Healthcare and Medicine Reference
Box 8.1 Equipment for ascitic tap
Sterile gloves and gown
Dressing pack containing gauze and sterile drape
Antiseptic skin preparation
5 mL 1% lidocaine
25 G (orange) needle
21 G (green) needle × 2
Universal containers × 3
Blood culture bottles × 1 set
Figure 8.3 The equipment required for ascitic tap.
The ideal site for a diagnostic tap is in the area of fl ank dullness
in the lower left or right quadrant of the abdomen. Depending on
patient size this is typically 5 cm superior and medial to the anterior
superior iliac spine.
It is important to remember that the inferior epigastric vessels
run adjacent to the rectus abdominis muscles and therefore the site
should be as far lateral as possible to avoid vascular damage.
Avoid superfi cial veins and surgical scars, as they may have
collateral vessels or underlying adherent bowel.
Figure 8.2 How to percuss for ascites.
The most reliable clinical sign is the presence of shifting dull-
ness. Fluid within the abdomen will accumulate in the lowest, most
dependent region. Conversely, gas-fi lled, less dense loops of bowel
will fl oat on top of the fl uid and accumulate in the highest region.
Detecting shifting dullness (Figure 8.2)
Position patient in the supine position.
Step-by-step guide: ascitic tap
Percuss from the umbilicus and move laterally down the abdom-
inal wall towards yourself.
Stop at the point of transition from tympanic to dull percussion.
Give a full explanation to the patient in simple terms and
ensure they consent to the procedure.
Set up your trolley (Box 8.1 and Figure 8.3).
Keep your fi ngers or mark this position and ask the patient to
roll towards you.
Pause briefl y to allow the fl uid to shift within the abdomen.
Prepare your trolley as a sterile fi eld. Wear a plastic
disposable apron and non-sterile gloves, and take alcohol
hand rub with you.
Positive test: when ascites is present, the area of dullness will shift to
the dependent side. The area of tympany will shift towards the top.
Ensure the patient is comfortable, lying with the head of the bed
slightly elevated and with an empty bladder.
Percuss the ascites and mark the selected site (as above).
When performing a diagnostic ascitic tap the patient should be in
the supine position with the head of the bed slightly elevated to
allow fl uid to accumulate in the lower abdomen.
Wash hands thoroughly, put on sterile gloves and a gown and
clean the area with antiseptic fl uid (e.g. 2% chlorhexidine in 70%
isopropyl alcohol) (Figure 8.4a).