The flamboyant batsman played only the first two Ashes Tests at Cardiff and Lord's with the help of pain-killing injections and underwent a surgery to get back for the seven-match ODI series.
"He was seen by a wound-care specialist and will receive a course of antibiotics in order to exclude infection," an England and Wales Cricket Board (ECB) statement said on Thursday.
"Medical advice is that a complication can occur post-surgery and in this case resulted despite Kevin closely following specialist advice on management of the wound," it said.
The ECB had played down Pietersen's operation at that time.
"The operation involved a small incision and trimming of the blood vessels and nerves around the inflamed tendon and appears, at this early stage, to have been routine," Nick Peirce, the ECB's chief medical officer, had said.
"Kevin will look to undertake a comprehensive rehabilitation program to ensure there is no risk of recurrence. This is expected to be approximately six weeks but will be taken at an appropriate pace following constant review."