An abscess is a pocket of pus. You can get an abscess almost anywhere in your body. When an area of your body becomes infected, your body's immune system tries to fight the infection. White blood cells go to the infected area, collect within the damaged tissue, and cause inflammation. During this process, pus forms. Pus is a mixture of living and dead white blood cells, germs, and dead tissue.

Bacteria, viruses, parasites and swallowed objects can all lead to abscesses. Skin abscesses are easy to detect. They are red, raised and painful. Abscesses inside your body may not be obvious and can damage organs, including the brain, lungs and others. Treatments include drainage and antibiotics.

Accumulation of purulent material in tissues, organs, or circumscribed spaces, usually associated with signs of infection.

Subtypes:

• Abdominal Abscess
• Brain Abscess
• Epidural Abscess
• Lung Abscess
• Periapical Abscess
• Periodontal Abscess
• Peritonsillar Abscess
• Psoas Abscess
• Retropharyngeal Abscess

Introduction

Incision and drainage (I&D) is a widely used procedure in various care settings, including emergency departments and outpatient clinics. It is the primary treatment for skin and soft tissue abscesses, with or without adjunctive antibiotic therapy. This activity will focus specifically on its use in the management of cutaneous abscesses. Based on 2013 data from the CDC, cutaneous abscesses accounted for about 2% of all presentations to the emergency department. The same data reports that 0.9% of all patients who presented to the emergency department underwent incision and drainage. In the pediatric population, the incidence of skin and soft tissue infection (SSTI) has increased, and hospitalization due to SSTI doubled in the last 20 years. As such, being well versed in I&D is essential for clinicians in both the adult and pediatric care settings.

Anatomy and Physiology

Cutaneous abscesses are localized collections of pus that occur within the dermis and subcutaneous space. They occur virtually anywhere on the body; however, common locations for an abscess to develop are the groin, buttocks, axillae, and extremities.

In most cases, a cutaneous abscess can be diagnosed clinically on the basis of physical examination alone. The classic characteristics of an abscess are erythema, induration, tenderness to palpation, and fluctuance. Care must be taken to differentiate between cellulitis and abscess, as the treatment for cellulitis is antibiotic therapy without drainage. Typically an abscess will be fluctuant on exam, whereas this is not a feature of cellulitis. In cases of equivocal clinical findings, ultrasonography can be used to assess for the presence of an abscess, in addition to providing information on size and location.

Studies have been done to compare the use of physical exam and ultrasonography in the detection of an abscess. A prospective study in the pediatric population revealed that in cases when abscesses could not be diagnosed clinically, bedside ultrasound had higher sensitivity and specificity than the exam alone. In the same study, there was no difference in sensitivity and specificity between exam and ultrasound when the abscess was diagnosed clinically. In terms of differences in outcomes (i.e., treatment failure), there is a study that assessed treatment failure rates ten days after I&D. Patients who were diagnosed by ultrasound in addition to physical exam had lower treatment failure rates ten days after I&D in comparison to patients who were evaluated by exam alone. This suggests that performing an ultrasound to evaluate for abscess improves treatment outcomes; this is, of course, reliant on the availability of experienced technicians and radiologists.

Indications

Most patients with an abscess should have incision and drainage performed, as antibiotic therapy alone is not sufficient for treatment. In cases of small fluid collections, conservative management with antibiotics, in addition to the manual expression of pus can be considered.

Contraindications

Possible contraindications to bedside incision and drainage include large and deep abscesses, the presence of a pulsatile mass at the site of infection, proximity to the vasculature and nervous structures, the presence of a foreign body, and particular locations of an abscess.

Certain locations on the body make bedside incision and drainage more technically difficult to perform, whether due to the inherent sensitivity of the area (e.g., the palms, soles, and face) or associated complications. Examples of locations that warrant evaluation by surgery due to a high potential for complications include perirectal and periareolar abscesses, which could be complicated by fistula formation. An otolaryngologist should evaluate neck abscesses that could potentially have developed from preexisting cystic lesions.

Consider also the need for prophylactic antibiotics in patients with abnormal or artificial heart valves as this may delay the procedure. Additionally, it is prudent to inquire about underlying bleeding disorders and to determine a history of allergy to lidocaine, epinephrine, or latex if using latex gloves.

Equipment

Generally, the following sterile equipment is required for a safe and successful procedure: cleansing agent (typically povidone-iodine or chlorhexidine), a local injectable anesthetic agent (1% or 2% lidocaine, lidocaine with epinephrine, or bupivacaine), 5 to 10 mL syringe with 25 to 40 gauge needle, 4x4 gauze, scalpel blade with a handle, curved hemostat, normal saline solution with large syringe/splash guard/bowl for irrigation, packing material (iodoform or plain gauze), swabs for wound culture (if desired), scissors and tape for dressing the wound.

Incision and drainage is a painful procedure that, in addition to local anesthetic, may also require oral or even parenteral analgesia.

Personnel

The procedure is relatively simple and is often performed by a single clinician.

In certain situations, the presence of support staff may be warranted. In the pediatric population, child life services can play a critical role in facilitating a successful procedure. Child life specialists are professionals whose role is to provide emotional support to children and families in a health care setting. A recent study published in pediatric emergency medicine evaluated the impact of child life on the emotional response of pediatric patients who underwent laceration repair in the emergency department. Comparing children who underwent the procedure without the presence of these specialists with children assisted by child life, those with support were found to have less emotional distress during the procedure.

Preparation

Informed consent from the patient or the patient’s legal guardian must be obtained before the procedure. Risks including bleeding, pain and possible scar formation should be relayed. The verification of tetanus immunization status is also an important step in preparation.

The clinician performing the procedure should follow universal precautions that include wearing a gown, gloves, and a facemask or goggles for protection. Although I&D is not considered a sterile procedure (given that the area of interest is already infected), it is prudent to practice sterile precautions.

Technique or Treatment

Holding the scalpel with a steady grip, an incision is made directly over the center of the abscess until pus is expressed. The incision should be made parallel to skin tension lines in order to prevent scar tissue formation. A curved hemostat can then be used for blunt dissection to further disrupt loculations within the infected cavity. Manual expression can be used to facilitate drainage as well. After the abscess is drained, the wound should be copiously irrigated with sterile normal saline solution. Wound packing is not recommended for abscesses that are 5 cm or less in diameter, as it has not been shown to affect outcomes and may contribute to increased pain. Furthermore, packing has not been shown to reduce the risk of abscess recurrence.

The next step is to cover the site with sterile dressing and tape. A follow-up visit is advised 2 to 3 days after the procedure for removal of the packing. Wounds are then left to close by secondary intention.

An alternative to I&D is needle aspiration, though this is much less commonly used, given that it is both more invasive and less effective than I&D. In a randomized clinical control trial comparing outcomes with I&D to ultrasound-guided needle aspiration, the overall success of producing purulent drainage with needle aspiration was 26% compared to an 80% success rate in patients who underwent I&D.

Another alternative to conventional incision and drainage is the loop drainage technique, which may reduce pain and scarring at the site of infection. Studies suggest that loop drainage is associated with a lower failure rate than conventional therapy, although it is not yet a widely used procedure.

Complications

Typically I&D is well tolerated with pain being the most common complication. Inadequately drained abscesses can lead to the extension of the infection into adjacent tissues and worsening of clinical status.

Clinical Significance

As stated, incision and drainage is a common procedure in a variety of care settings. It is the standard of treatment for subcutaneous abscesses, with or without adjunctive antibiotic therapy.

Enhancing Healthcare Team Outcomes

The successful treatment of skin abscesses is not limited to clinician proficiency in performing incision and drainage. Often patients will understandably have questions regarding disease recurrence and prevention, and there is a significant amount of research to address these topics.

Although bacterial etiology was not discussed in this article, skin and soft tissue infections are many times caused by Staphylococcus aureus, with the prevalence of MRSA increasing. IDSA (Infectious Diseases Society of America) guidelines on the management of skin and soft tissue infections due to MRSA discuss measures to prevent recurrence. These guidelines are derived from important research performed by not only physicians but other integral members of the healthcare team as well. There have been multiple publications by nursing on the subject of recurrence prevention. The results of these studies support IDSA guidelines of proper hand hygiene and post-drainage MRSA decolonization with mupirocin. It is important to recognize that standards of care are the result of interprofessional efforts.

While the microbiota of the skin can play a protective role, it can also cause harm in certain cases. Often, an opportunistic pathogen residing in the skin microbiota of one individual may be transmitted to another individual more susceptible to an infection. For example, methicillin-resistant Staphylococcus aureus (MRSA) can often take up residence in the nares of health care workers and hospital patients; though harmless on intact, healthy skin, MRSA can cause infections if introduced into other parts of the body, as might occur during surgery or via a post-surgical incision or wound. This is one reason why clean surgical sites are so important.

Injury or damage to the skin can allow microbes to enter deeper tissues, where nutrients are more abundant and the environment is more conducive to bacterial growth. Wound infections are common after a puncture or laceration that damages the physical barrier of the skin. Microbes may infect structures in the dermis, such as hair follicles and glands, causing a localized infection, or they may reach the bloodstream, which can lead to a systemic infection.

In some cases, infectious microbes can cause a variety of rashes or lesions that differ in their physical characteristics. These rashes can be the result of inflammation reactions or direct responses to toxins produced by the microbes. It is important to note that many different diseases can lead to skin conditions of very similar appearance; thus the terms used in the table are generally not exclusive to a particular type of infection or disease.

An abscess located in the abdominal cavity, i.e., the cavity between the diaphragm above and the pelvis below. (From Dorland, 27th ed)

Introduction

Abdominal cavity infections commonly arise following the inflammation or disruption of the gastrointestinal tract. Less frequently, they might originate from the gynecologic or urinary tract. Abdominal infections are typically polymicrobial and result in either an intra-abdominal abscess and phlegmon in more localized cases or secondary peritonitis in more diffuse conditions.

An abdominal abscess is a collection of cellular debris, enzymes, and liquefied remains from an infection or non-infectious source. An intra-abdominal abscess usually signals that something serious is happening to the patient. In many cases, the omentum, viscera, or mesentery may wall off an intraabdominal abscess. An abdominal abscess is quite common and is a serious condition. To avoid high morbidity and mortality, the condition must be promptly diagnosed and treated. In general, sepsis that occurs after perforation in the upper gastrointestinal (GI) tract or leak is often associated with less morbidity and mortality compared to leaks that result from a colonic perforation or injury.

Etiology

Intra-abdominal infections usually occur following the breach in the mucosal defense barrier that would cause the normal bowel flora to inoculate the abdominal cavity. The microbiological spectrum depends on the specific gastrointestinal source, including the small versus large intestine.

Four to six main colonic flora are generally common in intra-abdominal abscesses and infections, reflecting the frequency of associated diseases originating from this anatomic site, including, but not limited to acute appendicitis, complicated diverticulitis, colon malignancies, inflammatory bowel disease, and former colon surgeries. Accordingly, the predominant organism involved in such infections is coliforms bacteria (including Escherichia coli, Klebsiella spp, Proteus spp, and Enterobacter spp), streptococci, enterococci, and the spectrum of anaerobic bacteria. However, Bacteroides fragilis and E. coli are the two major organisms isolated from abdominal cavity infections and abscess formations. B. fragilis, as an obligate anaerobic gram-negative bacillus, is a highly invasive anaerobic pathogen in abdominal infections.

Considering the phases of the early abdominal sepsis and intra-abdominal abscess, coliform bacteria mainly contribute to early sepsis and anaerobes implicated in the late sequelae and complications with abscess formation.

Perforation of the proximal intestines and peptic ulcer results in ubiquitous infections with aerobic and anaerobic gram-positive bacteria or Candida spp. Several critical points in the past medical history review enable the diagnosis of the possible culprit. Accordingly, the history of former antimicrobial therapy and exposures are associated with microbiologic alterations in the gut flora. Therefore, intra-abdominal infections in such settings are more likely nosocomial pathogens, including Pseudomonas aeruginosa and other drug-resistant organisms. Specific organisms, including Enterococci, are more likely to be found in hospital-acquired settings than in community-acquired infections.

Moreover, candida infections have been reported in both the small and large intestines-originated infections, particularly in the following patient groups; 1. history of antibiotic therapy, 2. immunocompromised patients, and 3. history of recurrent infection.

Collectively, the most common organisms cultured from an abdominal abscess includes aerobic and anaerobic bacteria originating from the gastrointestinal tract. Most intra-abdominal abscess formations result from perforations in the GI tract, including complicated peptic ulcer disease, appendicitis, and diverticulitis, or chronic complications related to pancreatic necrosis, ischemic bowel disease, and anastomotic leaks. Moreover, penetrating abdominal trauma, including stab wounds, gun-shot wounds, post-operative surgical complications with anastomotic leaks, sigmoid and less-commonly cecal volvulus, intussusception, retained cholelithiasis, and fistula formations due to gallstone ileus might cause an abdominal abscess. However, rarely do injections result in abdominal sterile abscess formation. Therefore, organisms involved in an abdominal abscess could be summarized as the following: 1. Escherichia coli, 2. Bacteroides, 3. Neisseria, 4. Chlamydia, and 5. Candida.

Epidemiology

In most cases, intra-abdominal abscesses derive from an intra-abdominal organ and often develop after operative procedures. It is estimated that about 70% are postsurgical and that 6% of patients undergoing colorectal surgery may develop a postoperative abscess. Hepatic abscesses account for 13% of all intra-abdominal abscesses. Most hepatic abscesses involve the right lobe, probably due to the larger size and greater blood supply. Complicated intra-abdominal infections (cIAIs) originate from the three most frequent organ-specific reasons for patients admitted with septic shock, with mortality rates of up to 40%.

Pathophysiology

An intra-abdominal abscess may be confined or generalized within the peritoneal cavity. Localized collections of pus may have a barrier that may include adhesions, omentum, or other adjacent viscera. In almost all cases, abdominal abscesses contain a polymicrobial collection of both aerobic and anaerobic organisms from the GI tract. The bacteria usually incite an inflammatory reaction that often results in a hypertonic environment that continues to expand as an abscess cavity. If left untreated, an abdominal abscess can lead to septic shock.

Anaerobic infections originate from the leakage of endogenous bacteria into the affected cavity. However, disturbed host defense mechanisms would allow the anaerobic organism to be displaced.

History and Physical

Patients with an intra-abdominal abscess may present with abdominal pain, fever, anorexia, tachycardia, or prolonged ileus. The presence of a palpable mass may or may not be present. If the presentation is delayed, some individuals may appear in septic shock.

If the abscess is retroperitoneal or located deep in the pelvis, there may be no clinical signs. In such cases, the only suspicion may be a fever, mild liver dysfunction, or prolonged ileus.

In post-surgery patients, the diagnosis of an abdominal abscess is difficult because of analgesia and antibiotics, which often mask the signs of an infection.

A subphrenic abscess may present with shoulder tip pain, hiccups, or atelectasis.

Most patients with an abdominal abscess will show signs of dehydration, oliguria, tachycardia, tachypnea, and respiratory alkalosis.

The following clues imply that anaerobic infections are the leading cause of abdominal abscess formations; 1. putrid odor, 2. gas formation with the crepitus sensation in palpation and the vascular structure, including the hepatic-portal venous gas formation, 3. gram staining of the aspirate, indicating a polymicrobial flora, or anaerobes, 3. classic presentations of clostridial syndromes, including but not limited to necrotizing enteritis.

Evaluation

Blood work is not specific for an intra-abdominal abscess but may reveal leukocytosis, abnormal liver function, anemia, or thrombocytopenia. These are features that signal an infection. Blood cultures are often negative but, when positive, may reveal predominantly anaerobic organisms, the most common being Bacteroides fragilis.

Plain abdominal x-rays are not sensitive for identifying an intraabdominal abscess; hence a CT scan is required and is considered the most definitive test to rule out an intra-abdominal abscess. A CT scan can reveal the location, size, and presence of bowel thickening, thumbprinting, and ileus. Intra-abdominal abscess almost always requires intravenous (IV) antibiotics. If the abscess is localized, CT-guided aspiration can be performed to drain the abscess. CT scan has the advantage that it avoids general anesthesia and wound complications. It also prevents contamination of other parts of the abdominal cavity.

In some patients, ultrasound may help identify abdominal abscesses.

Nuclear scans are rarely used today to detect abscesses because the technique is time-consuming and has a high rate of false positives.

Treatment / Management

Broad-spectrum antibiotics and hydration are essential. Once cultures become available, one can use specific antibiotics, as noted by their sensitivity. Intravenous hydration is required. A nasogastric tube may help decompress the bowel and lower the emesis.

Percutaneous CT-guided drainage is widely used to drain abdominal abscesses. The procedure can be done under local anesthesia and decreases the duration of hospitalization. In most patients, improvement occurs within 48 hours after drainage. In localized abscesses, CT-guided drainage has a success rate of over 90%.

Percutaneous abscess drainage (PAD) has been a widely approved treatment modality for accessible postoperative intra-abdominal abscesses. Percutaneous drainage in managing inta-abdominal abscesses (IAA) was first introduced in the 1970s. The preliminary outcomes showed a success rate of up to 86%. The contributing factors in the success rate of percutaneous drainage in managing IAA have not been well established yet. However, according to some research on adult patients with a single appendicular abscess, the success rate was higher than those with multiple abscesses. On the other hand, the favorable results of the non-operative management of appendicular abscesses in the pediatric population have been well-documented. It should be noted that the major factor affecting the success rate in the pediatric population is the abscess size of less than 4 cm.

The threshold for percutaneous drainage interventions in IAA differs according to the abscess origin, and an abscess size of 3 to 6 cm is generally accepted as a cutoff for diverticular abscess treatments.

If the patients fail to improve within 24 to 48 hours, surgical consultation is required. Both laparoscopic, interventional radiology and open procedures can be used to evacuate the abdominal abscess. However, if surgery is required, the necrotic tissue will be removed, and all adhesions can be lysed. Most of these patients require monitoring in the intensive care unit (ICU) and need aggressive resuscitation with fluids. If the abscess is localized and promptly treated, the prognosis is good.

A pelvic abscess may be drained transrectally or transvaginally. Pelvic abscesses present a serious and challenging management problem. Endoscopic ultrasound (EUS)-guided drainage provides a safe and effective minimally invasive treatment option. The likelihood of a successful outcome is dependent on appropriate patient selection, drainage technique, and postoperative management.

Open surgery for an abdominal abscess is a difficult undertaking and can be difficult because of adhesions and the lack of proper anatomical pathways to separate the bowel.

As with most abscesses and contained infected spaces, drainage is the definitive treatment of a subdiaphragmatic abscess. It prevents progressive sepsis. It can be accomplished either by percutaneous or surgical drainage. Percutaneous drainage is the least invasive and just as effective as surgical drainage and is currently the standard of care. CT-guided drainage with interventional radiology is highly effective and can prevent the morbidity and mortality associated with surgical drainage.

Percutaneous computed tomography (CT)-guided drainage is considered the gold standard in management and has a very high success rate. The advantages include that it avoids general anesthesia, especially in the elderly with multiple comorbidities, prevents complications of the surgical wound, and reduces the length of hospitalization. Percutaneous drainage can be used as both a diagnostic and therapeutic modality. Especially in critically ill patients, it can be used to control sepsis and improve the general condition of the patient before definitive surgical treatment. Persistent drainage usually suggests the presence of an enteric fistula, which can be diagnosed with a contrast CT. Complications include bleeding, injury to nearby visceral organs, pleural effusion, pneumothorax, and mediastinitis. Hence, transmural drainage has been developed using endoscopic ultrasound (EUS-TD). It is beneficial due to real-time visualization of the abscess cavity, a doppler to avoid major vessels, and a high success rate. Trans-esophageal and trans-gastric approaches have been tried to drain the subphrenic abscess.

If percutaneous or endoscopic drainage fails, then surgical drainage, either by an open or laparoscopic method, is indicated. Laparoscopic drainage is minimally invasive and permits exploration of the abdominal cavity without the use of a wide incision, and hence purulent exudate can be aspirated under direct vision. If the patient does not improve with the laparoscopic technique, an open surgical technique should be considered. The open approach may be difficult due to adhered bowel, loss of anatomic delineation, and fragile viscera. Of late, there has been increased use of open abdomen therapy (OAT), mainly in managing abdominal compartment syndrome and trauma patients. The concept of damage control surgery is being used. The use of a vacuum dressing to close the abdomen is preferred.

Most patients with a timely intervention will recover with supportive care like intravenous hydration. Patients who worsen and develop septic shock will need admission to the intensive care unit. Need for multiorgan support like mechanical ventilation, vasopressors, and dialysis will be needed in patients with significant organ failures.

Differential Diagnosis

• Prolonged ileus
• Fever of unknown origin
• Crohn disease
• Ulcerative colitis
• Complicated perianal infection
• Perforated colon cancer
• Diverticular abscess

Prognosis

The prognosis of patients with an abdominal abscess before the era of the CT scan was very high. Today, with the availability of CT scans, the diagnosis is made much earlier, and, in many cases, CT-guided drainage has helped lower morbidity. However, if an abdominal abscess is misdiagnosed and not treated, the mortality is very high. Risk factors that increase mortality and morbidity include the following:

• Advanced age
• Multi-organ failure
• Multiple recent surgeries
• Complex abscess
• Delay in diagnosis

Complications

An abdominal abscess can lead to the following complications:

• Multiorgan failure
• Formation of fistula
• Septic shock
• Both CT-guided drainage and surgery can lead to bowel perforation
• Death
• Deep vein thrombosis
• Malnutrition

Postoperative and Rehabilitation Care

Patients with an abdominal abscess usually require a stay in the hospital. Repeat imaging is often done to ensure that there is no more residual abscess after treatment.

Depending on the complexity of the abscess, some patients may require total parenteral nutrition.

Because the patients are often frail, physical therapy is recommended to help recover muscle strength and flexibility.

Consultations

Once a diagnosis of an abdominal abscess is done, a general surgeon and a radiologist should be consulted.

Pearls and Other Issues

Those with gross contamination of the abdominal cavity can develop multiorgan failure and consequently have a high mortality rate.

Today with the availability of CT scans, diagnosis and drainage can be accomplished with very low morbidity.

A complex abscess may require a laparoscopic or an open approach.

Enhancing Healthcare Team Outcomes

An abdominal abscess is not an uncommon presentation on the general surgery ward or in the emergency department. Because of its vague clinical presentation, the disorder is best managed by an interprofessional group of health professionals that includes a surgeon, dietitian, pharmacist, radiologist, gastroenterologist, and a wound care nurse. An abdominal abscess has significant morbidity and can rapidly become fatal if left untreated. To improve outcomes, communication between the interprofessional team is highly recommended.

While initial antibiotics are broad-spectrum, the pharmacist and clinicians need to watch the blood cultures to determine the type of organisms growing and their sensitivity. In many cases, patients with an abdominal abscess may not be able to eat and may require peripheral or central parenteral nutrition hence, a dietary consult should be involved. While there are no universal guidelines on the management of an abdominal abscess, the current consensus indicates that percutaneous drainage by a radiologist has low morbidity compared to an open procedure.

All patients with an abdominal abscess need close monitoring as they can quickly become septic. The nursing responsibility lies in measuring vital signs, urine output, pressure sore prevention, DVT prophylaxis, ambulation, and timely antibiotics. Any change in the patient's clinical status should be immediately communicated to the clinician.

There should not be any delay in consulting with the surgeon, as delay can lead to adverse outcomes and significant healthcare costs. Many of these patients also develop wound infections that do not heal. Hence a consult with a wound care nurse for daily dressings is necessary.

The progress and monitoring of patients with an abdominal abscess are made by regular physical exams, vital signs, and imaging tests. Often these patients have drainage devices that also need to be monitored for the type and amount of fluid discharge. Only through a systematic clinical interprofessional team approach can the morbidity and mortality of an abdominal abscess be lowered.(Level III)

Outcomes

The outcomes after an abdominal abscess depend on patient morbidity, the cause, extent of contamination, and age. When multiple organs are involved and the patient is septic, the outcomes are poor. However, for localized abscesses from a rupture of an appendix or sigmoid diverticulitis, the outcomes are good. Many of these patients have significant comorbidity which affects their long-term survival. The key to improving mortality is an interprofessional approach with prompt diagnosis, close monitoring, and early treatment. [Level 5}

Solitary or multiple collections of PUS within the liver as a result of infection by bacteria, protozoa, or other agents.

Accumulation of purulent EXUDATES beneath the DIAPHRAGM, also known as upper abdominal abscess. It is usually associated with PERITONITIS or postoperative infections.

A circumscribed collection of purulent exudate in the brain, due to bacterial and other infections. The majority are caused by spread of infected material from a focus of suppuration elsewhere in the body, notably the PARANASAL SINUSES, middle ear (see EAR, MIDDLE); HEART (see also ENDOCARDITIS, BACTERIAL), and LUNG. Penetrating CRANIOCEREBRAL TRAUMA and NEUROSURGICAL PROCEDURES may also be associated with this condition. Clinical manifestations include HEADACHE; SEIZURES; focal neurologic deficits; and alterations of consciousness. (Adams et al., Principles of Neurology, 6th ed, pp712-6)

Circumscribed collections of suppurative material occurring in the spinal or intracranial EPIDURAL SPACE. The majority of epidural abscesses occur in the spinal canal and are associated with OSTEOMYELITIS of a vertebral body; ANALGESIA, EPIDURAL; and other conditions. Clinical manifestations include local and radicular pain, weakness, sensory loss, URINARY INCONTINENCE, and FECAL INCONTINENCE. Cranial epidural abscesses are usually associated with OSTEOMYELITIS of a cranial bone, SINUSITIS, or OTITIS MEDIA. (From Adams et al., Principles of Neurology, 6th ed, p710 and pp1240-1; J Neurol Neurosurg Psychiatry 1998 Aug;65(2):209-12)

Solitary or multiple collections of PUS within the lung parenchyma as a result of infection by bacteria, protozoa, or other agents.

Abscess of the PSOAS MUSCLES resulting usually from disease of the lumbar vertebrae, with the pus descending into the muscle sheath. The infection is most commonly tuberculous or staphylococcal.

An accumulation of purulent material in the space between the PHARYNX and the CERVICAL VERTEBRAE. This usually results from SUPPURATION of retropharyngeal LYMPH NODES in patients with UPPER RESPIRATORY TRACT INFECTIONS, perforation of the pharynx, or head and neck injuries.

A hair-containing cyst or sinus, occurring chiefly in the coccygeal region.A hair-containing cyst or sinus, occurring chiefly in the coccygeal region.

Introduction

Pilonidal derives its name from Latin- pilus meaning “hair,” and nidus meaning “nest.” The name “pilonidal disease” has been attributed to R.M. Hodges in 1880. The disease was first described in 1833 by O.H. Mayo. Another early reference of the disease, with a description of management, followed shortly after by A.W. Anderson, in 1847. Many U.S. soldiers were diagnosed with pilonidal disease during the wars, and was referred to as “Jeep disease.”

Etiology

Early after its description, many clinicians considered the disease as congenital in origin, being derived from vestiges of the medullary tube, dermoid traction, inclusion dermoid, or preen glands. Currently, pilonidal disease is considered an acquired disease. Patey et al. proposed the hypothesis of pilonidal disease being an acquired disease., suggesting that pilonidal disease results from the suction of hair from surrounding soft tissue and skin, ultimately leading to a foreign body reaction and foreign body granuloma. This proposal of pilonidal disease being an acquired, infective, and foreign body reaction was corroborated by King around the same time.

Karydakis simplified the description of the etiologic process citing three main factors- the hair or foreign body, a force causing deposition of hair into the sinus, and skin vulnerability.

Epidemiology

The incidence of pilonidal disease is estimated to be 26 per 100,000 people and affects men 2.2 times more than women. It is estimated that pilonidal disease affects approximately 70,000 people in the United States annually.

Pathophysiology

The pathophysiology is mostly unknown; the etiology is thought to be related to trapped hair follicles (as noted above).

Histopathology

Microscopically it’s noted that hair within the pilonidal cysts originates from the overlying, surrounding skin; but, the follicles are never found within the wall of the cyst but rather free in granulation and scar tissue. The walls of pilonidal cysts are not lined with squamous epithelium but are composed of vascular pyogenic granulation tissue. In 1984, Stelzner used light microscopy to note hairs obtained from pilonidal pits had a hook architecture and suggested hair migration was unidirectional. Electron microscopy has also been used to evaluate hair involved in the pathogenesis of pilonidal disease; Dahl et al. confirmed the hook morphology and proposed sharp ends contribute to hair piercing the skin, with hooks preventing retraction. Gosselink et al. suggest the orientation of the hair scales likely encourages hair to be driven deeper into the tissue.

History and Physical

Pilonidal disease is a clinical diagnosis based on history, physical exam (including anorectal exam), and evaluation of symptoms and risk factors. Physical exam findings include midline pits in the superior gluteal cleft and may be associated with cephalad or lateral tracking sinuses. Risk factors include male sex, family history, being overweight or obese, trauma or irritation, sedentary occupation or lifestyle, hirsute habitus, and poor hygiene.

Evaluation

Diagnosing pilonidal disease is clinical, and no further labs, tests, or imaging is required. However, imaging may be helpful in cases where the diagnosis is less clear. Imaging modalities have been used to differentiate and/or rule out more significant disease processes and can aid in determining the extent of disease and required excision when combined with surgical treatment.

Methylene blue has been used to evaluate the extent of pilonidal sinuses and can be used in conjunction with surgery. One study found that the use of methylene blue may reduce the long term recurrence rate of pilonidal disease by showing the extent of necessary resection of soft tissue at the time of surgery. Doll et al. studied 247 patients with a mean follow up of about 15 years and found that intraoperative methylene blue had a decreased recurrence rate of 16% vs. 30%. Another study evaluated 33 patients in a prospective randomized trial where methylene blue was injected into each sinus, with subsequent resection of stained areas; microscopic parameters were assessed, but the authors warn that the use of methylene blue to direct surgical excision may cause inadequate excision. This differs from a more recent study assessing the volumes of specimens surgically removed with methylene blue. In a retrospective study looking at 135 specimens, Ardelt et al. found that samples excised using methylene blue had significantly higher volumes facilitating complete resection; interestingly, volumes were also larger in recurrent disease. Modifications to methylene blue have been used to make it more manageable by turning it into a gel with the addition of chloramphenicol ointment.

Ultrasound can be used to evaluate pilonidal disease. Mentes et al. evaluated 73 patients with preoperative ultrasound and found that determining pilonidal disease borders with ultrasonography was consistent with palpation 76.7% of the time, but in the remaining patients, ultrasound detected sinus tracts that exceeded the planned margins of excision with palpation alone. They concluded that ultrasound provides more information in regards to the borders of pilonidal disease when compared to palpation and methylene blue. Both external ultrasound and endoanal ultrasound were found to be useful in evaluating the extent of pilonidal disease and excluding perianal sepsis in a more recent study. This was corroborated with another study using transperineal ultrasound to evaluate for low perianal fistula. When comparing ultrasound findings of pilonidal disease with hidradenitis suppurativa, there were no statistically significant differences in morphological characteristics, but the density of hair tracts was higher in pilonidal disease.

MRI is more expensive and time-consuming than ultrasound but may aid in diagnosis when there is a concern for inflammatory bowel disease, fistula in ano, pelvic sepsis, or neoplastic processes. Recent studies have also suggested a role for a photodynamic eye with indocyanine green for the elucidation of disease extent to aid in resection.

Treatment / Management

Treatment can be divided into two broad categories - nonoperative vs. operative, and often there is a combination of the two. Pilonidal disease is largely considered a surgical disease, especially in acute instances with secondary infection and abscess. Infection or abscess requires incision and drainage. Definitive treatment is delayed the majority of the time if there is an acute infection or abscess until after the infection has been addressed. There are many options when it comes to surgical treatment of pilonidal cysts and pilonidal sinuses. The surgical treatment must be individualized to the patient. Lifestyle changes and modifiable risk factors should be addressed and be incorporated into the treatment algorithm.

Because of the role of hair in the pathogenesis of pilonidal disease, epilation and hair removal may be used as a primary or adjunct treatment, in the absence of abscess. Epilation may take the form of shaving, waxing, laser, or creams.

A study at an Army medical center found that conservative therapy in the form of weekly shaving a 5cm strip from the anus to the rectum, combined with hygiene education, resulted in decreased operations, and near-normal work status. In the treatment of chronic pilonidal disease, Solla et al. found good results when operative techniques were combined with shaving skin weekly or biweekly; patients were advised to keep the gluteal cleft free from hair for three to six months. Despite the rationale for hair removal, there is some evidence that hair removal may actually increase the rate of long-term pilonidal recurrence after surgery.

Laser epilation has been used in pilonidal disease with mixed results. Oram et al. evaluated 60 patients that were treated with laser therapy as an adjunct to surgery and found an overall recurrence rate of 13.3% and concluded laser hair removal after surgery decreases recurrence long-term with a mean follow up of 4.8 years. Conroy et al. evaluated 14 patients who underwent adjunct laser therapy and reported that of the 12 patients who completed the full course of therapy, and none developed recurrence. They recommend that laser depilation should be routinely offered to all patients suffering from pilonidal disease. Other studies have corroborated the effectiveness and safety of laser epilation, which requires multiple treatments. Pain was the most frequent side effect and can be seen in up to 40% of patients.A review study evaluating the effectiveness of laser hair removal included 35 studies and found that the recurrence rate after laser depilation ranged from 0-28%. However, among all five comparative studies, there was a decreased recurrence rate associated with laser hair removal. The authors of the study note the heterogeneity in studies and caution their generalizability. Laser hair removal often requires multiple treatments, can be limited by cost and may require local or topical anesthetic. Some hair removal products may be irritating to the anal mucosa or cause rashes.

Maurice and Greenwood proposed phenol, a sclerosing agent, as a treatment for pilonidal disease in 1964. It has been used in liquid and crystallized forms. It has been employed as a primary nonoperative treatment, as well as an adjunct to surgical treatment. Dogru et al. found success using phenol as an outpatient treatment. They reported a success rate of 95.1%, and had decreased recurrence rates, and decreased lost work time; they propose phenol as a viable first-line treatment. The patients in the study were shaved throughout treatment, and the majority required multiple phenol applications. Kaymakcioglu et al. reported an 8.3% recurrence rate using 80% phenol on a study of 143 patients; the volume of the sinus tract and the number of sinus orifices were risk factors affecting recurrence. A randomized controlled study of 140 patients compared phenol injection with excision and open healing found no significant difference in the recurrence rate. They reported that phenol was associated with decreased time to complete wound healing, less operative procedure time, decreased time to resume daily activities; and, visual analog pain scores and analgesic use were both decreased with phenol, compared to excision and open healing. This was corroborated with another more recent, smaller randomized trial of 100 patients. Pronk et al. compared radical excision with phenol application and found shorter return to normal activities, less pain, and more frequent complete wound epithelialization associated with phenol; they also noted an increased risk of surgical site infection with radical excision. Dag et al. reported early return to work with phenol use, and low rates of recurrence and complications, noting an overall success rate of 67% with only one patient having a recurrence; mean time to complete healing was 16 days, and time off of work was 0 days. There was a higher risk of treatment failure with a history of abscess drainage and greater than three sinus openings. Overall, phenol administration is relatively cheap, can be performed as an outpatient, and has success either as primary nonoperative treatment or adjunct to surgical options. Patients may require multiple treatments with phenol.

Fibrin and thrombin products have also been used for the treatment of pilonidal disease, either as a primary treatment or as adjuncts to surgical techniques. Greenberg et al. proposed using fibrin glue in addition to surgical excision, using the fibrin glue to obliterate the dead space; 30 patients were treated in this fashion, and there were four patients with temporary purulent drainage with an average of 11 days to return to work/ normal activities. A similar method was employed by Seleem et al., which reported primary healing in 24/25 (96%) of patients within two weeks. Patti et al. reported mean healing of 25.8 days, with a mean return to work 5.3 days when using fibrin glue with minimal surgical excision. Randomized control studies have studied the use of fibrin glue. When comparing standard Limberg flap vs. Limberg flap with fibrin glue, it was found that the addition of fibrin glue was associated with decreased drainage volume, and decreased hospital length of stay. A review study determined that the effectiveness of fibrin glue, alone as monotherapy or as a surgical adjunct, was uncertain. The use of fibrin glue appears to have high patient satisfaction, and up to 82% would recommend fibrin glue for the treatment of pilonidal disease.

Another nonsurgical option that has been proposed is platelet-rich plasma (PRP). Platelet-rich plasma is derived from autologous blood that is centrifuged and contains a high concentration of platelets and growth factors; it has been used in many subspecialties for its proposed wound healing properties and regenerative factors. A study by Sevinc et al. evaluated the long term results of a minimally invasive approach to treating pilonidal disease with PRP; their study evaluated 138 patients with a median follow up of 60.2 months. They reported a success rate of 97.1% after the first month with a recurrence rate of 8.2% at 60.2 months; mean healing time was 13.3 days, with 82.6% complete healing after a single application. The methods employed by Sevinc et al. included preparing PRP from 40 cc of the patient’s blood, and once the gel form was obtained, the procedure was performed under local anesthesia in the outpatient setting. There were no complications related to the use of PRP during their study. There has been a meta-analysis evaluating PRP for the treatment of pilonidal disease which included four studies and a pooled 484 patients, which found that the healing time was 36% less than the healing time of the control group which was calculated as 27.1 days in the PRP group versus 43 days in the control arm. They also reported a decreased return to work of 24.99 days in the treatment group versus 34.82 days in the control group.

A prospective randomized clinical trial from Turkey evaluated the benefits of adjunct hyperbaric oxygen, specifically regarding pilonidal disease. They reported a significantly shorter complete epithelization time in surgically excised pilonidal disease, allowed to heal by secondary intention, 50 days versus 83 days.

Pilonidal disease is largely considered a surgical disease, despite the many nonoperative approaches. The mainstay of acute pilonidal disease, or abscess, is similar to any abscess and requires incision and drainage (I&D). An early study looking at simple incision and drainage reported an immediate return to work, with 58% of patients healing within ten weeks; 21% of patients developed recurrence, but the overall cure rate was reported as 76% at 18 months. The incision and drainage procedure prior to definitive surgery has been associated with lower long term recurrence rates. In a study of 583 patients over 20 years, Doll et al. reported a 16% recurrence rate in the I&D group compared to a 34% recurrence in the primary open treatment group, and concluded that a preceding I&D has a better outcome than primary surgical treatment; optimal timing between I&D and surgery was not determined. Often, an incision and drainage procedure will employ the use of wound packing, but in a study of 100 pediatric patients undergoing I&D of subcutaneous abscesses, there was no difference in recurrence rates in those abscess with packing versus no packing, and the discomfort and nuisance of wound packing were avoided.

Surgical options for treating pilonidal disease are numerous and can include “pit picking,” curettage, aspiration, unroofing, or surgical excision. Defects can be closed primarily, with flaps or grafts, or allowed to heal by secondary intention. Another tool used for the healing of surgical treated pilonidal disease is negative pressure wound therapy. A randomized control study of 49 patients comparing negative pressure dressings vs. healing by secondary intention found little difference.

In the early 1980s, Bascom described a technique, cleft lift procedure, to remove the hair follicles parallel to, but to the side of, the natal cleft using local anesthesia. The initial 50 patients averaged a disability of one day, and healing time without disability averaged three weeks; there was a recurrence of four patients that healed in an average of two weeks.The follow-up study of 161 patients reported 94% of patients healed at 0-6 months, and 71% remained healed at 5-9 years. More recently, 31 patients with refractory pilonidal disease were evaluated, and it was reported that 28 patients healed after a single procedure, without recurrence. In a subsequent study, there was a 96% healing rate in 69 patients treated for refractory pilonidal disease.

Karydakis described a technique to excise an ovoid area of pathologic tissue off-midline and provide coverage lateral to the midline by mobilizing a fasciocutaneous flap and securing it to the sacrococcygeal fascia. In his series of >6500 cases, there was a 2% recurrence rate with an 8% complication rate. In a randomized controlled study of 321 patients evaluating the Karydakis flap versus excision and healing via secondary intention, it was found the meantime of wound healing, return to work, rate of wound complications and recurrence were all significantly lower in the group undergoing the Karydakis flap, but operative time was longer; pain was higher on the first operative day, but was significantly less after one week.

Another type of flap used for the treatment of pilonidal disease includes the Limberg or rhomboid flap. The Limberg flap excises the pilonidal disease in a rhomboid shape and rotates a fasciocutaneous flap for wound closure. Bozkurt et al. evaluated the Limberg flap in 24 patients under spinal anesthesia and reported mean hospital length of stay 4.1 days, with an average 17.5 days until return to work; 12.5% of patients had minor complications, and during the follow up (range 6-27 months, mean 18 months), there were no recurrences. A randomized control study comparing the Limberg flap, to primary closure and deep suturing reported improved wound healing, decreased hospital stay, earlier return to work, and decreased recurrence. Another more recent randomized control trial of 200 patients reported less postoperative pain, earlier mobilization, decreased hospital stay, with fewer complications employing the Limberg flap compared to primary closure. Numerous randomized control studies and meta-analyses have compared the Limberg and Karydakis flaps, which have shown to be comparable in outcomes with the exception that the Limberg flap has less risk of seroma formation.

Other flaps include VY advancement flaps and Z-plasty. Small case series have demonstrated the ease and efficacy of a tension-free repair using the VY fasciocutaneous advancement flap. A larger study employing VY advancement in recurrent pilonidal disease reported tension-free repairs with reliable coverage and flattening of the natal cleft; however, 90.7% of patients were dissatisfied with the cosmetic appearance of scars. Z-plasty to treat pilonidal disease was introduced as early as the 1960s. In a randomized control study comparing Z-plasty with I&D or marsupialization, Z-plasty was definitive treatment compared to 40% of the control group requiring further surgery. Fazeli et al. compared Z-plasty with healing by secondary intention and found that wounds healed faster with the Z-plasty, and there were no complications.

Other, less widely used methods of treating pilonidal disease include endoscopic treatment and video-assisted ablation. Endoscopic pilonidal sinus treatment (EPSiT) was introduced as a minimally invasive video-assisted technique, performed under spinal anesthesia or local anesthesia, that uses a fistuloscope to remove hair and debris while performing ablation under direct visualization. In multinational prospective studies, Meinero all reported healing rates of 95%, with the incomplete healing rate being related to the number of external pits; it was deemed to be safe, effective in primary pilonidal disease and recurrent disease, and had good patient satisfaction.

The use of antibiotics for the treatment is controversial. It has been evaluated in regards to perioperative prophylaxis, postoperative treatment, and topical use; the American Society of Colon and Rectal Surgeons provide a “weak recommendation based on moderate-quality evidence, 2B.”

Differential Diagnosis

Pilonidal disease is diagnosed clinically, through history and physical, and the treatment is surgical. If there is concern for other differential diagnoses, imaging modalities can be used. Other conditions on the differential diagnosis include abscess, hidradenitis suppurativa, inflammatory bowel disease (Crohn, ulcerative colitis), anal fistula, or epidural abscess. It can also represent other soft tissue infections like folliculitis, furuncles, or carbuncles. Various types of cancer have been diagnosed as or in conjunction with pilonidal disease.

Pilonidal disease is typically found in the sacrococcygeal region but has been reported in other parts of the body. Benharroch et al. performed a retrospective review of unexpected pilonidal sinus locations and reported pilonidal disease on the penis, scalp, abdomen, neck, groin, and axilla. There have been case reports of pilonidal sinus located on the nasal dorsum, and nose. Pilonidal disease has been found on the vulva and clitoris. Additionally, pilonidal disease has been found on the hand, interdigital, and periungual; often, these patients have a history of occupational exposure as barbers, hairdressers, or animal groomers. Pilonidal disease of the hand has also been reported associated with Dupuytren contracture. Pilonidal disease has been reported in the anal canal, and there may be a higher prevalence of sacrococcygeal pilonidal disease in those patients with ankylosing spondylitis. Epidural abscesses and osteomyelitis may be associated with pilonidal disease and should be included in the differential diagnosis, in rare instances. Tuberculosis has also been reported in association with pilonidal disease. Other infectious processes, such as syphilis and actinomycosis, have been reported as resembling pilonidal disease.

Most surgeons elect to send pilonidal specimens for pathological evaluation. Some authors have questioned the need to perform histologic evaluation, but Tamer et al. reviewed articles spanning 2000 to 2018 and found twenty-two articles reporting 83 patients with malignancy including squamous cell carcinoma, epidermoid carcinoma, basal cell carcinoma, and malignant degeneration; they advise all specimens should be sent for histopathologic evaluation.

Prognosis

The prognosis associated with pilonidal disease is very good as it is a benign disease, despite some reports of malignant degeneration, or skin cancer. Pilonidal disease, however, has a relatively high recurrence rate and may require multiple procedures. The overall prognosis with pilonidal disease is very good with lifestyle modifications and accurate diagnosis.

Complications

Complications associated with pilonidal disease largely include recurrence and wound healing issues such as wound breakdown or surgical site infection. They may initially present as an abscess or can become secondarily infected. In rare cases, pilonidal disease has been associated with osteomyelitis or malignant transformation.

Deterrence and Patient Education

Patients should be educated about risk factors, which include male sex, family history, being overweight/obesity, trauma or irritation, sedentary occupation or lifestyle, hirsute habitus, and poor hygiene. Modifiable risk factors should be directed towards weight loss, lifestyle modification, good hygiene, and hair removal.

Enhancing Healthcare Team Outcomes

Pilonidal disease is a relatively common and benign disease process where surgery is usually the definitive treatment. Certainly, these patients should be evaluated by a surgeon, but they are usually not the first clinician to which a patient presents. Interprofessional communication is necessary as these patients can present to any clinician, primary care provider, or general practitioner. The diagnosis is clinical, so prompt recognition and diagnosis can lead to faster treatment and resolution. Pilonidal disease is a relatively common disease, and there is an extensive amount of published material. This includes various types of studies, including randomized control studies, cohort and case-control studies, case series, and expert opinions. Pilonidal disease is a broad topic, so narrowing the specific question can provide specific publications and research studies. There are numerous treatment modalities and treatment combinations. There is no single best treatment modality, and treatment must be individually tailored to the patient.