Third degree perineal tear is involvement of?

AIIMS Bhatinda NO - 2019

Obstetrics & Gynaecology

Easy

Appeared in: AIIMS Bhatinda NO - 2019

Explanation

A third-degree perineal tear is defined as an injury sustained during childbirth that extends from the perineal muscles into the anal sphincter complex.
This classification specifically includes tears of the external anal sphincter (EAS) and/or the internal anal sphincter (IAS).
The classification is further subdivided into 3a, 3b, and 3c based on the extent of sphincter damage, guiding the complexity of the required surgical repair.
The image provided clearly illustrates that a 3rd-degree tear involves the anal sphincter, distinguishing it from less severe (1st and 2nd degree) and more severe (4th degree) tears.

Option A: A tear involving only the vaginal mucosa and/or perineal skin is classified as a first-degree tear, which is the most superficial type of perineal injury.
Option B: Tears involving the urethral mucosa are classified as anterior perineal lacerations. The standard 1st to 4th-degree classification system applies to posterior perineal tears.
Option C: The levator ani is a major muscle of the pelvic floor. While it can be avulsed or damaged during a traumatic birth, the standard classification for a third-degree tear is specifically defined by injury to the anal sphincter, not the levator ani muscle.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Classification of obstetric perineal tears as background academic context rather than a clinical decision trigger.
Accurate identification and classification of perineal tears are critical nursing responsibilities post-delivery. This ensures appropriate surgical repair and management to prevent long-term complications.
Third and fourth-degree tears, collectively known as Obstetric Anal Sphincter Injuries (OASIS), require meticulous repair by an experienced provider to reduce the risk of fecal incontinence, perineal pain, and wound breakdown.
Nurses play a key role in post-repair care, including pain management, promoting hygiene to prevent infection, and educating the patient on signs of complications.

How to Approach the Question

This is a factual recall question based on a standard medical classification system.
First, identify the key term in the question: 'third degree perineal tear'.
Recall the four-tiered classification system for perineal lacerations that occur during childbirth.
Mentally review the structures involved at each level: 1st degree (skin/mucosa), 2nd degree (perineal muscles), 3rd degree (anal sphincter), and 4th degree (rectal lining).
Match the definition of a third-degree tear, which is the involvement of the anal sphincter, with the provided options.
Eliminate the other options based on their definitions within the classification system (e.g., vaginal mucosa is 1st degree).

Concept Tested & Keywords

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E6 Obstetrics Williams pp. 15-30, 8-23