ACUTE ABDOMENACUTE ABDOMEN

PROF. S.O. MGBORPROF. S.O. MGBOR

By

Radiology of:

Definition: Severe pain in abdomen that evokes thoughts of possible surgical intervention.

- May truly arise in abdomen or outside it.- May be spurious.- Maybe traumatic or atraumatic

- Spurious or extrabdominal causes include:

a. Medical cause eg porphyria

b. Intrathoracic causes. - diseases arising from embryologically related organs which result in referred pain (heart, pleura, oesaphagus, aorta etc .

eg – Pleuro pneumonia:- Pulmonary embolism- Mediastinal diseases such a aortic dissection, mediastinitis oesaphageal rupture.- Cardiac infarction (Dressler’s syndrome).- Pericarditis.

True Abdominal causes can True Abdominal causes can be categorized as follows:be categorized as follows:

1. Infection – Inflammed organs like appendix, colon, fallopian tubes, diverticulum etc.

- Resulting in abscess

formation.

2.Inflammations: - Caused by free chemically active or irritant body fluid eg. bile, urine, chyle; pancreatic juices, blood, faeces which has gained access into the peritoneal cavity.

3. Ischaemia: - Dissections, Aneurysms, thromboemboli Infarctions (SCI).

4. Obstruction of hollow or tubular organs.These obstructions may be extrinsic, intramural, intraluminal -eg volvulus, herniations,webs,Torsions, intussusceptions, Bands.

Organs usually affected include stomach, intestine fallopian tubes, ureters, urethra, ovaries.

5. Perforation of organs

- As observed in appendicitis, typhoid fever, diverticulitis.

- Rupture of gall bladder, stomach, colon.

6. Trauma

Radiological Investigation of the Radiological Investigation of the Patient with Acute AbdomenPatient with Acute Abdomen

1. Routine: Radiography: Five densities distinguishable by conventional radiography are as follows: Air, Fat, Soft tissue, Bone, Heavy

metal.

Radiologic Diagnosis is based on abnormal interface between air andand soft tissue.

-Free intraperitoneal air contacts various soft tissue not normal outlined.

Routine views: - Chest X-ray (PA)

- Abdominal Radiographs (erect/supine views)- Lateral Decubitus- Lateral cross table supine- Lateral view of rectum (to distinguish air in rectum as in paralytic ileus from

collapsed rectum in mechanical Ileus)

-Additional imaging studies almost always required.

-US particularly useful in evaluation of biliary to biliary colic, jaundice; hepatic, vascular disease tumors.

- Probes of 3, 5, 7, 5mHz

- Duplex doppler should also be routinely used.

- Color flow Doppler.

Best Indications for CT-Best Indications for CT-Abdomen/chest includeAbdomen/chest include::

• Trauma• Hepatic masses• Metastatic disease• Surgical complications• Best done with contrast and with

multislice CT which has reconstruction facilities.

MRI: MRI: Useful in evaluation of Useful in evaluation of complex anatomy and diffusecomplex anatomy and diffuse parenchymal disease.parenchymal disease.

Advantages: Advantages: Multiplanar capabilities Multiplanar capabilities + sensitivity to small differences in + sensitivity to small differences in tissue composition.tissue composition.

Nuclear Imaging:1. Useful in assessment of hepato-

biliary structures; imaging done using Tc 99m - labelled HIDA

(Iminodiacetic acid derivates - Nucleide taken up by hepatocytes and excreted via biliary system.

- Indications:

a. Hepatitis/Biliary atresiab. Biliary leakc. Choleduchal cystd. Caroli disease.e. G.I.T. Bleedingf. Torsion of testis/ovaries.

Angiography: Indications:G.I.T Bleeding for diagnosis andInterventional procedures Other Contrast studies:

- Barium meal- Barium enema- I.v.urography - M.C.U

Ordered Approach to Ordered Approach to Abdominal RadiographAbdominal Radiograph

A = AIRB = BONESD = DensitiesO = OrgansM = Masses/MusclesE = EdgesN = Nil

A - AIR: Assess collections of

air/gas inside and outside

the gut.

- Including air within the walls of the intestine.

(pneumatosis intestinalis) or Abdominal wall (subcutaneous emphysema):

-Assess degree of distension, size of coils of gut, site; haustra / venaeconniventes.

-Determine site, size and shape of the gas collections eg large or small, mottled or homogeneous .

- Air in the lower chest region.- Air in the liver/bladder, gallbladder, spleen, kidneys.

B. BONES: lytic/sclerotic lesions fractures, dislocations in pelvic spine, ribs; femurs.

D. DENSITIES: eg Foreign bodies a. Abdominal wall calcifications

as in general fibromatosis, fat necrosis,

Common Causes of Abdominal Common Causes of Abdominal Calcifications in Children/AdultsCalcifications in Children/Adults

• Abd. Wall: Fat Necrosis,

calcium salt injection,

generalised fibromatosis.

Peritoneal: Meconium peritonitisplastic peritonitis dueto hydrometrocolpos.

Liver: A. Parenchymal B. Liver

Inflammation: Toxoplasnosis Rubella, CMV,(TORCHS) herpes, Syphilis.Tumor – Hemangioma

- Hepatoblastoma - Hepatoma

- Metastases eg. - Neuroblastoma

Vascular: Portal vein thrombo- emboli - Post- umbilical vein catheterisation.

C. Spleen: - SCD-TORCHS -Dermoid, epidermoid

Bowel Calcifications:Extramural cause:Cyst: mesenteric; omentalPeritoneal calcificationMummified BowelIntramural: Bowel atresia/

infarcted bowel.

Intraluminal densities:- Bowel Stenosis/Atresia- Hirschsprung’s- Rectourinary fistula- Foreign body- Appendicolith- Stone in meckel’s diverticulum- Gallstone

Pancreas: Pancreatitis (Chronic)Pseudocyst

Kidney: Nephro-calcinosisNephrolithiasisDystrophic eg.Tumor:renal cell Ca,metastasis.

Adrenal: Adrenal infarct/hemorrhage Tumor

Scrotum: - Meconium peritonitis- Teratoma

Gallbladder:- Idiopathic- Hemolytic Anemia- Diuretic therapy

Vascular System:- I.V.C Thrombus- Arterial calcifications.- Tumor Thrombosis.- Obliterated structures,

umbilical veins/arteries.- Aortic aneurysms.

Miscellaneous: - Fetus in fetu.- Ovarian dermoid.- Fibroids.

LIVER EMERGENCIESLIVER EMERGENCIES Acute Hepatic DiseasesAcute Hepatic Diseases

Trauma: US and CT applicable- CT is more suitable for assessment of degree of laceration and haemorrhage

- High risk injuries usually involve large branches of portal vein.

Acute Cholestasis:Defined as Serum bilirubin greater than 2mg/dL.

- May result from gall stones obstructing the biliary tract

and causing acute cholecystitis

-

- US is the diagnostic method of choice for accurately evaluating the gall Bladder.

- Features of acute cholecystitis include; wall thickening, pericholecystic fluid, point tenderness

Tumors: Primary hepatic tumor may present as a:- Rapidly enlarging painful abdominal mass.- Due to intratumoral bleeding- three tumors which commonly present this way include:- Mesenchymal hamartoma, hepatoblastoma, hepatocellular Ca.- Large liver abscesses.

Vascular DiseasesVascular Diseases

•Acute portal hypertension

•Caused by portal vein thrombosis;

•And Budd-Chiari Syndrome (Venocclusive).

•Best demonstrated by US doppler CT/MRI.

- Hemangioma - Hemangioendothelioma

Pancreatic EmergenciesPancreatic Emergencies

Acute Pancreatitis. (mild or severe).

- Caused mostly by abdominal trauma eg. Battered Baby syndrome, drug toxicity.

PresentationsPresentations:: Peripancreatic inflammationPeripancreatic inflammation

•Pseudocyst•Pancreatic necrosis•Pancreatic abscess•Hemorrhagic pancreatitis.

-Extrapancreatic fluid collections may be the only sign of inflammation. Angiography is used to define vascular complications such as hemorrhage and Pseudoaneurysm and for effecting embolotherapy.

- Vascular complications occur when proteolytic enzymes leak into the organ causing arterial wall erosion hemorrhage or Pseudoaneurysm.

- Most frequently affected vessels are splenic, pancreatico-duodenal arteries.

Splenic EmergenciesSplenic Emergencies

•Infarction•Wandering spleen/torsion.•Acute splenic sequestration (in SCD) and in adults with sickle –C or sickle thalassaemia.

Splenic RuptureSplenic Rupture

• Can occur as a result of trauma.

• Or enlarged spleen following minor trauma.

Splenic Infection and abscessSplenic Infection and abscessMay be solitary or multiple- Gas or septations may be identified in the abscess.

- Microabscesses are usually caused by fungi eg. Candida especially in the immunocompromised

Pathophysiology of Pathophysiology of intestinal obstructionintestinal obstruction

At the onset of the process ofintestinal obstruction there is distension of bowel lumenproximal to the site ofobstruction.

Swallowed air, saliva, + GITsecretions gather above this point. The law of La Place saysif the intraluminal pressure isconstant, doubling the radiusof a viscus will cause also doubling of the intramuralpressure. In a state of ongoingintestinal obstruction vis a vizdistending the bowel,

Intramural pressure rises. Raised intramural tension can actually exceed the capillary perfusion pressure.

This in turn leads to ischaemic injury subsequent necrosis, and perforation and peritonitis.

a.Mechanical obstruction

b.Paralytic ileus.

This principle explains the extreme vulnerability of caecum to perforation duringobstruction.Types of obstruction:

- Simple – (no Vascular compromise)

- Closed loop - Strangulated

Small Bowel ObstructionSmall Bowel Obstruction

- Centrally located bowel loops; numerous; 25mm – 50mm diameter.

- Small radius of curvature

- Valvulae conniventes extends across bowel.

-No solidNo solid faecesfaeces-Multiple fluid levels on erect film

- String of beads on erect view due to small gas pockets trapped between valvulae conniventes.

- Absent or little air in large bowel

Large, bowel Large, bowel obstruction:obstruction:

•Dilated peripheral loops.•Fewer loops.•Large, above 5cm in

diameter.•Large haustra which do not

extend right across bowel.•Thick/widely separated.

- Contains solid faeces.- Caecum and small bowel maybe dilated.- Ba. Contrast exam may help in localising the site or point of obstruction and diagnosing cause of obstruction.- Can help rule out pseudo- obstruction.

Caecal Volvulus- dilated caecum ++ located in R.I.F or LUQ.-Attached appendix maybe gas - filled.

-Small bowel dilatation also present.

-Left colon collapsed.

SIGMOID VOLVULUSThis massively dilated viscus extends above T10 overlapping the liver.

No haustral markings. Outer wall and adjacent walls form 3 thick white lines of the inverted U.

Strangulated Hernia:

- Gas- containing soft tissue mass in inguinal region.

- Fluid level in erect view

- Pneumatosis intestinalis if infarction has occurred.

Other G.I.T EmergenciesOther G.I.T Emergencies1. Intussussception

Plain film findings:-soft tissue mass-nonvisualization of air filled Rt. colon-+ small bowel obstruction.-+ extraluminal air.

Diagnosis can be confirmedwith Barium Enema/US/CTAbdomen.

-Reduction can be achieved With Barium or air or dilutedWater soluble contrast(meglumine sodiumditrizoate)

Acute Appendicitis.Imaging method of choiceis called graded- compressionSonography.

-Criteria for sonographic Diagnosis consist of:a. Appendix with cross sectional diameter greater than 6mm.

b. Identifiable appendicolith.c. demonstrable complex mass.d. demonstrable focal fluid. (abscess).e. demonstrable wall hyperaemia using Doppler.

Traumatic Bowel RuptureTraumatic Bowel Rupture

• CT diagnosis criteria:

1.Large amounts of unexplained peritoneal fluid

in the absence of solid viscus injury or bony pelvic fracture.

2. Abnormally intense bowel wall enhancement.

Plain film findings in BowelRupture

1.Extraluminal air.2.Bowel obstruction.3.Indistinct psoas margin.

Uroradiologic Uroradiologic EmergenciesEmergencies

1.Pyonephrosis following urinary tract infection. - Danger of losing renal

parenchyma. - US evaluation useful.

- CT maybe elucidatory.

2.Pain + Hematuria maybe caused by rapidly enlarging tumors and calculi.

3.Urinary RetentionCauses include (a) Functional bladder

- Neurogenic bladder- Coma

b.Structural causes:- Neoplasm- F. Body- Prolapsing ureterocele- Pelvic Abscess- Bladder diverticulum- Pelvic mass.

c. Urethral obstruction:- Urethral stricture.- P. urethral valves. - FB.- Meatal stenosis.

4. Intermittent UPJ obstruction.

5. Urethral Trauma:- Retrograde urogaphy + infusion cystography as initial exam.

Obs/Gyn Emergencies 1. Ectopic Pregnancy:- Simple ectopic.- heterotopic.

2.Degenerating fibroid3.Pedunculated fibroid.

4.Ovarian torsion.

5.Hemorrhagic ovarian cyst.6.Endometriosis.

7.P.I.D.

8.Ovarian neoplasms - cystic teratoma - dermoid.

9. Serous and mucinous cystadenoma and cystadenocarcinoma.

The Acute ScrotumThe Acute Scrotum

Causes of acute scrotal swelling and pain.1.Testicular torsion. 2.Torsion of appendix testis3.Epididymitis

4. Orchitis.

5. Acute vasculitis (Henoch SchÖnlein Purpura).

6. Incarcerated Hernia.

7. Trauma.

Imaging methods include: US + color doppler a. Radionucleide studies.

Trauma: Etiology; RTA; athletics; straddle injury.

- Rupture of testis.

- Hematoma.

- Hematocele – Complex extratesticular fluid collections which separate layers of tunica vaginalis .

- Testicular fracture.

Torsion: best diagnosed withGrayscale + Dopplercolour flow.

- Salvage rate decreases after 6 to 12 hrs of torsion.

- Salvage rate is virtually nil after 24 hrs of torsion.

Interventional Radiology in Acute Interventional Radiology in Acute Abdomen (Pediatric)Abdomen (Pediatric)

a. Non Vascular: interventional technique.

b. Vascular: Interventional technique.- US is the most widely used technique in

children for monitoring procedures- CT and Flouroscopy and

MRI are the more widely modalities in adults.

2. Types of transducers available i. transducer with central hole for needle insertion.

ii. Transducer with needle guide attached to transducer.

Sector Type ideal.

Aspiration of : - Peritoneal fluid - Perirenal urinoma - Ovarian cyst

Biopsy: Use spring-loaded biopsy needle for core biopsy; 2 to 3 passes usually needed-Percutaneous biopsy for liver Ca,Lymphoma and soft tissue sarcoma.

Drainage:

-Single lumen catheter system for low viscosity fluids.-Sump catheter-Large bore single lumen catheter

Indications: Appendiceal abscess- Transrectal drainage of pelvic

abscess - Iliopsoas abscess- Pancreatic pseudocyst- Acute acalculous cholecystitis

• Enteric access (Jejunal feeding).

Vascular Intervention:

- Digital subtraction angiography better than conventional for angiography diagnosis.

Indications for vascular intervention: a Embolizationb. Sclerotherapyc. Angioplastyd. Stent placemente. Thrombolysisf. Intravascular

foreign body removal