As we enter the summer heat again, the roadside barbecue stalls are inundated with all kinds of food, lamb skewers, beer, spicy crayfish, cold drinks, etc., etc. With this comes a significant increase in the incidence of various anorectal diseases, such as perianal abscess, hemorrhoids, necrotizing fasciitis. Today we are talking about necrotizing fasciitis, an acute and serious anorectal condition. What is necrotizing fasciitis?
Necrotizing fasciitis is also known as “scrotal fulminant gangrene”. Perianal necrotizing fasciitis is a rare soft tissue infection characterized by extensive and rapid necrosis of the subcutaneous tissue and fascia, often accompanied by systemic toxic shock. The disease is a mixed infection of multiple bacteria, with the important feature that the infection only damages the subcutaneous tissue and fascia and does not involve the muscle tissue at the site of infection. Patients often die from sepsis and toxemia if not treated promptly.
How necrotizing fasciitis occurs
Perianal necrotizing fasciitis is often a mixed infection of multiple bacteria, including Streptococcus hemolyticus, Staphylococcus aureus, gram-negative anaerobes, and streptococci. With the development of anaerobic culture techniques, it has been confirmed that anaerobic bacteria are an important pathogenic organism, and perianal necrotizing fasciitis is often the result of the synergistic effect of aerobic and anaerobic bacteria. Perianal necrotizing fasciitis is often associated with systemic and local tissue immune impairment, such as minor skin injuries secondary to abrasions, contusions, insect bites, post-appendectomy, post-colonic surgery, and poor drainage of perianal abscesses are also very prone to perianal necrotizing fasciitis.
What are the symptoms of necrotizing fasciitis?
The onset of the disease is rapid, and the early local signs are often not noticed by the patient because they are relatively insidious, but can spread to the whole limb within 24 hours.
1. Local symptoms
(1) Patchy redness and swelling, painful early skin redness and swelling, purple-red flakes, unclear borders, pain. At this time, the subcutaneous tissue has been necrotic, because the lymphatic pathways have been rapidly destroyed, so there is little lymphangitis and lymphadenitis. The infection can spread to the entire limb within 24 hours. The affected skin is red or white and edematous, with obvious tenderness and indistinct lesion borders in the form of diffuse cellulitis.
(2) Pain relief and numbness of the affected area Due to the stimulation of inflammatory substances and the invasion of germs, there is severe local pain in the early infection. When the sensory nerves at the site of the lesion are destroyed, then the severe pain can be replaced by numbness or paralysis, which is one of the characteristics of the disease.
(3) Strange-smelling bloody exudate subcutaneous fat and fascial edema, exudate is sticky, cloudy, black, and eventually liquefied and necrotic. The exudate is a bloody plasma fluid with a strange odor. The necrosis spreads widely and is subterranean, sometimes producing subcutaneous gas, and may be twisted on examination.
(4) Cutaneous blood blisters Sometimes patients appear typical, scattered cutaneous blood blisters of different sizes, which ulcerate to reveal the black dermis.
2.Symptoms of systemic toxicity
In the early stage of the disease, when the local infection symptoms are still mild, patients have severe systemic toxic symptoms such as chills, high fever, anorexia, dehydration, impaired consciousness, hypotension, anemia and jaundice. If not treated in time, diffuse intravascular coagulation and toxic shock may occur. Apathy and unresponsiveness.
Examination
1.Blood routine
(1) Red blood cell count and hemoglobin measurement Due to the inhibition of bone marrow hematopoietic function by bacterial hemolytic toxins and other toxins, 60% to 90% of patients have mild to moderate decrease in red blood cell and hemoglobin count.
(2) The white blood cell count shows a leukemia-like reaction with elevated white blood cell count, mostly between (20-30) × 109/L, with leftward nuclear shift and toxic granules.
2. Serum electrolytes
Low blood calcium may appear.
3.Urine examination
(1) Urine volume and urine specific gravity appear as oliguria or anuria when fluid supply is sufficient, and urine specific gravity balance, etc., which help to judge the early damage of kidney function.
(2) Urine protein qualitative urine protein positive indicates the presence of damage to the glomerulus and tubules.
4.Bacteriological examination of blood
(1) Smear microscopy to take the secretion and blister fluid from the edge of the lesion and do smear examination.
(2) Bacterial culture to take the secretion and blister fluid for aerobic and anaerobic bacteria culture respectively, no Clostridium difficile was found to help the judgment of this disease.
5.Serum antibody
The presence of streptococcal-induced antibodies in the blood (hyaluronidase and deoxyribonuclease B released by streptococci can induce the production of high titers of antibodies) is helpful for diagnosis.
6.Serum bilirubin
Elevated serum bilirubin indicates the presence of erythrocyte hemolysis.
7.Imaging examination
(1) X-ray radiographs show gas in the subcutaneous tissue.
(2) CT shows small bubble shadow in the tissue.
How to treat
1.Local treatment
The key to treatment is to remove the necrotic fascia early and make multiple incisions in the affected area. Make the wound fully open, then drain and flush with hydrogen peroxide or potassium permanganate solution to increase the redox potential difference of the wound tissue and create conditions unfavorable to the propagation of anaerobic bacteria to control the continued spread and diffusion of infection. Then wet dressing with gauze soaked with antibiotic solution, and change the medication every 4-6 hours. The presence of skin, subcutaneous tissue and deep fascial separation needs to be probed at the time of dressing change to determine whether further expansion of drainage is needed.
2.Systemic treatment
(1) Antibiotics and then wet dressing with gauze soaked with antibiotic solution, change every 4 to 6 hours. When changing the dressing, it is necessary to explore whether there is any separation of skin, subcutaneous tissue and deep fascia to decide whether further expansion of drainage is needed.
(2) Supportive treatment actively corrects the water and electrolyte disorders. In case of anemia and hypoproteinemia, fresh blood, albumin or plasma can be transfused; adequate caloric intake can be ensured by nasal feeding or intravenous high nutrition, elemental diet, etc.
Prognosis
1.If the disease is treated in time, the patient can be turned into a safe and even cured.
2.If treatment is not timely, patients often die from sepsis and toxemia.
Prevention
1.Surgical operation is standardized to prevent secondary infection. Antibiotics must be applied in a timely manner after surgery, and if gastrointestinal surgery or perianal abscess surgery is performed, anti-anaerobic bacteria drugs should be given appropriately. Perianal abscess incision and drainage must be unobstructed.
2.Control blood sugar before surgery.
3.Give systemic drug support to increase immunity after surgery if necessary.