Every sonographer has walked into a room, introduced themselves to a patient, and immediately thought: this is going to be hard. Difficult scans are part of the job — but having a toolkit of strategies makes the difference between a non-diagnostic study and a clinically useful one.

The Large Patient

Large body habitus is the most common scanning challenge. Ultrasound attenuates with depth, so what works on a 150-lb patient fails completely on a 350-lb patient.

Probe selection matters most:

Switch to a lower-frequency transducer (2–3 MHz for abdominal work in large patients)
Curved array with the widest footprint possible
Phased array can penetrate through rib spaces when all else fails

Position changes are underused:

Left lateral decubitus for liver/gallbladder — shifts bowel gas and liver moves inferiorly into a better scanning window
Right lateral decubitus for spleen and left kidney
Prone for kidneys when supine access is poor
Upright or semi-upright for fluid assessment

Harmonic imaging: Turn it on. It reduces artifact and improves contrast resolution at depth. Most modern machines default to harmonic — if your image looks noisy and poorly defined, confirm harmonic is active.

Compress the abdomen: Apply firm, sustained pressure. Let the transducer sink in slowly rather than pushing hard instantly. The tissue will eventually displace and give you better depth. Warn the patient first.

Use natural windows: The liver is your friend — scan through it to reach the right kidney and IVC. The spleen is your window to the left kidney. Work with anatomy, not against it.

The Gassy Patient

Gas is the enemy of ultrasound. It reflects nearly all sound energy and creates reverberation behind it.

Ask about bowel prep: For elective abdominal studies, a low-gas diet the day before (avoiding beans, broccoli, carbonated drinks) makes a real difference. Not always possible in hospital settings.

Use patient positioning:

Upright or sitting: gas rises to epigastrum, clears the pelvis and lower abdomen
Right lateral decubitus: gas floats left, opens right-sided structures
Post-fasting: ideally 4–6 hours NPO before abdominal imaging

Patience and pressure: Apply sustained firm pressure over a gas-filled loop. Often you can displace the bowel enough to see through. Give it 30 seconds of steady pressure before moving on.

Alternate windows: For the aorta, scan from the side (lateral decubitus) rather than straight through the anterior abdomen. For the CBD, try scanning from the right flank rather than epigastric.

The Uncooperative or Combative Patient

Agitated patients, those with dementia, intubated patients in the ICU — these require a different approach.

Scan fast: Get your key images first. Don't optimize for perfect images when you might lose access to any images.

Maximize each breath-hold: For patients who won't hold their breath on command, watch their breathing pattern and release your probe trigger (or freeze) at end-expiration when the diaphragm is most still.

Work with the nurse: Have nursing staff help hold the patient's arm, reposition, or briefly sedate if ordered. You're not expected to scan alone in a dangerous situation.

Document your limitations: "Limited study due to patient inability to cooperate. Key structures visualized include…" is a legitimate report. Don't push for perfect images at the expense of safety.

Patients with Wounds, Dressings, and Drains

Surgical wounds, ostomies, PICC lines, and drains all occupy real estate on the abdomen.

Scan around them: You often have more access than you think. Work from adjacent areas and use angled approaches.

Communicate with nursing: Ask if a dressing can be temporarily peeled back. Many can be — especially transparent adhesive dressings. Always have nursing replace what you moved.

Sterile gel and probe covers: If scanning near an open wound or sterile field, use sterile ultrasound gel and a sterile probe cover. Your department should stock these.

Paracentesis or thoracentesis guidance: For procedural guidance near wounds, a smaller footprint probe (linear or phased array) often fits in tighter spaces.

The Pediatric Patient

Scanning children — especially infants and toddlers — requires patience, speed, and a different probe strategy.

High frequency is your friend: Pediatric patients are small. Use a 7–15 MHz linear transducer for most abdominal work in infants. The penetration is more than adequate and the resolution is dramatically better.

Distraction: Have parents read a book or show a video on their phone. A pacifier dipped in sucrose solution (if available) calms neonates during pyloric stenosis scanning.

Scan during feeding: Infants are naturally still during and just after feeding. The pyloric canal is best evaluated after a feed anyway (look for gastric emptying delay in pyloric stenosis).

Position: Hold infants in your non-scanning arm if needed. Toddlers in a parent's lap is far more effective than a squirming child on a cold table.

The Pregnant Patient in Third Trimester

Supine hypotension becomes real at about 20 weeks when the gravid uterus compresses the IVC.

Left lateral tilt: Always. Even a 15-degree tilt with a wedge under the right hip improves maternal cardiac output and patient comfort.

Fetal position matters more than you think: You cannot make the baby move, but you can encourage it:

Have mom drink cold water and walk (if able)
Scan when baby is naturally active (varies by patient — ask)
Scan the spine in the sagittal plane when posterior, then wait for spontaneous movement to complete the face/profile view

Transabdominal vs transvaginal: For cervical length, placental position near the cervix, or very early pregnancies, transvaginal gives dramatically better images than transabdominal. Know when to switch.

When to Call It and Document

Not every scan yields diagnostic images. Know when to stop and communicate:

State what you did see: "Liver is well-visualized and normal in echogenicity. Gallbladder not adequately visualized due to overlying bowel gas."
Suggest what might help: "CT or HIDA scan may be needed for further evaluation."
Never write "normal" for something you could not see. Write "not visualized" or "limited evaluation."

The ordering clinician would rather know a structure wasn't seen than assume your absence of pathology equals absence of disease.

Closing Thought

Difficult scans are frustrating but also where you grow the most as a sonographer. Each challenging patient teaches you something — a new position, a new probe trick, a new patience threshold. Keep a mental (or physical) log of techniques that worked in tough cases. You'll use them again.

SonoBuddy helps you stay sharp on protocols and normal values — reference the measurement tables and exam protocols when you need a quick reminder mid-scan.

Scanning Difficult Patients: Ultrasound Techniques for Challenging Cases