Acute Abdomen - Practical & Diagnostic Approach

• Presented By

• DR Laith Fadhil Al-hialy • MBchB PGSR

The 'acute abdomen' is a clinical condition characterized by severe abdominal pain, requiring the clinician to make an

urgent therapeutic decision- surgical or none surgical

Major causes Acute appendicitis. Acute Cholecystitis Diverticulitis. or Meckel's diverticulitis Acute pancreatitis. Ectopic pregnancy. Peptic ulcer disease, perforated DU ( 80% duodenum , pyloric antrum ) Salpingitis , PID , Expelled IUCCD Intestinal obstruction, including paralytic ileus (a dynamic obstruction). Gastroenteritis. Acute intestinal ischemia/infarction or vasculitis. Renal colic or renal tract pain , acute urinary retention. Abdominal aortic aneurysm (AAA). Gastrointestinal (GI) haemorrhage Testicular torsion. Nonsurgical disease, e.g. myocardial infarction, pericarditis, pneumonia, sickle cell

crisis, hepatitis, inflammatory bowel disease, opiate withdrawal, typhoid.

acute abdomen includes a wide spectrum of disorders, ranging from life-threatening diseases to benign self-limiting conditions

Radiological strategy Before you perform an examination, obtain relevant information from the referring

clinician. Don't let the clinician simply 'order' a plain X-ray film , sonogram or CT, but discuss the patient's age and posture, laboratory results and the number one clinical diagnosis and differential diagnosis. Based on that information and your own degree of confidence with the modalities decide for yourself whether to perform plan X-Ray film ,Sonography or CT. Sonography has the advantage of close patient contact, enabling assessment of the spot of maximum tenderness and the severity of illness without ionizing radiation. In general the diagnostic accuracy of CT is higher than Sonography.

We advocate the following two-step radiological approach of an acute abdomen.

1. Confirm or exclude the most common disease

2. Screen whole abdomen for general signs of pathology

Confirm or exclude most common disease1st step focusing on most common causes

Location of pain determined strategy

• RLQ : Appendicitis • RUQ : Cholecystitis• LLQ : Diverticulitis • LUQ : rare – mostly related to gastric pathology

• 2nd step is Screen the whole abdomen for the

pathological signs • Bowel wall thickening • Ileus ( dilated a tonic loop ) • Air ( Pneumoperitoneum )• Fluid ( ascites )• Inflamed surrounding fat• Renal , uretric stone – pathology

A plain X-Ray abdominal film

A normal film does not exclude an ileus or other pathology and may falsely reassure the clinician. An ileus may not be appreciated on a plain abdominal film if bowel loops are filled with fluid only without intraluminal air (figure).Alternatively if a plain abdominal film does indicate an ileus than Sonography or CT are usually needed to identify its cause. Thus, a plain abdominal film is seldomly useful, with the exception of detection of kidney stones 70 % , GS 20 % , fecolith 10 % or a Pneumoperitoneum. For all other indications use Sonography or CT.

LEFT: Plain abdominal film in a patient with an acute abdomen, showing no abnormalities. RIGHT: Subsequent CT shows distended small bowel loops (arrowheads) that are not seen on plain abdominal film because they are filled with fluid only and do not contain intraluminal air.

RLQ : Appendicitis

Pain in the RLQ, regardless of any other symptom or laboratory results, should be considered to be appendicitis until proven otherwise.If you are unable to find the appendix you cannot rule out the diagnosis of appendicitis unless a good alternative diagnosis is found.If you do not find the appendix and there is no alternative diagnosis call the results of the examination indeterminate. Do not call it:' no appendicitis'.

Inflamed AppendixAn inflamed appendix ( none compressible tubal lesion ) has a diameter larger than 6 mm, and is usually surrounded by inflamed fat. The presence of a fecolith or hypervascularity on power Doppler strongly supports inflammation.

DDX of RLQ disease Mesenteric lymphadenitis.

Mesenteric lymphadenitis is a common mimicker of appendicitis. It is the second most common cause of right lower quadrant pain after appendicitis.It is defined as a benign self-limiting inflammation of right-sided mesenteric lymph nodes without an identifiable underlying inflammatory process, occurring more often in children than in adults..This diagnosis can only be made confidently when a normal appendix is found, because adenopathy also frequently occurs with appendicitis.Key finding: Lymphadenopathy with a normal appendix and normal mesenteric fat.

Bacterial ileocecitis

Infectious enter colitis may cause mild symptoms resembling a common viral gastroenteritis, but it may also clinically present with features indistinguishable from appendicitis especially in bacterial ileocecitis, caused by Yersinia, Campylobacter, or Salmonella.Key finding: ileocecal wall thickening without inflamed fat, adenopathy, normal appendix

Right-sided diverticulitis

Right-sided colonic diverticulitis may clinically mimic appendicitis or Cholecystitis, though the patient's history is generally more protracted. In contrast to sigmoid diverticula, right-sided colonic diverticula are usually true diverticula, that is, outpunching of the colonic wall containing all layers of the wall. This may possibly explain the essentially benign self- limiting character of right-sided diverticulitis

Salphingitis

Salphingitis is a common mimicker of both of appendicitis and diverticulitis.Transvaginal Sonography depicts an inhomogeneous enlarged inflamed ovary. ( adenixial mass lesion )

Epiploic appendagitis.

Epiploic appendages are small adipose protrusions from the serosal surface of the colon. An epiploic appendage may undergo torsion and secondary inflammation causing focal abdominal pain that simulates appendicitis when located in the right lower quadrant or diverticulitis when located in the left lower quadrant. The characteristic ring-sign corresponds to inflamed visceral peritoneal lining surrounding

an infracted fatty epiploic appendage. Epiploic appendagitis has been reported in approximately 1% of patients clinically suspected of having appendicitis.It is very important to make a positive diagnosis of this characteristic entity since epiploic appendagitis is a self-limiting disease. Both US and CT will depict an inflamed fatty mass adjacent to the colon.Key finding: inflamed fatty mass adjacent to the colon with characteristic ring sign.

Urolithiasis

Urolithiasis often causes flank pain, but an ureteral stone (arrowhead) may occasionally present with clinical signs simulating appendicitis, Cholecystitis or diverticulitis.Appendicitis on the other hand may cause hematuria, pyuria and albuminuria in up to 25% of patients because of direct invaded ureteral inflammation

Note Renal colic may associated by paralytic ileus , sever pain air swallowing commonly lead to ileus

LLQ : Diverticulitis

If the pain is located in the LLQ your main concern is sigmoid diverticulitis.In diverticulitis Sonography and CT show diverticulosis with segmental colonic wall thickening and inflammatory changes in the fat surrounding a diverticulum.

Complications of diverticulitis such as abscess formation or perforation, can best be excluded with CT.

LEFT: Sigmoid diverticulitis. Diverticulum (arrow) is surrounded by hyper attenuating fat. The sigmoid wall is thickened. RIGHT: Sigmoid carcinoma with limited fat stranding.

As DDX of LLQ lesion

Ruptured Aneurysm

Most abdominal aortic aneurysms rupture into the left retro peritoneum (4). Clinically this may simulate sigmoid diverticulitis or renal colic due to impingement of the hematoma on adjacent structures. However most patient will present with the classic triad of hypotension, a pulsating mass and back pain. Continuous leakage will lead to rupture into the peritoneal cavity and eventually death.Sonography is a quick and convenient modality, but it is much less sensitive and specific for the diagnosis of aneurysmal rupture than CT.The absence of sonographic evidence of rupture does not rule out this entity if clinical suspicion is high

RUQ : Cholecystitis

Cholecystitis occurs when a calculus obstructs the cystic duct. The trapped bile causes inflammation of the gallbladder wall. As gallstones are often occult on CT, Sonography is the preferred imaging method for the evaluation of Cholecystitis, Some gallbladders happen to be small and others are

large. The imaging appearance of Cholecystitis consists of an enlarged hydropic (meaning non-compressible) gallbladder with a thickened wall in the region of maximum tenderness (the so-called 'Murphy sign‘)

Epigastric or upper

abdominal pain Pancreatitis

CT depicts fat-stranding (arrowheads) surrounding the primary focus of the inflammation: the pancreas BY US focal edema on the pancreatic fat , enlarge hypoechoic texture pancreasBy X-ray , duodenal ileus , Lt plural effusion , obliteration Lt poses shadow

Screen the whole abdomen for general signs of pathology

1. Bowel wall thickening 2. Air ( Pneumoperitoneum )3. Ileus ( dilated a tonic loop )4. Fluid ( ascites )5. Renal , uretric stone and

pathology6. Inflamed surrounding fat

Bowel wall thickeningThickening of bowel wall indicates inflammation or tumor, and has an extensive differential diagnosis. Thickening of small bowel loops usually indicates regional inflammation, as small bowel tumors (carcinoid, lymphoma, GIST) are relatively infrequent. In patients with local colonic wall thickening a carcinoma is a prime concern.

Free air

The presence of free intraperitoneal air is proof of bowel perforation, and indicates a surgical emergency. A Pneumoperitoneum has only two frequent causes: - Perforation of a duodenal , gastric ulcer 80%- Perforation of colonic diverticulitis Free air is usually not seen in perforated appendicitis).Always examine the images in lung setting for better detection of free intraabdominal air (figure).

Ileus

Pathologic distention of bowel loops may be caused by obstruction or paralysis. Firstly determine which parts of the gut are affected: small bowel, large bowel, or both. Look for normal non distended bowel loops, which, if present, strongly suggest an obstructive cause for the ileus

Causes of paralytic Ileus• post operative• Peritonitis• Inflammation ( appendicitis , cholecystis , pancreatitis ) • Trauma • CHF , Uremia • Hypokalaemia • Pneumonia •Drugs – morphine •Renal colic

Causes of SBO• adhesion 70-80 %• Hernia • volvulus • intussusception• GS Ileus • tumor – lymphoma • mesenteric ischemia

Causes of LBO • Ca 60% - mostly sigmoid • volvulus • diverticulitis • fecal impaction • IBD - toxic mega colon

Distinction between small and Large bowel dilation • Few• peripheral • 5 cm +• present • haustra • large

• No. of loops• distribution of loops• diameter • Sold feces • structure • Radius of curvature

• Many• Central• 3-5 cm • absent • valvule conniventes • small

Ascites

Asymptomatic person do not have a detectable amount of free intraperitoneal fluid, with the exception of an incidental drop of fluid in Douglas in fertile women. The presence of ascites is a nonspecific sign of abdominal pathology, indicating that 'something is wrong'. You may want to perform a US-guided diagnostic puncture of the ascites, in order to investigate whether it is sterile reactive fluid, pus, blood, urine, or bile.