Causes and epidemiology
Soft tissue injuries of the birth canal most commonly affect nulliparous women. Key etiological factors include:
- Delivery of a macrosomic fetus.
- Precipitous or rapid labor.
- Secondary uterine inertia.
- Deflexion presentations and breech presentation.
- Anatomically narrow pelvis.
- Cicatricial or inflammatory soft tissue changes.
- Operative vaginal delivery (obstetric forceps or vacuum extraction).
Perineal tears themselves are classified as spontaneous or traumatic (iatrogenic) during vaginal operations.
Classification by degree of injury
The depth of trauma determines the clinical picture and repair strategy:
- Grade I: injury involves only the perineal skin and the mucosa of the lower third of the vaginal wall.
- Grade II: in addition to Grade I injuries, there is a rupture of the pelvic floor muscles, primarily the levator ani muscle (m. levator ani).
- Grade III: a deep tear involving the anal sphincter (m. sphincter ani externus) and sometimes the wall of the rectum itself. This is a severe trauma which, without skilled repair, leads to flatal and fecal incontinence.
Stages of perineal rupture threat
Before tearing, tissues undergo three sequential clinical stages of circulatory impairment:
- Stage I (venous congestion): overstretching of tissue structures by the fetal presenting part causes impaired venous outflow, manifesting as cyanosis of the perineal skin.
- Stage II (edema): a characteristic glossy appearance of the skin is added to the cyanosis.
- Stage III (arterial ischemia): arterial blood flow is disrupted, and cyanosis is replaced by pallor. Tissues completely lose elasticity and tear.
Diagnostics and surgical treatment
Diagnosis is based on a careful visual inspection of the birth canal immediately after the completion of labor.
Principles of treatment:
- The surgery is performed on a gynecological chair or delivery bed observing asepsis rules.
- Intravenous anesthesia is used (or the ongoing regional analgesia is extended).
- Sutures are placed layer by layer to accurately restore anatomical relationships.
- For Grade I tears, suturing begins at the upper angle of the vaginal wound.
Briefly: answers to topical questions
Which specific pelvic floor muscles are torn in Grade II perineal trauma?
- Levator ani muscle (m. levator ani) is the main structure damaged in a second-degree perineal tear along with first-degree tissues.
What maternal risk factors contribute to the occurrence of perineal tears?
- Narrow pelvis.
- Cicatricial or inflammatory tissue changes.
- Limited tissue distensibility and rigidity.
- Rapid and precipitous labor.
What methods of analgesia are used for surgical repair of Grade I and II perineal tears?
- Intravenous anesthesia is the primary method of pain relief for surgical perineal repair.
- Regional analgesia — if this type of anesthesia was used directly during labor, its effect is extended for the duration of suturing.
What manual maneuvers are included in the classic obstetric safeguard of the perineum during labor?
- First moment — prevention of premature head extension by gently holding it against the pubic symphysis.
- Second moment — reduction of perineal tissue tension and its protection, performed simultaneously with the first moment.
- Third moment — delivery of the fetal shoulder and humerus.
- Fourth moment — birth of the posterior shoulder.
The stages of rupture threat are easy to remember by the change in skin color: Blue (venous congestion and cyanosis) → Glossy (edema) → White (ischemia and rupture).
Class and exam questions
Which muscles are damaged in a Grade II perineal tear?
In second-degree tears, in addition to the skin and vaginal mucosa, there is a rupture of the pelvic floor muscles, primarily the levator ani muscle (m. levator ani).
What is the danger of a grade III perineal tear?
This trauma is accompanied by damage to the anal sphincter and sometimes its wall. Incorrect or delayed repair leads to severe patient disability — flatal and fecal incontinence.
What are the clinical signs of the third stage of impending perineal rupture?
The main sign is skin pallor, replacing the preceding cyanosis due to impaired blood flow in the arterial vessels. Tissues lose their ability to stretch and tear.
What else to study on this topic
- Anatomical features and injuries of the clitoris and labia minora
- Classification and diagnosis of vaginal hematomas
- Features of manual uterine exploration in vaginal fornix tears
- Rare types of trauma: central perineal rupture and atypical occult forms
- Technique of layered suturing of Grade II perineal tears
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