Indications for needle aspiration in liver abscess are :a) Recurrentb) Left lobec) Refractory to treatment after 48-72 hrs.d) > 10 cms sizee) Multiple
The abscesses referred to in this question are amebic abscesses and not pyogenic abscesses as drainage is indicated in every pyogenic abscess.
The mainstay of treatment for amebic abscesses is metronidazole which is curative in over 90% of pts. Clinical improvement is seen within 3 days.

Aspiration is only recommended for following conditions

for diagnostic uncertainty
for failure to respond to therapy in 3 to 5 days (5 to 7 days according to Maingot's)
abscesses with high risk to rupture (abscess > 5 cms, left lobe abscess)
pyogenic super infection
c
d
ab
bd