Fourth degree perineal laceration during delivery

This code represents a severe obstetric laceration involving the perineum, extending through the rectal mucosa, anal sphincter complex (internal and external), and into the rectal lumen. It signifies the most extensive degree of perineal trauma sustained during childbirth.

Apply this code when documentation explicitly states a fourth-degree perineal laceration occurred during the delivery encounter. This diagnosis is supported by operative reports or delivery notes detailing the extent of the tear through the rectal mucosa.

• Ensure the documentation clearly specifies "fourth-degree" and involvement of the rectal mucosa.
• Do not confuse with O70.2 (third-degree perineal laceration), which involves the anal sphincter but not the rectal mucosa.
• Sequence this code as a secondary diagnosis following the appropriate code for the outcome of delivery (e.g., Z37.xx).