Application of point of care ultrasound and relevance of anatomy in necrotizing fasciitis Aplicação ultrassom point of care e relevância da anatomia na Ideas and Innovations

Introduction: Ultrasound is currently being used in intensive care medicine. When not diagnosed and treated quickly, necrotizing fasciitis has a rapid progression and high mortality. The objective is to present the importance of anatomy in necrotizing fasciitis and the use of ultrasound in early diagnosis. Methods: The application of point-of-care ultrasound and the relevance of anatomy in necrotizing fasciitis were presented. Results: The anatomical communications between the fasciae of the scrotal, perineal, penile and abdominal regions allow the spread of the infectious process resulting from Fournier’s gangrene to the adjacent regions. Ultrasound enabled early diagnosis of necrotizing fasciitis. Conclusion: Communications between the fasciae of the scrotal, perineal, scrotal, penis and abdominal regions contributes to the progression of the infectious process resulting from Fournier gangrene and ultrasound permitted earlier diagnose.


INTRODUCTION
Necrotizing fasciitis has high mortality rates when diagnosis and treatment do not occur early, particularly in patients with diabetes mellitus and immunosuppression, which are the main risk factors [1][2][3] .
Necrotizing fasciitis resulting from Fournier's gangrene is characterized by ischemia and thrombosis of the subcutaneous vessels of the scrotal region, resulting in necrosis [4][5][6] , which requires debridement [7][8][9] as soon as the diagnosis is established. Point of care ultrasound has been used successfully in intensive care.

Relevance of anatomy in Fournier's gangrene
The Colles, Buck, dartos, and Scarpa fascial lining layers represented respectively anatomical communications between the fascial lining layers of the perineal, scrotal, penile, and abdominal regions that contribute to the rapid spread of infection in Fournier's gangrene necrotizing fasciitis. Communication between Buck's scrotal lining layer and Scarpa's lamellar layer in the abdomen occurred through continuity with the fascial lining layer of the inguinal region.

DISCUSSION
The infectious process of necrotizing fasciitis resulting from Fournier's gangrene spreads through the continuity of the fasciae, hence the importance of anatomy. The scrotum, a cutaneous pouch that contains the testes and lower parts of the spermatic cord, is made up of two layers, one of skin, superficially, and the other of a thin layer, the dartos, which, anatomically, consists of a layer of smooth muscle, located under the skin of the scrotum. In women, this musculature is less developed and is called dartos mulierbris, being under the skin of the labia majora 3,4 .
Dartos communicates with the superficial muscular fascia of the perineum called Colles' fascia, which lines the muscles of the superficial portion of the perineum. The fascia that lines the cavernous bodies of the penis is called Buck's fascia. Colles' fascia of the perineum has anatomical continuity with Scarpa's fascia, the deep layer of the abdominal wall lining 4,5 . The important communication between Colles' fascia, dartos, Buck's fascia and Scarpa's fascia is responsible for the rapid spread of the infectious process initiated in the perinealscrotal region to the penis and the abdominal wall in the most severe cases.
The delay in defining the diagnosis, late initiation of treatment 6,8 , diabetes mellitus and immunosuppression [6][7][8] were conditions related to increased mortality in Fournier's gangrene. Imaging methods, such as ultrasound and computed tomography, are important diagnostic aids 9,10 . The pathophysiology of Fournier's necrotizing fasciitis is characterized by vessel ischemia and thrombosis, resulting in fascial necrosis 11,12 . After ischemia and thrombosis, bacteria spread, and the anaerobic gasproducing bacteria are responsible for the crepitus found in the first 48 hours of infection 13 , which can develop under the apparently normal skin 14,15 .

OBJECTIVE
The study's objectives are to present the application of point-of-care ultrasound in early diagnosis and the relevance of anatomy in necrotizing fasciitis from Fournier's gangrene.

METHODS
The application of point-of-care ultrasound in early diagnosis and the relevance of anatomy in necrotizing fasciitis were studied, through a careful evaluation of the literature, including scientific articles based on PubMed, VHL, SciELO and Lilacs databases, as well as books established in the literature. The descriptors used were: Fasciitis Necrotizing, Anatomy, Ultrasound, Surgery and Plastic Surgery.

Application of point of care ultrasound in the early diagnosis of necrotizing fasciitis
The application of ultrasound in necrotizing fasciitis consisted of using acoustic window concepts to visualize the presence of thickening of the affected fascia associated with gases, which may be present in the first 48 hours of necrotizing fasciitis evolution. The use of ultrasound enabled the early diagnosis of necrotizing fasciitis, followed by initiation of antibiotic therapy and surgical treatment, with a consequent reduction in mortality. (Figure 1). The application of ultrasound has shown great growth today, especially in anesthesia and intensive care. In anesthesia, ultrasound has helped to locate nerves during peripheral blocks. In intensive care medicine and trauma, ultrasound is highlighted in diagnosing pleural effusion, pneumothorax and cardiac alterations during cardiogenic shock [30][31][32] . In the present study, the application of ultrasound was important in the early diagnosis of necrotizing fasciitis, enabling the rapid initiation of treatment.

CONCLUSION
Anatomical communications between the lining layers of the perineum, scrotum, penis, inguinal, and abdomen regions contribute to the progression of infection in Fournier's gangrene necrotizing fasciitis. The application of ultrasound allowed the early diagnosis of infection in necrotizing fasciitis, allowing the rapid initiation of treatment with antibiotic therapy and surgical treatment.