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Obstetrics Simplified - Diaa M. EI-Mowafi

Obstructed Labour

Definition

It is the arrest of vaginal delivery of the foetus due to mechanical obstruction.

Aetiology

Maternal causes

  • Bony obstruction: e.g.
    • Contracted pelvis.
    • Tumours of pelvic bones.
  • Soft tissue obstruction:
    • Uterus: impacted subserous pedunculated fibroid, constriction ring opposite the neck of the foetus.
    • Cervix: cervical dystocia.
    • Vagina: septa, stenosis, tumours.
    • Ovaries: Impacted ovarian tumours.

Foetal causes

  • Malpresentations and malpositions: e.g.
    • Persistent occipito-posterior and deep transverse arrest,
    • Persistent mento-posterior and transverse arrest of the face presentation.
    • Brow,
    • Shoulder,
    • Impacted frank breech.
  • Large sized foetus (macrosomia).
  • Congenital anomalies: e.g.
    • Hydrocephalus.
    • Foetal ascitis.     
    • Foetal tumours.
  • Locked and conjoined twins.

Diagnosis

It is the clinical picture of obstructed labour with impending rupture uterus (excessive uterine contraction and retraction).

History

  • prolonged labour,
  • frequent and strong uterine contractions,
  • rupture membranes.

General examination

It shows signs of maternal distress as:

  • exhaustion,
  • high temperature (³ 38oC),   
  • rapid pulse,
  • signs of dehydration: dry tongue and cracked lips.

Abdominal examination

  • The uterus:
    • is hard and tender,
    • frequent strong uterine contractions with no relaxation in between (tetanic contractions).
    • rising retraction ring is seen and felt as an oblique groove across the abdomen.
  • The foetus:
    • foetal parts cannot be felt easily.
    • FHS are absent or show foetal distress due to interference with the utero-placental blood flow.

Vaginal examination

  • Vulva: is oedematous.            
  • Vagina: is dry and hot.
  • Cervix: is fully or partially dilated, oedematous and hanging.
  • The membranes: are ruptured.
  • The presenting part: is high and not engaged or impacted in the pelvis. If it is the head it shows excessive moulding and large caput.
  • The cause of obstruction can be detected.

Differential diagnosis

  • Constriction ring.  
  • Full bladder.
  • Fundal myoma.

Complications

  • Maternal:
    • Maternal distress and ketoacidosis.
    • Rupture uterus.
    • Necrotic vesico-vaginal fistula.
    • Infections as chorioamnionitis and puerperal sepsis.
    • Postpartum haemorrhage due to injuries or uterine atony.
  • Foetal:
    • Asphyxia.       
    • Intracranial haemorrhage from excessive moulding.
    • Birth injuries.
    • Infections.

Management

  • Preventive measures:
    • Careful observation, proper assessment, early detection and management of the causes of obstruction.
  • Curative measures:
    • Caesarean section is the safest method even if the baby is dead as labour must be immediately terminated and any manipulations may lead to rupture uterus.

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