Healthcare and Medicine Reference
Figure 8.4 Step-by-step guide: ascitic tap. (a) Cleaning the area (2% chlorhexidine in 70% alcohol). (b) Infi ltration of local anaesthetic. (c) Aspirating whilst
advancing the green needle. (d) Successful aspiration of peritoneal fl uid (the needle is not advanced any further).
Infi ltrate the skin at the chosen site with local anaesthetic (e.g. 1% lido-
Table 8.1 Samples required from diagnostic tap.
caine), using an orange needle and 10-mL syringe (Figure 8.4b).
Use a green needle to infi ltrate the deeper subcutaneous tissues;
a 'fl ashback' of ascitic fl uid will occur when the peritoneal space
Using a green needle and 20-mL syringe, insert the needle
Sterile universal container (for Gram
stain and cell count)
Blood culture bottles (for culture and
EDTA blood tube (for cell count if
sample heavily bloodstained)
M, C and S
perpendicular to the skin and slowly advance. Aspirate gen-
tly as you advance the needle until fl uid can be easily aspirated
Aspirate 20 mL fl uid and withdraw the needle (Figure 8.4d).
Apply pressure to the site and cover with an adhesive dressing.
Distribute the aspirate into the containers described in Table 8.1,
ensuring sterility throughout.
M, C and S, microscopy, cultures and sensitivities.
Analysis of ascitic fl uid
infection. Transudates result from reduced plasma oncotic pressure
or increased plasma hydrostatic pressure:
total protein concentration: transudate <30 g/L; exudate >30 g/L.
Fluid protein and fl uid albumin concentrations will identify
the fl uid as either a transudate or exudate. Exudates are usu-
ally caused by infl ammatory conditions such as malignancy and
Total protein concentration alone is an unreliable method as,
for example, cardiac ascites may have a high protein content,