Preoperative CT Findings and Interobserver Reliability of Fournier Gangrene

Abstract

Objective: The objective of our study was to delineate CT findings and anatomic areas of involvement of surgically proven Fournier gangrene (FG) and determine interobserver reliability.

Materials and methods: This study was a single-center retrospective study of patients with FG who underwent CT before surgical débridement of FG during a 9-year period. Thirty-eight patients with FG, 17 male and 21 female patients, underwent preoperative CT. Two radiologists reviewed the CT studies and recorded findings and anatomic areas of involvement. CT findings were categorized according to a previously described CT scoring system for necrotizing fasciitis and included the presence or absence of fascial air, muscle or fascial edema, fluid tracking, lymphadenopathy, and subcutaneous edema. Cohen kappa was calculated for interobserver reliability.

Results: Mean body mass index (BMI [weight in kilograms divided by height in meters squared]) was 42, and 22 of 38 (58%) patients had diabetes. Mean BMI and proportion of patients with diabetes were significantly higher in female patients (mean BMI = 46; 16/21 with diabetes) than male patients (mean BMI = 36; 6/17 with diabetes). CT studies of most patients showed fascial air (36/38 [95%], both readers 1 and 2). Interobserver reliability was substantial to almost perfect for all CT findings except lymphadenopathy, for which it was fair (κ = 0.37). Genital, perineal, and ischiorectal involvement were seen in 87% (33/38), 87% (33/38), and 32% (12/38) of patients for reader 1 and 84% (32/38), 84% (32/38), and 26% (10/38) of patients for reader 2 (κ = 0.29, penis; κ = 0.65, scrotum; κ = 0.91, vulva and labia; κ = 0.68, perineal involvement; κ = 0.80, ischiorectal involvement).

Conclusion: Most CT findings of FG and anatomic areas of involvement showed good interobserver reliability. A high proportion of female patients with FG were observed in this study compared with prior series.

Keywords: CT; Fournier gangrene; acute care surgery; necrotizing fasciitis; radiology.

Fig. 1—

49-year-old man with locally invasive rectal adenocarcinoma to sphincter complex and prostate who was undergoing chemoradiation and presented with rectal fluctuance. CT was performed to assess extent of clinically suspected perirectal abscess; Fournier gangrene was not clinically suspected. A–C, Sequential axial contrast-enhanced CT images show perirectal abscess (thin arrows, A and B) and tract of gas along right perineum and scrotum (thick arrows, A and B) with gas surrounding right testicle (arrow, C). At surgery, perirectal abscess due to rectal perforation was confirmed as well as necrotizing fasciitis involving perineum and scrotum. Patient underwent extensive serial débridements of perirectum, perineum, and scrotum and required diverting colostomy. Both study readers concurred with findings of fascial air, fascial edema, fluid tracking, and subcutaneous edema in keeping with necrotizing soft-tissue infection score of 13.

Fig. 2—

84-year-old morbidly obese woman with diabetes who presented with hyperglycemia, leukocytosis, and right groin ulcerative wound with foul discharge on physical examination. A, CT scout image shows patient’s habitus as well as soft-tissue air about right groin and thigh (arrow). B–D, Sequential axial contrast-enhanced CT images show fascial air involving right labia, perineum, and thigh (thin arrows) along with extensive subcutaneous fat and muscle edema about right thigh (thick arrows). E, Sagittal CT reconstruction image centered to right of midline shows extent of dominant tract of fascial air (arrows), which extends into lower anterior abdominal wall. Patient underwent extensive surgical débridement of lower abdominal wall, labia, perineum, and right thigh, where Fournier gangrene was confirmed. Patient died shortly after surgical débridement. Both study readers concurred with findings of fascial air, fascial edema, and subcutaneous edema in keeping with necrotizing soft-tissue infection score of 10.

Fig. 2—

84-year-old morbidly obese woman with diabetes who presented with hyperglycemia, leukocytosis, and right groin ulcerative wound with foul discharge on physical examination. A, CT scout image shows patient’s habitus as well as soft-tissue air about right groin and thigh (arrow). B–D, Sequential axial contrast-enhanced CT images show fascial air involving right labia, perineum, and thigh (thin arrows) along with extensive subcutaneous fat and muscle edema about right thigh (thick arrows). E, Sagittal CT reconstruction image centered to right of midline shows extent of dominant tract of fascial air (arrows), which extends into lower anterior abdominal wall. Patient underwent extensive surgical débridement of lower abdominal wall, labia, perineum, and right thigh, where Fournier gangrene was confirmed. Patient died shortly after surgical débridement. Both study readers concurred with findings of fascial air, fascial edema, and subcutaneous edema in keeping with necrotizing soft-tissue infection score of 10.

Fig. 3—

84-year-old obese woman with diabetes who presented with leukocytosis and painful buttock boil clinically evident on left gluteal cleft. A, CT scout image shows patient’s habitus as well as soft-tissue air about perineum extending along left abdominal wall subcutaneous fat (arrows). B–D, Axial contrast-enhanced CT images show fascial air involving left buttock, perineum, and labia (thin arrows, B and C) extending cranially about mons pubis into left anterior abdominal wall (arrows, D). Areas of soft-tissue edema (thick arrow, B) are evident as well. Fournier gangrene was confirmed at surgery, which included extensive débridement of left buttock, perineum, radical left vulvectomy, and anterior abdominal wall. Both study readers concurred with findings of fascial air, fascial edema, and subcutaneous edema in keeping with necrotizing soft-tissue infection score of 10.

Fig. 3—

84-year-old obese woman with diabetes who presented with leukocytosis and painful buttock boil clinically evident on left gluteal cleft. A, CT scout image shows patient’s habitus as well as soft-tissue air about perineum extending along left abdominal wall subcutaneous fat (arrows). B–D, Axial contrast-enhanced CT images show fascial air involving left buttock, perineum, and labia (thin arrows, B and C) extending cranially about mons pubis into left anterior abdominal wall (arrows, D). Areas of soft-tissue edema (thick arrow, B) are evident as well. Fournier gangrene was confirmed at surgery, which included extensive débridement of left buttock, perineum, radical left vulvectomy, and anterior abdominal wall. Both study readers concurred with findings of fascial air, fascial edema, and subcutaneous edema in keeping with necrotizing soft-tissue infection score of 10.