Malpresentation The presenting part of the fetus that is in or over pelvic brim&in relation to the cervix is any part other than the vertex.
Face presentation
Incidende &aetiology: Face presentation has an incidence of 1 in 500 labours.common causes are: 1-the head is normal &extended which continue even after labour for few days. 2-prematurity&multiple pregnancy.3-presence of multiple loops of the cord around the neck. 4-anencephaly 5-congenital tumours of the neck 6-musculoskeletal abnormalities
Diagnosis
Abdominal examination: With mentoposterior position the cephalic prominence is felt on the same side as the back from which is separated by deep sulcus&it may be difficult to hear fetalheart In mentoanterior position ,in addition ,the fetal heart is easily heard over the chest &the small parts may be felt on the same side.Vaginal examination As the face fits less well than the vertex ,the membranes may rupture early .When the face engaged ,supra-orbital ridges ,bridge of nose &the alveolar margins within mouth are recognized.
Mechanism of labour
The chin is the denominator,mentoanterior position is more common than mentoposterior. In mentoanterior position the head engages&descends with increasing extention,so that submentobrigmatic diameter of 9.5cm comes through the cervix.When the chin reachs the pelvic floor it undergoes internal rotation through one-eighth of acircle&submental region comes to lie under subpubic arch. The head is then born by flexion .Restitution occur&followed by external rotation.
In mentoposterior position the chin undergo internal rotation through three eights of the circle &delivered as mentoannterior position.
Persistant mentopostoerior position or mentotransverse position occur only in 10% of face presentation ,in these cases the baby can not be delivered vaginally unless is very small or macerated because the head is already fully extended so further extention to deliver the head is impossible.
Management of labour
The patient is kept in bed in the first stage &vaginal examination is made as soon as the membranes ruptures to exclude cord prolapse.If any delay occur in the second stage: 1-satisfactory uterine contraction with syntocinon drip 2-forceps application 3-with episiotomy By these methods delivery is completed in cases of mentoanterior position
With mentoposterior positiontime should be allowed for spontaneous rotation which usually occur in the second stage.If not occur manual rotatrion with epidural block or general anesthesia may be tried&its failure indicate c/s.
C/S indicated in face presentation if: failure of presenting part to descend cord prolapse in first stage fetal distress in first stage prolonged first stage persistant mentoposterior position
BROW PRESENTATION
Causes: Extention of the head before labour called primary &during labour called secondary. The causes in clude those of face presentation. Secondary cases occur in cotracted pelvis&some cases of o-p position
Apersistant brow presentation is rare in which the longest diameter of mentovertical diameter that is 13 cmacross the brim of normal pelvis,it can not engage&obstructed labour will result. However when the baby is very small&the pelvis is of wide proportions it may be driven down into pelvic cavity&born as brow presentation.
The head becomes very much moulded with compression of the mentovertical diameter&lengthening of the occipitofrontal diameter.
Diagnosis
Abdominal examination: The head is above pelvic brim&the cephalic prominence is at the same side as the back,this malpresentation should always be suspected when non engagement of the heads is notedespecially after the membranes ruptures in patient who had previous easy deliveries.Vaginal examination
The membranes may rupture early in labour with risk of cord prolapse,on pelvic examination the presenting part is high &the finger feels the forehead with orbital ridges&bridge of nose in front&anterior fontanelle behind.Management
In few cases brow presentationis discovered by ultrasound in the antenatal period.If there is no evidence of disproportion or any other abnormality nothing is done ,in most cases the head will flex &spontaneous delivery will occur.If the head is partially extended in early labour &there is no evidence of severe disproportion ashort trial of labour is permitted which may result in further extension of the head to face presentation&engagement with following normal delivery.
C/S is indicated: If there is evidence of disproportion Brow presentation above pelvic brim If the head fail to engage
Q-enumerate predisposing factors of face presentation Q-discuss management of labour in face presentation