopic approach can be safely performed in old-age patients with an ASA I-II class without increasing the incidence of complications and mortality [25, 199, 200]. However, some concerns still exist regarding emergent laparoscopic repair of incarcerated inguinal hernia, and little evidence exists about the technique’s efficacy [4, 201]. In addition, it is reported that the laparoscopic procedure has some limitations. A minimally invasive approach requires general anesthesia, is time-consuming, has a long learning curve, is not cost-effective, and entails specific complications such as bladder, vascular, and visceral injuries, which are unusual in an open approach and sometimes result in the death of the patient [202, 203, 204, 205]. Only 10% of all inguinal hernia repairs are estimated to be performed via laparoscopic approach in the United States [202, 203].

However, several studies have shown that minimally invasive technique presents several advantages over open repair, even for the treatment of incarcerated inguinal hernia [206, 207, 208, 209]. For example, laparoscopy allows a careful reduction of herniated bowel, an accurate assessment of its viability, reduces the postoperative pain, and allows faster recovery, and, finally, the procedure shows a lesser or similar recurrence rate compared to the open approach [210, 211, 212].

Among laparoscopic techniques, either transabdominal pre-peritoneal repair (TAPP) or totally extraperitoneal approach (TEP) is a feasible and reliable method [213, 214], although an increased risk of recurrence is reported for TEP repair [203].

An interesting use of the laparoscopic technique is the hernia sac laparoscopy, also known as hernioscopy [215]. This method, defined as a mixed laparoscopic-open surgical approach, can be employed to assess the viability of the intestine in case of spontaneous reduction of the sac content during an open emergent inguinal repair before the assessment of the viability of the intestine [216, 217]. This event, which occurs in about 1% of patients during anesthetic induction, poses the risk of leaving the necrotic bowel inside the abdomen with the consequent development of peritonitis [218]. In this circumstance, hernioscopy is a reliable and accurate method to assess the viability of the retracted intestine, and allows to avoid unnecessary laparotomy in high-risk patients [219, 220].

The choice of anesthetic methods is an important issue in inguinal hernia repair, especially in elderly patients and in complicated hernias [221, 222, 223]. Virtually, all anesthetic techniques such as general, regional (epidural and spinal), and local anesthesia can be used [224, 225, 226]. However, epidemiological data show that nearly 80% of inguinal hernia repairs are performed under general anesthesia, although the evidence to support this choice is low [21, 227]. Furthermore, these data contrast those originating from specialized centers where local anesthesia is used in more than 95% of patients [228, 229].

The choice of anesthetic technique depends on several factors including patient or surgeon preference, technique feasibility in a given patient, and intra- and postoperative pain control [230]. However, general anesthesia is usually preferred in emergency inguinal repair since the technique provides the surgeon with optimal operating conditions in terms of immobility and muscular relaxation [231]. Furthermore, general anesthesia remains the method of choice in anxious or uncooperative patients, in morbid obesity, and in cases where intestine ischemia is suspected, and bowel resection could be performed [5, 71, 222].

Regional anesthesia offers some advantages compared with general technique. For example, control of postoperative pain favors the regional approach; nausea and vomiting are less frequent, just like deep vein thrombosis and pulmonary edema [232, 233, 234]. However, regional anesthesia is burdened with common complications such as postdural puncture headache, hypotension, and urinary retention [233]. Furthermore, meta-analysis does not show definitive data concerning the advantage of regional over general anesthesia [235].

Local anesthesia has become a popular technique for inguinal hernia repair, and it is strongly recommended in elderly patients and in those with comorbidities [236, 237, 238]. Moreover, European Hernia Society Guidelines (EHS) suggest that this technique should be used in patients with ASA III or IV class. Local anesthesia has advantages over general and regional anesthesia such as less postoperative pain, shorter hospital stay, early mobilization, and avoiding urinary retention and cognitive dysfunction [231, 237, 239]. Despite these advantages, the role of local anesthesia for inguinal hernia repair is still under debate, especially in emergency settings [225, 240, 241]. Incarcerated hernia has a complicated local anatomy, tissues are swollen, the patient often complains of pain, and muscle relaxation is not satisfactory [242]. Furthermore, local anesthesia is considered a risk factor for recurrence [240]. For these reasons, the technique is rarely used in emergencies, although some studies have shown the feasibility and safety of local anesthesia for treating incarcerated inguinal hernia in high-risk patients [236, 237, 241].

7. Conclusion

Incarcerated inguinal hernia represents a serious clinical problem. Moreover, its incidence is high in elderly people with several comorbidities and presents a high surgical risk. An early diagnosis is of paramount importance in order to establish a prompt and tailored patient treatment. Surgical open tension-free repair is still the treatment of choice, especially in high-risk patients, and should be performed under general/regional anesthesia if bowel necrosis is suspected. The laparoscopic approach has grown in popularity and is currently considered a valid option to open surgery for incarcerated inguinal hernias in old-age patients.