Significance of Extraluminal Abdominal Gas

SIGNIFICANCE OF EXTRALUMINAL ABDOMINAL GAS:

LOOKING FOR AIR IN ALL THE WRONG PLACES Richard M. Gore, MD North Shore University Health System University of Chicago Evanston, IL

SCBT/MR 2012 October 26, 2011 3:00-3:10

NO DISCLOSURES [email protected] TOPICS

• PNEUMOPERITONEUM

• PNEUMORETROPERITONEUM

• PNEUMATOSIS INTESTINALIS

• PORTAL-MESENTERIC VENOUS GAS

• PNEUMOBILIA PNEUMOPERITONEUM THE SPECTRUM OF PNEUMOPERITONEUM

• Expected and benign finding requiring no treatment

• Sensitive indicator of sudden and life- threatening perforation of the GI tract

PNEUMOPERITONEUM: BENIGN CAUSES

• Surgery • PSurgeryercutaneous Endoscopic Gastrostomy • PeritonealPercutaneous dialysis Endoscopic Gastrostomy • BiopsyPeritoneal dialysis • PercutaneousBiopsy abscess drainage • PneumothoraxPercutaneous abscess drainage • Pneumomediastinum PNEUMOPERITONEUM: LIFE-THREATENING

• Perforation of benign ulcer • Diverticulitis • Appendicitis • Perforation of neoplasm • Pneumatosis • Bowel obstruction PNEUMOPERITONEUM: LIFE-THREATENING

• Intestinal ischemia and infarction • Toxic megacolon • Necrotizing enterocolitis • Inflammatory bowel disease • Typhlitis • Pseudomembranous colitis PNEUMOPERITONEUM: LIFE-THREATENING

• Anastomotic leak • Upper GI endoscopy • Colonoscopy RIGLER’S SIGN LIVER EDGE SIGN FALCIFORM LIGAMENT SIGN

BENIGN CAUSES OF PNEUMOPERITONEUM POSTOPERATIVE

PERITONEAL DIALYSIS

PERCUTANEOUS GASTROSTOMY

POSTOPERATIVE PNEUMOPERITONEUM

POSTOPERATIVE (OPEN) PNEUMOPERITONEUM ON UPRIGHT CXR

• POD # 5 28.4% • POD # 6 20.0% • POD # 7 11.0%

Tang Dis Colon Rectum 43: 1116-1120, 2000 FACTORS INFLUENCING DURATION OF POST OPERATIVE PNEUMOPERITONEUM

• Obesity: prevalence of PP is less in fat compared to thin patients • Gender: PP more prevalent in men • Drains: greater incidence of PP • No effect: age, surgery duration, presence and location of anastomosis, time to flatus, time to first bowel movement

PP IN THE ERA OF LAPAROSCOPIC SURGERY

• Iatrogenic GI tract perforations due to trocar insertion and thermal injury: 0.06%- 0.4% • Artificial pneumoperitoneum • Small incisions minimize room air PP IN THE ERA OF LAPAROSCOPIC SURGERY

• Iatrogenic GI tract perforations due to trocar insertion and thermal injury: 0.06%- 0.4% • Artificial pneumoperitoneum • Small incisions minimize room air PP IN OPEN vs LAPAROSCOPIC CHOLECYSTECTOMY ON CXR-24 hrs

• Open cholecystectomy: 60%, minimal to moderate 2:1 • Laparoscopic cholecystectomy: 24%, minimal to moderate 5:1

Gayer Semin Ultrasound, CT, MR 25: 1286-289, 2004 PP: CT vs RADIOGRAPH

• 3 days postoperative: 87% on CT, 53% on plain radiograph • 6 days postoperative: 50% on CT, 8% on plain radiograph

Earls AJR 161: 781-785, 1993 IN PATIENTS WITH COMPLICATIONS

• The amount of free air should be decreasing • Any increase is very worrisome • Difficult to exactly compare quantity of gas on CT study with radiograph PERITONEAL DIALYSIS PERITONEAL DIALYSIS

• Seen in 30% of patients on PD • The presence, quantity, and distribution of free air is not helpful in separating perforations from nonperforations

Lee JCAT 18: 439-442, 1994 PERCUTANEOUS ENDOSCOPIC GASTROSTOMY PNEUMOPERITONEUM S/P PEG TUBE INSERTIONS

• 8.6%-55.6% • Free air on CXR 1 to 3 days • Free air on CT 1 to 9 days • In the absence of clinical symptoms is of no clinical significance and does not need further evaluation

LIFE- THREATENING CAUSES OF PNEUMOPERITONEUM GI TRACT PERFORATION PERFORATION

• Emergent condition that requires prompt surgery • Spontaneous, traumatic, or iatrogenic causes • Variable clinical presentations, particularly in the early clinical course GI TRACT PERFORATION

• Concentration of air bubbles next to gut • Supramesocolic vs inframesocolic space • Preponderance of abdominal vs pelvic gas • Perivisceral fat stranding • Segmental bowel wall thickening • Abscess • Extraluminal fluid • Focal defect in bowel wall GI TRACT PERFORATION

• Extraluminal contrast • Focal defect in bowel wall • Segmental bowel wall thickening • Abscess-fluid GI TRACT PERFORATION

• Concentration of air bubbles next to gut • Supramesocolic vs inframesocolic space • Preponderance of abdominal vs pelvic gas • Perivisceral fat stranding GI TRACT PERFORATION

• Concentration of air bubbles next to gut • Supramesocolic vs inframesocolic space • Preponderance of abdominal vs pelvic gas • Perivisceral fat stranding FISSURE LIGAMENTUM VENOSUM- FALCIFORM LIGAMENT CT FEATURES OF PNEUMOPERITONEUM

PROXIMAL GI DISTAL GI PERFORATION PERFORATION FALCIFORM LIG 60% 0% POCKETS OF AIR 10% 69% WALL THICKENING 50% 100% ABSCESS 20% 53% ASCITES 90% 63% FAT STRANDING 30% 72% Yeung J Clin Imaging 28: 329-333, 2004 GI TRACT PERFORATION: LOCATION OF GAS BUBBLES IN 86 PATIENTS

Stomach Inframesocolic Infra- and and liver supramesocolic

Gastroduodenal 29 0 8 perforation

Small bowel 1 2 6 perforation

Colon 0 15 24 perforation

Hainaux AJR 187: 1179-1183, 2006 CT FEATURES OF PNEUMOPERITONEUM (n=53)

UPPER GI LOWER GI PERFORATION PERFORATION PERIPORTAL 93 35 FREE AIR

FALCIFORM 80 43 LIGAMENT LIGAMENTUM 53 8 TERES

Cho HS Eur J Radiology 2007 GASTRODUODENAL PERFORATIONS

• Peptic ulcer disease • Necrotic or ulcerated malignancies • Large amount of extraluminal air • Air in lesser sac, ligamentum teres, ligamentum venosum • Ulceration, focal interruption of wall, abrupt wall thickening with adjacent increased fat density GASTRODUODENAL PERFORATIONS

• Traumatic injures involve 2nd and 3rd portions of the duodenum • Blunt trauma in children and penetrating trauma in adults • Cause pneumoretroperitoneum in the anterior pararenal space GASTRODUODENAL PERFORATIONS

• DUODENAL 38.3% • JUXTA-PYLORIC 35.6% • GASTRIC 19.1% • PYLORIC 6.8%

Grassi Eur J Radiology 50: 30-36, 2004 PEPTIC ULCER DISEASE DIVERTICULITIS PERFORATED NSAID ULCER PERFORATED ANTRAL ULCER PEPTIC ULCER DISEASE SUPERIOR RECESS LESSER SAC SMALL BOWEL PERFORATIONS

• Diverticulitis • Ischemic or bacterial enteritis • Crohn’s disease • Ingested foreign bodies • Bowel obstruction • Volvulus • Intussusception SMALL BOWEL PERFORATIONS

• Abdominal trauma • Iatrogenic injury • Postoperative perforation • Anastomotic leakage • Amount of extraluminal air is small or absent in most cases unlike UGI perf • Extraluminal air seen in only 50% of CTs SMALL BOWEL PERFORATIONS

• Findings often subtle- search for gas trapped in mesenteric folds • Postoperative perforation and anastomotic leakage usually occur within first week of surgery • Suggest perforation or leak with persistent or progressively increasing free air PERFORATED ILEUM BY CHICKEN BONE PERFORATED ILEUM BY CHICKEN BONE SMALL BOWEL PERFORATION COLONIC PERFORATION

• Malignant neoplasm • Diverticulitis • Spontaneous perforation • Trauma • Ischemia COLONIC PERFORATION

• Free air on plain radiograph 33% • Free air on MDCT 100% • Dirty fat sign 100% • Wall thickening at perf site 100% • Extraluminal fluid 100% • Dirty mass 83% • Interruption of colon wall 67%

Miki JCAT 31: 169-176, 2007 COLONIC PERFORATION: LEFT SIDED

• Malignant neoplasm • Diverticulitis • Spontaneous perforation • Blunt trauma • Ischemia COLONIC PERFORATION: RIGHT SIDED

• Inflammatory lesions • Penetrating trauma • Cecum- LBO, toxic megacolon, ileus

DIVERTICULITIS DIVERTICULITIS ANASTOMOTIC LEAKS

• Leak rate 3.6% to 9% • 30% may have clinically occult leaks • High risk: low rectal anastomosis and Whipple’s procedure ANASTOMOTIC LEAKS

• Peri-anastomic fluid and gas are the best indicators of anastomotic leaks

A A PNEUMORETROPERITONEUM PNEUMORETROPERITONEUM

• Postoperative • Postdiagnostic procedure (ERCP) • Penetrating trauma • Blunt traumatic rupture of duodenum • Pelvic trauma with rectal perforation PNEUMORETROPERITONEUM

• Spontaneous colonic perforation volvulus, obstruction, carcinoma, diverticulitis • Extension from pneumomediastinum • Gas-containing retroperitoneal abscess PERFORATION DURING ERCP PERFORATION FROM COLONOSCOPY OCCULT COLONIC PERFORATION WITH INCOMPLETE COLONOSCOPY

• Optical colonoscopy perforation rate is 1/3,115 (.032%) to 1/510 (0.196%) • 2/262 (0.8%) had occult perforation • Recommend low dose CT before rectal tube insertion and gas insufflation in all patients with same day or next day CTC

Hough AJR 191: 1077-1081, 2008 ACCURACY OF MDCT IN DETECTING PERFORATION SITE OF GI TRACT

• Axial images only: 87.8% • Axial + MPR images: 93.9%

Kim JW Abdominal Imaging 36: 503-508, 2011 (Oct)