Obstetric Topic 35. Lesions of the birth canal. Uterine rupture

I. Genital Tract Lacerations

Definition and Risk Factors

• Genital tract laceration: tear/injury of the birth canal during or after delivery.
• Sites: cervix, vagina, perineum and uterus.
• Risk factors: fetal macrosomia, malpresentation, operative/rapid delivery, prolonged labor, rigid perineum and episiotomy.
• Exam clue: postpartum bleeding despite a well-contracted uterus → think trauma until proven otherwise.

Sites and Clinical Features

• Cervical laceration: may bleed heavily; repair is important for hemostasis and future pregnancy.
• Vaginal/perineal tears: common after episiotomy, rapid delivery, macrosomia or malpresentation.
• Hematoma: vulvar/vaginal swelling, severe pelvic pain, pressure symptoms, shock out of proportion to visible bleeding.
• General signs: visible tear, persistent bleeding, pelvic pain, tachycardia, hypotension and pallor.

Perineal Tear Classification

1. 1st degree: vaginal epithelium or perineal skin only.
2. 2nd degree: perineal muscles/subepithelial tissue, no anal sphincter injury.
3. 3rd degree: involves anal sphincter complex.
4. 4th degree: anal sphincter complex + rectal/anal mucosa.

Diagnosis and Treatment

• Diagnosis: clinical inspection with good light; speculum examination for cervix/vagina and bimanual examination if needed.
• Rule out uterine atony, retained tissue and uterine rupture.
• Rectal examination: for suspected 3rd-4th degree tear and after repair.
• Treatment: surgical repair under adequate anesthesia; small superficial non-bleeding tears may not need sutures.
• Cervical laceration: repair if bleeding, deep or distorting cervix.
• Hematoma: evacuate if expanding/large or unstable; control bleeding and transfuse if needed.
• Antibiotic prophylaxis and follow-up for infection, wound breakdown and anal sphincter injury.

II. Uterine Rupture

Definition and Classification

• Uterine rupture: tear of the uterine wall during pregnancy or labor.
• Complete rupture: disruption of all uterine layers → communication with peritoneal cavity.
• Incomplete rupture / dehiscence: serosa remains intact → hematoma within uterine wall; often less dramatic.
• Most ruptures occur through a previous uterine scar.

Risk Factors and Etiology

• Previous cesarean section or uterine surgery.
• Obstructed labor: CPD, malpresentation, unrecognized dystocia.
• Excessive uterine stimulation: oxytocin/prostaglandins, especially with scarred uterus.
• Multiple pregnancy, polyhydramnios, macrosomia and grand multiparity.
• Trauma, version, instrumental manipulation and excessive fundal pressure.

Clinical Features and Diagnosis

• Most sensitive sign: abnormal fetal heart rate, especially fetal bradycardia.
• Pain: sudden severe constant abdominal pain, different from contractions.
• Contractions: change in pattern, cessation or hypertonus.
• Vaginal bleeding may be present but can be absent.
• Loss of fetal station: presenting part recedes; fetal parts may be palpable abdominally.
• Maternal signs: tachycardia, hypotension, pallor, shock out of proportion to visible bleeding, hemoperitoneum/abdominal distension.
• Diagnosis is clinical; ultrasound may help but must not delay treatment. Laparotomy confirms and treats.

Management

1. Call emergency obstetric, anesthesia, neonatal, surgical and blood bank team.
2. Resuscitate: oxygen, 2 large-bore IV lines, IV fluids, blood transfusion and urine-output monitoring.
3. Stop uterotonics/oxytocin/prostaglandins immediately.
4. Immediate laparotomy with cesarean delivery if fetus undelivered.
5. Surgical choice after delivery:
   • Uterine repair: small rupture, controlled bleeding, repairable tissue and fertility desired.
   • Total/subtotal hysterectomy: large rupture, uncontrolled bleeding, severe tissue destruction or completed family.
6. Correct hemorrhage/coagulopathy and inspect bladder/ureter/broad ligament if injury suspected.