A woman has just delivered her second baby on the labour ward. She is 37 years old and had a previous premature delivery at 34 weeks. In this pregnancy she went into sponta- neous labour at 38 weeks after an uncomplicated pregnancy.
The symphysiofundal height was consistent with dates until 37 weeks when the midwife measured it as 41 cm. However, before an ultrasound scan for growth and liquor volume could be arranged the woman went into spontaneous labour.
At the time of admission she was 5 cm dilated and spontaneous rupture of membranes occurred soon after. The baby was delivered 30 min later in the direct occipitoanterior position.
The placenta was delivered by controlled cord traction, after which the midwife noticed a perineal tear. The tear extended from the introitus in the midline and she could see torn muscle fibres suggestive of the torn ends of the external anal sphincter. She has called you to review the patient.
· What is the likely diagnosis?
· What factors predispose to this condition?
· How would you manage this patient?
The history suggests a third-degree tear
Third-degree tears occur in 2–4 per cent of women with the following conditions:
· birthweight over 4 kg
· persistent occipitoposterior position
· induction of labour
· second stage of labour lasting more than 1 h
· forceps delivery.
Third-degree tear diagnosis depends on the vigilance of the person inspecting a tear and may easily be missed. This has far-reaching consequences, as failure to perform adequate primary repair may increase the chance of longer-term faecal incontinence.
The woman should be transferred to theatre for repair. This enables adequate analgesia (spinal or epidural), good exposure, good lighting and availability of appropriate instruments.
The tear should be repaired in layers:
· rectal mucosa (if involved)
· internal anal sphincter (if involved)
· external anal sphincter
· perineal muscle
· vaginal epithelium
· perineal skin.
Broad-spectrum antibiotics should be administered to prevent infection from possible contamination by bowel organisms.
Laxatives should be administered to prevent constipation that might compromise the repair.
Adequate postoperative analgesia is needed.
The woman should not generally be discharged until she has opened her bowels.
A follow-up appointment should be made after approximately 6 weeks to ensure that the woman has no significant bowel symptoms and to refer on to a colorectal specialist if she has.
Elective Caesarean section should be discussed as a possibility for any subsequent deliveries.