Rare Case of Large Bowel Injury due to Direct Blunt Trauma to a Preexisting Femoral Hernia

We report a case of an 85-year-old man with a known asymptomatic left femoral hernia who was admitted to the emergency ward a few hours after falling from a bicycle and suffering from blunt trauma of the handlebar to the left inguinal region. The clinical findings and a computed tomography (CT) scan detecting free air in the femoral hernia sac suggested bowel perforation. Emergency laparotomy 6 hours after the incident confirmed a tear of the sigmoid colon accompanied by free blood and faeces in the left inguinal region of the abdomen. A segmental sigmoid resection and a primary end-to-end colorectal anastomosis were performed. The postoperative course was complicated by delayed oral feeding, a local infection, and a partial left testicle necrosis that led to secondary resection. The patient was discharged after 32 days of in-hospital care. Three months post trauma, we recorded a restitutio ad integrum. The case exemplifies that blunt trauma to preexisting femoral hernias may cause potentially lethal bowel perforation and that the time interval between time of injury and surgical treatment may be a prognostic factor. CT scans seem most suitable for ruling out bowel perforation. The scarce literature for blunt trauma to hernias is reviewed.


Introduction
Groin hernias are common, with an estimated prevalence of between 5 and 10 percent [1]. Although femoral hernias account for less than 10 percent of groin hernias, they occur more often than inguinal hernias associated with complications like incarceration and strangulation [2]. Femoral hernias are frequently found in elderly women, whereas inguinal hernias are more common in men [3]. On clinical examination, a groin hernia is easily detected, but diagnosis of a femoral hernia is more di cult and is more often con rmed during surgery. Symptomatic hernias are commonly treated surgically. However, considering that severe complications such as incarceration are uncommon, not all patients with asymptomatic hernias pro t equally from surgical treatment. For patients with a high operative risk, conservative treatment may be a viable alternative. Guidelines for optimal surgical treatment have been published by the European Hernia Society [4,5]. As femoral hernias are more prone to complications like incarceration, there is a general consensus that surgical repair should be the standard of care at an early stage [2]. Many patients with asymptomatic femoral hernias are unaware of their potential risks and do not seek medical advice. erefore, femoral hernias are eventually diagnosed when becoming symptomatic and often require emergent admission and treatment. Very unusual, though potentially fatal, is another complication of untreated hernias, namely, the traumatic rupture of bowel trapped in a hernia sac. Only a few cases of traumatic bowel injuries associated with inguinal hernias are described in the literature. is is to our knowledge the rst case report of a large bowel perforation due to a trauma to femoral hernia.

Case Presentation
An 85-year-old patient with a medical history of appendectomy, prostatic hyperplasia, and a known but untreated asymptomatic groin hernia had a bicycle accident with a blunt handlebar injury to his left inguinal area. Later on, he complained of pain in the left groin, whereupon his family brought him to the emergency department. He was alert and fully oriented. e abdominal examination revealed di use pain, a tense abdomen, and absent bowel sounds. In the left inguinal area, a tennis ball-sized hernia with purplish blue skin discoloration was still visible. Palpation tenderness of the hernia and the lower abdomen was present. e rest of the physical examination was inconspicuous. Laboratory tests revealed no abnormalities (C-reactive protein (CRP) < 1 mg/l, white blood cell count 9.4 × 10 9 /l). A computed tomography (CT) scan detected free air in the femoral hernia sac and abdomen, suggesting bowel perforation ( Figure 1). e clinical presentation and the CT ndings were indicative for laparotomy. Six hours post trauma, emergency laparotomy revealed a circumferential tear of the sigmoid colon accompanied with intra-abdominal perforation. e left inguinal fossa was contaminated with blood and faeces. e subphrenic site and the space between the bowel loops were free of neither faeces nor purulent uid. A segmental sigmoid resection of 22 cm and a primary end-to-end colorectal anastomosis were performed. Optimal conditions with vital and uncontaminated bowel segments with excellent arterial perfusion justi ed omitting a diverting stoma. Following extensive lavage, the abdomen was closed leaving   Case Reports in Surgery a drain. e postoperative course was complicated by delayed oral feeding and a local infection. Ten days after emergency laparotomy, the local conditions needed a surgical revision. e ndings included a well-healed anastomosis as well as a partially necrotic left testicle, which had to be removed in an additional inguinal approach. e skin wound healed by secondary intention. With subsequent parenteral nutrition and simultaneous oral feeding, the patient was discharged 32 days after the accident and recovered fully until follow-up three months later.

Discussion
is case demonstrates that a simple hernia can be complicated by an uncommon and potentially dangerous trauma. In the English literature, we found only few reports on bowel perforation due to blunt trauma in the presence of inguinal hernias (Table 1). High pressure in the hernia sac combined with shearing injury of an irreducible hernia by direct blunt trauma may be causative. Reynolds described in 1995 how incoming and outgoing bowel loops are compressed on direct trauma to an inguinal hernia [14]. In an experimental setup, a pressure of 150-260 mmHg was sufcient to rupture a closed intestinal loop segment. A sudden blunt impact by, for example, an elbow to a gas-lled pouch could generate pressure peaks greater than 300 mmHg [14]. In the present case, the sudden external pressure applied to the sealed loop in the hernia by falling onto the handlebar must have generated su cient intraluminal pressure to cause perforation. Femoral hernias may be even more prone to such complications than inguinal hernias, as femoral hernias tend to be immobilized in the hernia sac, and they may also less easily slide back than inguinal hernias. e outcome after surgery for colonic perforation is associated with high morbidity and mortality [15]. e most important determinant for the outcome is time to surgery [16]. Faria et al. analysed the American Society of Anaesthesiologists (ASA) classi cation, New Injury Severity Score (NISS), and the presence of colonic lesions and identi ed them as independent prognostic factors for postoperative morbidity. In case of severe faecal peritonitis, colostomy may be considered [17]. Robles-Castillo et al. compared primary closure to colostomy for treatment of traumatic colon injury and concluded that it should be case speci c [18]. Chol and Lim showed that laparoscopy is a safe, feasible, and e ective procedure for the evaluation and treatment of haemodynamically stable patients with abdominal trauma [19]. However, in cardiopulmonary unstable patients with high probability for intra-abdominal injuries, primary laparotomy is mandatory. Once decided, surgical intervention should occur without delay, as it is crucial to shorten the time for intraperitoneal contamination and associated morbidity.

Conclusion
Preexisting inguinal or femoral hernias render the bowel more vulnerable to direct physical trauma potentially resulting in a life-threatening bowel perforation. is is one reason more to consider surgical repair in t patients. In case of groin trauma, even if unspectacular, and subsequent signs of local peritonitis, the possibility of bowel perforation due to a preexisting hernia should be thought of and adequate diagnosis by CT scan should follow.
Disclosure is manuscript was presented as an abstract on ECTES-Abstracts 2017 and presented as a poster on "Digital Poster Presentation SGC-SSC Congress 2017."

Conflicts of Interest
e authors declare that they have no con icts of interest.