Tuesday, January 8, 2008
Definition: It is arrest of vaginal delivery of the foetus due to mechanical obstruction. Aetiology: (I) Maternal causes: 1-Bony obstruction : e.g. - Contracted pelvis. - Tumours of pelvic bones. 2-Soft tissue obstruction: i) Uterus: - Impacted subserous pedunculated fibroid. - Constriction ring opposite the neck of the foetus. ii) Cervix: cervical dystocia. iii) Vagina: - Septa. - Stenosis. - Tumours. iv) Ovaries : Impacted ovarian tumours. (II) Foetal causes: 1- 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. 2- Large sized foetus ( macrosomia). 3- Congenital anomalies : e.g. - Hydrocephalus. - Foetal ascitis. - Foetal tumours. 4- Locked and conjoined twins. Diagnosis: It is the clinical picture of obstructed labour with impending rupture uterus (excessive uterine contraction and retraction). (A) History: of - prolonged labour, - frequent and strong uterine contractions, - rupture membranes. (B) General examination : shows signs of maternal distress as: - exhaustion, - high temperature (³ 38oC), - rapid pulse, - signs of dehydration : dry tongue and cracked lips. (C) Abdominal examination: 1- 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. 2- The foetus : - foetal parts cannot be felt easily. - FHS are absent or show foetal distress due to interference with the utero-placental blood flow. (D) Vaginal examination: 1- Vulva: is oedematous. 2- Vagina : is dry and hot. 3- Cervix: is fully or partially dilated, oedematous and hanging. 4- The membranes : are ruptured. 5- 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. 6- The cause of obstruction can be detected. (E) Differential diagnosis: 1- Constriction ring. 2- Full bladder. 3- Fundal myoma. Complications: (I) Maternal : 1- Maternal distress and ketoacidosis. 2- Rupture uterus. 3- Necrotic vesico -vaginal fistula. 4- Infections as chorioamnionitis and puerperal sepsis. 5- Postpartum haemorrhage due to injuries or uterine atony. (II) Foetal: 1- Asphyxia. 2- Intracranial haemorrhage from excessive moulding. 3- Birth injuries. 4- Infections. Management: (A) Preventive measures: Careful observation , proper assessment, early detection and management of the causes of obstruction. (B) 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.