A8. Signs and differential diagnosis of pending uterine rupture and placental abruption

From greek.doctor

You should read topics A9 and A13 before this.

Vaginal bleeding in the second half of pregnancy

Definition

There are many possible causes of vaginal bleeding in the second half of the pregnancy. Some are life-threatening and some aren’t. In either case, it’s important to identify the cause of bleeding and treat it if possible.

As the topic name suggests, we’ll focus on signs and differential diagnosis of pending uterine rupture and placental abruption.

Etiology

  • Life-threatening
    • Placenta praevia (topic A10)
    • Placental abruption (topic A9)
    • Ruptured vasa praevia
    • Uterine scar disruption
    • Uterine rupture (topic A13)
  • Non-life-threatening
    • Cervical polyp
    • Bloody show
    • Cervicitis
    • Etc.

No digital examination before ultrasound

Placenta praevia is a possible cause of late pregnancy vaginal bleeding. Digital examination of the cervix may cause immediate, severe haemorrhage in case of placenta praevia. For this reason, digital examination must not be performed until placenta praevia is ruled out by ultrasound.

Signs and differential diagnosis of pending uterine rupture

Uterine rupture typically occurs during labour in a woman who’s previously had C-section, but it may occasionally occur during the second half of pregnancy as well. Possible signs of pending uterine rupture include:

  • Presence of Bandl’s ring above the umbilicus
  • Excessive uterine activity (frequent, strong contractions)
  • Overdistended and tender lower uterine segment
  • Vaginal bleeding
  • Macrohaematuria

Symptoms of frank uterine rupture include pathological CTG (especially foetal bradycardia), vaginal bleeding, and severe abdominal pain. There may be major intraabdominal haemorrhage despite modest vaginal bleeding; haemodynamic instability may occur and may be the cause of presentation. If occurring during labour, there will be a sudden cessation of contractions.

Foetal parts may be palpable through the maternal abdomen, as the foetus may leave the uterine cavity through the uterine rupture. Loss of foetal station, referring to the presenting part moving back up into the uterine cavity, is typical.

Signs and differential diagnosis of pending placental abruption

Placental abruption most commonly occurs in the final weeks of gestation. There are no warning symptoms ahead of abruption (that I could find at least). Symptoms of placental abruption include vaginal bleeding, abdominal or back pain, uterine tenderness, and contractions. However, the pain may range from mild cramping to severe. Vaginal bleeding may be small despite a large amount of blood loss, as blood may be retained behind the placenta. CTG may be abnormal.

The diagnosis is based on clinical features. However, ultrasound can assist the diagnosis and will show a retroplacental clot.