Abnormal Labour — Causes & Diagnosis

Abnormal Labour

Definition

Abnormal labour refers to a labour that does not progress normally, either due to issues with the power (uterine contractions), the passenger (fetus), or the passage (birth canal).

Aetiologies

The causes of abnormal labour can be categorized into three main areas:

• Power: Poor uterine contraction; 1st stage, poor maternal effort; 2nd stage.
• Passenger: Large baby, malpresentation.
• Passage: Contracted pelvis, soft tissue abnormalities (myoma, cervical cancer).

Abnormal Labor IndicatorsY

Indication	Nullipara	Multipara
Prolonged latent phase	>20 h	>14 h
Average second stage	50 min	20 min
Prolonged second stage without (with) epidural	>2 h (>3 h)	>1 h (>2 h)
Protracted dilation	< 1.2 cm/h	< 1.5 cm/h
Protracted descent	< 1 cm/h	< 2 cm/h
Arrest of dilation*	>2 h	>2 h
Arrest of descent*	>2 h	>1 h
Prolonged third stage	>30 min	>30 min

When We Consider Labour as Abnormal

1. Poor progress (as evidenced by a delay in cervical dilatation or descent of the presenting part)
2. The fetus shows signs of compromise.
3. There is a fetal malpresentation
4. A multiple gestation
5. A uterine scar
6. Labour has been induced.

Complications

• Maternal infection
• Fetal compromise.
• Hyperstimulation of the uterus. ⇒ rupture
  • fetal compromise.
  • cord compression.
  • Uteroplacental insufficiency.
  • Uterine rupture.
• Postpartum hemorrhage

Power (Uterine Contraction)

Types of Abnormal Uterine Contraction

1. hypotonic uterine dysfunction

   • oxytocin

2. hypertonic/uncoordinated uterine dysfunction

   • tocolytic / position fluid

Poor Progress

First Stage of Labour

Defined as cervical dilatation of less than 2 cm in 4 hours. Usually associated with failure of descent and rotation of the fetal head. Divided into: Primary and secondary arrest

Poor Progress in the Second Stage of Labour

Diagnosed if delivery is not imminent after 2 hours in a nulliparous & 1 hour in a parous woman. With epidural use …3 hours in nulliparous (prolonged w/ epidural) …and 2 hours in parous women

Causes of Poor Progress in Labour

• A. Dysfunctional uterine activity
• B. Abnormal fetal size, presentation, and position.
• C. Abnormalities of the birth canal (the ‘passages’)

passage - passenger - power

Assessing Uterine Activity

1. By clinical examination
2. By using external uterine topography (CTG)
3. Intrauterine pressure catheters

Efficient Uterine ContractionsZ

• 3-4 cont. 10 min.
• Each lasting 45-60 sec.

Passenger (Fetal Causes)

• Abnormal fetal size…fetal macrosomia:
• Abnormal fetal presentation
• Abnormal Fetal position

Passage (Birth Canal)

• Abnormalities of the birth canal.
• The bony pelvis may cause delay in the progress of labour (android pelvis).
• Abnormalities of the uterus and cervix can also delay labour
  • fibroid in the lower uterine segment.
  • cervical dystocia (noncompliant cervix)
    • …….usually as a result of cone biopsy.

Cephalopelvic Disproportion (CPD)

Anatomical disproportion between the fetal head and maternal pelvis

Causes of CPD

• Large head. B
• Small pelvis. P
• Combination of the two. B&P
• Previous fracture. P
• Metabolic bone disease. P
• Fetal anomaly (hydrocephaly). B
• Malposition like OP. B

Diagnosis of Cephalopelvic Disproportion

1. Progress is slow or actually arrests despite efficient uterine contractions
2. The fetal head is not engaged
3. Vaginal examination shows severe moulding and caput formation
4. The head is poorly applied to the cervix
5. Haematuria