Page created on December 15, 2021. Last updated on January 17, 2022 at 18:55
Multiple injuries may befall the mother during labour. The most common maternal obstetrical injuries include perineal ruptures, labial and vaginal lacerations, cervical injury, genital haematoma, nerve injuries, and uterine rupture (covered in topic A13).
During vaginal birth, the perineum may rupture, which constitutes the most common form of maternal obstetric injury. Most nulliparous women sustain a perineal injury during vaginal birth. These injuries are less common in multipara.
Risk factors for this include:
- Nulliparity (first vaginal birth)
- Operative vaginal delivery
- Occiput posterior delivery
We classify perineal rupture into four degrees:
- 1st degree – tear in skin only
- 2nd degree – involvement of perineal muscles
- 3rd degree – involvement of external anal sphincter
- 4th degree – lesion of the anterior wall of the anal canal or rectum
Treatment is surgical repair. After repair, digital rectal examination should be performed to evaluate. Laxatives should be used postoperatively to reduce the pressure on the surgical wound.
The modified Ritgen manoeuvre can be used to reduce the risk of perineal injury. This involves using one hand to control the deflexion of the foetal head (so it doesn’t deflex too fast) and using the other hand to support the perineum and to “push” the chin of the foetus upwards though the perineum.
Application of warm compress to the perineum during delivery reduces the risk for perineal rupture and should be performed in all cases. In case of high risk for perineal rupture, a mediolateral or lateral (not median) episiotomy should be made to reduce the pressure on the perineum.
3rd and 4th degree perineal injury may cause faecal incontinence or formation of fistulae. Despite treatment, many patients remain faecally incontinent.
Labial and vaginal laceration
Lacerations of the labia and vagina are also common birth injuries. They are associated with operative delivery. Like the perineal injuries, we can classify them according to degrees of severity:
- 1st degree – superficial laceration
- 2nd degree – deeper laceration
- 3rd degree – rupture of the posterior vaginal wall
Vaginal and rectal examination should be performed to rule out 3rd degree laceration. Small lacerations usually don’t require definitive treatment, but larger ones may require suturing. If there are multiple lacerations, a tight vaginal pack with a catheter may be inserted to stop the bleeding.
A genital haematoma can occur if a concealed vessel (usually a varicose vein) starts to bleed adjacent to the genital tract. The haematoma often presents as a vulval swelling, or in the worst case as haemodynamic instability.
Haematomas usually cause vaginal or vulval swelling, and they can expand rapidly and be very painful and tender. The overlying skin has a purplish discoloration. Haematomas present 12 – 48 hours after of delivery.
Retroperitoneal haematomas may cause significant blood loss into the abdomen, potentially causing haemodynamic instability.
Small, nonexpanding haematomas may be managed conservatively (ice packs, analgesics). Large or expanding haematomas should be treated with incision and evacuation. If retroperitoneal haematoma is suspected, the patient should undergo laparotomy.
During birth, lacerations of the cervix may occur. Cervical injuries are associated with operative delivery and manual dilatation. Lacerations may bleed and may be palpable on examination. These are often minor and don’t require specific treatment. Deeper lacerations require surgical repair, usually in the operating theatre with anaesthesia.
Multiple nerves may be injured during labour, but nerve injuries are rare in general. Nerves may be injured due to stretching, lumbar disc herniation, or prolonged compression of the nerve in the lithotomy position. Commonly injured nerves and their outcomes include:
- Peroneal nerve – foot drop
- Lumbar roots – foot drop, paraesthesia of the leg
- Pudendal nerve – incontinence, paraesthesia of the genital area and perineum