OCCIPITOPOSTERIOR POSITION

OCCIPITOPOSTERIOR POSITION

DefinitionIn Cephalic presentation when the occiput is in relation to the posterior quadrants of the pelvis it is said to be an occipitoposterior.

TypesRight occipitoposteriorLeft occipitoposteriorDirect occipitoposterior

LOP

IncidenceAt onset of labour 10% of vertex presentations are occipitoposterior2/3rd of occipitoposterior presentations at delivery are result if malrotation of occipitoanterior position80% of occipitoposterior presentations rotate to occipitoanterior during labourAmong occipitoposterior positions incidence of ROPis 5 times LOP

CausesShape of pelvic inletAndroid Anthropoid

Fetal factors- deflexion of head due toHigh pelvic inclinationAttachment of placenta brachycephaly

Uterine causes abnormal uterine contraction

Diagnosis of ROPAbdominal ExaminationSubumbilical flatteningBack in one or other flanksLimbs felt easilyShoulder is felt out in flanksUnengaged head at termSinciput and occiput at same levelFetal heart sounds- flanks, indistinct

Vaginal examinationEarly in labourEarly rupture of membranesSagittal suture in right oblique diameter of pelvisSmaller posterior fontanelle- right posterior quadranttLarger ant. Fontanelle in left ant quadrant

Late in labourLarge caput may obscure the sutures. In such situations feel for pinna as it always points to occiput.Perineum gapes much before head distends it and premature straining can occurDifficulty in applying forceps in unrecognised occipitoposterior

Mechanism of labourIn 90 % cases head is in attitude of flexion.

Posterior rotation and face to pubis delivery-deflexed head

Incomplete anterior rotation and deep transverse arrest- head arrested with sagittal suture in traansvrse diameter at level of ischial spines.Usually in android pelvis

Failure of rotation- head remains as ROP or LOP- persistent occipitoposteriorOblique posterior arrestReasons for failure of rotationDeflexion of headInefficient uterine contractions Weak pelvic floor preventing anterior rotationPendulous abdomen and poor muscle toneCPD , android pelvisLarge baby >3.5 kgPremature rupture of membranes

Course of labour1st stage- delayEarly rupture of membranesEngaging diameter- occipitofrontal or suboccipitofrontal.Lack of uterine stimulaionEarly efforts of bearing down

2nd stage- delayed due to long interval of rotation/malrotation and sometimes arrest.3rd stage increased chance of PPH and genital trauma

Moulding in face to pubis delivery-tenctorial tears due to extreme elevation of falx cerebri

MECHANISM OF LABOURProlonged labour Well flexed/deflexedRelative disproportionOccipitofrontal(11.5)/suboccipitofrontal diameters(10.5)

FAILURE OF ROTATIONDeflexion of headInefficient uterine contractionsWeak pelvic floorPendulous abdomen and poor muscle toneCPDAndroid pelvis

MANAGEMENT

advantagesPromotes flexion- suboccipitobregmaticAutorotation of headLess traumaticLess space No need of general aneasthesia

KEILLAND FORCEPS

Keilland forceps