Lukasz Robert Pawlowski of Pembroke Dock, appeared for sentence at the Pembrokeshire court on Wednesday after pleading guilty to sexual assault.
He was airlifted to Swansea's Morriston Hospital and is said to be recovering.
Dyfed-Powys Police confirmed they have arrested a 33-year-old man on suspicion of possession of an article with a blade or point.
It is understood he lost consciousness and bled heavily after cutting himself.
The court was closed after the incident but reopened on Thursday.
A sex attacker who cut his own throat in the dock at Haverfordwest Magistrates' Court has been arrested.