AP Abdomen

AP Abdomen positioning diagram

Reference AP Abdomen radiograph

MAIN INDICATION AND CLINICAL UTILITY

Pathologies demonstrated: Abnormal masses, abnormal intestinal gas patterns, and calculi (stones).

OBTAIN BEFORE CONTRAST STUDIES OR WHEN CLINICALLY INDICATED

Also known as "KUB" (Kidneys, Ureters, Bladder) or "plain abdominal film".

Exposure Factors

70-80

Kilovoltage (kV)

Milliamperage (mAs)

105-115 cm

Source-Image Distance

With Bucky

Configuration

Medium exposure: Parameters for optimal visualization of abdominal structures

Anatomical Structures Visible

Should be clearly observed:

Lower thoracic vertebrae (T12-L1) and upper sacrum
Abdominal cavity from diaphragm to pelvis
Psoas muscles bilaterally (if patient not too obese)
Intestinal gas pattern throughout abdomen
Renal shadows and bladder outline if distended

Cassette Size and Orientation

35 × 43 cm

Longitudinal

Longitudinal orientation to cover from diaphragm to pelvis

Patient Positioning

Patient in supine position on radiographic table

Arms at sides of body or crossed on chest

Midsagittal plane of body centered to midline of table/bucky

Legs extended or knees slightly flexed with feet flat on table

No rotation of pelvis or shoulders

Cassette centered to include diaphragm and complete abdomen

Central Ray Point

Midway between xiphoid process and symphysis pubis

Direction: Perpendicular to center of cassette

Location: Approximately at level of iliac crests for adequate coverage

Special Patient Considerations

Obese Patients

Increase kV and mAs according to thickness adjustment chart. Ensure complete inclusion of abdomen.

Acutely Ill Patients

If patient cannot lie supine, obtain upright abdomen projection first for air-fluid levels.

Pediatric Patients

Reduce exposure according to age and ALARA principles. Use gonadal shielding when appropriate.

CRITICAL NOTE FOR WOMEN OF CHILDBEARING AGE

Always document last menstrual period date before exposure.

Follow the "10-day rule": Perform only during first 10 days after onset of menstruation when pregnancy is unlikely.

Apply gonadal shielding when possible without obscuring diagnostic area

Patient Instructions

"Take a deep breath in, hold it, and remain completely still during the exposure"

Maintain position without movement and apnea during radiographic exposure

Specific Findings to Look For

Bowel Gas Pattern

Distribution and caliber of intestinal gas

Calculi

Renal, ureteral or bladder stones

Masses

Abnormal soft tissue densities

Psoas Shadows

Bilateral visualization of psoas muscles

Common Technical Challenges

Frequent problems in AP abdomen projection:

Inadequate coverage excluding diaphragm or pelvis
Patient rotation causing asymmetry of abdominal structures
Inadequate exposure for obese patients
Respiratory motion blurring diaphragmatic outlines

Solution: Ensure full inspiration breath-hold and center midway between xiphoid and symphysis

Clinical Indications

Abdominal Pain

Renal Colic

Abdominal Mass

Follow-up Studies