Perineal Tears

Trauma to the perineum occurring during vaginal delivery, classified by degree: first degree (skin only), second degree (perineal muscle involved, not the anal sphincter, the most common significant tear), third degree (involving the anal sphincter complex, further subdivided 3a, less than 50% external anal sphincter thickness torn; 3b, more than 50% torn; 3c, internal anal sphincter also torn), and fourth degree (extending through the anal sphincter complex into the rectal mucosa).

Third and fourth degree tears are collectively termed obstetric anal sphincter injuries (OASIS).

Risk factors include nulliparity, instrumental delivery (particularly forceps), macrosomia, occipito-posterior position, prolonged second stage, and shoulder dystocia.

First and second degree tears: repaired under local anesthesia (or existing regional analgesia) using absorbable suture material, with a continuous, non-locked technique for the perineal skin generally associated with less short-term pain than interrupted sutures
Third and fourth degree tears (OASIS) require repair in theatre under regional or general anesthesia by an appropriately trained practitioner, given the technical demands of sphincter repair: the torn sphincter ends are identified and repaired (commonly using an end-to-end or overlap technique for the external anal sphincter), with the internal sphincter, if torn, repaired separately, and the rectal mucosa (fourth degree) closed first
Broad-spectrum prophylactic antibiotics are given at the time of OASIS repair (commonly a single dose or short course, e.g. IV co-amoxiclav or cefuroxime plus metronidazole), given evidence this reduces wound infection and breakdown risk
Laxatives (a stool softener such as lactulose, often combined with a bulking agent) are routinely prescribed after OASIS repair to reduce straining and protect the repair
Analgesia (regular paracetamol and NSAIDs, with opioids as needed), and physiotherapy input for pelvic floor exercises
Follow-up at 6 to 12 weeks in a dedicated perineal clinic after OASIS, assessing continence and wound healing, with endoanal ultrasound and anorectal manometry available where symptoms of incontinence or urgency persist
Counseling regarding mode of delivery in a subsequent pregnancy after OASIS is individualized, with the option of elective cesarean discussed, particularly if the woman remains symptomatic

Referral: appropriately trained obstetrician for repair of any third or fourth degree tear; dedicated perineal clinic follow-up after OASIS; colorectal surgery for persistent, significant incontinence despite conservative management.

Clinical toolsCalculators

BMI GCS EDD Parkland Formula

Corrected Sodium Corrected Calcium Anion Gap Creatinine Clearance Insulin Calculations qSOFA Wells PE Wells DVT CHA₂DS₂-VASc HAS-BLED CURB-65 Centor/McIsaac

Preterm Labour

Onset of regular uterine contractions with cervical change before 37 completed weeks gestation.

Risk factors include previous preterm birth (the strongest predictor), multiple pregnancy, uterine or cervical anomaly, cervical insufficiency, infection (chorioamnionitis, bacterial vaginosis, UTI), polyhydramnios, and antepartum hemorrhage.

Clinical assessment of contraction frequency and cervical examination (dilation, effacement)
Transvaginal ultrasound cervical length: a length under 15 mm supports a high risk of imminent delivery; a length over 15 mm makes preterm birth within 7 days unlikely
Fetal fibronectin (a biomarker present in cervicovaginal fluid), a negative result has a high negative predictive value for delivery within 7 to 14 days and can avoid unnecessary intervention; used particularly when cervical length is equivocal (15 to 30 mm)
Exclude and treat infection: MSU, high vaginal swab, and, where membranes are ruptured, assessment for chorioamnionitis (see PPROM entry)

Tocolysis to delay delivery by 48 hours, allowing time for corticosteroids and, where relevant, in-utero transfer to a unit with appropriate neonatal facilities: nifedipine 20 mg PO loading dose, then 10 to 20 mg PO every 6 to 8 hours (maximum 24 hour dose per local protocol, commonly up to 60 to 160 mg/day), or atosiban (oxytocin receptor antagonist) by IV infusion where available; tocolysis is generally not continued beyond 48 hours and is avoided where there are contraindications (chorioamnionitis, severe pre-eclampsia, abruption, or non-reassuring fetal status)
Corticosteroids for fetal lung maturation: betamethasone 12 mg IM, 2 doses 24 hours apart, given for anticipated preterm delivery between roughly 24 and 34+6 weeks (up to 35+6 in some protocols); a single rescue course may be considered if delivery remains imminent more than 1 to 2 weeks after an initial course, per specialist guidance
Magnesium sulfate for fetal neuroprotection: given before anticipated delivery under 30 to 32 weeks (threshold varies by protocol), typically 4 g IV loading dose over 15 to 30 minutes, then 1 g/hour maintenance, reduces the risk of cerebral palsy in survivors
Group B streptococcus prophylaxis if status unknown or previously positive: benzylpenicillin 3 g IV loading dose, then 1.5 g IV every 4 hours until delivery (alternatives per allergy status: cefazolin, clindamycin, or vancomycin depending on allergy severity and local resistance)
Antibiotics are not given routinely for preterm labor with intact membranes in the absence of confirmed infection, given lack of proven benefit and some evidence of harm in this specific context
Mode and timing of delivery individualized by gestation, presentation, and fetal status

Referral: obstetric-led care with neonatal team involvement; in-utero transfer to a tertiary unit with appropriate NICU facilities if delivery under roughly 27 to 28 weeks is anticipated and local facilities are insufficient.

Perineal Tears

Overview

Clinical Features

Diagnosis

Management

Overview

Clinical Features

Diagnosis

Management