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MAL POSITIONS / MAL PRESENTATIONS • Occiptio-posterior position 1 in 5 deliveries • Face presentation 1 in 500 deliveries • Brow presentation 1 in 1000 deliveries • Breech presentation 1-2 in 50 deliveries • Shoulder presentation 1 in 200 deliveries • Unstable lie 1 in 350 deliveries Occipito – posterior position.. In a vertex presentation when the occiput is placed posteriorly over the sacrum / sacro – iliac joint, it is called an occipito – posterior position. R.O.P. – Occiput on right sacro - iliac joint. L.O.P. – Occiput on left sacro – iliac joint. Direct occipito – posterior – occiput points towards sacrum. LOP Occipito – posterior is an abnormal position of the vertex rather than an abnormal presentation. (In most of cases (90%) anterior rotation of occiput occurs.) But as the posterior position may give rise to Dystocia (abnormal labour & delivery), it is associated with mal presentation. Incidence – upto 13% of all vertex presentation. R.O.P. is 3 times more common than L.O.P. WHY ?? -Dextro-rotation of the uterus favours occipito-posterior than right occipito- anterior position -The right oblique diameter is slightly longer than the left one -The left oblique diameter is reduced by the presence of sigmoid colon Causes :- Not clear but factors abound – 1. CPD , Maternal kyphosis 2. Contracted pelvis:-50% or more occipito –posterior position is associated with either an anthropoid or android pelvis due to narrow fore-pelvis. 2. Fetus – deflection of fetal head favours posterior position of the vertex. Causes of deflection are – a. High pelvic inclination. b. Placenta praevia, pelvic tumors. 3. Uterus – abnormal uterine contraction. 4. Pendulous abdomen esp. in multipara. Diagnosis: – Inspection :- - Abdomen looks flat below the umbilicus. Palpation :- Fundal height :- corresponds with period of amenorrhoea. Fundal grip :- breech. Lateral grip :-Foetal back is felt on rt. Flank of mother in in ROP & in left flank in LOP. Fetal limbs are felt easily as knob like structure anteriorly. Pelvic grip :-Head is not engaged. -Cephalic prominance (sinciput) is not felt so prominent as found in well flexed occipito – anterior. -In direct occipito – posterior the small sinciput is confused with breech. -Auscultation :- FHS is best heard in flank in direct occipito – posterior / R.O.P. but difficult in L.O.P. Vaginal examination :- 1. Finding depends upon degree of flexion of head. 2. Conformed dx. Is made during 2nd stage of labour on rupture of membrane by:- a. Sagittal suture:- occupies any of the oblique diameter of pelvis. b. posterior fontanelle :-felt near the sacro-iliac joint. c. anterior fontanelle :- felt near the ilio-pectineal eminence. Mechanism of labour – 1. Head engages through the right oblique diameter in R.O.P. & Left oblique diameter in L.O.P. Because of deflection engagement is delayed. 2. In most of the cases (90%) – a. flexion – due to good uterine contraction there is flexion of head. b. internal rotation of the head – occiput rotates to 135 degrees anteriorly to lie behind the symphysis pubis, shoulder rotates to occupy right oblique diameter. 3. Further descent & delivery of the head occurs like occipito – anterior position. 4. Birth of shoulders & trunk – is the same as that of occipito anterior. Fate of OPP OPP Engaging diameter :- occipito-frontal 11.5cm or sub-occipitofrontal 10cm. Unfavorable (10%) Favorable (90%) 3/8th rotation Mild deflexion Moderate deflexion Severe deflexion occipit comes under Occiput rotate by Non-rotation Occiput rotate symphysis pubis (rt/lt 1/8th circle posteriorly by 1/8th occipito anterior) Oblique posterior POPP/ occipito- Deep Normal vaginal delivery arrest sacral position transverse arrest Face to pubis delivery Arrest Factors favouring long anterior rotation (1) Well flexed head. (2) Good uterine contractions. (3) Roomy pelvis. (4) Good pelvic floor. (5) No premature rupture of membranes. Causes of failure of long anterior rotation: (1) Deflexed head. (2) Uterine inertia. (3) Contracted pelvis: rotation of the head cannot easily occur in android pelvis due to projection of the ischial spines and convergence of the side walls. (4) Lax or rigid pelvic floor. (5) Premature rupture of membranes or its rupture early in labour. Management During 1st stage:- 1. Early diagnosis 2. Fetal, maternal condition and pelvic assessment should be done. 3. Prevent rupture of membrane by bed rest in lt. lateral position. 4. Partograph to be strictly maintain. 5. Early c/s in contracted pelvis. Second stage p/v exam:- To see level of presenting part, 2nd stage degree of flexion, position, caput, moulding, cx. Unfavorable (10%) Favorable (90%) Ant. 3/8th rotation Mild deflexion Moderate deflexion Severe deflexion occipit comes under Occiput ant. Non-rotation Occiput rotate symphysis pubis (rt/lt rotate by 1/8th posteriorly by 1/8th occipito anterior) circle Oblique Deep posterior POPP/ occipito- Normal vaginal delivery transverse arrest sacral position arrest Management of DTA DTA or oblique posterior arrest Assisted delivery Dead baby Pelvis adequate Inadequate pelvis -Manual rotation of occiput to C/S Craniotomy anterior position followed by forceps extraction - vacuum delivery - forceps rotation Manual rotation and extraction by forceps: Under general anaesthesia the following steps are done: 1-Disimpaction: the head is grasped bitemporally and pushed slightly upwards. 2-Flexion of the head. 3-Rotation of the occiput anteriorly by the right hand vaginally aided by, - Rotation of the anterior shoulder abdominally towards the middle line by the left hand or an assistant. 4-- Fix the head abdominally by an assistant, apply forceps and extract it POPP POPP Arrest Spontaneous face to pubis delivery Adequate pelvis Inadequate pelvis Dead baby C/S Head above the ischial Head below the spines Craniotomy spine / big baby Forceps with deep C/S (best) Manual rotation + episiotomy forceps Prognosis – Increased maternal morbidity due to pronlonged labour & increased incidence of operative delivery.
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